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. 2024 Jan 9;19(1):e0296244. doi: 10.1371/journal.pone.0296244

The Fit After Baby randomized controlled trial: An mHealth postpartum lifestyle intervention for women with elevated cardiometabolic risk

Jacinda M Nicklas 1,*, Laura Pyle 2,3, Andrey Soares 1, Jennifer A Leiferman 4, Sheana S Bull 4, Suhong Tong 3, Ann E Caldwell 5,6, Nanette Santoro 7, Linda A Barbour 5,6
Editor: Megan L Gow8
PMCID: PMC10775990  PMID: 38194421

Abstract

Background

Postpartum women with overweight/obesity and a history of adverse pregnancy outcomes are at elevated risk for cardiometabolic disease. Postpartum weight loss and lifestyle changes can decrease these risks, yet traditional face-to-face interventions often fail. We adapted the Diabetes Prevention Program into a theory-based mobile health (mHealth) program called Fit After Baby (FAB) and tested FAB in a randomized controlled trial.

Methods

The FAB program provided 12 weeks of daily evidence-based content, facilitated tracking of weight, diet, and activity, and included weekly coaching and gamification with points and rewards. We randomized women at 6 weeks postpartum 2:1 to FAB or to the publicly available Text4baby (T4B) app (active control). We measured weight and administered behavioral questionnaires at 6 weeks, and 6 and 12 months postpartum, and collected app user data.

Results

81 eligible women participated (77% White, 2% Asian, 15% Black, with 23% Hispanic), mean baseline BMI 32±5 kg/m2 and age 31±5 years. FAB participants logged into the app a median of 51/84 (IQR 25,71) days, wore activity trackers 66/84 (IQR 43,84) days, logged weight 17 times (IQR 11,24), and did coach check-ins 5.5/12 (IQR 4,9) weeks. The COVID-19 pandemic interrupted data collection for the primary 12-month endpoint, and impacted diet, physical activity, and body weight for many participants. At 12 months postpartum women in the FAB group lost 2.8 kg [95% CI -4.2,-1.4] from baseline compared to a loss of 1.8 kg [95% CI -3.8,+0.3] in the T4B group (p = 0.42 for the difference between groups). In 60 women who reached 12 months postpartum before the onset of the COVID-19 pandemic, women randomized to FAB lost 4.3 kg [95% CI -6.0,-2.6] compared to loss in the control group of 1.3 kg [95% CI -3.7,+1.1] (p = 0.0451 for the difference between groups).

Conclusions

There were no significant differences between groups for postpartum weight loss for the entire study population. Among those unaffected by the COVID pandemic, women randomized to the FAB program lost significantly more weight than those randomized to the T4B program. The mHealth FAB program demonstrated a substantial level of engagement. Given the scalability and potential public health impact of the FAB program, the efficacy for decreasing cardiometabolic risk by increasing postpartum weight loss should be tested in a larger trial.

Introduction

Adverse pregnancy outcomes (APOs) provide an early warning of future cardiometabolic risk [1, 2], often before traditional risk factors for diabetes and cardiovascular disease (CVD) are detected [1]. Preeclampsia, preterm delivery, delivery of a small-for-gestational age (SGA) neonate, gestational hypertension, and gestational diabetes mellitus (GDM) are independently associated with a 50–300% increased risk for CVD in later life [3, 4]. Women with pregnancies complicated by GDM have a ~50% increased risk for developing type 2 diabetes mellitus (T2DM) within 10 years, develop atherosclerosis earlier [5], and have increased risk for hypertension [6] and CVD, as compared to women with non-GDM pregnancies [1, 2]. A history of preeclampsia also increases a woman’s risk for T2DM [7, 8]. Nearly 30% of parous US women will have at least one of these predictive conditions during pregnancy [1]. Retention of weight gained during gestation is a major contributor to adult weight gain in women and contributes to their cardiometabolic risk. Even as little as 1 kg of postpartum weight retention is linked to further weight gain and the development of T2DM [9]. Excess body weight increases risk for CVD and T2DM in women at every age and in every ethnic group, by 40% for overweight and by as much as 300–400% for severe obesity [10].

Despite guidelines to achieve a healthy weight after delivery, engage in regular moderate to vigorous physical activity (MVPA), and eat a healthy diet [1114], studies of women with a history of APOs show that they do not engage in risk reduction behavior more than women without a history of pregnancy complications [15, 16]. In fact, one study of at-risk women found that more gained than lost weight after their affected pregnancy, suggesting an urgent need for support for lifestyle modification [17, 18]. Pregnancy weight retained beyond 6–12 months postpartum is usually retained long-term and is a powerful independent risk factor for future obesity [19]. Given the significance of postpartum weight retention, the postpartum year is a critical window of opportunity to make lifestyle changes to decrease future risk of obesity and cardiometabolic disease [1, 20, 21], as well as APOs in subsequent pregnancies. In one study an increase of 1–2 BMI units between pregnancies was associated with a 20–40% increased risk of GDM and gestational hypertension, while a loss of 12 lbs between pregnancies decreased the risk for GDM by 75% [22, 23].

Postpartum women describe multiple barriers to face-to-face participation in risk reduction interventions, including time constraints, infant and breastfeeding demands, older childcare responsibilities, and reluctance to spend time away from family [24, 25]. However, postpartum women are heavy users of smartphones and show interest in health related apps [26], across race and ethnicity [27], which poses an opportunity for a customized intervention. Employing mobile technology for health promotion using mobile health (mHealth) is an innovative approach for high-risk women with multiple family/work demands [28]. Using an mHealth lifestyle intervention for this population leverages the widespread adoption of mobile devices among women of reproductive age and offers the potential of a scalable and cost-effective program that could extend health promotion into home and daily life. Scalable programs have potential for a substantial public health impact, even if effect sizes are modest [29].

Although some mHealth programs have been tested for postpartum weight loss [30], few have been developed specifically for women with recent APOs [31, 32]. Women with recent APOs may benefit from an intervention specifically addressing their pregnancy complications and increased risk as part of a comprehensive lifestyle program. We previously developed an mHealth intervention called Fit After Baby (FAB) [33]. We adapted the content from the Diabetes Prevention Program [34] to target postpartum women at elevated cardiometabolic risk due to a history of APOs, including women with a history of GDM, preeclampsia, gestational hypertension, pre-term birth, or delivery of an SGA baby. The intervention integrates multiple behavior change techniques known to be effective for behavior change among postpartum women [35], is designed with concepts from user-centered design and mobile technology in health promotion, and includes a gamification component with modest incentives [3639]. FAB builds upon current evidence specific to the postpartum period, including: recommended weight loss after pregnancy [40], breastfeeding [41, 42], exercise [13], and the effects of diet and physical activity (PA) on breastfeeding [43]. We refined the FAB program through an iterative beta-testing process [33]. The primary objective of this study was to test the feasibility, acceptability, and preliminary efficacy of Fit After Baby in a randomized controlled trial.

Methods

Participants

We recruited women between 18 and 45 years of age with a postpartum BMI of 26 to 45 kg/m2 (≥24 for Asians based on their greater cardiometabolic susceptibility at a lower BMI [44]) who were between 4–12 weeks postpartum from a recent singleton delivery complicated by gestational hypertension (new hypertension diagnosed after 20 weeks without proteinuria), preeclampsia (high blood pressure and proteinuria diagnosed after 20 weeks gestation, or meeting other American College of Obstetrics and Gynecology diagnostic criteria consistent with preeclampsia), preterm delivery (32–36 6/7 weeks), delivery of an SGA neonate (weight <10th percentile for gestational age), and/or gestational diabetes (defined as a 3-hour 100-g oral glucose tolerance test result meeting Carpenter-Coustan criteria [45] or by medical record documented clinician diagnosis). Women were eligible regardless of the number of previous pregnancies. We identified participants by diagnosis codes, and pregnancy complications were confirmed via chart review by the study physician. Recruitment took place during prenatal or postpartum clinic visits, or after delivery at the University of Colorado Hospital on the University of Colorado Anschutz Medical Campus in Aurora, Colorado. Women were required to have access to an iPhone or iPod (Apple Inc, California) (iOS 5 or higher) because at the time of the study the FAB app was only available for iOS platforms. We excluded women with a history of preexisting diabetes, cancer, cardiovascular disease, or other major chronic illness, or a history of bariatric surgery, who delivered before 32 weeks of gestation, or who experienced net weight loss during pregnancy. We also excluded women taking medications known to affect body weight, women planning to participate in commercial weight loss programs or planning bariatric surgery, and women unable to read eighth grade-level English. The Colorado Multiple Institutional Review Board at the University of Colorado approved the study (17–0045) on April 26, 2017, and all participants gave written informed consent.

Study visits

We asked women to come for baseline visits at the Clinical and Translational Research Center (CTRC) at the University of Colorado at ~6 weeks postpartum. Six weeks postpartum was selected because this is the time of the typical maternal postpartum visit, including the oral glucose tolerance test for women with a recent pregnancy complicated by GDM. In addition, previous studies have shown that this is a reasonable time to begin a postpartum lifestyle intervention [24, 46, 47]. At the conclusion of the visit, we randomized women in a 2:1 ratio to the FAB mHealth Intervention group or to the Text4baby active control group using a permuted block scheme with randomly varying block sizes. Twice as many participants were randomized to the FAB program to maximize the amount of acceptability data collected from users of the program. A statistician not otherwise involved in the study prepared sealed sequentially numbered envelopes containing group assignment, and clinical research staff opened these at the end of the baseline study visit. Due to the nature of the study, neither participants nor all study staff were blinded to randomization group, but participants were blinded to the study hypotheses and whenever possible individuals who took outcome measurements were blinded to the randomization assignment of participants. The investigators including the study statistician remained blinded throughout the study. Following the baseline visit we asked participants to come to the CTRC for subsequent study visits at 6 and 12 months postpartum.

Measures

All measures were collected at baseline, 6 month, and 12 month study visits unless otherwise noted. At each visit trained staff measured body weight twice wearing light clothing, and weights were averaged (SECA 360) and height was measured by stadiometer (SECA). We used kg/m2 to determine BMI. Trained staff also measured waist circumference. Fasting blood samples were collected to measure secondary outcomes to measure changes in cardiometabolic risk factors, including glucose, insulin, hemoglobin A1C (HbA1c), lipid profiles, adiponectin, and hsCRP. At the 6 month and 12 month visits we measured urine human chorionic gonadotropin to ensure that participants were not pregnant and serum TSH to detect abnormal thyroid function using standard assays.

Self-reported questionnaires

Participants completed questionnaires for additional secondary outcomes including diet and physical activity changes using a validated food frequency questionnaire (2005 Block FFQ) [48], (administered via NutritionQuest), which provides an estimate of habitual intake and an adapted version of the validated Pregnancy Physical Activity Questionnaire (PPAQ), which provides a reasonably accurate measure of a broad range of physical activities [49]. Additional questionnaires included: sociodemographic, medical history, Edinburgh Postnatal Depression Scale [50] (EPDS), and breastfeeding status. Participants completed questionnaires using Research Electronic Data Capture (REDCap), a secure, HIPAA compliant web application for data collection.

Outcomes

The two primary outcomes were change in measured body weight at 12 months from 1) first postpartum measured weight and 2) self-reported prepregnancy weight. We recorded self-reported prepregnancy weight at enrollment, either during pregnancy or after delivery and before the randomization study visit. We reviewed medical records to ascertain gestational age at delivery, and mode of delivery. We used the pregnancy weight recorded in the anesthesia record within 2 days before delivery or the last recorded prenatal weight within 10 days of delivery to calculate gestational weight gain. We used measured height with self-reported prepregnancy weight to calculate prepregnancy BMI. For participants who did not attend a follow-up study visit in person, we extracted clinically measured weights from the medical record.

The Fit After Baby intervention program

Participants randomized to the FABi program were given a Fitbit and a body weight scale at the baseline study visit and shown how to use these, and then shown how to download the FAB mobile app. The FAB intervention consisted of a 12-week intensive phase with daily content centered around weekly themes, and tracking of diet, physical activity, and weight. Participants received daily notifications prompting them to open the app, and the app delivered interactive content requiring 3–10 minutes per day over the 12-week period, including quizzes, physical activity suggestions and yoga poses, recipes, inspirational quotes, and self-efficacy strategies. Participants were given a weight loss goal of returning to pre-pregnancy weight and losing additional weight up to 7% if still overweight/obese. Physical activity data from provided Fitbits were passively transmitted through wireless/Bluetooth connections, and participants had the option to manually enter physical activity into the app as well. Participants were asked in the app to gradually increase PA by 1000 steps/day each week, until they reached 10,000 steps/day, with an additional goal to increase PA by 10 minutes per day until they reached 45–60 minutes per day (the amount recommended for weight loss maintenance) [51]. Participants could earn points by opening app content, contacting the lifestyle coach, engaging in physical activity, tracking diet, setting goals, and entering weights. Points earned counted towards four levels of a “Health Warrior badge,” and participants reaching each level received a small gift card via email. Completing at least 75% of all app activities would allow participants to reach the highest level.

Lifestyle coaching

The lifestyle coach was a registered dietitian trained in motivational interviewing with previous lifestyle coaching experience during the initial FAB pilot study. Participants were also asked to communicate with the lifestyle coach via the app, or by text or phone at least weekly for the first 12 weeks, and monthly thereafter. When possible, the first lifestyle coach session was conducted over video chat to promote a personal connection. The coach viewed progress of participants weekly during the 12-week program using a dedicated FAB portal via a coaching app where she could track diet, physical activity, weight, and responses to questions. This allowed her to provide individualized coaching towards graded goals, including identifying barriers to meeting goals and strategies to overcome barriers. The study physician, trained in patient-centered counseling, periodically reviewed de-identified email and text interactions, as well as notes from phone calls, to ensure fidelity to the study. She and the coach met monthly to review this content.

Engagement and usage data

We collected data on use of the app, including the number of days the app was opened, which content was opened, steps and minutes of physical activity, days activity trackers were worn, number of coaching interactions, and Health Warrior points accumulated. Usage data were collected in BigQuery (Google).

Text4baby control group

Subjects randomized to the control group were shown how to download the free publicly available app Text4baby [52]. The Text4baby app delivers 2–4 free text messages per week from the Text4baby program, a nonprofit maternal child health program providing information including baby care and resources for women tailored to their number of weeks postpartum. Since Text4baby did not emphasize weight loss it served as an active control [53]. If women were already enrolled in Text4baby at the time of randomization they were asked to continue with the program through 12 months postpartum.

Sample size determination

Based on our previous study [54], our original sample size calculation was to have 54 participants in the intervention group and 27 subjects in the control group, such that an ANCOVA controlling for baseline weight using an intent-to-treat analysis would have at least 80% power to detect a 4.2 kg difference between groups in 12-month weight change.

Statistical analysis

We compared baseline characteristics with Pearson’s chi-square or Fisher’s exact tests for categorical variables and t tests for continuous variables. Participants were categorized based on treatment allocation in an intent-to-treat fashion for analyses. We compared differences between groups over time for weight, and BMIusing mixed-effects models, which allow for missing outcome data. Models included a random intercept and a compound symmetric covariance matrix and were adjusted for baseline values. Women who became pregnant were censored at the time of the event. We also estimated models that adjusted for gestational weight gain and breastfeeding. We examined changes in dietary intake over time using similar models, adjusted for kilocalorie intake at each timepoint when appropriate, and adjusted for baseline values. We used similar models to examine changes over time in physical activity and measures of cardiometabolic risk. We used a linear regression model to determine whether points earned in the program predicted weight loss. The COVID-19 pandemic interrupted data collection for the primary endpoint (weight at 12 months from baseline), and impacted diet, PA, and body weight for many participants. The University of Colorado Anschutz Medical Campus closed down clinical research visits for four months, and when operations resumed many women were unwilling to attend in-person study visits. As a sensitivity analysis, we conducted analyses excluding women who were still enrolled at the onset of the COVID pandemic in March 2020, given the well documented impact of the COVID-19 pandemic on lifestyle behaviors [55, 56]. We performed analyses using SAS version 9.4 and JMP Pro 14 (SAS Institute, Cary NC). App usage data were analyzed using BigQuery (Google) and Tableau (Mountain View, CA).

Results

Participants were recruited from September 4, 2017 through October 7, 2019, and the study was completed August 13, 2020. The consort diagram in Fig 1 includes study enrollment and participation details. Of 1208 women identified as potentially eligible, 995 were screened for the study, 325 met initial eligibility criteria, and 154 consented to participate. Of these, 82 (53%) attended a baseline visit and were randomized 2:1 to FAB (n = 54) or the T4B program (n = 28) at 6 weeks postpartum. After removing one participant who should not have been randomized because she did not meet criteria for participation, 81 women were included for the final intent-to-treat analysis. The final follow-up visit occurred August 13, 2020. Participants were 31 (SD ±5.4) years old on average and 77% White and 15% African-American, with 24% identifying as Hispanic. Overall 53% were college graduates, 50% were primiparous, and 34% were enrolled in the Women, Infants and Children (WIC) program for low income women. The most common pregnancy complication was gestational hypertension, and 34% of participants had two or more pregnancy complications. Overall there were no significant differences in baseline characteristics between the two groups, with the exception of breastfeeding, which was significantly higher in the Text4baby group (85% vs. 62%) (Table 1). No adverse events or unintended harms occurred throughout the study.

Fig 1. Screening, recruitment, and follow-up for the Fit After Baby trial.

Fig 1

Table 1. Baseline characteristics in the entire cohort and the cohort unaffected by the COVID-19 pandemic.

Characteristic All Participants Participants Unaffected by COVID
(N = 81) (N = 60)
Intervention Control Intervention Control
(n = 53) (n = 28) (n = 38) (n = 22)
(Fit After Baby) (Text4Baby) (Fit After Baby) (Text4Baby)
Age, mean (SD) 30.8 (5.5) 31.6 (5.2) 30.2 (5.5) 31.7 (5.5)
Race:
 White, N (%) 42 (79%) 20 (71%) 31 (82%) 17 (77%)
 Black, N (%) 8 (15%) 4 (14%) 5 (13%) 4 (18%)
 Asian, N (%) 3 (6%) 4 (14%) 2 (5%) 1 (4%)
Hispanic/Latina, N (%) 12 (23%) 7 (25%) 9 (24%) 7 (32%)
Education level attained:
 Some or all of high school, N (%) 8 (15%) 3 (11%) 6 (16%) 2 (9%)
 Some college, N (%) 17 (32%) 10 (36%) 13 (34%) 9 (41%)
 College graduate, N (%) 28 (53%) 15 (54%) 19 (50%) 11 (50%)
Annual household income:
 <$35,000, N (%) 11 (22%) 4 (17%) 7 (20%) 4 (21%)
 $35,000–<$75,000, N (%) 11 (22%) 5 (21%) 9 (26%) 4 (21%)
 ≥$75,000, N (%) 28 (56%) 15 (63%) 19 (54%) 11 (58%)
Enrolled in WIC, N (%) 18 (38%) 7 (27%) 14 (41%) 7 (33%)
Has a partner, N (%) 43 (81%) 23 (82%) 31 (82%) 17 (77%)
Primiparous, N (%) 26 (50%) 14 (50%) 20 (53%) 10 (45%)
Pre-pregnancy weight (kg), mean (SD) 81.7 (15.3) 83.6 (17.6) 81.5 (16.8) 84.9 (17.0)
Pre-pregnancy BMI (kg/m2), mean (SD) 30.3 (6.0) 30.8 (5.2) 30.2 (6.3) 31.3 (5.3)
Gestational weight gain (kg), mean (SD) 15.3 (8.4) 12.2 (7.3) 15.4 (8.9) 12.4 (7.2)
Pregnancy condition:
 Gestational diabetes, N (%) 8 (15%) 9 (32%) 4 (11%) 6 (27%)
 Preeclampsia, N (%) 22 (42%) 6 (21%) 14 (37%) 5 (23%)
 Gestational hypertension, N (%) 25 (47%) 11 (39%) 20 (53%) 9 (41%)
 Pre-term delivery (32–37 weeks), N (%) 11 (21%) 3 (11%) 9 (24%) 3 (14%)
 Small-for-gestational age (<10%ile), N (%) 13 (25%) 7 (25%) 9 (24%) 6 (27%)
More than one pregnancy condition, N (%) 21 (40%) 7 (25%) 14 (37%) 6 (27%)
Cesarean delivery, N (%) 21 (40%) 11 (39%) 14 (37%) 9 (41%)
Weeks postpartum at baseline visit, median (range) 7.7 (2.7) 8.0 (2.4) 7.6 (2.7) 8.1 (2.6)
Baseline weight (kg), mean (SD) 87.5 (14.6) 87.5(15.6) 87.0 (16.0) 89.4 (14.4)
Baseline BMI (kg/m2), mean (SD) 32.3 (5.2) 32.4 (4.6) 32.3 (5.4) 33.1 (4.5)
Breastfeeding at baseline visit, n (%) 33 (62%) 24 (86%) 26 (71%) 18 (82%)
Depressive symptoms (EPDS ≥9) 11 (22%) 3 (11%) 7 (19%) 2 (9%)

Primary outcome

Among all women randomized into the study, including those impacted by the COVID-19 pandemic, weight change at 12 months from baseline was -2.8 kg [95% CI -4.2, -1.4] compared to a loss of -1.8 kg [-3.8, 0.3] in the T4B group (p = 0.42 for the difference between groups). In 60 women who reached 12 months postpartum before the onset of the COVID-19 pandemic, women randomized to FAB lost 4.3 kg [-6.0, -2.6] compared to loss in the control group of 1.3 kg [-3.7, +1.1] (p = 0.0451 for difference between groups). (Table 2, Fig 2). Twenty-one participants had not reached the primary endpoint by the onset of the COVID pandemic. Of these the 15 randomized to FAB had a mean weight increase of 0.2 kg [-2.2, +2.6] compared to a mean weight loss of 3.2kg [-7.0, +0.7] in the T4B group. Adjustment for breastfeeding and gestational weight gain did not substantially change findings. A comparison of baseline characteristics and randomization assignments of participants with and without missing data showed no significant differences.

Table 2. Change in weight and BMI from baseline and from postpartum weight in the entire cohort and the cohort unaffected by the COVID-19 pandemic*.

All Participants Participants unaffected by COVID
Mean weight change (95%CI) Mean weight change (95%CI)
Variable Mean (SD) at Baseline Month 6 Month 12†† Mean (SD) at Baseline Month 6§ Month 12§§
Control Weight (kg) 87.5 (15.6) -0.5 (-2.5 to 1.4) (p = 0.60) -1.8 (-3.8 to 0.3) (p = 0.09) 89.4 (14.4) -0.4 (-2.6 to 1.9) (p = 0.75) -1.3 (-3.7 to 1.1) (p = 0.30)
Intervention Weight (kg) 87.5 (14.6) -1.6 (-3.1 to -0.1) (p = 0.0359) -2.8 (-4.2 to -1.4) (p = 0.0002) 87.0 (16.0) -2.3 (-4.0 to -0.6) (p = 0.0088) -4.3 (-6.0 to -2.6) (p < 0.0001)
Mean difference between groups (kg), (p value) -1.1 (-3.5 to 1.4) (p = 0.40) -1.0 (-3.5 to 1.5) (p = 0.42) -2.0 (-4.7 to 0.8) (p = 0.17) -3.0 (-5.9 to -0.1) (p = 0.0451)
BMI Change BMI Change
Mean (SD) at Baseline Month 6 Month 12†† Mean (SD) at Baseline Month 6§ Month 12§§
Control BMI (kg/m2) 32.4 (4.6) - 0.1 (-0.8 to 0.6) (p = 0.76) -0.5 (-1.3 to 0.3) (p = 0.20) 33.1 (4.5) -0.0 (-0.9 to 0.8) (p = 0.93) -0.5 (-1.4 to 0.4) (p = 0.28)
Intervention BMI (kg/m2) 32.3 (5.2) -0.5 (-1.1 to 0.0) (p = 0.0589) -1.3 (-1.8 to -0.7) (p < 0.0001) 32.3 (5.4) -0.8 (-1.5 to -0.2) (p = 0.0148) -1.6 (-2.3 to -0.9) (p < 0.0001)
Mean difference between groups (kg/m2) -0.4 (-1.3 to 0.5) (p = 0.37) -0.8 (-1.7 to 0.2) (p = 0.13) -0.8 (-1.8 to 0.3) (p = 0.16) -1.1 (-2.2 to 0) (p = 0.0535)
Weight change from pre-pregnancy weight, mean (95%CI) Weight change from pre-pregnancy weight, mean (95%CI)
Month 6 Month 12†† Month 6§ Month 12§§
Control (kg) 2.9 (0.2 to 5.6) (p = 0.0342) 1.5 (-1.3 to 4.3) (p = 0.30) 3.7 (0.6 to 6.9) (p = 0.0211) 2.7 (-0.7 to 6.0) (p = 0.12)
Intervention (kg) 3.8 (1.8 to 5.8) (p = 0.0002) 2.5 (0.6 to 4.5) (p = 0.0115) 2.4 (0.0 to 4.8) (p = 0.0485) 0.57 (-1.8 to 3.0) (p = 0.64)
Mean difference between groups 0.9 (-2.4 to 4.3) (p = 0.58) 1.1 (-2.3 to 4.4) (p = 0.54) -1.3 (-5.2 to 2.6) (p = 0.51) -2.1 (-6.2 to 2.0) (p = 0.31)

*Models adjusted for baseline weight/BMI.

There were data from 61 participants at the 6-month time point, but for the purposes of analysis, the model predicted data for all 81 women

††There were data from 51 participants at the 12-month time point, but for the purposes of analysis, the model predicted data for all 81 women

§There were data from 48 participants at the 6-month time point, but for the purposes of analysis, the model predicted data for all 60 women unaffected by COVID

§§There were data from 45 participants at the 12-month time point, but for the purposes of analysis, the model predicted data for all 60 women unaffected by COVID

Fig 2. Postpartum weight loss in the Fit After Baby trial.

Fig 2

*Significantly different when compared to T4B no COVID.

Changes in diet, physical activity, and measures of cardiometabolic risk

Table 3 shows the baseline values for secondary outcomes of diet, physical activity and measures of cardiometabolic risk among the 60 participants unaffected by the COVID pandemic. Total energy intake, glycemic load, and percentage from saturated fat were different between groups at baseline. Table 4 demonstrates changes in diet among the 60 participants unaffected by the COVID pandemic. There were no significant differences in diet change between groups. Within the FAB intervention group, significant decreases were observed in overall kilocalorie intake, % kilocalories from carbohydrates, glycemic load, and % of kilocalories from sweets at 6 and 12 months, as well as a significant increase in vegetable servings at 6 months. A decrease in the percent of calories from sweets and increase in vegetable servings were also significant in the control group at 12 months (Table 4). Both groups significantly decreased their sedentary activity during the study period but there was no difference between groups. Both groups decreased their moderate and light physical activity as well (Table 5).

Table 3. Baseline data for diet, physical activity, and cardiometabolic risk factors among 60 participants unaffected by the COVID pandemic.

Characteristic Intervention Control P-Value
Fit After Baby (n = 38) Text4Baby (n = 22)
Dietary Intake
 Kcal, median(IQR) 1824.0 (1463.5,2134.8) 2255.9 (1700.2,2651.2) 0.0109
 Percent of Kcal from Carbohydrates, mean(SD) 44.9 (8.4) 44.0 (5.9) 0.6701
 Glycemic Load, median(IQR) 89.6 (73.9, 116.4) 112.3 (89.3, 137.5) 0.0242
 Saturated Fat (g), median(IQR) 25.4 (23.1, 30.7) 30.1 (26.1, 38.3) 0.0122
 Dietary Fiber (g), median(IQR) 17.2 (15.6, 22.2) 20.3 (16.5, 25.2) 0.0801
 Percent of Kcal from Sweets, mean(SD) 15.2 (9.4) 14.6 (8.1) 0.8070
 Vegetable Servings, mean(SD) 2.8 (1.5) 2.6 (1.9) 0.6712
 Fruit Servings, mean(SD) 1.4 (1.0) 1.2 (0.8) 0.5899
 Whole Grain Servings, median(IQR) 0.3 (0.1, 0.8) 0.6 (0.5, 0.9) 0.3713
Physical Activity
 Sedentary Hours per Week, mean(SD) 47.3 (17.9) 46.7 (24.1) 0.9214
 Moderate Activity Hours per Week, mean(SD) 50.6 (28.5) 47.9 (23.3) 0.7085
 Light Activity Hours per Week, mean(SD) 57.9 (20.8) 57.0 (19.4) 0.8773
Lab Assessment
 Fasting Glucose, mean(SD) 84.8 (7.9) 87.1 (9.5) 0.3583
 Fasting Triglycerides, median(IQR) 87.0 (58.0, 148.0) 83.0 (69.0, 108.0) 0.2849
 Low Density Lipoprotein (LDL), mean(SD) 114.5 (30.2) 114.8 (27.7) 0.9766
 High Density Lipoprotein (HDL), mean(SD) 51.9 (11.4) 49.9 (10.0) 0.4876
 C Reactive Protein (CRP), median(IQR) 2.5 (1.5, 5.8) 4.5 (2.6, 6.5) 0.1749
 Adiponectin, mean(SD) 9.2 (4.6) 8.8 (4.1) 0.7555
 Waist Circumference, mean(SD) 107.4 (13.6) 108.1 (9.5) 0.8297
 Systolic BP, mean(SD) 115.0 (8.5) 114.1 (10.9) 0.7335
 Diastolic BP, mean(SD) 74.6 (7.9) 71.4 (10.0) 0.1794
 HOMA-IR, mean(SD) 3.5 (0.3) 3.6 (0.4) 0.1552
 Hemoglobin A1c, mean(SD) 5.2 (0.3) 5.3 (0.2) 0.2952

Table 4. Changes in diet over time among participants unaffected by the COVID-19 pandemic#.

Group Assignment Variable
Kilocalories (Kcal)
Month 6§ Month 12§§
Control (Text4Baby) -175.3 (-722.2 to 371.5) (p = 0.52) -262.3 (-809.2 to 284.5) (p = 0.34)
Intervention (Fit After Baby) -718.2 (-1107.5 to -328.9) (p = 0.0004) -784.1 (-1186.7 to -381.5) (p = 0.0002)
Mean difference between groups -542.9 (-1203.3 to 117.5) (p = 0.11) -521.8 (-1189.8 to 146.2) (p = 0.13)
% of Kcal from Carbohydrates
Month 6§ Month 12§§
Control (Text4Baby) -2.8 (-6.5 to 0.8) (p = 0.13) -3.3 (-7.0 to 0.4) (p = 0.08)
Intervention (Fit After Baby) -2.9 (-5.4 to -0.3) (p = 0.0310) -6.5 (-9.2 to -3.8) (p < 0.0001)
Mean difference between groups 0.0 (-4.4 to 4.4) (p = 0.99) -3.2 (-7.7 to 1.3) (p = 0.16)
Glycemic Load (% Change)
Month 6§ Month 12§§
Control (Text4Baby) -19.9 (-38.3 to 4.0) (p = 0.09) -24.1 (-41.6 to -1.5) (p = 0.0384)
Intervention (Fit After Baby) -35.9 (-46.7 to -23.0) (p = < .0001) -44.2 (-54.0 to -32.5) (p = < .0001)
Mean difference between groups -20.0 (-41.6 to 9.5) (p = 0.17) -26.5 (-46.5 to 1.0) (p = 0.06)
Saturated Fat* (% Change)
Month 6§ Month 12§§
Control (Text4Baby) -0.24 (-9.2 to 9.6) (p = 0.96) 3.5 (-5.8 to 13.8) (p = 0.47)
Intervention (Fit After Baby) -5.0 (-11.5 to 2.0) (p = 0.16) 5.6 (-2.0 to 13.8) (p = 0.15)
Mean difference between groups -4.8 (-15.0 to 6.6) (p = 0.40) 2.0 (-9.0 to 14.4) (p = 0.73)
Fiber* (% Change)
Month 6§ Month 12§§
Control (Text4Baby) -3.6 (-15.5 to 10.0) (p = 0.58) -8.4 (-19.8 to 4.5) (p = 0.19)
Intervention (Fit After Baby) -1.9 (-11.1 to 8.4) (p = 0.71) -9.0 (-17.9 to 1.0) (p = 0.08)
Mean difference between groups 1.8 (-13.2 to 19.4) (p = 0.83) -0.6 (-15.4 to 16.8) (p = 0.94)
% of Kcal from Sweets
Month 6§ Month 12§§
Control (Text4Baby) -2.3 (-6.0 to 1.3) (p = 0.21) -6.0 (-9.6 to -2.4) (p = 0.0015)
Intervention (Fit After Baby) -5.1 (-7.7 to -2.5) (p = 0.0002) -6.7 (-9.4 to -4.1) (p < .0001)
Mean difference between groups -2.7 (-7.1 to 1.6) (p = 0.22) -0.74 (-5.2 to 3.7) (p = 0.74)
Vegetable Servings (per day)
Month 6§ Month 12§§
Control (Text4Baby) 1.0 (0.1 to 1.8) (p = 0.0253) 0.52 (-0.3 to 1.4) (p = 0.22)
Intervention (Fit After Baby) 0.63 (0.0 to 1.2) (p = 0.0381) 0.23 (-0.4 to 0.9) (p = 0.47)
Mean difference between groups -0.33 (-1.4 to 0.7) (p = 0.52) -0.3 (-1.3 to 0.7) (p = 0.57)
Fruit Servings (per day)
Month 6§ Month 12§§
Control (Text4Baby) 0.2 (-0.2 to 0.6) (p = 0.37) 0.2 (-0.3 to 0.6) (0.46)
Intervention (Fit After Baby) 0.0 (-0.3 to 0.3) (p = 0.94) -0.3 (-0.6 to 0.0) (p = 0.09)
Mean difference between groups -0.2 (-0.7 to 0.3) (p = 0.44) -0.4 (-0.9 to 0.1) (p = 0.11)
Whole Grains* (% change)
Month 6§ Month 12§§
Control (Text4Baby) -7.4 (-54.3 to 87.5) (p = 0.83) 52.7 (-24.7 to 209.9) (p = 0.24)
Intervention (Fit After Baby) -20.0 (-52.5 to 34.7) (p = 0.40) -18.7 (-52.8 to 40.1) (p = 0.45)
Mean difference between groups -13.6 (-63.3 to 103.4) (p = 0.74) -46.7 (-77.6 to 26.6) (p = 0.16)

#All models adjusted for baseline values

*Adjusted for total kilocalorie intake. All log transformed dependent variables have been back transformed with formular of (exp(β)– 1)*100.

There were data from 45 participants at the 6-month time point, but for the purposes of analysis, the model predicted data for all 81 women

††There were data from 40 participants at the 12-month time point, but for the purposes of analysis, the model predicted data for all 81 women

§There were data from 34 participants at the 6-month time point, but for the purposes of analysis, the model predicted data for all 60 women unaffected by COVID

§§There were data from 36 participants at the 12-month time point, but for the purposes of analysis, the model predicted data for all 60 women unaffected by COVID

Table 5. Changes in measures of physical activity among participants unaffected by the COVID-19 pandemic*#.

Sedentary Hours Per Week Month 6§ Month 12§§
Control (Text4Baby) -19.0 (-30.5 to -7.5) (p = 0.001) -16.5 (-28.0 to -5.0) (p = 0.005)
Intervention (Fit After Baby) -19.4 (-28.2 to -10.7) (p < 0.0001) -19.6 (-28.3 to -10.8) (p < 0.0001)
Mean difference between groups -0.04 (p = 0.96) -3.1 (p = 0.67)
Moderate Activity Hours Per Week Month 6§ Month 12§§
Control (Text4Baby) -18.3 (-32.7 to -4.0) (p = 0.01) -12.8 (-27.1 to 1.5) (p = 0.08)
Intervention (Fit After Baby) -16.6 (-27.5 to -5.7) (p = 0.003) -18.8 (-29.7 to -5.7) (p = 0.001)
Mean difference between groups 1.70 (p = 0.85) -6.0 (p = 0.51)
Light Activity Hours Per Week Month 6§ Month 12§§
Control (Text4Baby) -19.0 (-31.4 to -6.5) (p = 0.003) -22.3 (-34.8 to -9.8) (p = 0.0006)
Intervention (Fit After Baby) -22.5 (-32.0 to 13.0) (p < 0.0001) -26.6 (-36.0 to -17.1) (p < 0.0001)
Mean difference between groups -3.57 (p = 0.65) -4.25 (p = 0.59)

#All models adjusted for baseline values

*Not enough data for vigorous activity for participants unaffected by COVID

There were data from 45 participants at the 6-month time point, but for the purposes of analysis, the model predicted data for all 81 women

††There were data from 40 participants at the 12-month time point, but for the purposes of analysis, the model predicted data for all 81 women

§There were data from 34 participants at the 6-month time point, but for the purposes of analysis, the model predicted data for all 60 women unaffected by COVID

§§There were data from 36 participants at the 12-month time point, but for the purposes of analysis, the model predicted data for all 60 women unaffected by COVID

Changes in cardiometabolic risk measures

Table 6 shows the changes in cardiometabolic risk indices. These were not different between groups. However, within the intervention group, among those not impacted by COVID, there was a significant decrease in LDL at 6 and 12 months from baseline, a significant increase in adiponectin at 6 and 12 months from baseline, and a significant decrease in HDL at 6 months from baseline. Within the control group there was a significant decrease in LDL at 6 months from baseline. There was no significant difference in change in waist circumference between groups, however within the intervention group there was a significant decrease in waist circumference from baseline by 5.3 and 7.1 cm, at 6 and 12 months respectively, and a significant decrease of 4.0 cm at 12 months in the control group (Table 6).

Table 6. Changes in measures of cardiometabolic risk among participants unaffected by the COVID-19 pandemic#.

Group Variable
Fasting Glucose* (% change)
Month 6§ Month 12§§
Control (Text4Baby) 2.0 (-2.5 to 6.7) (p = 0.39) 6.2 (1.4 to 11.2) (p = 0.0112)
Intervention (Fit After Baby) -0.2 (-3.1 to 2.9) (p = 0.91) 2.6 (-0.5 to 5.9) (p = 0.10)
Mean difference between groups -2.1 (-7.2 to 3.3) (p = 0.44) -3.4 (-8.5 to 2.0) (p = 0.22)
Fasting Triglycerides* (% change)
Month 6§ Month 12§§
Control (Text4Baby) -11.2 (-26.2 to 6.9) (p = 0.21) -0.1 (-17.0 to 20.3) (p = 0.99)
Intervention (Fit After Baby) -9.8 (-20.9 to 3.0) (p = 0.13) -10.0 (-21.4 to 3.0) (p = 0.12)
Mean difference between groups 1.6 (-18.8 to 27.0) (p = 0.89) -10.0 (-28.1 to 12.8) (p = 0.37)
Low Density Lipoprotein (LDL) mg/dL
Month 6§ Month 12§§
Control (Text4Baby) -16.4 (-26.0 to -6.7) (p = 0.0011) -8.8 (-18.4 to 0.8) (p = 0.07)
Intervention (Fit After Baby) -15.6 (-22.4 to -8.8) (p < .0001) -14.7 (-21.6 to -7.7) (p = 0.0001)
Mean difference between groups 0.82 (-10.8 to 12.4) (p = 0.89) -5.9 (-17.6 to 5.8) (p = 0.33)
High-density Lipoprotein (HDL) (mg/dL)
Month 6§ Month 12§§
Control (Text4Baby) -2.3 (-6.2 to 1.7) (p = 0.25) -3.3 (-7.3 to 0.6) (p = 0.09)
Intervention (Fit After Baby) -4.1 (-6.9 to -1.3) (p = 0.0043) -2.6 (-5.4 to 0.3) (p = 0.08)
Mean difference between groups -1.9 (-6.6 to 2.9) (p = 0.45) 0.8 (-4.0 to 5.6) (p = 0.74)
C-Reactive Protein* (% change)
Month 6§ Month 12§§
Control (Text4Baby) 8.0 (-32.9 to 73.7) (p = 0.75) -16.6 (-48.2 to 34.1) (p = 0.45)
Intervention (Fit After Baby) 33.1 (-5.1 to 86.9) (p = 0.10) -23.1 (-45.5 to 8.3) (p = 0.13)
Mean difference between groups 23.3 (-30.5 to 118.6) (p = 0.48) -7.8 (-48.3 to 64.2) (p = 0.78)
Adiponectin (ug/mL)
Month 6§ Month 12§§
Control (Text4Baby) 0.3 (-1.8 to 2.4) (p = 0.78) 0.5 (-1.6 to 2.6) (p = 0.62)
Intervention (Fit After Baby) 1.9 (0.4 to 3.4) (p = 0.0119) 2.5 (1.0 to 4.0) (p = 0.0012)
Mean difference between groups 1.6 (-0.9 to 4.1) (p = 0.21) 2.0 (-0.5 to 4.5) (p = 0.12)
Waist Circumference (cm)
Month 6§ Month 12§§
Control (Text4Baby) -3.0 (-6.4 to 0.3) (p = 0.08) -4.0 (-7.3 to -0.7) (p = 0.0168)
Intervention (Fit After Baby) -5.3 (-7.7 to -2.9) (p < .0001) -7.1 (-9.5 to -4.7) (p < .0001)
Mean difference between groups -2.3 (-6.3 to 1.8) (p = 0.27) -3.1 (-7.1 to 0.9) (p = 0.13)
Systolic Blood Pressure (mmHg)
Month 6§ Month 12§§
Control (Text4Baby) 2.0 (-2.7 to 6.7) (p = 0.41) -1.9 (-7.0 to 3.1) (p = 0.45)
Intervention (Fit After Baby) 0.5 (-3.0 to 4.0) (p = 0.78) -1.8 (-5.3 to 1.7) (p = 0.32)
Mean difference between groups -1.5 (-7.2 to 4.3) (p = 0.62) 0.2 (-5.9 to 6.3) (p = 0.95)
Diastolic Blood Pressure (mmHg)
Month 6§ Month 12§§
Control (Text4Baby) 0.5 (-3.7 to 4.8) (p = 0.81) 0.9 (-3.7 to 5.5) (p = 0.70)
Intervention (Fit After Baby) -0.3 (-3.5 to 2.9) (p = 0.86) -1.7 (-4.9 to 1.4) (p = 0.28)
Mean difference between groups -0.8 (-6.0 to 4.4) (p = 0.77) -2.6 (-8.1 to 2.9) (p = 0.35)
HOMA-IR
Month 6§ Month 12§§
Control (Text4Baby) 0.1 (-0.1 to 0.2) (p = 0.41) 0.2 (0.0 to 0.3) (p = 0.07)
Intervention (Fit After Baby) 0.0 (-0.2 to 0.1) (p = 0.54) 0.1 (0.0 to 0.2) (p = 0.23)
Mean difference between groups -0.1 (-0.3 to 0.1) (p = 0.31) -0.1 (-0.3 to 0.1) (p = 0.38)

#All models adjusted for baseline values

*All log transformed dependent variables have been back transformed with formula of (exp(β)– 1)*100 to arrive at percentage change

There were data from 45 participants at the 6-month time point, but for the purposes of analysis, the model predicted data for all 81 women

††There were data from 40 participants at the 12-month time point, but for the purposes of analysis, the model predicted data for all 81 women

§There were data from 34 participants at the 6-month time point, but for the purposes of analysis, the model predicted data for all 60 women unaffected by COVID

§§There were data from 36 participants at the 12-month time point, but for the purposes of analysis, the model predicted data for all 60 women unaffected by COVID

Acceptability and user engagement

Participants logged into the app a median of 61% of all days over the first 12 weeks (51/84, IQR 25,71), wore activity trackers a median of 79% of days (66/84, IQR 43,84), entered their weight a median of 17 times (IQR 11,24), and completed weekly coach check-ins 5.5/12 (IQR 4,9) weeks. The majority of participants (45/53, 85%) reached the Bronze level of the Health Warrior badge, signifying 18.5% of all app related tasks completed. 41/53 (77%) reached Silver, 36/53 (68%) reached Gold, and 34/63 (64%) reached Platinum, signifying 37.5%, 56% and 75% of all app-related tasks completed, respectively. Accumulating total points in the app was significantly associated with greater weight loss at 6 months (p < .05). A greater number of interactions with the coach, more days wearing an activity tracker, and greater accumulation of reward points all predicted weight loss at 12 months (all p<0.05).

Discussion

In this study we did not find a significant difference between the FAB and Text4baby groups in postpartum weight loss. The latter part of this study was conducted during the early days of the COVID-19 pandemic, which likely impacted the results. In our sensitivity analysis looking at participants unaffected by the COVID pandemic, those randomized to the Fit After Baby program lost significantly more weight than those randomized to the Text4baby program (active control). We demonstrated promising engagement with the intervention and notably the level of engagement with coaching and gamification within the app predicted weight loss. Given the many constraints on face-to-face participation, employing an mHealth strategy is an innovative approach to reach this high-risk population.

Twenty-five percent of our participants were still enrolled in the study at the onset of the COVID-19 pandemic, which impacted our results. Other studies have been impacted by the effect of the pandemic on diet, exercise, and weight loss [55, 56], which, particularly early in the pandemic, likely overwhelmed the impact of a lower intensity intervention. The lack of significant difference between groups may be due to the higher than typical weight loss in the control group, particularly after the start of the COVID pandemic. Since the active part of the FAB program was the first 12 weeks, the COVID pandemic began when FAB participants were no longer in the active phase of the intervention. Women in the Text4baby group, however, were still receiving 3–4 texts per week, which may have helped with a sense of connection and may have promoted behaviors such as continuation of breastfeeding leading to increased weight loss in the Text4baby group. In addition, women in the control group were significantly more likely to be breastfeeding at baseline, which may have influenced their weight loss. We show a significant difference in weight loss of 3.0 kg in the intervention group compared to the control group among women completing the study before the onset of the COVID-19 pandemic. The difference in weight loss achieved prior to the pandemic with this intervention is promising given the influence of the postpartum period for determining future obesity and cardiometabolic disease. Postpartum women may need ongoing and more intensive interactions with a lifestyle program to continue/maintain lifestyle behaviors. Future versions of the intervention would benefit from a longer intervention period and a more active maintenance phase.

The difference in weight loss between groups in our study, about 3 kg, is similar to the majority of studies aiming to increase postpartum weight loss. Although there is a lot of variability in postpartum weight loss, studies show that 15–27% of women have major postpartum weight retention at one year of at least 4.55 kg [28]. Nearly all women (97%) who have obesity before pregnancy will continue to be classified as such at one year [57], with 40% increasing by two or more BMI units [58]. Among women with overweight, 40–50% will move into the obesity category by 12 months postpartum [59]. A recent systematic review of 9 lifestyle intervention studies among postpartum women showing a mean weight loss of 1.7 kg [35] and meta-analysis of 46 articles showed a mean weight difference of 2.5 kg [60]. The Mothers after Gestational Diabetes in Australia (MAGDA) study enrolled 573 Australian women with previous GDM into a trial of 5 in-person and 2 telephone sessions. There was a small significant difference in body weight between groups at 12 months of 1 kg [61], and the Active Mothers Postpartum study of 450 overweight/obese postpartum women showed no significant difference in weight loss between groups at 12 months [62]. The Gestational Diabetes’ Effects on Moms (GEMS) pragmatic trial in 2,280 women with GDM utilized mailings during pregnancy and delivered a Diabetes Prevention Program [34] (DPP)-derived intervention postpartum by 13 phone counseling sessions. They found a modest improvement in reaching weight goals, with a significant difference between groups at 6 months of -0.64 kg (95% CI -1.13,-0.14) but not at 12 months [63].

Two studies addressing postpartum weight retention with mobile apps also showed small effect sizes. In one study among women receiving WIC, women randomized to a personalized health intervention delivered via the “E-Moms” app did not show more weight loss, but women with high adherence to the intervention did have a significant change in weight and percent body fat [64]. In one recent study of 200 postpartum women with a GDM history in Singapore in the Smartphone App to Restore Optimal Weight (SPAROW), those randomized to a mobile app lost 1 kg more than those randomized to control, which did not reach significance (p = .08) [32].

We demonstrated promising engagement in our study, as compared to other similar programs in postpartum women. Women in our study interacted with the app more than half of the days during the 12 week intervention and wore activity trackers more than 75% of the time. More than half of participants in the FAB program reached the highest level of points corresponding to at least 75% of all app-related tasks completed and content read. Previous studies in this population have shown varying levels of engagement. In the MAGDA study, only 10% of participants completed all sessions, and 34% attended no sessions at all. Among the 1,087 women randomized to the GEMS intervention, only 50% completed one or more telephone sessions, with just 15% completing all 13 sessions [63]. In the Fit Moms study for low-income women, participants spent about 3 hours of total time on the intervention website during the year-long intervention [65]. Although the SPAROW trial did not show significant differences in weight loss, Singaporean participants used at least one component of the mobile app for 66% of the days of the first four months, and made significant dietary changes, suggesting that mobile apps may promote better engagement than other methods for postpartum women [32]. Engagement is a key factor for intervention efficacy [66], and has been associated with increased weight loss and improvement in healthy behaviors [67, 68].

We were not powered for our secondary outcomes, but we did see some promising changes within the intervention group with respect to diet and markers of cardiometabolic risk. Decreasing saturated fat intake was one of the primary diet changes emphasized during the week of content focusing on fat. There were many other significant dietary changes within the intervention group as well, including kilocalorie intake, glycemic load, and the percent of calories from carbohydrate and added sugars. Although we did not see changes in lab values overall between groups, there were significant within group differences for LDL and adiponectin in the expected direction in the intervention group. Pregnancy is known to be associated with a more atherogenic lipid profile, and this tends to improve in the postpartum period [42, 69] in all women and to a greater degree in lactating women [70].

We did not see significant differences between randomized groups in changes in physical activity. Postpartum women rarely meet the American College of Obstetricians and Gynecologists recommendations for 150 minutes of moderate intensity physical activity per week [13], and this is even lower among women with a history of APOs [1517]. Other studies of lifestyle interventions in postpartum women have not shown a significant difference between groups in physical activity [54, 7173]. In addition, as has been seen in other studies, the PPAQ may overestimate the amount of physical activity in the early postpartum period, given the higher level of physical activity attributed to household activities with babies, including carrying babies around the house and pushing babies in strollers [74]. This may be why the physical activity estimates are highest in the early postpartum months in our study.

Strengths of our study include the randomized controlled design and promising engagement with the intervention when compared to similar interventions in this population. There are several limitations to our study. The COVID-19 pandemic affected retention as well as outcomes, and therefore the observed effect size was smaller than the effect size for which the study was powered for the primary weight outcome at 12 months postpartum. As a single-center trial, results may not be generalizable to other regions. We had a large proportion of eligible women decline to participate and a large number of consented women who did not come to a baseline visit. This is often seen in postpartum studies, as postpartum women face a lot of barriers to attending in-person study visits, and this may limit generalizability in that women who do participate may be more motivated than those who do not. In addition, because the intervention was only available for participants with an iOS operating system at the time of the study, our population may have been biased towards those of higher socioeconomic status. We collected pre-pregnancy weight by self-report, which could result in recall bias; however, other studies have demonstrated a strong correlation between self-reported and clinically measured pre-pregnancy weight [75]. In addition, these self-reported data were obtained before randomization and therefore the effect of the bias on the primary outcome should be minimized. We collected physical activity and dietary data by self-report, which are not as accurate as objective measures of physical activity and diet. We had some missing data, but since the participants with and without missing data did not differ for major characteristics, this was unlikely to cause significant bias. In addition, we adjusted for baseline values in our models.

In summary, although the Fit After Baby mHealth intervention did not show a significant overall difference in postpartum weight loss as compared to the Text4baby program, those randomized to the Fit After Baby mHealth intervention who were unaffected by the COVID pandemic had significantly more weight loss than those randomized to the Text4baby program. We demonstrated substantial engagement with the intervention. An improved version of the app, with increased intensity, more interactive coaching, and a longer maintenance period, may be more effective. We will also consider whether using updated technology like smart watches and building upon gamification may be more effective for weight loss.

Supporting information

S1 Checklist. CONSORT 2010 checklist of information to include when reporting a randomised trial*.

(DOC)

S1 File

(DOCX)

Acknowledgments

We would like to thank the Fit After Baby participants. We would like to acknowledge the support from research assistants Danielle Cook, Chelsea Arent, Emily Dunn, and Jamie Siegart. We are very grateful for extensive contributions and support from Dean Hovey, Susan Gilbert, Sue Arment, and Glenn Bachmann.

Data Availability

Because patient-level (e.g. “row-level” or “line-level”) data is more readily re-identifiable than summary data, CU Anschutz has a risk management policy of provisioning these data only via secure means such as NIH approved repositories (e.g. dbGap or other NIH clinical research registries: https://www.nih.gov/health-information/nih-clinical-research-trials-you/list-registries) or directly to investigators via secure campus data access control mechanisms. Summary level data and metadata about the patient-level data can be provided in support of the FAIR principles. Here are the contacts: Melissa Haendel, PhD, FACMI Chief Research Informatics Officer MELISSA.HAENDEL@CUANSCHUTZ.EDU Alison Lakin RN, LLB, LLM, PhD Associate Vice Chancellor for Regulatory Compliance ALISON.LAKIN@CUANSCHUTZ.EDU.

Funding Statement

Author JMN was supported by three grants: - NIH BIRCWH K12 HD057022, National Institutes of Health, URL: https://orwh.od.nih.gov/career-development-education/building-interdisciplinary-research-careers-in-womens-health-bircwh NIH NHLBI 1K23HL133604, National Heart Lung and Blood Institute, https://www.nhlbi.nih.gov/grants-and-training/training-and-career-development/early-career - NIH/NCATS Colorado CTSA UL1 TR002541, National Institutes of Health, National Center for Advancing Translational Sciences, URL: https://ncats.nih.gov/ctsa The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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Decision Letter 0

Hanna Landenmark

4 Apr 2023

PONE-D-23-03981The Fit After Baby randomized controlled trial: An mHealth postpartum lifestyle intervention for women with elevated cardiometabolic riskPLOS ONE

Dear Dr. Nicklas,

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Journal Requirements:

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This information should be included in your cover letter; we will change the online submission form on your behalf.

3. Thank you for stating the following in the Acknowledgments Section of your manuscript: 

"We would like to thank the Fit After Baby participants. We would like to acknowledge the support from research assistants Danielle Cook, Chelsea Arent, Emily Dunn, and Jamie Siegart. We are very grateful for extensive contributions and support from Dean Hovey, Susan Gilbert, Sue Arment, and Glenn Bachmann. This study was supported by National Institutes of Health NIH (BIRCWH K12 HD057022 and NIH NHLBI 1K23HL133604) and NIH/National Center for Advancing Translational Sciences Colorado (CTSA UL1 TR002541). This trial is registered at ClinicalTrials.gov, NCT03215173 (https://clinicaltrials.gov/ct2/show/NCT03215173). "

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"Author JMN was supported by three grants: 

- NIH BIRCWH K12 HD057022, National Institutes of Health, URL: https://orwh.od.nih.gov/career-development-education/building-interdisciplinary-research-careers-in-womens-health-bircwh 

NIH NHLBI 1K23HL133604

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- NIH/NCATS Colorado CTSA UL1 TR002541, National Institutes of Health, National Center for Advancing Translational Sciences, URL: https://ncats.nih.gov/ctsa 

The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript."

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7. We note that the original protocol file you uploaded contains a confidentiality notice indicating that the protocol may not be shared publicly or be published. Please note, however, that the PLOS Editorial Policy requires that the original protocol be published alongside your manuscript in the event of acceptance. Please note that should your paper be accepted, all content including the protocol will be published under the Creative Commons Attribution (CC BY) 4.0 license, which means that it will be freely available online, and any third party is permitted to access, download, copy, distribute, and use these materials in any way, even commercially, with proper attribution.

Therefore, we ask that you please seek permission from the study sponsor or body imposing the restriction on sharing this document to publish this protocol under CC BY 4.0 if your work is accepted. We kindly ask that you upload a formal statement signed by an institutional representative clarifying whether you will be able to comply with this policy. Additionally, please upload a clean copy of the protocol with the confidentiality notice (and any copyrighted institutional logos or signatures) removed.

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Partly

Reviewer #2: Yes

Reviewer #3: Yes

Reviewer #4: Yes

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

Reviewer #4: Yes

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3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: No

Reviewer #2: Yes

Reviewer #3: Yes

Reviewer #4: No

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: No

Reviewer #2: Yes

Reviewer #3: Yes

Reviewer #4: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Thank you for the opportunity to review this manuscript which presents the outcomes from an RCT comparing the efficacy of an mHealth intervention with the free Text4baby app to achieve weight loss in postpartum women with overweight or obesity and affected by a previous pregnancy complication. I have the following suggestions for authors below.

Introduction: the introduction is very well written, with clear background, rationale for study and objectives stated.

Methods: the methods are much less clearly written and overall would benefit from revision to improve clarity and logic. I have the following specific comments for consideration.

1. Ethical approval number – study approval is stated, but it is good practice to include the approval number, as well as the institute that gave approval

2. When/how was height measured? It says in statistical analysis that measured height was used to calculate BMI, but measurement of height is not specified in Measures section

3. Study participants should be described as ‘participants’ rather than ‘patients’, please check throughout manuscript

4. How was high risk pregnancy identified? Hospital notes? By physician?

5. Please give more detail about self-report diet and PA questionnaires. Are they validated questionnaires? What types of outcomes/data do they collect and record?

Results: revision of results is also recommended to improve clarity. Specific comments are as follows.

1. You state that Data not shown for Physical Activity results. However, could you please state overall activity levels of participants to give context to reader (even though there were no significant findings/ differences between groups).

2. For dietary intake data, you only show differences from baseline to 6/12 months. This gives no indication of what the intake actually was. This information is required to allow the reader to make any sort of interpretation of your findings. Could include baseline measure, if not in the table, in the text?

Discussion: logical flow and clarity of discussion could also be improved.

1. Can you place your findings within any literature concerning the amount of typical weight loss experienced during the first 6-12 months postpartum (i.e. without intervention), as women may experience gradual weight loss and return to pre-pregnancy weight postpartum without intervention.

2. In your discussion you refer to literature reporting that women have inadequate levels of physical activity postpartum. However, you have not stated that actual amount of physical activity by women in your study. Please add to findings to allow give this discussion point more context.

3. The conclusion for this study should answer to the aim of your study, i.e. that your study did not find a difference between the FAB and Text4baby groups. Also, please be careful not to overstate your findings, saying that engagement was ‘excellent’ may be considered an overstatement. Women only engaged with the weekly coaching sessions less than half of the time, and you were not able to compare intervention with control group engagement.

General comments:

1. There are several typos throughout the Methods, Results and Discussion, including line 254 and line 393

2. Person-first language should be used throughout (it is done in the introduction, but then discontinued throughout methods, results and discussion) to describe “women with overweight/obesity”, rather than “overweight/obese women”. See advice from Obesity Action Coalition: https://www.obesityaction.org/action-through-advocacy/weight-bias/people-first-language/

Reviewer #2: Dear Authors,

Thank you for the opportunity to review this interesting and valuable paper. I have some minor suggestions for changes below:

Introduction:

You assert the link between complications in pregnancy with adverse pregnancy/delivery/neonatal/postpartum outcomes, but it would be good to have some information on risk to subsequent pregnancies – for example, those with GDM are at an increased risk of GDM in any subsequent pregnancies. Recognition of the impact of these conditions and associated weight management issues on the interconception period would also be advantageous.

Methods:

Apologies if I missed this, but it would be good to understand if you excluded women who had a certain number of previous pregnancies. Also, did you exclude women pregnant with twins/triplets etc.?

It would be good to understand why in particular you have decided to approach women at 6 weeks postpartum. A line of justification would be good in this section.

There is no mention in this section of how you measure app acceptability/engagement or how it is analysed. Some addition of this information would substantially help with the claims made in the discussion around ‘excellent’ engagement.

Lines 168-169 – You mention an android coaching app, but before you say that FAB is only available on iPhone. This is confusing, were participants provided with another android phone? Related to this it would be good to understand who the coach was – a psychologist? Someone training in motivational interviewing?

Discussion

Lines 326-328 – I find this explanation confusing as the T4B intervention was not aimed at weight loss (making it an active control) – the breastfeeding explanation makes much more sense, perhaps the first sentence could be linked to the next point? E.g. the continuation in texts may have promoted behaviours such as breastfeeding which may have impacted weight.

Line 361 – how do you define ‘excellent’ engagement? How was this measured? Is this in comparison to the other studies you’ve detailed? It would be good to have some more detail here in regards to what your thoughts are on what it was about this app in particular that was so engaging? Your argument reads a bit like it was because it was an app, but there are plenty of apps out there that are not. For example, was it the gamification elements that make it stand out from other competitors?

Related to engagement it would be good to understand women’s compliance with things like charging the FitBit. Perhaps some qualitative work around the practicalities of this intervention is something you plan to include for future work?

Line 393 – I think the end of this sentence might be missing.

In your limitations section it would be good to see some discussion around retention. For example, 325 participants met eligibility but 154 consented. Do you know why? Out of the 154 consented only 82 attended the baseline visit. Some discussion about this drop would be useful. For example, is it possible that those who made it to the baseline visit were more motivated to manage their weight than those who did not attend? Is it possible that those who took part had greater resources to take part in research activities and therefore had more resources to manage their weight? I realise that you have some diversification in your population but the majority are college graduates and earn over $75,000.

Conclusions/summary – this section was lacking slightly. It would be good to understand your future directions and plans for future research here and any recommendations you might have for further app development. E.g. inclusion of gamification/wearables.

Reviewer #3: The authors report an mHealth intervention to support postpartum women who had experienced adverse pregnancy outcomes. This makes a significant contribution to research to improve the health and wellbeing of mothers and reduce risk factors for future cardiometabolic disease.

Comments:

Line 212 – It is preferable to write out dates clearly to avoid confusion about whether you are using MM/DD/YYYY or DD/MM/YYYY date convention. E.g, is recruitment between 9th April 2017 to 10th July 2019 or 4th September 2017 to 7th October 2019?

In the discussion, the authors did not discuss the possible long-term effects of this findings. For example, it seems that the benefits gained from the intervention was not sustained beyond the active phase of the intervention.

Can the authors discuss the implications of their finding of a sustained effect in the T4B group during pandemic which was absent from the FAB group? Does that suggest that low intervention dose over a long period may be equally as effective for this population as short intensive (12 weeks) intervention dose? Sustainability of weight loss and healthy lifestyle behaviours is important in this population. Although the authors attempted to explain why there were differences in intervention effects during the pandemic, they have not sufficiently discussed the possible implications of this (e.g., for the modification of the FAB intervention dose/intensity/duration). Perhaps there is not enough power to draw a conclusion here, but this should be acknowledged. Also, since this is an mHealth intervention, why would the pandemic have affected outcomes, since participants were not physically visiting any facility? This is not clear to the reader.

Line 393 is not complete.

Reviewer #4: The manuscript addresses an interesting topic. The collected data are unique and the employed statistical methods are generally sound, though more details are required. The results are consistent and offer a nice view also for further researches on the topic. Some comments follow.

1. The data are not fully available for the reviewers. This does not allow for the correctness of the methods and the replicability of the results. Moreover, it would be nice to have more details on the used statistical software/package/function to obtain the results; the code should be uploaded as supplementary material, along with the data (for review purposes only).

2. The statistical methods are generally sound. I really appreciate the use of mixed models. However, more details are required:

a) It is rather unclear how the linear predictor is specified. Are you considering a growth model? How do you account for the baseline effect as it is well known to affect the random effects distribution (see e.g. https://doi.org/10.1007/s11222-006-7072-5)? Please, write down the linear predictor to appreciate the model you fit to the data.

b) Missing mechanism may be completely at random, at random or not at random. It is rather unclear how missingnes is accounted for. Did you consider a pattern mixture or a selection model or...to deal with missing not at random?

c) The random effects distribution is often taken for granted and a Gaussian distribution is considered. I guess it is so also for you model. Please, provide evindence of the robustness of your results with respect to a misspecification of the random effects distribution.

d) All methods and parametric tests must fulfill some strict assumptions to avoid misleading inference. As data are not available, it is rather impossible to verify the adequacy of a linear model, rather than e.g. a heavy tails or a skew model. Please, provide evidence that all model's assumptions are met; the residual analysis would be helpful to clarify this point. This is also true for t-tests, whose main assumption is that the data follow a gaussian homoschedastic distribution; I guess you are considering paired t-tests, please clarify.

e) I am wondering if interactions may arise or if collinearity may be an issue. A discussion on variable selection would be helpful.

**********

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Reviewer #1: No

Reviewer #2: No

Reviewer #3: Yes: Dr Maureen Makama

Reviewer #4: No

**********

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PLoS One. 2024 Jan 9;19(1):e0296244. doi: 10.1371/journal.pone.0296244.r002

Author response to Decision Letter 0


10 Aug 2023

Dear Editors,

We appreciate the reviews to our manuscript entitled, “The Fit After Baby randomized controlled trial: an mHealth postpartum lifestyle intervention for women with elevated cardiometabolic risk.” We have made every effort to address the issues raised.

We have addressed the additional requirements as follows:

1.Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at

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https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf

We have edited the manuscript to follow PLOS ONE’s style requirements.

2. Please expand the acronym “NHLBI” (as indicated in your financial disclosure) so that it states the name of your funders in full.

This information should be included in your cover letter; we will change the online submission form on your behalf.

We have added National Heart Lung and Blood Institute to the cover letter so that it can be added to the online submission form.

3. Thank you for stating the following in the Acknowledgments Section of your manuscript:

"We would like to thank the Fit After Baby participants. We would like to acknowledge the support from research assistants Danielle Cook, Chelsea Arent, Emily Dunn, and Jamie Siegart. We are very grateful for extensive contributions and support from Dean Hovey, Susan Gilbert, Sue Arment, and Glenn Bachmann. This study was supported by National Institutes of Health NIH (BIRCWH K12 HD057022 and NIH NHLBI 1K23HL133604) and NIH/National Center for Advancing Translational Sciences Colorado (CTSA UL1 TR002541). This trial is registered at ClinicalTrials.gov, NCT03215173 (https://clinicaltrials.gov/ct2/show/NCT03215173). "

We note that you have provided funding information that is not currently declared in your Funding Statement. However, funding information should not appear in the Acknowledgments section or other areas of your manuscript. We will only publish funding information present in the Funding Statement section of the online submission form.

Please remove any funding-related text from the manuscript and let us know how you would like to update your Funding Statement. Currently, your Funding Statement reads as follows:

"Author JMN was supported by three grants:

- NIH BIRCWH K12 HD057022, National Institutes of Health, URL: https://orwh.od.nih.gov/career-development-education/building-interdisciplinary-research-careers-in-womens-health-bircwh

NIH NHLBI 1K23HL133604

https://www.nhlbi.nih.gov/grants-and-training/training-and-career-development/early-career

- NIH/NCATS Colorado CTSA UL1 TR002541, National Institutes of Health, National Center for Advancing Translational Sciences, URL: https://ncats.nih.gov/ctsa

The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript."

Please include your amended statements within your cover letter; we will change the online submission form on your behalf.

We have taken funding information out of the acknowledgements section. There were three funding sources listed which match the three listed in the funding statement. We do not think we need to amend the statement. We have removed the clinicaltrials.gov number.

4. We note that you have indicated that data from this study are available upon request. PLOS only allows data to be available upon request if there are legal or ethical restrictions on sharing data publicly. For information on unacceptable data access restrictions, please see http://journals.plos.org/plosone/s/data-availability#loc-unacceptable-data-access-restrictions.

We requested permission to share a de-indentified dataset from our governing body and we were told that we are not allowed to do so. We received the following response:

Because patient-level (e.g. “row-level” or “line-level”) data is more readily re-identifiable than summary data, CU Anschutz has a risk management policy of provisioning these data only via secure means such as NIH approved repositories (e.g. dbGap or other NIH clinical research registries: https://www.nih.gov/health-information/nih-clinical-research-trials-you/list-registries) or directly to investigators via secure campus data access control mechanisms. Summary level data and metadata about the patient-level data can be provided in support of the FAIR principles.

Here are the contacts:

Melissa Haendel, PhD, FACMI

Chief Research Informatics Officer

MELISSA.HAENDEL@CUANSCHUTZ.EDU

Alison Lakin RN, LLB, LLM, PhD

Associate Vice Chancellor for Regulatory Compliance

ALISON.LAKIN@CUANSCHUTZ.EDU

We have added this to our cover letter.

5. We note that you have included the phrase “data not shown” in your manuscript. Unfortunately, this does not meet our data sharing requirements. PLOS does not permit references to inaccessible data. We require that authors provide all relevant data within the paper, Supporting Information files, or in an acceptable, public repository. Please add a citation to support this phrase or upload the data that corresponds with these findings to a stable repository (such as Figshare or Dryad) and provide and URLs, DOIs, or accession numbers that may be used to access these data. Or, if the data are not a core part of the research being presented in your study, we ask that you remove the phrase that refers to these data.

We have removed “data not shown,” and include the relevant tables in the manuscript.

6. Please include your full ethics statement in the ‘Methods’ section of your manuscript file. In your statement, please include the full name of the IRB or ethics committee who approved or waived your study, as well as whether or not you obtained informed written or verbal consent. If consent was waived for your study, please include this information in your statement as well.

We have added the full name of our review board to our Methods section as follows:

The Colorado Multiple Institutional Review Board at the University of Colorado approved the study, and all patients gave written informed consent. (lines 155-157)

7. We note that the original protocol file you uploaded contains a confidentiality notice indicating that the protocol may not be shared publicly or be published. Please note, however, that the PLOS Editorial Policy requires that the original protocol be published alongside your manuscript in the event of acceptance. Please note that should your paper be accepted, all content including the protocol will be published under the Creative Commons Attribution (CC BY) 4.0 license, which means that it will be freely available online, and any third party is permitted to access, download, copy, distribute, and use these materials in any way, even commercially, with proper attribution.

Therefore, we ask that you please seek permission from the study sponsor or body imposing the restriction on sharing this document to publish this protocol under CC BY 4.0 if your work is accepted. We kindly ask that you upload a formal statement signed by an institutional representative clarifying whether you will be able to comply with this policy. Additionally, please upload a clean copy of the protocol with the confidentiality notice (and any copyrighted institutional logos or signatures) removed.

The Colorado Multiple Institutional Review Board at the University of Colorado approved an amendment for a publishable protocol. We include a letter from the Colorado Multiple Institutional Review Board at the University of Colorado stating that we may share this protocol publicly. We have included a publishable protocol with our revision.

Review Comments to the Author

Reviewer #1: Thank you for the opportunity to review this manuscript which presents the outcomes from an RCT comparing the efficacy of an mHealth intervention with the free Text4baby app to achieve weight loss in postpartum women with overweight or obesity and affected by a previous pregnancy complication. I have the following suggestions for authors below.

Introduction: the introduction is very well written, with clear background, rationale for study and objectives stated.

Methods: the methods are much less clearly written and overall would benefit from revision to improve clarity and logic. I have the following specific comments for consideration.

We have reordered and added headings to the Methods to improve clarity and logic.

1. Ethical approval number – study approval is stated, but it is good practice to include the approval number, as well as the institute that gave approval

We have added the full name of our review board to our Methods section as follows:

The Colorado Multiple Institutional Review Board at the University of Colorado approved the study (17-0045), and all patients gave written informed consent. (lines 155-157)

2. When/how was height measured? It says in statistical analysis that measured height was used to calculate BMI, but measurement of height is not specified in Measures section

We have added information about the measurement of weight and height to the manuscript in the Methods section.

At each visit trained staff measured body weight twice wearing light clothing, and weights were averaged (SECA 360), and height was measured by stadiometer (SECA). We used kg/m2 to determine BMI. Trained staff also measured waist circumference. (lines 181-183)

3. Study participants should be described as ‘participants’ rather than ‘patients’, please check throughout manuscript

We have changed ‘patients’ to ‘participants’ throughout the manuscript.

4. How was high risk pregnancy identified? Hospital notes? By physician?

We have added the following to the Methods section:

We identified patients by diagnosis codes, and pregnancy complications were confirmed via chart review by the study physician. (lines 144-145)

5. Please give more detail about self-report diet and PA questionnaires. Are they validated questionnaires? What types of outcomes/data do they collect and record?

The validated diet questionnaire we used was the 2005 Block Food Frequency Questionnaire (administered via NutritionQuest). This questionnaire provides an estimate of habitual intake. The validated physical activity questionnaire was the Pregnancy Physical Activity Questionnaire (PPAQ). This questionnaire provides a reasonably accurate measure of a broad range of physical activities.

Results: revision of results is also recommended to improve clarity. Specific comments are as follows.

1. You state that Data not shown for Physical Activity results. However, could you please state overall activity levels of participants to give context to reader (even though there were no significant findings/ differences between groups).

We have added the data for the physical activity results and summarized them in the Results section.

2. For dietary intake data, you only show differences from baseline to 6/12 months. This gives no indication of what the intake actually was. This information is required to allow the reader to make any sort of interpretation of your findings. Could include baseline measure, if not in the table, in the text?

We have added a table of baseline measures to the manuscript.

Discussion: logical flow and clarity of discussion could also be improved.

1. Can you place your findings within any literature concerning the amount of typical weight loss experienced during the first 6-12 months postpartum (i.e. without intervention), as women may experience gradual weight loss and return to pre-pregnancy weight postpartum without intervention.

-We have included the following on typical weight loss in postpartum women in the Discussion.

Although there is a lot of variability in postpartum weight loss, studies show that 15-27% of women have major postpartum weight retention at one year of at least 4.55 kg. Nearly all women (97%) who have obesity before pregnancy will continue to be classified as such at one year, with 40% increasing by two or more BMI units. Among women with overweight, 40-50% will move into the obesity category by 12 months postpartum. (lines 474-479)

2. In your discussion you refer to literature reporting that women have inadequate levels of physical activity postpartum. However, you have not stated that actual amount of physical activity by women in your study. Please add to findings to allow give this discussion point more context.

-We have included baseline data on physical activity in our population.

3. The conclusion for this study should answer to the aim of your study, i.e. that your study did not find a difference between the FAB and Text4baby groups. Also, please be careful not to overstate your findings, saying that engagement was ‘excellent’ may be considered an overstatement. Women only engaged with the weekly coaching sessions less than half of the time, and you were not able to compare intervention with control group engagement.

We have changed the conclusion to address our primary outcome and the failure to reach significance. We have changed our assessment of engagement to be “promising.” We have also edited the abstract to be consistent with these conclusions.

General comments:

1. There are several typos throughout the Methods, Results and Discussion, including line 254 and line 393

We have corrected the typos on line 254 and removed the sentence in 393.

2. Person-first language should be used throughout (it is done in the introduction, but then discontinued throughout methods, results and discussion) to describe “women with overweight/obesity”, rather than “overweight/obese women”. See advice from Obesity Action Coalition: https://www.obesityaction.org/action-through-advocacy/weight-bias/people-first-language/

We have revised the manuscript to use person-first language throughout.

Reviewer #2: Dear Authors,

Thank you for the opportunity to review this interesting and valuable paper. I have some minor suggestions for changes below:

Introduction:

You assert the link between complications in pregnancy with adverse pregnancy/delivery/neonatal/postpartum outcomes, but it would be good to have some information on risk to subsequent pregnancies – for example, those with GDM are at an increased risk of GDM in any subsequent pregnancies. Recognition of the impact of these conditions and associated weight management issues on the interconception period would also be advantageous.

-In the introduction we have added data from the literature on the importance of weight loss for the interconception period on GDM and other pregnancy complications in subsequent pregnancies. (lines 91-94)

Methods:

Apologies if I missed this, but it would be good to understand if you excluded women who had a certain number of previous pregnancies. Also, did you exclude women pregnant with twins/triplets etc.?

-We excluded all non-singleton pregnancies for this study. There were no exclusion criteria based upon the number of previous pregnancies. We have added this to the methods section.

It would be good to understand why in particular you have decided to approach women at 6 weeks postpartum. A line of justification would be good in this section.

-We decided to start the trial at 6 weeks postpartum because this is typically when women will return for their postpartum visit, and women with a pregnancy complicated by gestational diabetes should have postpartum glucose testing at this time. Our previous qualitative work and previous studies demonstrated that this is a reasonable time to begin a lifestyle intervention in postpartum women. We have added this information and citations to the manuscript.

There is no mention in this section of how you measure app acceptability/engagement or how it is analysed. Some addition of this information would substantially help with the claims made in the discussion around ‘excellent’ engagement.

-We have added information about how we measured app engagement to the Methods section. We collected data on use of the app, including the number of days the app was opened, which content was opened, collected data on app use, steps and minutes of physical activity, days activity trackers were worn, and number of coaching interactions, and Health Warrior points accumulated. Usage data were collected in BigQuery (Google). App usage data were analyzed using BigQuery (Google) and Tableau (Mountain View, CA).

Lines 168-169 – You mention an android coaching app, but before you say that FAB is only available on iPhone. This is confusing, were participants provided with another android phone? Related to this it would be good to understand who the coach was – a psychologist? Someone training in motivational interviewing?

-The coaching app was built on an Android platform. This was purely based on the coding preference of the coders who built the app. Consequently the coach used an Android platform to access the coaching data. Participants used iPhones for access to the app. Since the reference to the Android platform is confusing and not essential to the discussion we have removed this. The coach was a registered dietitian with training in motivational interviewing. We have added this to the coaching section of the methods.

Discussion

Lines 326-328 – I find this explanation confusing as the T4B intervention was not aimed at weight loss (making it an active control) – the breastfeeding explanation makes much more sense, perhaps the first sentence could be linked to the next point? E.g. the continuation in texts may have promoted behaviours such as breastfeeding which may have impacted weight.

-This is a good point and I have linked these concepts in the text. In addition, the ongoing texts from T4B, particularly in the early part of the pandemic, may have led to an increased sense of connection for those in the control group.

Line 361 – how do you define ‘excellent’ engagement? How was this measured? Is this in comparison to the other studies you’ve detailed? It would be good to have some more detail here in regards to what your thoughts are on what it was about this app in particular that was so engaging? Your argument reads a bit like it was because it was an app, but there are plenty of apps out there that are not. For example, was it the gamification elements that make it stand out from other competitors?

-We have re-written this to describe the engagement as “promising.” We believe that the engagement is better than many similar technologically-based interventions in this population, but agree that it is not to the level of excellent. We have added more detail about the way the user data were collected and analyzed. We have added more data on the attainment of reward badges to further explain the gamification component.

Related to engagement it would be good to understand women’s compliance with things like charging the FitBit. Perhaps some qualitative work around the practicalities of this intervention is something you plan to include for future work?

-We do not have quantitative data on Fitbit charging in this study. We did do focus groups at the conclusion of this study and we are in the process of analyzing these data.

Line 393 – I think the end of this sentence might be missing.

-we have removed this sentence.

In your limitations section it would be good to see some discussion around retention. For example, 325 participants met eligibility but 154 consented. Do you know why? Out of the 154 consented only 82 attended the baseline visit. Some discussion about this drop would be useful. For example, is it possible that those who made it to the baseline visit were more motivated to manage their weight than those who did not attend? Is it possible that those who took part had greater resources to take part in research activities and therefore had more resources to manage their weight? I realise that you have some diversification in your population but the majority are college graduates and earn over $75,000.

-We have added some discussion around retention to the limitations section. We do not have detailed data on why those who met eligibility were not consented. Among those who consented we know that among the 57 women we either could not schedule them or they were no longer interested. We agree with the importance of discussing the ways those who decided to participate may be different from those who did not and we have added this to the manuscript.

Conclusions/summary – this section was lacking slightly. It would be good to understand your future directions and plans for future research here and any recommendations you might have for further app development. E.g. inclusion of gamification/wearables.

-We have edited the conclusion to better represent the results and to discuss plans for improvements that could enhance efficacy.

Reviewer #3: The authors report an mHealth intervention to support postpartum women who had experienced adverse pregnancy outcomes. This makes a significant contribution to research to improve the health and wellbeing of mothers and reduce risk factors for future cardiometabolic disease.

Comments:

Line 212 – It is preferable to write out dates clearly to avoid confusion about whether you are using MM/DD/YYYY or DD/MM/YYYY date convention. E.g, is recruitment between 9th April 2017 to 10th July 2019 or 4th September 2017 to 7th October 2019?

We have written out dates throughout the manuscript.

In the discussion, the authors did not discuss the possible long-term effects of this findings. For example, it seems that the benefits gained from the intervention was not sustained beyond the active phase of the intervention.

Can the authors discuss the implications of their finding of a sustained effect in the T4B group during pandemic which was absent from the FAB group? Does that suggest that low intervention dose over a long period may be equally as effective for this population as short intensive (12 weeks) intervention dose?

-This is an important point. The number of Text4baby participants during the pandemic was only 6, so it is difficult to draw a lot of conclusions from their data. It is possible that women in the Text4baby group, who were still receiving 3-4 texts per week, may have had a greater sense of connection. Text4baby may have promoted behaviors such as continuation of breastfeeding leading to increased weight loss. In addition, women in the control group were significantly more likely to be breastfeeding at baseline, which may have influenced their weight loss. We have added more to the discussion on this topic. A larger study would be needed to test the difference between a low intervention dose over a long period vs. a more intensive intervention over a shorter period. We have added more to the manuscript to reflect this.

Sustainability of weight loss and healthy lifestyle behaviours is important in this population. Although the authors attempted to explain why there were differences in intervention effects during the pandemic, they have not sufficiently discussed the possible implications of this (e.g., for the modification of the FAB intervention dose/intensity/duration). Perhaps there is not enough power to draw a conclusion here, but this should be acknowledged. Also, since this is an mHealth intervention, why would the pandemic have affected outcomes, since participants were not physically visiting any facility? This is not clear to the reader.

-We have added further ideas about the implications of dose and intensity and duration. We believe that the pandemic affected lifestyles for the women in our study in that it impacted diet and exercise and weight. We believe that the impact of the pandemic overwhelmed what lifestyle changes could have been driven by the Fit After Baby program, particularly after the active part of the intervention had finished. Even though the intervention was remote, the more intensive/interactive part of the program was finished for the FAB participants before the start of the COVID pandemic.

Line 393 is not complete.

-We have removed line 393.

Reviewer #4: The manuscript addresses an interesting topic. The collected data are unique and the employed statistical methods are generally sound, though more details are required. The results are consistent and offer a nice view also for further researches on the topic. Some comments follow.

1. The data are not fully available for the reviewers. This does not allow for the correctness of the methods and the replicability of the results. Moreover, it would be nice to have more details on the used statistical software/package/function to obtain the results; the code should be uploaded as supplementary material, along with the data (for review purposes only).

-We were not given permission to upload the dataset at the individual level. We used SAS software (SAS Inc., Cary, NC), version 9.4 for analysis, as stated in the statistical methods of the manuscript.

2. The statistical methods are generally sound. I really appreciate the use of mixed models.

Thank you for the positive review of our work.

However, more details are required:

a) It is rather unclear how the linear predictor is specified. Are you considering a growth model? How do you account for the baseline effect as it is well known to affect the random effects distribution (see e.g. https://doi.org/10.1007/s11222-006-7072-5)? Please, write down the linear predictor to appreciate the model you fit to the data.

Thank you for your comment. We used a mixed-effects model with a random intercept. The general form of the mixed-effects models that we used is as follows:

Y_ij= β_0+ β_1 X_ij+ u_j+ e_j

where u_j ~ N(0,σ_u^2 ) is the random intercept. Our models were adjusted for the baseline value of the outcome. We also noted that the reference you provided referred to models for longitudinal count data and therefore would not apply to our data.

b) Missing mechanism may be completely at random, at random or not at random. It is rather unclear how missingnes is accounted for. Did you consider a pattern mixture or a selection model or...to deal with missing not at random?

We agree with the reviewer that consideration of missing data is an important part of all statistical analyses. By using mixed-effects models, we were able to include all outcome data regardless of whether a participant had one or more missing values. The amount of missing data in our study was relatively low and therefore was unlikely to cause significant bias even if the assumption of missing completely at random/missing at random was violated, so we did not consider pattern mixture models or other models to account for missing data. We also performed a sensitivity analysis by comparing the results of our analyses using all available data with one using data only from participants with complete data, and our findings were unchanged; therefore, we concluded that the amount of missing data in this study was not likely to introduce errors in our conclusions.

c) The random effects distribution is often taken for granted and a Gaussian distribution is considered. I guess it is so also for you model. Please, provide evidence of the robustness of your results with respect to a misspecification of the random effects distribution.

To evaluate the assumption of the normality of the random effects, we created histograms of the model residuals using the BLUP (best unbiased linear prediction) estimates for the models of our primary outcome, weight. These plots (provided below) do not show any evidence of significant non-normality. Note that the plot labeled “analweight_kg” comes from a model using the post-partum week 6 visit as the baseline, and the plot labeled “analweight2_kg” comes from a model using pre-pregnancy weight as the baseline.

d) All methods and parametric tests must fulfill some strict assumptions to avoid misleading inference. As data are not available, it is rather impossible to verify the adequacy of a linear model, rather than e.g. a heavy tails or a skew model. Please, provide evidence that all model's assumptions are met; the residual analysis would be helpful to clarify this point. This is also true for t-tests, whose main assumption is that the data follow a gaussian homoschedastic distribution; I guess you are considering paired t-tests, please clarify.

Please see our response above regarding the residuals from the linear mixed-effects models. Our primary analyses used mixed-effects models rather than t-tests. The only t-tests reported in the paper are two-sample t-tests in Table 1. Because we had a sample size of 81 women, the results of the t-tests in Table 1 are most likely robust to deviations from assumptions.

See: Posten, H.O., Yeh, H.C. and Owen, D.B. (1982): Robustness of the two-sample t-test under violations of the homogeneity of variance assumptions. Communications in Statistics: Theory and Methods 11, 109-126

e) I am wondering if interactions may arise or if collinearity may be an issue. A discussion on variable selection would be helpful.

Thank you for your question. Variables in our models were selected a priori based on subject matter expertise. We did not hypothesize that there would be important interactions, and in order to minimize the amount of statistical testing and therefore the risk of type I error, we did not test interactions of pairwise combinations of covariates. There was no evidence of collinearity (e.g., inflated standard errors for parameter estimates) in our model results.

Attachment

Submitted filename: FAB_ResponseToReviewers (1).docx

Decision Letter 1

Megan L Gow

4 Sep 2023

PONE-D-23-03981R1The Fit After Baby randomized controlled trial: An mHealth postpartum lifestyle intervention for women with elevated cardiometabolic riskPLOS ONE

Dear Dr. Nicklas,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

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Megan L Gow

Guest Editor

PLOS ONE

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #3: All comments have been addressed

Reviewer #4: (No Response)

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #3: Yes

Reviewer #4: Partly

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #3: Yes

Reviewer #4: No

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #3: Yes

Reviewer #4: No

**********

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Reviewer #3: Yes

Reviewer #4: Yes

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Reviewer #3: (No Response)

Reviewer #4: Thank you very much for all the efforts to reply to my previous comments. Some clarifications are still required.

1. You state that "We also noted that the reference you provided referred to models for longitudinal count data and therefore would not apply to our data." This is far from being true. Your model casts into the generalized linear mixed framework, as well as the provided reference. It is well-known that the initial conditions may strongly bias the estimated coefficients, see also the Heckman model. Accordingly, the model must be modified accordingly and results compared with those presented in the current version of the paper.

2. According to your reply about the missing data mechanism is at random. This assumption is hardly tenable. Moreover, the nature of missing data mechanism does not depend on the amount of missingnes, please refer to the statistical literature on the topic and to Little's work in particular.

3. Please, provide more details on the check of model's assumptions. It is rather unclear why the BLUP graph should provide information about the random effects distribution. Similarly, having a sample of 80 or more observations does not guarantee that normality is met. Even one outlying observation only may strongly affect the results.

**********

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Reviewer #3: No

Reviewer #4: No

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PLoS One. 2024 Jan 9;19(1):e0296244. doi: 10.1371/journal.pone.0296244.r004

Author response to Decision Letter 1


15 Nov 2023

Dear reviewers,

Thank you for your help improving the manuscript thus far. Below please find our responses to the latest round of comments.

Reviewer #4: Thank you very much for all the efforts to reply to my previous comments. Some clarifications are still required.

1. You state that "We also noted that the reference you provided referred to models for longitudinal count data and therefore would not apply to our data." This is far from being true. Your model casts into the generalized linear mixed framework, as well as the provided reference. It is well-known that the initial conditions may strongly bias the estimated coefficients, see also the Heckman model. Accordingly, the model must be modified accordingly and results compared with those presented in the current version of the paper.

Thank you for your comment; that is an excellent point. We have re-run all of our models including baseline values as a covariate. This led to some changes in our results and we have rewritten our manuscript accordingly. We have also rewritten the Methods to state that we have run our models with baseline as a covariates, and we have added this as a footnote to all tables.

2. According to your reply about the missing data mechanism is at random. This assumption is hardly tenable. Moreover, the nature of missing data mechanism does not depend on the amount of missingnes, please refer to the statistical literature on the topic and to Little's work in particular.

Thank you for the opportunity to clarify. We did not mean to imply that the nature of the missing data mechanism depended on the amount of missing data, but rather that because the amount of missing data was relatively low, it would be less likely to impact our conclusions even if the assumption of missing completely at random or missing at random was violated.

The table below provides a comparison of the baseline characteristics and randomization assignments of participants who did and did not have missing data. These two groups are quite similar, further supporting the idea that missing data in this study was unlikely to cause significant bias.

Baseline Characteristics Missing data

Yes No P values

Age 29.4 (5.4) 31.3 (5.4) 0.1639

BMI 32.9 (4.9) 32.1 (5.0) 0.5241

Weight(Kg) 89.0 (15.4) 86.8 (14.8) 0.5369

Group 0.8795

Intervention 16 (66.7%) 37 (64.9%)

Control 8 (33.3%) 20 (35.1%)

Affected by COVID 0.4974

Yes 5 (20.8%) 16 (28.1%)

No 19 (79.2%) 41 (71.9%)

Finally, because this is an RCT, conditioning on the baseline value of the outcome reduces the potential for bias (PMID: 22262640). We have added a sentence about this comparison to the Results section and a sentence to the limitations.

3. Please, provide more details on the check of model's assumptions. It is rather unclear why the BLUP graph should provide information about the random effects distribution. Similarly, having a sample of 80 or more observations does not guarantee that normality is met. Even one outlying observation only may strongly affect the results.

Thank you for the opportunity to clarify. The BLUPs are an estimate of the random effects. Please see the following reference:

Christian Ritz. (2004). Goodness-of-Fit Tests for Mixed Models. Scandinavian Journal of Statistics, 31(3), 443–458. http://www.jstor.org/stable/4616841

Attachment

Submitted filename: response to reviewers v2.docx

Decision Letter 2

Megan L Gow

10 Dec 2023

The Fit After Baby randomized controlled trial: An mHealth postpartum lifestyle intervention for women with elevated cardiometabolic risk

PONE-D-23-03981R2

Dear Dr. Nicklas,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Kind regards,

Megan L Gow

Guest Editor

PLOS ONE

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Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #4: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #4: (No Response)

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #4: (No Response)

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #4: (No Response)

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

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Reviewer #4: (No Response)

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Reviewer #4: No

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Acceptance letter

Megan L Gow

27 Dec 2023

PONE-D-23-03981R2

PLOS ONE

Dear Dr. Nicklas,

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on behalf of

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Associated Data

    This section collects any data citations, data availability statements, or supplementary materials included in this article.

    Supplementary Materials

    S1 Checklist. CONSORT 2010 checklist of information to include when reporting a randomised trial*.

    (DOC)

    S1 File

    (DOCX)

    Attachment

    Submitted filename: FAB_ResponseToReviewers (1).docx

    Attachment

    Submitted filename: response to reviewers v2.docx

    Data Availability Statement

    Because patient-level (e.g. “row-level” or “line-level”) data is more readily re-identifiable than summary data, CU Anschutz has a risk management policy of provisioning these data only via secure means such as NIH approved repositories (e.g. dbGap or other NIH clinical research registries: https://www.nih.gov/health-information/nih-clinical-research-trials-you/list-registries) or directly to investigators via secure campus data access control mechanisms. Summary level data and metadata about the patient-level data can be provided in support of the FAIR principles. Here are the contacts: Melissa Haendel, PhD, FACMI Chief Research Informatics Officer MELISSA.HAENDEL@CUANSCHUTZ.EDU Alison Lakin RN, LLB, LLM, PhD Associate Vice Chancellor for Regulatory Compliance ALISON.LAKIN@CUANSCHUTZ.EDU.


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