Abstract
Objective
To assess the extent to which an obesity prevention intervention that embeds obesity-related messages within a parenting program, compared with controls who received weekly mailings, resulted in a smaller increase in children’s BMI (primary outcome) and improvements in weight-related behaviors from baseline to 9-month follow-up.
Methods
We randomized 56 families to the intervention and 56 to control. Children were primarily Hispanic (58%) or Black/African American (23%). Intervention included 9, weekly: 1) group parenting sessions, 2) children’s program, and 3) homework assignments. At baseline, post-intervention, and 9-month follow-up, staff assessed children’s weight and height. Parents completed surveys assessing parenting skills, feeding behaviors, and children’s weight-related behaviors.
Results
From baseline to 9-month follow-up, BMI decreased by a mean of 0.13 kg/m2 among children in the intervention and increased by 0.21 kg/m2 among children in the control, resulting in a non-significant difference (multivariate adjusted difference =−0.36; 95% confidence interval [CI] −1.23, 0.51; P=0.41). Parents in the intervention decreased restrictive feeding practices relative to control (−0.30; 95% CI −0.53,−0.07; P=0.01). Intervention and control arms showed similar changes in children’s weight-related behaviors.
Conclusions
The intervention improved restrictive feeding, but did not influence children’s BMI or weight-related behaviors compared to controls who received weekly mailings.
Trial Registration
Keywords: General parenting, behavior change, family-based intervention, obesity, overweight, children
Introduction
Approximately 14% of American children age 2–5 years are overweight and 8% are obese.1 Rates of overweight and obesity are higher among racial/ethnic minority children, making development of effective intervention strategies for these populations particularly urgent.
Parents are a primary influence on their young children’s weight-related behaviors, and resulting obesity risk. Parents influence their children’s obesity risk through feeding behaviors,2 modeling of behaviors3 and through the provision of a home environment that facilitates (or impedes) healthful eating and activity behaviors.4 General parenting practices, e.g., limit setting, have also been shown to influence children’s weight-related behaviors. 5 Thus, to change the behaviors of young children, we need interventions that can effectively engage their parents/caregivers.
Results from qualitative6 and quantitative research7 suggest that parents of young children are enthusiastic about learning general parenting skills, such as discipline strategies, but less interested in nutrition and physical activity. To capitalize on this enthusiasm, we developed Parents and Tots Together, a family-based obesity prevention intervention that embeds strategies to improve children’s weight-related behaviors within an empirically tested general parenting program. Although a number of obesity treatment interventions among preschool aged children have addressed both general parenting and weight-related messages,8, 9, 10, 11, 12 few prevention interventions have used this approach.13,14,15 Harvey-Berino & Rourke13 conducted a pilot randomized controlled trial of a home-based secondary prevention intervention that targeted 43 overweight Native American mothers of preschool aged children. As compared to controls, parents in the intervention reported a greater decrease in use of restrictive feeding practices.13 Children in the intervention experienced a decrease in their weight-for-height z-score whereas children in the control experienced an increase (mean change [SD]; intervention = −0.27 [1.1], control = 0.31 [1.1], P= 0.06).13 In a randomized controlled trial of 400 overweight mothers of preschoolers, Ostbye and colleagues14 intervened using 8 monthly coaching calls, mailed materials, and 1 group session. Although the intervention reduced maternal restrictive feeding behaviors and child snacking while watching TV, child body mass index z-score (BMIz) was unchanged (mean change [SE] intervention = 0.03 [0.05], control = −0.02 [0.05], P = 0.63).
While previous research has tested treatment and secondary prevention (targeted) interventions that address both general parenting and weight-related messages, this approach has not been tested as a primary prevention intervention. Data from the Early Childhood Longitudinal Study in the U.S. found that children who were overweight when they entered kindergarten were 4 times more likely to be obese at age 14 than children who entered kindergarten at a healthy weight.16 Once present, obesity is difficult to treat due to metabolic changes that resist weight loss.17 Effective primary prevention efforts are needed early in life before physiologic barriers to weight loss take hold and less healthful weight-related behaviours become entrenched. The current study examines the efficacy of a primary obesity prevention intervention that embeds weight-related messages within a parenting program that has been shown to improve parenting behaviors among racial/ethnic minority families.18 A formative pre-post uncontrolled trial with 16 families showed that we could feasibly implement the Parents and Tots Together intervention within a community setting and the intervention was acceptable to families.6 The purpose of the current study was to assess the extent to which the Parents and Tots Together intervention, compared with controls who received weekly mailings, resulted in a smaller increase in BMI (primary outcome) and improvements in children’s weight-related behaviors and parental feeding and general parenting behaviors among racial/ethnic minority families with children age 2 through 5 years of age.
Methods
Study design and participants
In 2012–2013, we conducted an individual-level (family), parallel-group randomized controlled trial of the Parents and Tots Together intervention compared to a control where parents received weekly mailings. Participants were parents with children age 2 to 5 years of age. We excluded 1) parents who were unable to respond to interviews in English or Spanish; 2) families who planned to move from the Boston area; 3) parents who were younger than 18 years of age; and 4) children with severe health conditions that would prohibit them from participating in study activities (e.g., severe cerebral palsy). As a primary prevention intervention, we made intervention available to families regardless of the children’s weight status.
We recruited participants from community health centers, as well as community agencies (e.g., the Special Supplemental Nutrition Program for Women, Infants and Children [WIC]) that primarily serve low-income families in the Boston area. Our recruitment materials stated that we were testing a program designed to provide parents with tools to raise “healthy and happy children” and did not mention weight. We used a number of strategies to recruit participants, including in-person presentations at community health center events, direct mailings and calls, and posters at the health centers and other area agencies that serve families.
Research staff conducted eligibility screening questionnaires with participants by phone or in-person. All eligible families were invited to a group information session. This information session served as a run-in period in an attempt to minimize loss to follow-up. At this information session, parents signed the informed consent, completed the baseline questionnaire, and had their children’s height and weight assessed. Families were considered enrolled once the baseline assessment (survey and heights and weights) was complete. Of the 211 families identified as eligible, 112 enrolled in the study (response rate = 53%; Figure).
Figure 1.
Participant Flow for the Parents and Tots Together intervention study.
Once the baseline assessment was complete, families were randomized to the intervention or control. We used a stratified block randomization scheme; stratum was site (community health center) blocked by child sex; condition was assigned by blocks of 4 in each stratum. The biostatistician (KK) used a pseudo-random number generator to randomly assign the stratified blocks to the intervention and control conditions, beginning at a random point mid-block. Assignments were implemented through opaque sealed sequentially numbered individual envelopes that research staff opened following completion of the baseline assessment. Neither the participants nor the research staff were blinded to the families’ intervention status.
At the end of the 9-week program (post-intervention) and at 9-months from baseline (9-month follow-up), families attended follow-up assessment sessions where parents completed surveys and had their children’s height and weight assessed. To minimize risk of contamination, measurement staff held separate follow-up assessments for families in the intervention and control arms. To minimize reporting bias among participants, the staff who conducted the follow-up measurement were not involved in the delivery of the intervention. Families received a $20 gift card for completing each assessment (baseline, post-intervention, and 9-month follow-up). At the 9-month follow-up, we also held a raffle where one family would win a $100 gift certificate for attending. All study activities were approved by the Institutional Review Board at Harvard Pilgrim Health Care.
Treatment Groups
Control
Families randomized to the control condition were mailed publically available educational materials on promoting healthful behaviors among preschoolers (e.g., My pyramid for preschoolers19) each week for 9 weeks.
Intervention
We have previously described in detail the development of the Parents and Tots Together intervention6 and provide an abbreviated description here. The intervention was guided by the social contextual framework,20 which posits that to be effective, interventions must take into account the social context in which participants live, as well as the key psychosocial constructs that influence behavior. The intervention is a family-based obesity prevention intervention delivered via group sessions. 6 The intervention was informed by formative research, which showed that general parenting issues, e.g., discipline, are of substantial concern and interest to parents of preschool age children. 6 We adapted an existing, empirically-tested general skills parenting program, the Chicago Parent Program (CPP),18, 21 to include lessons related to parental roles in promoting healthy nutrition and activity behaviors among their children. We present an overview of the general parenting and weight-related messages addressed in the Parents and Tots Together intervention in Table 1. In collaboration with the developer of CPP, we condensed the program from 12 to 9 sessions. We condensed two CPP sessions on strategies for reinforcing positive behaviors into one session and two sessions on managing misbehaviour using ignoring, distracting, and time out strategies into one session. The CPP booster session was eliminated based on previous studies suggesting that attendance was low. 18 In addition, we reduced the number of general-parenting vignettes and added vignettes and discussions focused on our weight-related behaviors.
Table 1.
Overview of general parenting and weight-related topic addressed in Parents and Tots intervention.
| Session | General parenting topic addressed | Weight-related topic addressed |
|---|---|---|
| 1 | Child–centered time | Being physically active with your child |
| 2 | Importance of family routines | Sleep: Creating a bedtime routine |
| 3 | Using praise and rewards | Alternatives to using food as rewards |
| 4 | Setting limits | TV: Setting limits on TV |
| 5 | Threats and consequences | When not to use threats: Identifying your child’s hunger and satiety cues |
| 6 | Using ignore and distract strategies | Ignore and provide alternatives: Reducing intake of sugar-sweetened beverages |
| 7 | Stress management | Family-based physical activities |
| 8 | Problem solving skills with adults | Problem solving with partners and other caregivers about child’s health behaviours |
| 9 | Putting it all together | Putting it together: Weight-related behaviours |
Each of the 9, 2-hour intervention sessions were held at a community health center and were led by 1 of 3 facilitators who received 8 hours of training on the curriculum and group facilitation process. All facilitators used a standardized manual and DVD set to deliver the intervention. At each session, facilitators assigned parents weekly homework assignments to enhance skill building and self-efficacy. Size of groups ranged from 9–13 participants. Additionally, we sent home a printed summary of key points discussed at each session to facilitate communication of messages with partners/other caregivers.
To both engage the children and enhance the prevention content, the intervention included an interactive children’s program that ran concurrently with the parent program. Each session focused on a weight-related behavior addressed in the parent program and included: a) reading a related book, b) an activity such as yoga, music/dance, and c) preparing a healthful snack. To further facilitate behaviour change, the children were given items, such as balls or water bottles.22
Outcome measures
Our primary outcome was change in children’s BMI from baseline to 9-month follow-up. We also assessed change in children’s BMI from baseline to post-intervention. Children were asked to remove their shoes and heavy shirts/sweaters and trained research staff measured children’s height using a calibrated stadiometer (Shorr Productions, Olney, MD) and children’s weight using a calibrated electronic scale. We calculated child BMI and age and sex-specific percentiles using the Centers for Disease Control and Prevention 2000 reference data. We chose BMI as the primary anthropometric outcome rather than BMI z-score, as BMI may be preferable for assessing change in adiposity in children.23
Our secondary outcomes included change, from baseline to 9-month follow-up, in children’s weight-related behaviors (i.e., sleep, TV, active play, and sugar-sweetened beverage intake), parent’s feeding behaviors, and parent’s general parenting skills and confidence in parenting. These secondary outcomes were assessed via parent-reported survey.
We assessed children’s sugar sweetened beverage intake using questions from the Children’s Harvard Service Food Frequency Questionnaire.24 To assess children’s television and video viewing, we used a validated measure that was used in the National Longitudinal Survey of Children and Youth.25 To assess children’s physical activity, we asked parents to report separately the number of minutes children spent in active play on weekdays and weekend days. We assessed average sleep duration over a 24 hour period, using a single question, which is associated with risk of obesity among young children.26 We used the Child Feeding Questionnaire to assess 2 parental feeding practices: use of restriction and pressure to eat.27
We used items from the Parenting Questionnaire to assess parenting strategies, specifically warmth (7 of 22 items) and following through on discipline (6 of 6 items).28, 18 We used items from the Toddler Care Questionnaire (20 of 38 items) to assess parental confidence (self efficacy) in managing general tasks and situations relevant to raising young children.29
We kept records of attendance at the intervention sessions. To assess parents’ satisfaction, we asked parents in the intervention group to rate how satisfied they were with the program components and whether they would recommend the program to their family or friends. To monitor intervention fidelity, the facilitators completed weekly checklists. The project manager (JM) and Principal Investigator (JH) also held weekly calls with the facilitators to discuss how the previous session went and to review the content for the following week.
Statistical Methods
Using intent-to-treat analyses, we used separate linear regression models to examine differences between the intervention and control groups from baseline to post-intervention and from baseline to 9-month follow-up. At post-intervention 16% of participants did not provide data and 14% of participants were missing data at the 9-month follow-up. To address missing data, we used chained equations to multiply impute values.30, 31 We generated 50 imputed data sets and combined parameter estimates from each imputed data set.30 We used all 112 participants in the imputation process. The results from the complete case and MI analyses were not substantively different; thus, we present only the MI results. We first ran unadjusted models and then ran models adjusted for sex and age at baseline. We performed all analyses using SAS version 9.3 (SAS Institute).
Results
We randomized 112 parent-child dyads to the intervention (n=56) or control condition (n=56; Figure). A total of 94 (84% of those enrolled at baseline) completed the 9-week post-intervention follow-up assessment and 96 (86% of those enrolled at baseline) completed the 9-month follow-up assessment. At baseline, the mean (SD) age of the children was 3.6 (1.0) years; 43% were overweight or obese (Table 2). Approximately 93% of the parents were mothers and 87% of the study sample had annual household incomes at or below $50,000. Children were primarily Hispanic (59%) or Black/African American (22%).
Table 2.
Baseline socio-demographic characteristics of 112 parents and children in the Parents and Tots Together Study, a randomized controlled trial conducted in the greater Boston area from 2012–2013, overall and by study arma
| Characteristics | Overall N=112 |
Intervention n=56 | Control n=56 |
|---|---|---|---|
| Parent and Household | N (%) or Mean (SD) | ||
| Parental Education, % | |||
| Less than high school | 45 (39.8) | 20 (35.3) | 25 (44.3) |
| High school graduate | 20 (17.6) | 13 (22.7) | 7 (12.5) |
| Some college or more | 48 (42.7) | 24 (42.1) | 24 (43.3) |
| Marital Status, Married/cohabiting, % | 83 (74.0) | 40 (71.6) | 43 (76.4) |
| Household income, % | |||
| $20,000 or less | 52 (46.1) | 28 (50.6) | 23 (41.6) |
| $20,001 to $50,000 | 46 (40.9) | 22 (38.8) | 24 (43.0) |
| > $50,000 | 15 (13.0) | 6 (10.6) | 9 (15.4) |
| Race/ethnicity, % | |||
| Black/African American | 25 (22.2) | 14 (25.2) | 11 (19.3) |
| Hispanic | 66 (59.1) | 34 (60.0) | 33 (58.1) |
| White/Other | 21 (18.7) | 8 (14.9) | 13 (22.6) |
| Relation to Child, % | |||
| Mother | 104 (92.9) | 52 (92.9) | 52 (92.9) |
| Father | 5 (4.5) | 2 (3.6) | 3 (5.4) |
| Step-Mother/Other | 3 (2.7) | 2 (3.6) | 1 (1.8) |
| Child | N (%) or Mean (SD) | ||
| Child age at baseline, years | 3.6 (1.0) | 3.6 (1.0) | 3.6 (0.9) |
| Female, % | 56 (50.0) | 29 (51.8) | 27 (48.2) |
| Child BMI at baseline | 17.3 (2.4) | 17.5 (2.6) | 17.2 (2.1) |
| Overweight/obese at baseline, % | 48 (43.1) | 23 (41.7) | 25 (44.6) |
Multiple imputation was used, no missing values. Baseline socio-demographics from complete case and multiple imputation did not differ substantively, so only the multiple imputation demographics are presented.
At 9-month follow-up, BMI decreased by a mean of 0.13 kg/m2 among children in the intervention arm and increased by 0.21 kg/m2 among children in the control arm, with an unadjusted difference of −0.34 (95% CI −1.21, 0.53) (Table 3). After adjusting for child sex and age, the difference was minimally changed (−0.36; 95% CI −1.23, 0.51; P = 0.41).
Table 3.
Change in BMI, child weight-related behaviors , parental feeding practices, and general parenting outcomes from baseline to post-intervention and baseline to 9-month follow-up by intervention assignmenta
| Baseline | Post- intervention |
Change at post- intervention |
Crude Difference |
Adjusted | 9-month follow-up |
Change at 9-month follow-up |
Crude Difference |
Adjusted | |||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Mean (SD) | Mean (SD) | Mean (SD) | β (95% CI) | β (95% CI)b | P-value | Mean (SD) | Mean (SD) | β (95% CI) | β (95% CI)b | P-value | |
| BMI outcomes | |||||||||||
| Child BMI, kg/m2 | |||||||||||
| Intervention | 17.5 (2.6) | 17.8 (3.4) | 0.32 (2.35) | 0.18 (−0.57,0.93) | 0.18 (−0.58, 0.93) | 0.64 | 17.3 (3.3) | −0.13 (2.56) | −0.34 (−1.21, 0.53) | −0.36 (−1.23, 0.51)c | 0.41 |
| Control | 17.2 (2.1) | 17.3 (2.0) | 0.14 (1.19) | 17.4 (1.9) | 0.21 (1.57) | ||||||
| Child BMI z-score | |||||||||||
| Intervention | 0.88 (1.40) | 1.07 (1.32) | 0.19 (1.18) | 0.06 (−0.36, 0.48) | 0.06 (−0.36, 0.48) | 0.78 | 0.82 (1.11) | −0.06 (1.34) | −0.25 (−0.75, 0.26) | −0.25 (−0.75, 0.25) | 0.33 |
| Control | 0.79 (1.36) | 0.92 (1.19) | 0.13 (0.82) | 0.98 (1.03) | 0.19 (1.02) | ||||||
| Child behaviors d | |||||||||||
| Sleep, h/d | |||||||||||
| Intervention | 10.1 (1.5) | 10.4 (1.5) | 0.34 (1.98) | 0.22 (−0.59, 1.03) | 0.23 (−0.58, 1.03) | 0.58 | 10.5 (1.3) | 0.43 (1.91) | 0.47 (−0.34, 1.28) | 0.46 (−0.35, 1.26) | 0.26 |
| Control | 10.1 (1.4) | 10.3 (1.7) | 0.12 (1.81) | 10.1 (1.6) | −0.04 (1.99) | ||||||
| Television, h/d | |||||||||||
| Intervention | 2.2 (1.2) | 1.9 (0.9) | −0.38 (1.23) | −0.08 (−0.56,0.41) | −0.08 (−0.56,0.40) | 0.74 | 1.8 (0.8) | −0.47 (1.24) | −0.21 (−0.73, 0.31) | −0.22 (−0.74, 0.31) | 0.41 |
| Control | 2.3 (1.4) | 2.0 (1.2) | −0.31 (1.02) | 2.0 (1.2) | −0.26 (1.38) | ||||||
| Active play, h/d | |||||||||||
| Intervention | 2.4 (2.0) | 1.3 (0.8) | −1.13 (1.84) | −0.37 (−1.04,0.30) | −0.36 (−1.03,0.31) | 0.29 | 2.3 (1.8) | −0.17 (2.34) | −0.28 (−1.16, 0.59) | −0.27 (−1.15, 0.60) | 0.54 |
| Control | 2.1 (1.2) | 1.3 (0.9) | −0.76 (1.37) | 2.2 (1.7) | 0.11 (1.92) | ||||||
| Sugar sweetened beverages, servings/d | |||||||||||
| Intervention | 2.4 (1.9) | 1.7 (1.5) | −0.73 (2.22) | −0.53 (−1.48,0.41) | −0.54 (−1.49,0.41) | 0.26 | 2.1 (2.1) | −0.38 (2.36) | −0.19 (−1.12, 0.73) | −0.21 (−1.13, 0.71) | 0.65 |
| Control | 2.5 (1.8) | 2.3 (2.0) | −0.20 (2.44) | 2.3 (1.9) | −0.19 (2.25) | ||||||
| Parental feeding practices | |||||||||||
| Restriction | |||||||||||
| Intervention | 3.0 (0.5) | 2.7 (0.6) | −0.32 (0.61) | −0.28 (−0.53,0.03) | −0.27 (−0.52,0.03) | 0.03 | 2.7 (0.5) | −0.28 (0.56) | −0.30 (−0.53,−0.07) | −0.30 (−0.53,−0.07) | 0.01 |
| Control | 2.9 (0.5) | 2.9 (0.5) | −0.04 (0.56) | 2.9 (0.5) | 0.01 (0.54) | ||||||
| Pressure to eat | |||||||||||
| Intervention | 2.6 (0.7) | 2.5 (0.7) | −0.14 (0.75) | 0.08 (−0.21, 0.38) | 0.08 (−0.21, 0.37) | 0.59 | 2.5 (0.7) | −0.11 (0.62) | 0.08 (−0.16, 0.33) | 0.08 (−0.16, 0.33) | 0.52 |
| Control | 2.7 (0.6) | 2.5 (0.5) | −0.23 (0.59) | 2.5 (0.6) | −0.20 (0.55) | ||||||
| Parenting self- efficacy | |||||||||||
| Confidence in general parenting | |||||||||||
| Intervention | 53.8 (8.7) | 56.6 (7.4) | 2.80 (8.79) | −0.65 (−4.61,3.32) | −0.68 (−4.65,3.29) | 0.74 | 56.2 (8.3) | 2.35 (9.68) | −1.37 (−5.26, 2.52) | −1.43 (−5.32, 2.46) | 0.47 |
| Control | 52.0 (9.8) | 55.5 (8.1) | 3.45 (11.0) | 55.7 (8.4) | 3.72 (8.97) | ||||||
| General parenting practices | |||||||||||
| Warmth | |||||||||||
| Intervention | 26.7 (3.6) | 27.5 (3.6) | 0.72 (3.20) | 0.43 (−0.84, 1.69) | 0.43 (−0.84, 1.71) | 0.50 | 27.2 (2.7) | 0.43 (3.08) | 0.76 (−0.56, 2.09) | 0.76 (−0.57, 2.09) | 0.26 |
| Control | 26.8 (3.6) | 27.1 (3.7) | 0.29 (2.87) | 26.5 (3.4) | −0.34 (3.22) | ||||||
| Following through on discipline | |||||||||||
| Intervention | 23.6 (5.3) | 25.4 (4.4) | 1.82 (4.49) | 0.63 (−1.27, 2.54) | 0.66 (−1.25, 2.57) | 0.49 | 25.3 (5.4) | 1.70 (4.94) | 0.42 (−1.51, 2.34) | 0.45 (−1.46, 2.35) | 0.64 |
| Control | 23.7 (4.4) | 24.9 (4.3) | 1.18 (4.12) | 25.0 (4.6) | 1.28 (4.33) |
Statistically significant results are bolded
Adjusted for child age at baseline and child sex
Primary outcome
Secondary outcomes
Although changes in children’s weight-related behaviors, i.e., sleep, TV, active play, and sugar-sweetened beverage intake, were in the desired direction at 9-month follow-up, confidence intervals substantially overlapped zero (Table 3). For example, sleep duration increased by a mean of 0.43 hours/day among children in the intervention arm and was virtually unchanged (−0.04 hours/day) among children in the control arm, with an adjusted difference of 0.46 (95% CI −0.35, 1.26; P = 0.26; Table 3).
Intervention parents decreased their use of restrictive feeding behavior more than parents in the control arm at 9-month follow-up (−0.30; 95% CI −0.53,−0.07; P = 0.01; Table 3). We did not observe an intervention effect on pressure to eat.
Parents in the intervention and control arms experienced similar mean changes in parental confidence (self-efficacy) with general parenting (adjusted intervention-control mean = -1.43; 95% CI −5.32, 2.62; P = 0.47), and similar mean changes in level of parental warmth (adjusted intervention-control mean = 0.76; 95% CI −0.57, 2.09; P = 0.26) and following through on discipline (adjusted intervention-control mean = 0.45; 95% CI −1.46, 2.35; P = 0.64; Table 3).
We aimed for intervention participants to attend 9 intervention sessions. Among the 56 families randomized to the intervention arm, 52% attended 6 or more of the 9 sessions, 11% attended 3 to 5 sessions, and 37% attended 2 or fewer of the sessions. Based on intervention participants’ responses to the follow-up process survey questions, 96% reported being “very satisfied” with the parent program, 71% being “very satisfied” with the children’s program, and 96% reported they would highly recommend the program to a friend or family member. Reports from facilitators suggest that all intervention content was covered. Parents and Tots Together was a low-risk intervention. We assessed physical risk associated with participating in the children’s program activities; there were no adverse events.
Discussion
We report findings from a trial of an innovative family-based obesity prevention intervention, in which we embedded strategies to improve children’s weight-related behaviors within a general skills parenting program, among low-income, racial/ethnic minority families. At 9-month follow-up, children in the intervention arm did not show decreased mean BMI relative to controls (primary outcome). Parents who received the intervention reduced their use of restrictive feeding behaviors as compared to parents in the control arm at post-intervention and 9-month follow-up, but there were no differences in children’s diet, activity, sleep and sedentary behaviours at either time point.
Our approach of embedding weight-related messages within a parenting intervention for primary obesity prevention is novel. A recent review of obesity prevention interventions for preschool-aged children32 identified that such an approach may be effective given the influence general parenting practices may have on children’s weight-related behaviors, but that there is a paucity of prevention trials testing this approach. Engaging families in health promotion interventions is challenging and our use of a prevention intervention that builds on parents’ identified interests. i.e., general parenting, is a type of “stealth” intervention that could be more effective than direct messaging.
Our adjusted mean difference in BMI of −0.36 (BMIz −0.25) was smaller than that found by Harvey-Berino and Rourke in their pilot study, in which the crude mean difference for weight-for-height z-score was 0.58.13 Ostbye and colleagues14 found no change in BMI z-score among children in the intervention (0.03) or control (−0.02) in their randomized controlled trial. Several factors may have contributed to the lack of a significant intervention effect on BMI. First, our intervention may not adequately address behavior change regarding children’s weight-related behaviours, i.e., diet, activity, sedentary time, and sleep. Although we developed intervention content focused on each weight-related behavior, there was less weight-related content compared to parenting. Thus, the dose of weight-related messages may not have been sufficient to change those behaviors. Future prevention research exploring the use of an integrated approach that addresses general parenting and weight-related behaviours may need to increase the length of the intervention and ensure that behavior change messages regarding weight-related behaviors are adequately addressed and reiterated throughout the intervention. Second, parent attendance at intervention sessions was not perfect; 37% attended 2 or fewer of the sessions. Although these participation rates are similar to other community-based interventions,14,18 low attendance rates may have diminished the effectiveness of the intervention. Third, it is possible that our strategy of engaging families in a primary prevention intervention whose slogan was “helping raise healthy, happy children” resulted in families who were not sufficiently primed to receive the weight- related messages. In a treatment context in which clinicians have identified children as obese, 9,12 families may be more motivated to aid their children in developing healthful weight-related behaviors than in a prevention context. In the current study, we did not assess how level of engagement with the intervention content affected the effect of the intervention.33 Future interventions should test how best to prime and engage parents to change their children’s weight-related behaviors within a prevention context.
Similar to our findings, the intervention tested by Ostbye and colleagues reduced restrictive feeding practices among parents who received the intervention as compared to controls, but had minimal effect on children’s weight-related behavior. Harvey-Berino & Rourke found similar results.13 Taken together, these results suggest that obesity prevention interventions that address general parenting strategies may be able to effectively change parental restrictive feeding practices. This may be because the messages regarding restrictive feeding practices (i.e., not using food as rewards for behavior) fit well within the context of general parenting messages (i.e., use of effective strategies to guide behavior).
Our lack of intervention effect on our general parenting outcomes differs from previous trials of the Chicago Parent Program, which did find intervention effects for parental confidence and following through on discipline.18 These results further support the idea of increasing the length of the intervention to ensure adequate dose to change parenting, as well as weight-related, behaviours. Follow-up or maintenance support may also improve outcomes and should be tested in future trials.
This study had several limitations. First, although we used validated measures to assess our behavioral outcomes, many are subject to large variability, which could have biased results towards the null. For this reason, we used BMI as our primary outcome. Second, of the 211 families that were identified as eligible, 112 enrolled in the study. It is unclear how our results would generalize to those who did not enroll. Third, our control group is an assessment-only control. This design does not allow us to assess the extent to which the general parenting or the weight-related content individually influenced our outcomes.
Finally, the study was powered to detect a difference of 0.55 BMI units between the two groups using 180 families to achieve 80% power. Recruitment was more difficult than anticipated and we were not able to achieve the targeted enrolment. The observed effect size was also smaller than the anticipated effect. A trial planned with 112 families and a difference of 0.36 BMI units would have an anticipated power of 0.60 . It is likely that a larger sample size would have found that the intervention and control arms differed with the observed effect sizes. However, this statement could be made for any effect size; thus, rather test the current intervention with a larger sample, future efforts in this area should focus on developing interventions that can achieve larger effects by ensuring that interventions adequately address both general parenting skills and weight-related behaviors and that parents are appropriately primed for behavior change in both areas.
In summary, nearly 7-months after a 9-week intervention, the Parents and Tots Together intervention improved restrictive feeding behaviors among racial/ethnic minority parents of preschool age children but did not result in improvements in children’s BMI or diet, activity, sleep or sedentary behaviors, when compared with controls who received weekly mailings. Future studies that address general parenting and weight-related behaviors for obesity prevention should test interventions that adequately prime parents for changing weight-related behaviors and that provide a stronger dose of weight-related and parenting behavior change messages.
Acknowledgments
Funding: This work was supported by Robert H. Ebert Fellowship, Eleanor and Miles Shore Scholars in Medicine Program, Department of Population Medicine, Faculty Scholars Grant and American Heart Association, Scientist Development Grant, National Affiliate (09SDG2050153), and National Institutes of Health (K24 HL 060804; Gillman).
Footnotes
Financial Disclosure: The authors have no financial relationships relevant to this article to disclose.
Conflict of Interest: The authors have no conflicts of interest to disclose.
Author Contributions: JH had full access to the study data and takes responsibility for the integrity of the data and accuracy of data analysis. JH, MWG, KK, and DG and obtained funding for the project. JH led the conception and design of the study. JH and JM were involved in data acquisition. All authors were involved in the interpretation of the data. All authors critically reviewed and revised the manuscript for important intellectual content and approved the final version of the paper.
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