Abstract
Objective:
To test if the INSIGHT responsive parenting (RP) intervention, delivered to parents of firstborns, is associated with the body mass index (BMI; kg/m2) of first and secondborn siblings during infancy.
Methods:
Participants included 117 firstborn infants enrolled in a randomized controlled trial, and their secondborn siblings enrolled in an observation only ancillary study. The RP curriculum for firstborns included guidance on feeding, sleep, interactive play, and emotion regulation. The control curriculum focused on safety. Anthropometrics were measured in both siblings at ages 3, 16, 28 and 52 weeks. Growth curve models for BMI by child age were fit.
Results:
Secondborns were delivered 2.5±0.9 years after firstborns. Firstborns and secondborns whose parents received the RP intervention with their first child had BMIs that were 0.44 kg/m2 95% CI [−0.82, – 0.06] and 0.36 kg/m2 95%CI [ −0.75, 0.03] lower than controls, respectively. Linear and quadratic growth rates for BMI for firstborn and secondborn cohorts were similar, but secondborns had a greater average BMI at one year of age (difference = −0.33 kg/m2, 95%CI [−0.53, −0.12]).
Conclusion:
A RP educational intervention for obesity prevention intervention delivered to parents of firstborns appears to spill-over to secondborn siblings.
Keywords: obesity prevention, infancy, responsive parenting, siblings, birth order
Introduction
Behavioral interventions with a responsive parenting (RP) framework have proven to be protective against infant overweight for firstborns,1 however these home delivered interventions are resource intensive. The Intervention Nurses Start Infants Growing on Healthy Trajectories (INSIGHT) trial is a randomized clinical trial comparing an early life RP intervention for the primary prevention of obesity against a safety control among first-time mother-infant dyads.2 The INSIGHT RP intervention includes guidance on feeding, sleep, interactive play, and emotion regulation. Firstborn infants randomized to INSIGHT’s RP intervention had slower weight gain during the first 6 months after birth, reduced overweight at age 1 year,3 and lower mean body mass index (BMI) z-scores at age 3 years compared with controls.4
While positive findings among firstborn participants are encouraging, the majority (80%) of parents in the United States have more than one child.5 Interestingly, studies from diverse cultures are relatively consistent in describing that firstborn children have a higher prevalence of obesity than subsequent children with the same parents, despite secondborns being more likely to experience an adverse prenatal environment characterized by higher maternal pre-pregnancy BMI, risk for gestational diabetes, and higher birthweight.6–9 However, obesity and its prevention are relevant issues for all children in today’s obesogenic environment regardless of birth order.
The aim of this analysis was to assess impact of the INSIGHT RP intervention on the growth of consecutively born siblings enrolled in the randomized, controlled INSIGHT trial with the firstborn and in an observation-only cohort study for the secondborn who received no booster messaging. Based on prior findings, the hypotheses were: 1) rate of growth for firstborn and secondborn siblings would be similar within each study group, 2) firstborns would be heavier than secondborns, 6–9 3) secondborns whose parents received the RP intervention with their firstborn would have lower BMIs compared to controls, but 4) for secondborns, the association between RP intervention and infant BMI would be stronger in mothers who had shorter spacing between births (e.g., less time since receiving intervention material).10
Methods
INSIGHT intervention study –firstborns
The Intervention Nurses Start Infants Growing on Healthy Trajectories (INSIGHT) is a randomized, clinical trial that provided first-time mothers with guidance on RP to reduce rapid weight gain in infancy and establish healthy growth trajectories during early life.2 First-time mothers and their infants were recruited after birth from a single maternity ward between January 2012 and March 2014. Major eligibility criteria were full-term (≥37 weeks’ gestation), singleton newborns delivered to English-speaking, primiparous mothers 20 years and older. Infants born <2500g were excluded. Mother and firstborns were randomized to the RP or home safety intervention (control) group 10 to 14 days after delivery. Research study nurses delivered intervention curricula to first-time mothers (n=279) in home, at 3, 16, 28, and 40 weeks followed by annual clinical research visits from ages 1-3 years. More details on study design, recruitment/eligibility, measures and a CONSORT diagram have been previously published.2,3
SIBSIGHT observational study – Secondborn children
INSIGHT mothers who gave birth to a second child between June 2013 and March 2017 were invited to participate in the observational cohort, SIBSIGHT. Secondborns were eligible if they were singleton, ≥36 weeks’ gestation, and ≥2250 g, with no medical conditions that would impact feeding, and if families had no plans to move from Central Pennsylvania in the year following the second child’s birth. Further details on recruitment and eligibility have been published elsewhere.2,11 No intervention was delivered at SIBSIGHT study visits. Both INSIGHT and SIBSIGHT studies were approved by the Human Subjects Protection Office of the Penn State College of Medicine and registered at www.clinicaltrials.gov (NCT01167270) prior to enrollment of the first participant. Mothers provided written consent for their own and their children’s participation.
RP intervention components in firstborns
A detailed description of the RP and control intervention components delivered to firstborns has been published elsewhere.2 The RP intervention included guidance on infant feeding, sleep, interactive play, and emotional regulation and how to respond to their child’s needs across 4 behavioral states: drowsy, sleeping, fussy, and alert. Following randomization, mothers in the RP group were mailed initial intervention content to be reviewed and practiced prior to the first study visit. The control group of firstborns received a home safety intervention that was matched to INSIGHT for equivalent time (dose) and intensity. For example, early visits included developmentally relevant information on prevention of sudden infant death syndrome for sleep, breastmilk storage and formula preparation for feeding, and safe bathing of infants as part of the drowsy time guidance, among others.
Measures
Background characteristics.
Family demographic information was collected at firstborn enrollment and updated at secondborn enrollment, and was classified by participants (e.g., race/ethnicity, income, marital status). Medical chart abstraction was performed to obtain maternal age, pre-pregnancy weight, gestational weight gain, and infant gestational age and sex. Data were collected and managed using REDCap (20).
Anthropometrics.
Trained research staff obtained firstborn and secondborn infant recumbent length and weight at 3, 16, 28, and 52 weeks. Weight was measured in duplicate to the nearest 0.1 kg using an electronic scale (Seca 354 or Seca 874; Seca). Length was measured to the nearest 0.1 cm using a recumbent length board (Shorr Productions). Additional measurements were taken until 2 measurements differed by no more than 0.1 kg or 1 cm, and means of the measurements were used for analysis. Child body mass index (BMI) was calculated as weight in kilograms divided by height in meters squared.
Statistical analysis
Multilevel mixed effects models were used to model BMI growth over time. Separate growth curves for BMI by child age in months were fit for the firstborn and secondborn cohorts. The models included effect of child sex, and linear and quadratic fixed effects for age and random linear slopes. Intervention group was a person-level predictor. For the secondborn cohort, we tested the interaction between birth spacing, calculated as the difference in birthdates from the firstborn to the secondborn, and RP intervention. Within person random intercepts and slopes were calculated for each model (i.e., firstborn and secondborns), and those slopes were correlated to test the degree of similarity of growth within family. The models allow us to 1) compare growth rates between the firstborn and secondborns; 2) test whether secondborns had lower BMIs at 12 months; 3) test the association between RP intervention and BMI in the secondborn cohort; and 4) test if sibling birth spacing influenced the association between RP intervention and secondborn BMI. An unstructured covariance structure and maximum likelihood estimation were utilized. Bootstrapped confidence intervals for comparing results from the firstborn and secondborn models were generated by resampling the participant IDs with replacement (N = 1000) and rerunning the models. This technique generated the 95% CIs for the difference in estimated 12-month BMI, the difference in intervention effects, and the correlation of the random effects. Lastly, a three-level quadratic growth curve model was fit to the combined 234 first and secondborn siblings. Level 3 (family) predictors were intervention group (coded −0.5 = control, 0.5 = responsive parenting), level 2 (sibling) predictors were birth order (coded −0.5 = first born, 0.5 = second born) and child sex (coded −0.5 = male, 0.5 = female), and level 1 predictors were linear and quadratic child age. Random intercepts for family and sibling as well as random slopes for age were included to model heterogeneity between and within families in intercept and slope. An unstructured covariance structure and maximum likelihood estimation were utilized. Step 1 tested the main effects and Step 2 tested the interaction between intervention group and birth order. Covariates tested and excluded from all models were maternal age at recruitment, maternal pre-pregnancy BMI, marital status, and family income. For all tests, significance was defined as P < .05. Analyses were conducted in SAS version 9.4.
Results
A total of 117 secondborns were enrolled and all remained in the study through age 12 months (100% retention). Of the 117 secondborn participants, 57 had firstborn siblings randomized to the RP study group, while 60 had siblings in the control group (Figure 1). Demographic characteristics for the 117 mothers, firstborns, and secondborns are presented in Table 1. As expected, mothers were older at the birth of their second child, with a mean of 2.5 (SD 0.8, range 0.9-5.1) years between births. Among the 117 sibling dyads, no mothers reported a change in their educational status between births, and the majority were college-educated and married with household incomes ≥$50,000 at both births. Infant sex data show that 47% and 43% of firstborn and secondborn infants, respectively, were male. Mean gestation age for secondborn infants was 39.4 weeks (SD 0.03, range 37.1 – 41.7); no secondborn was enrolled <37 weeks gestation or born <2500 grams. There was no difference between firstborns and secondborns in birth weight or sex distribution. Mean spacing of secondborn births was 28.6 months 95%CI [25.9, 31.3] in the responsive parenting group and 31.6 months 95% CI [29.0, 34.2] in the control group. Weight-for-age z-scores, weight-for-length z-scores and BMI were all found to graphically approximate normal distributions by Shapiro-Wilk test for normality.
Figure 1.
SIBSIGHT Consort Diagram
Table 1:
Firstborn (n=117) and secondborn (n=117) demographics by study group
| Firstborns (n=117) | Secondborns (n=117) | |||
|---|---|---|---|---|
| Responsive Parenting Group (n = 57) | Control Group (n = 60) | Responsive Parenting Group (n = 57) | Control Group (n = 60) | |
| Infant | ||||
| Male sex, N (%) | 27 (47.4) | 28 (46.7) | 22 (38.6) | 28 (46.7) |
| Gestational age (weeks), mean (SD) | 39.6 (1.2) | 39.5 (1.1) | 39.3 (1.1) | 39.4 (0.9) |
| Birth weight (kg), mean (SD) | 3.4 (0.4) | 3.5 (0.4) | 3.4 (0.4) | 3.5 (0.4) |
| Birth length (cm), mean (SD) | 50.9 (2.4) | 51.0 (2.1) | 51.1 (2.2) | 51.1 (2.2) |
| Mother | ||||
| Age (years), mean (SD) | 29.8 (4.4) | 28.4 (4.0) | 32.1 (4.2) | 31.1 (4.1) |
| Pre-pregnancy BMI (kg/m2), mean (SD) | 24.8 (4.7) | 25.3 (5.4) | 25.8 (5.1) | 26.0 (6.0) |
| Gestational weight gain (kg), mean (SD) | 14.9 (5.6) | 14.6 (5.1) | 11.1 (5.5) | 11.3 (6.5) |
| Diabetes during pregnancy, N (%) | 2 (4) | 8 (12) | 3 (5) | 6 (10) |
| Smoked during pregnancy, N (%) | 5 (9) | 2 (2) | 2 (4) | 1 (2) |
| Spacing between siblings (years), mean (SD) | - | - | 2.4 (0.9) | 2.6 (0.8) |
| Met birth spacing recommendations N (%) | - | - | 49 (86) | 57 (95) |
| Race, N (%) | ||||
| Black | 2 (4) | 1 (2) | 2 (4) | 1 (2) |
| White | 53 (93) | 58 (97) | 53 (93) | 58 (97) |
| Asian | 2 (4) | 1 (2) | 2 (4) | 1 (2) |
| Ethnicity, N (%) | ||||
| Hispanic/Latino | 0 (0) | 1 (1.7) | 0 (0) | 1 (1.7) |
| Non-Hispanic/Latino | 56 (100) | 59 (98) | 56 (100) | 59 (98) |
| Marital status, N (%) | ||||
| Married | 53 (93) | 54 (90) | 55 (97) | 56 (93) |
| Not married, living with partner | 3 (5) | 3 (5) | 2 (4) | 3 (5) |
| Single | 1 (2) | 3 (5) | 0 (0) | 1 (2) |
| Annual household income, N (%) | ||||
| < $10,000 | 1 (2) | 2 (3) | 1 (2) | 0 (0) |
| $10,000-$24,999 | 4 (7) | 2 (3) | 0 (0) | 1 (2) |
| $25,000-$49,999 | 1 (2) | 7 (12) | 2 (4) | 4 (7) |
| $50,000-$74,999 | 19 (33) | 13 (22) | 13 (24) | 13 (24) |
| $75,000-$99,999 | 16 (28) | 8 (13) | 17 (32) | 9 (16) |
| $100,000 or more | 16 (28) | 25 (42) | 20 (39) | 28 (51) |
| Education, N (%) | ||||
| HS graduate | 3 (5) | 5 (8) | 3 (5) | 5 (8) |
| Some college | 11 (19) | 9 (15) | 11 (19) | 9 (15) |
| College graduate | 25 (44) | 30 (50) | 25 (44) | 30 (50) |
| Graduate degree + | 18 (32) | 16 (27) | 18 (32) | 16 (27) |
Compare growth rates between firstborn and secondborn cohorts.
Results from the quadratic growth curve models are presented in Table 2. Fixed effects for linear and quadratic growth were the same in both the firstborn and secondborn cohorts. Estimates are negative since age was coded as zero at 12 months. Correlation analysis revealed that the random intercepts and random slopes for firstborn and secondborn BMI were correlated at r = .40 bootstrapped 95%CI [0.31, 0.49], and r = 0.36 95%CI [0.26, 0.46] respectively, indicating a high degree of within-family similarity in growth rates after fitting the common growth pattern. The three-level analysis (n=234 first and secondborn siblings) revealed similar results (See Appendix 1). There were significant main effects of intervention group, child age, child sex, and birth order (step 1), but no intervention group by birth order interaction (step 2) indicating that the protective effect of the RP intervention on BMI did not differ between first and secondborns.
Table 2.
Growth curve models associated with first and secondborn BMI (kg/m2) (n=117 for each sibling class)
| Firstborn Model (n=117) | Secondborn Model (n=117) | |||
|---|---|---|---|---|
|
|
|
|||
| Γ | 95% CI | γ | 95% CI | |
|
| ||||
| Fixed Effects | ||||
|
| ||||
| Intercept | 17.17*** | [16.89, 17.45] | 17.51*** | [17.24, 17.77] |
|
| ||||
| Child sex | −0.39 * | [−0.77, −0.008] | −0.23 | [−0.63, 0.16] |
|
| ||||
| Age (months) | −0.32*** | [−0.37, −0.26] | −0.32*** | [−0.37, −0.26] |
|
| ||||
| Age2 (months) | −0.05*** | [−0.06, −0.05] | −0.05*** | [−0.06, −0.05] |
|
| ||||
| Intervention | −0.44* | [−0.82, −0.06] | −0.36 | [−0.75, 0.03] |
|
| ||||
| Random Effects | ||||
|
| ||||
| Intercept Var | 1.91*** | [1.34, 2.49] | 1.60*** | [1.06, 2.14] |
|
| ||||
| Slope Var | 0.01*** | [0.004, 0.012] | 0.005** | [0.001, 0.008] |
|
| ||||
| Slope Covar | 0.09*** | [0.05, 0.14] | 0.06** | [0.02, 0.10] |
|
| ||||
| Residual Var | 0.56*** | [0.48, 0.64] | 0.64*** | [0.52, 0.76] |
Note:
p < 0.05,
p<.01;
p<.001.
For analysis, child age (in months) was mean centered at one year. Intervention was coded as −0.5 = control, 0.5 = responsive parenting. Child sex was coded as males=−0.5 and females=0.5. Models were estimated using maximum likelihood estimation and an unstructured covariance matrix. The model for firstborns was estimated based on 585 observations from 117 firstborns, and the model for secondborns was estimated based on 466 observations from 117 secondborns.
Compare firstborn and secondborn BMI at age 12 months.
The average BMI for the firstborn cohort at age 12 months was 17.17 kg/m2, (95% CI [16.89, 17.45] and for the secondborn cohort it was 17.51 kg/m2 (95% CI [17.24 17.77]. BMI was greater, on average for both firstborn and secondborn males (data not shown). The hypothesis that secondborns would have lower BMI relative to firstborn was not supported. The model estimated 12-month BMI was significantly greater for secondborns (difference = 0.33, bootstrapped 95% CI [0.15, 0.52]).
Association between treatment and BMI in firstborn and secondborn cohorts.
The estimated intervention effect for the firstborn cohort was 0.44 (95% CI [−0.82, −0.06] and for the secondborn it was 0.36 (95%CI [−0.75, 0.03]). We find that the estimated RP intervention effect for obesity prevention on the secondborn children was similar in magnitude to that of the firstborns. The 95% CI for the secondborn spillover effect does cross 0 by .03. There was no significant difference between the firstborn and secondborn estimated effect size.
Influence of sibling birth spacing on secondborn BMI.
The main effect for sibling birth spacing to the secondborn cohort growth model was non-significant (β=0.0, 95%CI [−.02, .02]). There was no interaction between sibling birth spacing and treatment on secondborn BMI (β=0.01, 95%CI [−.05, .02]).
Discussion
Consistent with our hypotheses, the INSIGHT RP intervention is associated with growth of both firstborn and secondborn siblings. At age 1 year, firstborn and secondborn infants of parents who received the RP intervention had BMIs that were .44 kg/m2 and .38 kg/m2, respectively, lower than infants of parents who did not receive the RP intervention. Correlation of the random linear slopes for BMI change between firstborn and secondborn infants indicated a high degree of within-family similarity in growth. In contrast to our hypothesis, firstborn infants were not significantly heavier than secondborns in this sample. Together, these findings suggest that the INSIGHT RP curriculum for firstborns was robust enough to influence the weight of secondborns. This is remarkable because mothers of secondborns received no INSIGHT RP booster messaging in the observation-only evaluation.
It was expected that interventions that aim to improve parenting skills such as monitoring, sensitivity, and appropriate limit setting that is structured and predictable (i.e., responsive parenting) for one child would likely “trickle down” or “spill-over” and influence sibling developmental outcomes. The findings presented in this manuscript make INSIGHT the first educational intervention for obesity prevention delivered to parents of firstborns to demonstrate spill-over to subsequent offspring. The developmental and parenting literature supports our findings of intervention spill-over effects on younger siblings’ cognitive and behavioral development. For example, family-based interventions that target the older sibling result in higher IQs,12 higher educational attainment, and reductions in crime among non-targeted younger siblings.13 Similarly, Brotman and colleagues found parenting interventions with preschool aged children improved non-targeted, older adolescent siblings’ peer relationships and reduced antisocial behavior.14,15 INSIGHT RP guidance given to mothers of firstborns also prevented the use of nonresponsive, controlling feeding practices while establishing consistent feeding routines 11 and positively influenced sleep health16 in subsequent siblings.
Together, these data support the notion that improving parenting stills for one child may likely have the benefit of improved parenting with all children in the family, including siblings who are not directly involved in treatment.
Previous data suggest that first-born children have a higher prevalence of obesity than subsequent children with the same parents.6–9 However, there are a lack of prospective within family sibling studies in the obesity literature. In contrast, findings from this prospective longitudinal study show that secondborns tended to be heavier on average than their older, firstborn siblings at 12 months. One potential explanation for this finding is that parents must divide their time, resources, attention and affection, after the birth of a sibling, based on their needs and demands, which may impact caregiving.17 For example, studies show that mothers spend significantly less time in social, affectionate, and caregiving interactions with their secondborns than they had with their firstborns.18 Mothers of firstborns are also more likely to use restrictive or coercive parenting practices,19 and tend to be more interfering, extreme in response, and inconsistent with parenting response than mothers with their later born children.20 In contrast, others studies report that inexperienced, first-time mothers tend to respond less to cues of the infants (i.e., less responsive),21 and to feed their infants significantly more frequently and for longer duration than multiparous mothers.22 More prospective, longitudinal data are needed to better understand family and sibling influences on child health outcomes, including weight.
The resource dilution theory suggests that parents may be less responsive to secondborns. In contrast to this hypothesis, when testing the generalizability of RP intervention messaging on non-targeted siblings independent of firstborns, results revealed the fixed effect for intervention group for secondborns were similar in magnitude to the firstborns. In other words, the INSIGHT RP intervention worked for both firstborn and secondborn siblings. A common criticism of resource intensive interventions such as INSIGHT that are delivered in the home is the lack of sustainability and scale up, however, findings from this study demonstrate a continued benefit to later born siblings and a potential cost-effective strategy to prevent obesity within a family. Despite firstborn infants being randomized to the intervention and control condition, it is important to consider that genetic and shared environmental influences within families may account for similar growth patterns within firstborn and secondborn dyads. Therefore, shared genetic and environmental factors may be potential unmeasured confounders impacting firstborn results that could also “spill-over” to the secondborn infant.
Contrary to our interaction hypothesis, birth spacing was not associated with secondborn growth. We expected that women would retain less information that they learned with their firstborns with greater birth spacing because more time passed since receiving the intervention. However, our birth spacing variable was restricted based on recruitment from June 2013-March 2017 and may not represent all possible spacing and fadeout effects. Another limitation is that our participants are mostly white, with a limited sample of low-income families, which limits the generalizability of our findings. Lastly, because of our limited sample size of sibling dyads, we were not powered to detect multiple interactions within the same model. For example, testing the effect of sibling sex differences, birth order, and study group interactions on sibling growth would require a larger sample.
The INSIGHT RP intervention, delivered to mothers of firstborns, appears to influence growth in the secondborn sibling. This multicomponent intervention not only affected various outcomes in firstborns, but results suggest some “spill-over” of the RP intervention into the observation-only cohort of secondborns. The 0.38 kg/m2 difference in BMI in secondborns is greater than the 0.20 to 0.25 difference suggested by the US Preventive Services Task Force as a threshold for a clinically important difference. Findings from this study suggest that intervening with first-time mothers may be an effective way to promote healthy growth trajectories in subsequent siblings.
Supplementary Material
What is already known about this subject?
Responsive parenting interventions, such as INSIGHT, for overweight prevention have shown promise among firstborn children. While positive findings for firstborns are encouraging, approximately 80% of firstborn children have at least one sibling. Obesity and its prevention are relevant issues for all children, regardless of birth order.
What are the new findings in your manuscript?
In an observation only ancillary study, secondborn infants with parents who were randomized to receive the responsive parenting intervention with their firstborns had BMIs that were .36 kg/m2 lower at age 1 year than secondborn infants with parents who did not receive the intervention.
How might your results change the direction of research or the focus of clinical practice?
Although home delivered parenting interventions are resource intensive, their protective effect on child weight appears to spill-over to secondborn siblings.
Acknowledgements
The authors acknowledge
Jessica Beiler, MPH, Penn State College of Medicine
Jennifer Stokes, BSN, RN, CCRN, Penn State College of Medicine
Patricia Carper, RN, BSN, CCRN, Penn State College of Medicine
Amy Shelly, LPN, Penn State College of Medicine
Lindsey Hess, MPH, Center for Childhood Obesity Research, The Pennsylvania State University
Each contributing to data collection, received salary support from the funding agency, and provided written permission to be included in the Acknowledgment section of the manuscript.
Funding:
This research was supported by grants NIDDK R01DK088244 and R01DK099364 to IP. USDA Grant # 2011-67001-30117 to LB supported graduate students. REDCap support was received from The Penn State Clinical & Translational Research Institute, Pennsylvania State University CTSA, NIH/NCATS Grant Number UL1 TR000127. AH was supported by the Prevention and Methodology Training Program and the Methodology Center (T32 DA017629, P50 DA039838), funded by the National Institute on Drug Abuse. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.
Role of funder/sponsor statement:
The funding agencies did not contribute to the design and conduct of the study; collection, management, analysis, or interpretation of the data; preparation, review, or approval of the manuscript; or decision to submit the manuscript for publication.
Disclosers:
The authors have no financial relationships relevant to the article to disclose. The first draft of this manuscript was prepared by Jennifer S. Savage and no honorarium, grant, or other form of payment was given to anyone to produce this manuscript
Abbreviations:
- RP
Responsive parenting
- INSIGHT
Intervention Nurses Start Infants Growing on Healthy Trajectories
- BMI
Body Mass Index
Footnotes
Clinical Trial Registry for firstborns: The Intervention Nurses Start Infants Growing on Healthy Trajectories (INSIGHT) Study. https://clinicaltrials.gov/ct2/show/NCT01167270 . Registry numbers: NCT01167270. Registered 21 July 2010. Note: secondborns were observational only, they were not randomized.
Data Sharing: Data described in the manuscript, code book, and analytic code will be made available upon request pending application and approval.
Access to data and data analysis: Dr. Jennifer Savage and Dr. Ian Paul had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Originality of content: All information and materials in the manuscript are original
Permission for personal communication: All authors have stated that they agree to be named and that the information cited in the personal communication is accurate.
Contributor Information
Jennifer S. Savage, Center for Childhood Obesity Research, The Pennsylvania State University; Nutritional Sciences, The Pennsylvania State University.
Anna K. Hochgraf, Human Development and Family Studies, The Pennsylvania State University.
Eric Loken, Educational Psychology, University of Connecticut.
Michele E. Marini, Center for Childhood Obesity Research, The Pennsylvania State University.
Sarah J.C. Craig, Center for Medical Genomics, The Pennsylvania State University; Biology, The Pennsylvania State University.
Kateryna D. Makova, Center for Medical Genomics, The Pennsylvania State University; Biology, The Pennsylvania State University.
Leann L. Birch, Foods and Nutrition, University of Georgia.
Ian M. Paul, Center for Medical Genomics, The Pennsylvania State University; Pediatrics and Public Health Sciences, Penn State College of Medicine.
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