The Trajectory of BMI-z Scores From Early Childhood to Adolescence: Its Early Predictors and Influences on Peer Competence

• In Event: Poster Session 09
  In Poster Session: PS 09 Topic - Health, Growth, Injury

Abstract

Numerous studies have documented the early risk and protective factors of obesity (Harrison et al., 2011; Reilly 2005), and attention has also been paid to the negative impact of obesity on child physical and socioemotional health (Sahoo et al., 2015). However, the interplay between early developmental factors as predictors of weight status over time, and its implication for social outcomes, has been understudied. This study aimed to 1) examine a moderating effect of negative temperament and parental sensitivity on two BMI-z growth rates (one is from 24 months to 54 months and the other is from 54 months to age 15) and 2) determine whether the BMI-z growth rates influence social competence at age 15.

A subsample of 655 families drawn from the NICHD-SECCYD (NICHD Early Child Care Research Network, 1998) was analyzed. Measured weight and height were used to compute age- and gender-adjusted BMI-z scores, and maternal sensitivity was assessed by observing mother-child interaction in semi-structured procedures. Growth measures and sensitivity were obtained at 7-time points from 15 months to age 15. Children’s negative temperament was rated by mothers at 6 months on a revised version of the Early Infant Temperament Questionnaire (EITQ). Adolescent’s peer competence was assessed with parent’s reports using the Social Skill Rating Scale (SSRS). The demographic information was statistical controls. Piecewise Latent Growth models were tested using M-plus 7.3, including an unconditional model (Model 1) and three conditional models with time-varying covariates (i.e., maternal sensitivity) and early predictors (Model 2), an interaction term (Model 3), and peer competence at age 15 (Model 4).

Model 1 indicated that the initial BMI z-score was .124 (p < .001) and the early BMI-z growth rate from 24 month to 54 months (b = .113, p < .001) was significantly greater than the rate from 54 months through age 15 (b = .014, p < .001), as expected. A positive correlation between early and later growth rate (r = .225, p < .01) indicated that those with a greater increase in BMI-z during early childhood experienced a greater increase in BMI-z later as well. In Model 2, there was no significant effect of either negative temperament or maternal sensitivity on any growth parameters. In Model 3, however, we found a significant moderating effect of the two factors on the early BMI growth rate (b = -.073, p < .001). Children higher on negativity showed a greater increase in BMI-z during early childhood when maternal sensitivity was low (Figure 2). However, it became nonsignificant as maternal sensitivity increased. Model 4 revealed that those with greater BMI-z increase during early childhood tend to have a lower level of peer competence in adolescence (b = -1.263, p < .05). Notably, the later BMI growth rate did not predict adolescent’s peer competence and the outcome was robust while controlling for previous peer competence. This study highlights the importance of both maternal sensitivity and negative temperament to better understand the BMI growth, and the significance of early BMI growth in social competence for adolescents.

Authors

• Joo Hyun Kim, Seoul National University
  Presenting Author

• Kelly K. Bost, University of Illinois at Urbana-Champaign
  Non-Presenting Author