Early Life Influences and Child Weight Outcomes in the Study to Explore Early Development (SEED)

Background:  Maternal pre-pregnancy obesity, excess gestational weight gain, and rapid weight gain during early infancy have all been associated with an increased risk of childhood obesity in typically developing children. Given the high prevalence of overweight/obesity among children with Autism Spectrum Disorder (ASD), there is a pressing need to examine early life influences on child weight outcomes in this population.

Objectives:  To examine the associations between 1) maternal pre-pregnancy weight status, 2) gestational weight gain, and 3) rapid weight gain during infancy and weight outcomes in children classified as ASD, developmental delay (DD), and general population controls (POP).

Methods:  SEED is a multi-site case-control study of children, aged 3-5 years, who were classified as ASD (n=668), DD (n=914), or POP (n=884). Maternal weight outcomes were derived from a maternal interview; child weight outcomes were ascertained from medical records (birth to 6 months) and a dysmorphology exam (age 3-5 years). Maternal pre-pregnancy body mass index (BMI) was calculated as weight (kg) divided by height (m) squared. Maternal gestational weight gain was compared to the Institute of Medicine (IOM) guidelines for weight gain during pregnancy, and categorized as meeting or not meeting (above or below) the recommendations. Child age- and sex-specific weight and BMI percentiles and z-scores were calculated using the WHO Growth Charts (birth to 24 months) and the CDC Growth Charts 2000 (>24 months). Rapid weight gain was defined as a change in infant weight-for-age z-scores from birth to 6 months greater than 0.67 SDs.

Results:  After adjusting for case status, mothers who were overweight/obese prior to pregnancy were 2.40 (95% CI: 1.98, 2.91) times more likely to have an overweight/obese child at ages 3-5 years as compared to mothers who were underweight/normal-weight prior to pregnancy (P<0.0001). Adherence to the gestational weight gain recommendations was a significant predictor of child weight status at ages 3-5 years (P=0.043). Mothers who exceeded the weight gain recommendations during pregnancy were 1.30 (95%CI: 1.06, 1.61) times more likely to have an overweight/obese child at ages 3-5 years as compared to mothers who met the weight gain recommendations (P=0.014). There also was a significant relationship between rapid weight gain during infancy and case status. Children in the ASD group showed the highest frequency of rapid weight gain (35.9%) when compared with children in the DD (31.0%) and POP (28.3%) groups (P=0.02). Among children with ASD, those with rapid weight gain during infancy showed a higher frequency of overweight/obesity at ages 3-5 years than those without (35.6% vs. 18.3%; P=0.0007).

Conclusions: The findings from this study suggest that maternal pre-pregnancy overweight/obesity and excess weight gain during pregnancy were significant risk factors for overweight/obesity in their children. Children with ASD experienced rapid weight gain during infancy with a greater frequency compared to children in the DD and POP groups, which may contribute to their higher weight status later in life. Subsequent analyses will parse out the independent and combined contributions of these maternal and child risk factors to childhood obesity while also controlling for possible confounders.