Examination of infant early-life risk factors for pediatric obesity

Childhood obesity is a major public health challenge of the 21 st century. The prevalence of children with overweight and obesity remains high in the United States with one in three children and one in six children being overweight and obese, respectively. Research has shown that the development of obesity can start before birth, during fetal development. The overall goal of this dissertation was to assess the effect of three important prenatal, perinatal and infant potential risk factors on children’s BMI z-score trajectories and weight status. The potential risk factors included prenatal maternal cigarette smoking, perinatal high birth weight (measured by birth weight in relation to gestational age), and postnatal infant feeding practices (such as breastfeeding and early complementary food introduction). These risk factors were quantitatively assessed using (a) a nationally-representative, longitudinal birth cohort of children born in 2001 and followed at 9 months, 2 years, and 4 years of age [the Early Childhood Longitudinal Study, Birth Cohort (ECLS-B)]; and (b) baseline data (2012-2014) from a Randomized Controlled Trial (RCT) study of 459 low-income, ethnically diverse children aged 2-12 years with overweight and obesity, in Houston and Austin, Texas. Utilizing a large nationally representative sample of children (ECLS-B) (the weighted n=5,221), our findings in Journal Article 1 indicated that maternal cigarette smoking during pregnancy was associated with membership in high BMI z-score quadratic trajectory group (aRR=2.1, 95% CI 1.11-3.98), and there was a dose-response relationship evident between the two. Furthermore, being small-for-gestational-age acted as suppressor in the association between maternal cigarette smoking during pregnancy and BMI z-score at 4 years suggesting that there were other significant variables such as infant rapid weight gain that acted in the pathway between small-for-gestational-age and BMI z-score at later-life. Utilizing the same dataset (ECLS-B) but limiting the sample to mothers who did not smoke during pregnancy (the weighted n=4,497), our findings in Journal Article 2 indicated that large-for-gestational-age increased the odds of belonging to high BMI z-score quadratic trajectory group by at least two fold (aRR 2.3, 95% CI 1.18-4.53). Results for infant feeding practices such as exclusive breastfeeding for 6 months and early (prior to 4 months) complementary food introduction were inconclusive. Using data from the TX CORD study, Journal Article 3 findings indicated that large-for-gestational-age, and not predominant breastfeeding for at least first 4 months of life, was significantly associated with severe obesity among low-income ethnically diverse children with overweight and obesity living in Austin and Houston, Texas