Associations between birthweight and overweight and obesity in school-age children.

BACKGROUND: Relationships between birthweight and future obesity risk remain unclear. OBJECTIVE: To assess associations between birthweight and later obesity in a nationally representative cohort of early school-aged children. METHODS: We used linear and logistic regression to evaluate 10 186 term- or preterm children in the Early Childhood Longitudinal Study-Kindergarten Cohort 2011 for relationships between birthweight and later obesity and change in BMI z-score from kindergarten-to-second grade. All analyses were adjusted for sex, race/ethnicity, parental education and household income. RESULTS: Compared to children born normal birthweight (NBW), high birthweight (HBW) term children and large-for-gestational-age (LGA) preterm children had significantly greater BMI z-scores from kindergarten-to-second grade (p < 0.001). Term children born HBW had higher odds of obesity by kindergarten (adjusted odds ratios [aOR] 1.91, p < 0.0001). Among preterm children, odds of obesity was higher among LGA children starting in first grade (aOR 2.34, p < 0.05) and among small-for-gestational age children in second grade (aOR 2.26, p < 0.05). Compared to NBW children, HBW children had greater change in BMI z-score between kindergarten-first grade (p < 0.01). CONCLUSIONS: High birthweight term and LGA preterm children had increased adjusted odds of obesity in school-age compared to their NBW counterparts. Physicians may provide counselling early in life for families of large infants to help prevent future obesity.

Executive functioning in low birth weight children entering kindergarten.

OBJECTIVES: Poor executive functioning is associated with life-long difficulty. Identification of children at risk for executive dysfunction is important for early intervention to improve neurodevelopmental outcomes. STUDY DESIGN: This study is designed to examine relationships between birthweight and executive functioning in US children during kindergarten. Our hypothesis was that children with higher birthweights would have better executive function scores. We evaluated data from 17506 US children from the Early Childhood Longitudinal Study-Kindergarten 2011 cohort. Birthweight and gestational age were obtained by parental survey. Executive functions were directly assessed using the number reverse test and card sort test to measure working memory and cognitive flexibility, respectively. Teacher evaluations were used for additional executive functions. Data were analyzed using SAS to run all linear and logistical regressions. RESULTS: For every kilogram of birthweight, scores of working memory increased by 1.47 (P<0.001) and cognitive flexibility increased by 0.28 (P<0.001) independent of gender, gestational age, parental education, and family income. Low birthweight infants were 1.5 times more likely to score in the bottom 20% of children on direct assessment OR=1.49 (CI 1.21-1.85) and OR=1.55 (CI 1.26-1.91). CONCLUSIONS: Infants born low birthweight are at increased risk of poor executive functioning. As birthweight increases executive function scores improve, even among infants born normal weight. Further evaluation of this population including interventions and progression through school is needed.

Longitudinal evaluation of 100% fruit juice consumption on BMI status in 2-5-year-old children.

BACKGROUND: Obesity in childhood is related to multiple lifestyle factors. Our objective was to evaluate the relationship between consumption of 100% fruit juice and weight status over time among pre-school children. METHODS: We used linear and logistic multivariable regression to evaluate body mass index (BMI) z-score and overweight/obese status as a function of 100% fruit juice intake for 8950 children examined at ages 2, 4 and 5 years as part of the Early Childhood Longitudinal Study-Birth Cohort, a representative sample of the United States. RESULTS: Cross-sectional analysis at ages 4 and 5 years showed no difference in the prevalence of overweight and obesity between consistent juice drinkers and inconsistent/non-drinkers. Longitudinal analysis found that children who drank 100% juice consistently at age 2 years had greater increases in BMI z-score by age 4 years than infrequent/non-drinkers (P < 0.0001), a difference driven by lesser increases in height z-score (P = 0.0003) and slightly greater increases in weight z-score (P = 0.0550) among consistent juice drinkers over the 2 to 4 year time period. Additionally, consistent juice drinkers at age 2 had higher odds of becoming overweight by age 4 (adjusted odds ratio 1.30; CI 1.06-1.60). These differences in growth parameters were not noted between ages 4 and 5 years. CONCLUSIONS: Drinking 100% fruit juice regularly at age 2 is associated with higher odds of becoming overweight between 2 and 4 years. Paediatricians and parents can discourage excessive fruit juice consumption as part of a larger effort to avoid unhealthy gain in BMI in young children.

Sleep timing and longitudinal weight gain in 4- and 5-year-old children.

BACKGROUND AND OBJECTIVE: Short night-time sleep duration is a possible factor contributing to childhood obesity. Our objective was to evaluate associations between sleep timing (including bedtime and waketime) and weight gain in 4- to 5-year-old children. METHODS: We used cross-sectional and longitudinal regression analyses of a large, nationally representative sample of children from the Early Childhood Longitudinal Study-Birth Cohort. Data regarding the timing and duration of weekday sleep were assessed via parent questionnaire. Short sleep duration, late bedtime and early waketime were defined as those greater than one standard deviation from the mean for the group. RESULTS: Using linear regression adjusted for confounders, sleep duration at 4 and 5 years and bedtime at 5 years were linked to body mass index (BMI) z-score (P < 0.001). Odds of obesity were higher at 4 years for children sleeping <9.44 h nightly (adjusted odds ratio 1.35, confidence interval 1.02-1.78, P < 0.05) and at 5 years for children going to bed at 9:00 pm or later (1.49, 1.16-1.45, P < 0.01) or waking before 6:30 am (1.23, 1.01-15.51, P < 0.05). Assessed longitudinally, both short sleep duration (P < 0.05) and later bedtime at 4 years (P < 0.01) were associated with increases in BMI z-score between 4 and 5 years. CONCLUSIONS: Children with shorter night-time sleep durations and later bedtimes were more likely to be obese and to gain weight over time. Pediatricians should encourage families to place children to bed at earlier times to promote longer sleep duration as a potential means of controlling weight gain.