Weight gain in infancy and early childhood is associated with school age body mass index but not intelligence and blood pressure in very low birth weight children

Abstract

Rates of weight gain in infancy and early childhood can influence later neurocognitive, metabolic and cardiovascular health. We studied the relationship of weight gain during infancy and early childhood to intelligence quotient (IQ), blood pressure (BP) and body mass index (BMI) at age 9 in children born with very low birth weight (VLBW). Sixty-five children born prematurely with VLBW were followed longitudinally and at 9 years IQ, BP and BMI were measured. The mean weight z-scores at birth, neonatal intensive care discharge, 1 year corrected for prematurity, 5 and 9 years were -0.17, -2.09, -1.3, -0.68 and 0.06, respectively. Weight gain during infancy (discharge to 1 year corrected for prematurity) and early childhood (1 year corrected age to 5 years) was expressed as rate of change in weight, rate of change in weight z-score and interval change in weight z-score. In multiple regression analyses that adjusted for race, gender, maternal education, antenatal steroids, birth weight z-score, major intracranial lesions on ultrasound and chronic lung disease, rates of weight gain in infancy and early childhood were predictive of BMI z-score at 9 years, regression coefficients (95% confidence intervals); 0.19 (0.02, 0.36) and 0.37 (0.11, 0.63), respectively, expressed as change in BMI z-score per 10 g/week weight increase. Rates of weight gain were not predictive of systolic BP z-score, Verbal IQ or Performance IQ. In VLBW infants, more rapid weight gain during infancy, and especially early childhood, is associated with higher BMI at school age.

Figure 1

Weight z scores through early childhood as a function of BMI z score at study year 9: Time plot of weight z score versus age in years (corrected for prematurity) at hospital discharge and three follow-up visits. Locally weighted regression (lowess) curves are displayed for comparison of patterns in weight z scores between participants grouped by BMI z score tertile.

Figure 2

Weight z scores through early childhood as a function of Verbal IQ at study year 9: Time plot of weight z score versus age in years (corrected for prematurity) at hospital discharge and three follow-up visits. Locally weighted regression (lowess) curves are displayed for comparison of patterns in weight z scores between participants grouped by Verbal IQ tertile.