The influence of low birth weight body proportionality and postnatal weight gain on anthropometric measures of 8-year-old children: a cohort study in Northeast Brazil.

Abstract

Low birth weight (LBW) and rapid postnatal weight gain are associated with future high body adiposity; however, the cumulative effect of LBW and postnatal weight gain remains unclear. The aim of this study was to investigate the influence of body proportionality of LBW infants and postnatal weight gain on body mass index (BMI) and waist circumference (WC) of 8-year-old children. A nested cross-sectional study was conducted in a cohort of children followed from birth to 6 months and reassessed at 8 years of age. The sample consisted of 167 children born at full term (67 with LBW and 100 with appropriate birth weight). Stunted LBW was defined as length <-2 z-score and wasted LBW as length ⩾ -2 z- score and Ponderal Index <2.5. Rapid growth was defined as weight gain greater than 0.67 s.d. score from birth to 6 months. Multivariate linear regression analysis was used to investigate the net effect of LBW and postnatal weight gain on BMI and WC, controlled for sex, total breastfeeding, socioeconomic status and maternal nutrition. The stunted and wasted LBW contributed significantly to the reduction of BMI and WC, and together explained 10% of the variation of these measurements. Rapid weight gain in the first 6 months of life, shorter total breastfeeding duration, higher socioeconomic status and maternal BMI significantly explained the increase in child BMI and WC. It was concluded that LBW led to lower body measurements, whereas rapid postnatal weight gain determined higher BMI and WC among school age children.