Relative effects of postnatal rapid growth and maternal factors on early childhood growth trajectories.

Abstract

A range of postnatal and maternal factors influences childhood obesity, but their relative importance remains unclear. This study aimed to assess the relative impact of postnatal rapid growth and maternal factors on early childhood growth trajectories. Secondary longitudinal analysis of pooled data from the Melbourne Infant Feeding Activity and Nutrition Trial (InFANT) Program and the InFANT Extend Program (n=977) was performed. Children's height and weight were collected at birth, 3, 9, 18, and 36/42months. Body mass index-for-age and height-for-age z-scores (BAZ, HAZ) were computed using WHO growth standards. Mixed-effect polynomial regression models were fitted to examine BAZ and HAZ trajectories and their determinants. Rapid growth from birth to 3months, maternal country of birth, and pre-pregnancy BMI were each independently associated with BAZ from 3 to 42months. Children with rapid growth, those whose mothers were Australian-born, and those whose mothers were overweight/obese pre-pregnancy had higher BAZ from 3 to 42months. Children with rapid growth had an increase in HAZ growth, but their average HAZ from 3 to 42months was smaller than children without rapid growth. Children of tall mothers (above average height) had higher HAZ than those of short mothers (below average height). Average HAZ from 3 to 42months did not differ by maternal country of birth. Children who experienced rapid growth from birth to 3months, whose mothers were Australian-born or whose mothers were overweight/obese pre-pregnancy demonstrated less favourable growth trajectories across early childhood, potentially predispose them for development of future obesity.