Associations between growth and childhood body composition in very preterm, late preterm and term children.

Abstract

To determine how gestational age at birth and postnatal growth relate to body composition in childhood. We calculated conditional growth (birth-2 years, 2 years-6 years) and measured body composition at 2 and 6 years using bioelectrical impedance in cohorts of New Zealand children born very preterm (VPT; 23-31 weeks), late preterm (LPT; 35- <37 weeks) and term (≥37 weeks). We explored the relationships between growth and fat mass (FM) index and fat-free mass (FFM) index at 6 years using multivariable linear regression. Of 1125 children (51% male), 202 were VPT, 114 LPT and 809 Term. Compared to Term, VPT but not LPT were lighter and shorter at 2 and 6 years and had lower FM index and FFM index. The association between weight growth from 2 to 6 years and both FM index and FFM index at 6 years was stronger than for weight growth from birth to 2 years or height growth at any period in all gestational age groups. Size and body composition at 2 and 6 years are different between infants born VPT, but not LPT, and at term. Later weight growth is more strongly associated with childhood body composition than earlier growth.