Postnatal conditional growth and size and body composition at 24 months in moderate-and-late preterm children

Abstract Background To assess the relationship between postnatal conditional growth and size and body composition at 24 months’ corrected age (CA) in children born moderate-and-late preterm (MLPT). Methods Children born MLPT (32 +0 -35 +6 weeks’ gestation) were recruited to the Different Approaches to Moderate & late preterm Nutrition: Determinants of feed intolerance, body composition, and development randomized trial from neonatal units in New Zealand. The relationships between growth in weight, length, and head circumference z-scores and body composition (fat mass (FM) and fat-free mass (FFM) z-scores) at discharge, 4 and 24 m and anthropometry and body composition at 24 m was assessed using conditional growth curve models. Results In 343 children with longitudinal data (mean (standard deviation) gestation 33.4 (1.0) weeks; birthweight 2120 (424) g), growth in size and body composition after hospital discharge, specifically FM z-score at 4 m and FFM z-score at 24 m, had stronger associations with size and body composition at 24 m than measures at or before discharge. Growth patterns were not different between moderate- and late-preterm infants (32–33 and 34–35 weeks) but differed between sexes, small-for-gestational-age ( < 10 th percentile) and ethnicities. Conclusion In children born MLPT, growth in size and body composition after discharge is important for size at 24 months. Impact The influence of timing of growth on later size and body composition in children born moderate-and-late preterm is unknown. Growth in fat mass z-score at 4 months and fat-free mass z-score at 24 months had stronger associations with size and body composition at 24 months than measures at or before discharge. Growth in size and body composition after discharge is important for size at 24 months in children born moderate-and-late preterm.