Growth and body composition changes in late preterm infants in the first months of life

Objectives: The aim of this study was to compare growth and body composition of late preterm infants to that of extremely preterm and full-term infants. Methods: Observational longitudinal study. Forty-nine late preterm infants and 63 extremely preterm infants were included in the study. Forty healthy, full-term, breast-fed infants were enrolled as a reference group. Anthropometric parameters and body composition by an air displacement plethysmography system were assessed at 36th week, at term, at 1 and 3 months of corrected age in all groups. Late preterm infants were also assessed on the fifth day of life. Results: Late preterm infants showed higher weight, length and head circumference values than those of very low birth weight infants but lower fat mass values on the fifth day of life and at 36th week of corrected age. However, at 3 months of corrected age, percentage of fat mass in late preterm infants reached values comparable with those of very low birth weight infants, probably because of the fast catch-up fat recorded between the fifth day of life and term corrected age. Moreover, percentage of fat mass in the first month of corrected age in preterm infants was higher as compared with full-term infants. This difference was no longer found at 3 months of corrected age. Conclusions: Further studies are needed to investigate whether this rapid increase in fat mass may modulate the risk of chronic diseases.