Early infancy growth, body composition and type of feeding in late and moderate preterms

Background: Late and moderate preterm (LMPT) infants are at risk for adverse later life outcomes. We determined the association between feeding method at enrolment and growth and body composition of LMPT infants until 3 months corrected age (3mCA). Methods: Infants born between 32+0 and 36+6 weeks of gestation (n = 107) were enrolled up to 4 weeks corrected age and stratified according to feeding at enrolment. We performed anthropometric measurements at enrolment, term equivalent age (TEA) and 3mCA, including skinfold measurements and body composition using dual X-ray absorptiometry (DEXA). Results: Feeding method at enrolment was associated with fat mass (FM) (breast 554.9 g, mixed 716.8 g, formula 637.7 g, p = 0.048), lean body mass (LM) (2512 g, 2853 g, 2722 g, respectively, p = 0.009) and lean mass index (LMI) (10.6 kg/m2, 11.6 kg/m2,11.2 kg/m2 respectively, p = 0.008) at TEA, but not 3mCA. Breastfed infants demonstrated greater increase in LM (breast 1707 g, mixed 1536 g, formula 1384 g, p = 0.03) and LMI (1.23 kg/m2, 0.10 kg/m2, 0.52 kg/m2, respectively, p = 0.022) between TEA and 3mCA. Conclusions: Breastfed LMPT infants have lower FM and greater LM increase and LMI increase up to 3mCA compared to formula or mixed-fed infants. These findings stress the importance of supporting breastfeeding in this population. Impact: Infants born late and moderate preterm age who are exclusively breastfed soon after birth gain more lean mass up to 3 months corrected age compared to mixed- or formula-fed infants.Breastfed infants have lower lean and fat mass at term equivalent age compared to mixed- and formula-fed infants.This is the first study exploring this population’s growth and body composition in detail at 3 months corrected age.Our results underline the importance of supporting mothers to initiate and continue breastfeeding at least until 3 months corrected age.