How does gestational age affect growth and body composition of preterm twins?

Background: Twins experience altered growth compared to singletons. The primary aim of this study was to compare growth and body composition (BC) of twin and singleton preterm infants from birth to 3 months according to gestational age (GA). Secondary aims were to evaluate the effect of chorionicity and mode of feeding on twins’ BC. Methods: Anthropometric measurements and BC were performed at term and 3 months in preterm infants (GA < 37 weeks). Infants were categorized as: extremely, very, moderate and late preterm infants. Chorionicity was assigned as monochorionic, dichorionic or multichorionic. Mode of feeding was recorded as any human milk feeding vs formula feeding. Results: Five hundred and seventy-six preterm infants were included (223 twins). Late-preterm twins were lighter and shorter at each study point; fat-free mass (FFM) was lower in these infants at each study point, compared to singletons. No differences were found between twins and singleton on the other category. Multichorionic infants had an FFM deficit compared to monochorionic and dichorionic at term, whereas no differences were found at 3 months. FFM at term was negatively associated with being twin and formula-fed. Conclusions: Twins and singletons born before 34 weeks’ GA showed similar anthropometry and BC. Conversely, twin late-preterm infants showed different growth and BC compared to singletons.