a1 Department of Neonatal Medicine, Hôpital Mère-et-Enfant, CHU de Nantes, 44093 Nantes cedex 1, France
a2 INRA UMR 1280, Physiologie des Adaptations Nutritionnelles, Université de Nantes, CRNH, Nantes, IMAD, CHU de Nantes, France
a3 Centre d'Investigation Clinique INSERM, CIC004 CHU de Nantes, France
To determine the effects of length of gestation and sex on infant body composition, air displacement plethysmography was performed in forty-six full-term neonates at 3 d of life and during the week prior to hospital discharge in 180 preterm neonates. Fat mass, as a percentage of body weight, was higher in preterm than in term infants (13·4 (sd 4·2) v. 10·1 (sd 3·7) %, respectively; P= 0·001). The absolute amount of fat mass did not differ between preterm and full-term newborns (323 (sd 126) v. 335 (sd 138) g; P= 0·58), whereas lean body mass was lower in preterm than in term infants (2055 (sd 280) v. 2937 (sd 259) g, respectively; P< 0·001). Among full-term infants, fat mass was higher in females than in males (11·1 (sd 3·7) v. 9·0 (sd 3·3) %, respectively; P= 0·047), whereas we did not observe any sex difference in preterm infants (13·5 (sd 4·1) v. 13·4 (sd 4·3) %; P= 0·89). Our data suggest that by the time they are discharged from hospital: (1) preterm infants have a higher percentage of body fat than term neonates and (2) this is presumably due to a lesser accretion in lean body mass in the first few weeks of extra-uterine life, particularly in boys.
(Received November 30 2011)
(Revised May 31 2012)
(Accepted June 01 2012)
(Online publication July 12 2012)
† These authors contributed equally to the present work.