title: Neonatal and infant outcome in boys and girls born very prematurely.
abstract: BACKGROUND
  Although important new strategies have improved outcomes for very preterm infants, males have greater mortality/morbidity than females. We investigated whether the excess of adverse later effects in males operated through poorer neonatal profile or if there was an intrinsic male effect.
  
  
  RESULTS
  Male sex was significantly associated with higher birth weight, death or oxygen dependency (72% vs. 61%, boys vs. girls), hospital stay (97 vs. 86 days), pulmonary hemorrhage (15% vs. 10%), postnatal steroids (37% vs. 21%), and major cranial ultrasound abnormality (20% vs. 12%). Differences remained significant after adjusting for birth weight and gestation. At follow-up, disability, cognitive delay, and use of inhalers remained significant after further adjustment.
  
  
  CONCLUSIONS
  We conclude that in very preterm infants, male sex is an important risk factor for poor neonatal outcome and poor neurological and respiratory outcome at follow-up. The increased risks at follow-up are not explained by neonatal factors and lend support to the concept of male vulnerability following preterm birth.
  
  
  METHODS
  Data came from the United Kingdom Oscillation Study, with 797 infants (428 boys) born at 23-28 wk gestational age. Thirteen maternal factors, 8 infant factors, 11 acute outcomes, and neurological and respiratory outcomes at follow-up were analyzed. Follow-up outcomes were adjusted for birth and neonatal factors sequentially to explore mechanisms for differences by sex.
authors.affiliation: Division of Health and Social Care Research, King's College London, London, UK. janet.peacock@kcl.ac.uk
authors.forename: Janet L
authors.initials: JL
authors.lastname: Peacock
authors.forename: Louise
authors.initials: L
authors.lastname: Marston
authors.forename: Neil
authors.initials: N
authors.lastname: Marlow
authors.forename: Sandra A
authors.initials: SA
authors.lastname: Calvert
authors.forename: Anne
authors.initials: A
authors.lastname: Greenough
mesh_terms: D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D007234:Infant, Premature; D007235:Infant, Premature, Diseases / Q000453:epidemiology*; D008171:Lung Diseases / Q000453:epidemiology*; D008297:Male; D009422:Nervous System Diseases / Q000453:epidemiology*; D012727:Sex Characteristics; D006113:United Kingdom