title: Sex differences in outcomes of very low birthweight infants: the newborn male disadvantage.
abstract: OBJECTIVE
  To determine the differences in short term outcome of very low birthweight infants attributable to sex.
  
  
  METHODS
  Boys and girls weighing 501-1500 g admitted to the 12 centres of the National Institute of Child Health and Human Development Neonatal Research Network were compared. Maternal information and perinatal data were collected from hospital records. Infant outcome was recorded at discharge, at 120 days of age if the infant was still in hospital, or at death. Best obstetric estimate based on the last menstrual period, standard obstetric factors, and ultrasound were used to assign gestational age in completed weeks. Data were collected on a cohort that included 3356 boys and 3382 girls, representing all inborn births from 1 May 1991 to 31 December 1993.
  
  
  RESULTS
  Mortality for boys was 22% and that for girls 15%. The prenatal and perinatal data indicate few differences between the sex groups, except that boys were less likely to have been exposed to antenatal steroids (odds ratio (OR) = 0.80) and were less stable after birth, as reflected in a higher percentage with lower Apgar scores at one and five minutes and the need for physical and pharmacological assistance. In particular, boys were more likely to have been intubated (OR = 1.16) and to have received resuscitation medication (OR = 1.40). Boys had a higher risk (OR > 1.00) for most adverse neonatal outcomes. Although pulmonary morbidity predominated, intracranial haemorrhage and urinary tract infection were also more common.
  
  
  CONCLUSIONS
  Relative differences in short term morbidity and mortality persist between the sexes.
authors.affiliation: Department of Pediatrics, Stanford University, Palo Alto, CA 94305-5119, USA. dstevenson@stanford.edu
authors.forename: D K
authors.initials: DK
authors.lastname: Stevenson
authors.forename: J
authors.initials: J
authors.lastname: Verter
authors.forename: A A
authors.initials: AA
authors.lastname: Fanaroff
authors.forename: W
authors.initials: W
authors.lastname: Oh
authors.forename: R A
authors.initials: RA
authors.lastname: Ehrenkranz
authors.forename: S
authors.initials: S
authors.lastname: Shankaran
authors.forename: E F
authors.initials: EF
authors.lastname: Donovan
authors.forename: L L
authors.initials: LL
authors.lastname: Wright
authors.forename: J A
authors.initials: JA
authors.lastname: Lemons
authors.forename: J E
authors.initials: JE
authors.lastname: Tyson
authors.forename: S B
authors.initials: SB
authors.lastname: Korones
authors.forename: C R
authors.initials: CR
authors.lastname: Bauer
authors.forename: B J
authors.initials: BJ
authors.lastname: Stoll
authors.forename: L A
authors.initials: LA
authors.lastname: Papile
mesh_terms: D001034:Apgar Score; D016001:Confidence Intervals; D005260:Female; D005865:Gestational Age; D005938:Glucocorticoids / Q000627:therapeutic use; D006801:Humans; D007226:Infant Mortality; D007231:Infant, Newborn; D019102:Infant, Very Low Birth Weight; D008297:Male; D016017:Odds Ratio; D011247:Pregnancy; D011295:Prenatal Care / Q000379:methods; D011379:Prognosis; D012044:Regression Analysis; D012189:Retrospective Studies; D012307:Risk Factors; D012737:Sex Factors; D014481:United States / Q000453:epidemiology
chemical_list: D005938:Glucocorticoids