title: Antepartum and intrapartum factors preceding neonatal hypoxic-ischemic encephalopathy.
abstract: OBJECTIVE
  To determine whether antepartum factors alone, intrapartum factors alone, or both in combination, are associated with term neonatal hypoxic-ischemic encephalopathy (HIE).
  
  
  METHODS
  A total of 405 infants ≥ 35 weeks' gestation with early encephalopathy, born between 1992 and 2007, were compared with 239 neurologically normal infants born between 1996 and 1997. All cases met criteria for perinatal asphyxia, had neuroimaging findings consistent with acute hypoxia-ischemia, and had no evidence for a non-hypoxic-ischemic cause of their encephalopathy.
  
  
  RESULTS
  Both antepartum and intrapartum factors were associated with the development of HIE on univariate analysis. Case infants were more often delivered by emergency cesarean delivery (CD; 50% vs 11%, P < .001) and none was delivered by elective CD (vs 10% of controls). On logistic regression analysis only 1 antepartum factor (gestation ≥ 41 weeks) and 7 intrapartum factors (prolonged membrane rupture, abnormal cardiotocography, thick meconium, sentinel event, shoulder dystocia, tight nuchal cord, failed vacuum) remained independently associated with HIE (area under the curve 0.88; confidence interval 0.85-0.91; P < .001). Overall, 6.7% of cases and 43.5% of controls had only antepartum factors; 20% of cases and 5.8% of controls had only intrapartum factors; 69.5% of cases and 31% of controls had antepartum and intrapartum factors; and 3.7% of cases and 19.7% of controls had no identifiable risk factors (P < .001).
  
  
  CONCLUSIONS
  Our results do not support the hypothesis that HIE is attributable to antepartum factors alone, but they strongly point to the intrapartum period as the necessary factor in the development of this condition.
authors.affiliation: MRCPCH, Department of Paediatrics, 5 Floor, Hammersmith House, Hammersmith Hospital, DuCane Rd, London W12 OHS, United Kingdom. f.cowan@imperial.ac.uk.
authors.forename: Miriam
authors.initials: M
authors.lastname: Martinez-Biarge
authors.forename: Jesus
authors.initials: J
authors.lastname: Diez-Sebastian
authors.forename: Courtney J
authors.initials: CJ
authors.lastname: Wusthoff
authors.forename: Eugenio
authors.initials: E
authors.lastname: Mercuri
authors.forename: Frances M
authors.initials: FM
authors.lastname: Cowan
mesh_terms: D016022:Case-Control Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D020925:Hypoxia-Ischemia, Brain / Q000175:diagnosis* / Q000453:epidemiology* / Q000473:pathology; D007223:Infant; D007231:Infant, Newborn; D008279:Magnetic Resonance Imaging; D008297:Male; D011247:Pregnancy; D011248:Pregnancy Complications / Q000175:diagnosis* / Q000453:epidemiology*; D011295:Prenatal Care / Q000379:methods; D012189:Retrospective Studies; D012307:Risk Factors
keywords: antepartum risk factors; hypoxic-ischemic encephalopathy; intrapartum risk factors; neonatal encephalopathy; perinatal asphyxia; perinatal brain injury