title: Infant and neonatal mortality for primary cesarean and vaginal births to women with "no indicated risk," United States, 1998-2001 birth cohorts.
abstract: BACKGROUND
  The percentage of United States' births delivered by cesarean section has increased rapidly in recent years, even for women considered to be at low risk for a cesarean section. The purpose of this paper is to examine infant and neonatal mortality risks associated with primary cesarean section compared with vaginal delivery for singleton full-term (37-41 weeks' gestation) women with no indicated medical risks or complications.
  
  
  METHODS
  National linked birth and infant death data for the 1998-2001 birth cohorts (5,762,037 live births and 11,897 infant deaths) were analyzed to assess the risk of infant and neonatal mortality for women with no indicated risk by method of delivery and cause of death. Multivariable logistic regression was used to model neonatal survival probabilities as a function of delivery method, and sociodemographic and medical risk factors.
  
  
  RESULTS
  Neonatal mortality rates were higher among infants delivered by cesarean section (1.77 per 1,000 live births) than for those delivered vaginally (0.62). The magnitude of this difference was reduced only moderately on statistical adjustment for demographic and medical factors, and when deaths due to congenital malformations and events with Apgar scores less than 4 were excluded. The cesarean/vaginal mortality differential was widespread, and not confined to a few causes of death.
  
  
  CONCLUSIONS
  Understanding the causes of these differentials is important, given the rapid growth in the number of primary cesareans without a reported medical indication.
authors.affiliation: Division of Vital Statistics, National Center for Health Statistics, Centers for Disease Control and Prevention, Hyattsville, Maryland 20782, USA.
authors.forename: Marian F
authors.initials: MF
authors.lastname: MacDorman
authors.forename: Eugene
authors.initials: E
authors.lastname: Declercq
authors.forename: Fay
authors.initials: F
authors.lastname: Menacker
authors.forename: Michael H
authors.initials: MH
authors.lastname: Malloy
mesh_terms: D002423:Cause of Death; D002585:Cesarean Section / Q000009:adverse effects / Q000706:statistics & numerical data; D015331:Cohort Studies; D036861:Delivery, Obstetric / Q000009:adverse effects / Q000379:methods; D005260:Female; D005865:Gestational Age; D006801:Humans; D007226:Infant Mortality; D007231:Infant, Newborn; D016015:Logistic Models; D008423:Maternal Age; D015999:Multivariate Analysis; D010298:Parity; D036801:Parturition; D011247:Pregnancy; D018570:Risk Assessment; D012307:Risk Factors; D014481:United States / Q000453:epidemiology