title: Extremely preterm infant mortality rates and cesarean deliveries in the United States.
abstract: OBJECTIVE
  To estimate trends in infant mortality rates and cesarean delivery rates for extremely preterm infants born in the United States.
  
  
  METHODS
  This national population-based study used public data from the Centers for Disease Control and Prevention to investigate extremely preterm infants born alive between 22 0/7 and 27 6/7 weeks of gestational age from 1999 to 2005.
  
  
  RESULTS
  There were 177,552 extremely preterm infant births (fewer than 1% of all births) from 1999 to 2005. The number of annual extremely preterm births increased by 7% compared with a 4.5% increase for births at all gestations. During the study years, the extremely preterm infant mortality rate (percentage of infants who died in the first year) remained steady (range 33-34%; P=.22), whereas the cesarean delivery rate increased from 43% to 54% (P<.001). The infant mortality rate after cesarean delivery increased from 24% to 26% (P=.012). At each gestational age, the annual cesarean delivery rate increased over time (P<.001 for each), whereas gestational age-specific infant mortality rates were unchanged except for a 2% decline from 2004 to 2005 for infants born at 24 weeks of gestation (P=.01).
  
  
  CONCLUSIONS
  A significant rise in the cesarean delivery rate in the United States from 1999 to 2005 for infants born at less than 28 weeks of gestation was not associated with an improvement in the infant mortality rate.
authors.affiliation: From the Departments of Pediatrics and Statistics and Research Consulting, Southern Illinois University School of Medicine, Springfield, Illinois.
authors.forename: Beau
authors.initials: B
authors.lastname: Batton
authors.forename: Christopher
authors.initials: C
authors.lastname: Burnett
authors.forename: Steven
authors.initials: S
authors.lastname: Verhulst
authors.forename: Daniel
authors.initials: D
authors.lastname: Batton
mesh_terms: D002585:Cesarean Section / Q000706:statistics & numerical data* / Q000639:trends; D005865:Gestational Age; D006801:Humans; D007226:Infant Mortality / Q000639:trends*; D052577:Infant, Extremely Low Birth Weight; D007231:Infant, Newborn; D050498:Live Birth / Q000453:epidemiology; D014481:United States / Q000453:epidemiology