Birthweight-specific infant mortality risk in cesarean section.

The role of cesarean section in improving infant survival has not been clearly documented. We calculated birthweight- and race-specific infant, neonatal, and postneonatal mortality risks by method of delivery for single- and multiple-delivery infants, using data from 14 states, reported to the Centers for Disease Control through the 1980 National Infant Mortality Surveillance project. For single-delivery infants, the risk of death for infants delivered by cesarean section was 1.6 times higher than for infants delivered vaginally among blacks and 1.2 times higher among whites. The risk was 1.7 times higher during the neonatal period and 1.2 times higher during the postneonatal period. For infants with birthweight less than 1,000 grams, the risk of death was lower when infants were delivered by cesarean section. The risk of death among multiple-delivery infants born by cesarean section was significantly lower than for those born vaginally. This analysis demonstrates that, unlike other birthweight categories, infants with a very low birthweight may have better outcomes if delivered by cesarean section. However, we cannot recommend the routine use of cesarean section for delivering very low birthweight infants. Further studies are needed to determine survival of such infants after controlling for maternal and infant conditions that prompted delivery by cesarean section.