Supplemental analyses of recent trends in infant mortality.

U.S. preliminary data for 2002 show a significant increase in the infant mortality rate to 7.0 infant deaths per 1,000 live births, the first rise in the infant mortality rate since 1958. The increase in infant mortality was concentrated in the neonatal period, particularly in deaths occurring within seven days of birth. Partially edited fetal death data suggest that the increase in neonatal mortality was accompanied by a decline in the late fetal mortality rate, and thus it appears that the 2002 perinatal mortality rate will remain level. Potential explanatory factors for the changes in the infant mortality rate are examined, including causes of infant death, percentage of births that are preterm, and low birthweight. Data from the 2002 linked birth and infant death file will allow an assessment of the contribution of maternal and infant factors such as multiple births and management of labor and delivery.