Objectives: This report presents 2005 period infant mortality statistics from the linked birth/infant death data file by a variety of maternal and infant characteristics. The linked file differs from the mortality file, which is based entirely on death certificate data.
Methods: Descriptive tabulations of data are presented and interpreted. Excluding rates by cause of death, the infant mortality rate is now published with two decimal places.
Results: The U.S. infant mortality rate was 6.86 infant deaths per 1,000 live births in 2005, which is statistically unchanged from 6.78 in 2004. Infant mortality rates ranged from 4.89 deaths per 1,000 live births for Asian or Pacific Islander (API) mothers to 13.63 for non-Hispanic black mothers. Among Hispanics, rates ranged from 4.42 for Cuban mothers to 8.30 for Puerto Rican mothers. Infant mortality rates were higher for infants who were born in multiple deliveries or whose mothers were born in the 50 states and the District of Columbia or were unmarried. Infant mortality was also higher for male infants and infants born preterm or at low birthweight. The neonatal mortality rate was essentially unchanged from 2004 (4.52) to 2005 (4.54). The postneonatal mortality rate increased 3 percent from 2.25 in 2004 to 2.32 in 2005. Infants born at the lowest gestational ages and birthweights have a large impact on overall U.S. infant mortality. For example, more than one-half (55 percent) of all infant deaths in the United States in 2005 occurred to the 2 percent of infants born very preterm (less than 32 weeks of gestation). Infant mortality rates for late preterm infants (34-36 weeks of gestation) were three times those for term infants (37-41 weeks). The three leading causes of infant death--congenital malformations, low birthweight, and sudden infant death syndrome (SIDS)--accounted for 44 percent all infant deaths. The percentage of infant deaths that were "preterm-related" increased from 34.6 percent in 2000 to 36.5 percent in 2005. The preterm-related infant mortality rate for non-Hispanic black mothers was 3.4 times higher and the rate for Puerto Rican mothers was 87 percent higher than the rate for non-Hispanic white mothers.