Mortality, infant: The death of an infant before his or her first birthday.

The infant mortality rate is, by definition, the number of children dying under a year of age divided by the number of live births that year. The infant mortality rate is also called the infant death rate.

The infant mortality rate is an important measure of the well-being of infants, children, and pregnant women because it is associated with a variety of factors, such as maternal health, quality and access to medical care, socioeconomic conditions, and public health practices.

In the United States, about two-thirds of infant deaths occur in the first month after birth and are due mostly to health problems of the infant or the pregnancy, such as preterm delivery or birth defects. About one-third of infant deaths occur after the first month and are influenced greatly by social or environmental factors, such as exposure to cigarette smoke or problems with access to health care.

The infant mortality rate in the US, which was 12.5 per 1,000 live births in 1980, fell to 9.2 per 1,000 live births in 1990. However, in 1999 it was reported that "Over the past 8 years, the death rate among black infants has remained nearly 2.5 times that among white infants." (Pediatrics 104: 1229-1246, 1999.)

The US Government ChildStats Health Indicators include the following additional information about the infant mortality rate:

• The 1997 infant mortality rate for the United States, according to preliminary data, was 7.1 deaths per 1,000 births, substantially below the 1983 rate of 10.9.

• Infant mortality data are available by mother's race and ethnicity through 1996. Black, non-Hispanics have consistently had a higher infant mortality rate than white, non-Hispanics. In 1996, the black, non-Hispanic infant mortality rate was 14.2, compared to 6.0 for white, non-Hispanics.

• Infant mortality has dropped for all race and ethnic groups over time, but there are still substantial racial and ethnic disparities in infant mortality. In 1996, black, non-Hispanic and American Indian/Alaska Native infants had significantly higher infant mortality rates than white, non-Hispanic, Hispanic, and Asian/Pacific Islander infants. In 1996, infant mortality rates varied from 5.2 among Asian/Pacific Islander infants and 6.1 for Hispanics, to 10.0 among American Indians/Alaska Natives.

• Infant mortality rates also vary within race and ethnic populations. For example, among Hispanics in the United States, the infant mortality rate ranged from a low of 5.0 for infants of Central and South American origin to a high of 8.6 for Puerto Ricans. Among Asians/Pacific Islanders, infant mortality rates ranged from 3.2 for infants of Chinese origin to 5.8 for Filipinos.