Infants with low birthweight, born preterm, or in multiple births have a higher risk of dying in the first year of life. Babies born to teens and women in their forties and to mothers who did not complete high school, were unmarried, did not receive timely prenatal care, or smoked during pregnancy also have higher infant mortality rates.

A new report from the National Center for Health Statistics, Centers for Disease Control and Prevention, presents infant mortality statistics from the latest linked birth/infant death data set to identify factors that impact infant mortality or survival. The report is a special analysis of birth and death information provided through the Nation's vital statistics system.

Birthweight is one of the most important predictors of an infant's subsequent health and survival. In 1995, 7.3 percent of infants were low birthweight, defined as less than 2,500 grams (5 lbs, 8 oz), however, 63 percent of all infant deaths were among low birthweight babies. Survival of low birthweight infants has improved, however. Over the past decade, mortality rates declined most rapidly for infants weighing 750-1,499 grams--the largest of the very low birthweight infants. Mortality for these babies dropped by more than 50 percent between 1985 and 1995.

The infant mortality rate for male infants was 8.3 in 1995, 22 percent higher than the rate of 6.8 for females. Babies born in multiple births have an infant mortality rate 5 times that of single births. Infant mortality rates are highest for teens and women in their 40's and lowest for women in their 20's and early 30's. The infant mortality rate was twice as high for unmarried women as for married women. In general infant mortality declined with increasing education of the mother. Mothers who had not completed high school had infant mortality rates more than twice that of women with college education.

Analysis of the vital statistics data also showed that mortality rates varied considerably by race of mother. In 1995 the overall infant mortality rate from the linked file was 7.6 deaths per 1,000 live births. Mortality rates were lowest for infants born to Asian and Pacific Islander mothers (5.3), followed by white (6.3), American Indian (9.0), and black (14.6) mothers. The Hispanic infant mortality rate (6.3) was the same as for non-Hispanic white infants, and ranged from 5.3 for infants of Cuban mothers to 8.9 for Puerto Rican infants.

For American Indian infants, death rates were highest in the postneonatal period with death rates from sudden infant death syndrome and accidents about 3 times the rate for white infants. For black infants, disorders related to short gestation and low birthweight was the leading cause of death with black infants more than 4 times as likely to die from this cause as white infants.

"Infant Mortality Statistics from the Linked Birth/Infant Death Data Set--1995 Period Data," by Marian F. MacDorman and Jonnae O. Atkinson is based on information from the death certificate linked to the corresponding birth certificate for each infant under 1 year of age who died in 1995. The purpose of the linkage is to use the additional information from the birth certificate to conduct more detailed analyses of infant mortality patterns to provide better information for prevention, research, and medical care. Birth and death certificates are linked by the State vital statistics offices where the original records are filed and reported to NCHS through the National Vital Statistics System. Copies of the report are available from NCHS.

© 1998