Update on Risk Factors for Infant Mortality

For Release: Thursday, August 27, 1998

Contact: NCHS Press Office (301) 458-4800

E-mail: paoquery@cdc.gov

Vol. 46, No. 12, Supplement, Infant Mortality Statistics From the 1996 Period Linked Birth/Infant Death Data Set [PDF – 433 KB]

In 1996 the infant mortality rate declined to 7.3 deaths per 1,000 live births, the lowest rate ever recorded and a decline of 3 percent from 1995. 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 teenagers and to 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 and follows up an earlier report released last February.

Birthweight is one of the most important predictors of an infant’s subsequent health and survival. In 1996, 7.4 percent of infants were low birthweight, defined as less than 2,500 grams (5 lbs, 8 oz); however, 64 percent of all infant deaths were among low birthweight babies. Survival of low birthweight infants has improved however. The largest declines (8 to 10 percent) in bodyweight-specific infant mortality rates from 1995-96 were for infants born weighing 750-1,250 grams and 1,500-1,999 grams.

The infant mortality rate for male infants was 8.0 in 1996, 21 percent higher than the rate of 6.6 for females. Babies born in multiple births have an infant mortality rate 5 times that of single births. Infant mortality rates are highest for teenagers and for women in their 40’s and lowest for women in their 20’s and early 30’s. The infant mortality rate was nearly 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 which were twice that of women with a college education.

Analysis of the vital statistics data also showed that mortality rates varied considerably by race of mother. In 1996 the overall infant mortality rate from the linked file was 7.3 deaths per 1,000 live births. Mortality rates were lowest for infants born to Asian and Pacific Islander mothers (5.2), followed by white (6.1), American Indian (10.0), and black (14.1) mothers. The mortality rate for infants of Hispanic mothers (6.1) was similar to the rate for non-Hispanic white mothers (6.0) and ranged from 5.0 for infants of Central and South American mothers to 8.6 for infants of Puerto Rican mothers.

For infants of American Indian mothers, death rates were highest in the postneonatal period with death rates from sudden infant death syndrome and accidents more than 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 1996 Period Linked Birth/Infant Death Data Set” 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 1996.

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.