An increase in the birth of very small infants is the major reason behind the increase in U.S. infant mortality in 2002, according to a report released today by the Centers for Disease Control and Prevention (CDC). The increase in infant mortality, from 6.8 infant deaths per 1,000 live births in 2001 to 7.0 in 2002, was the first increase in the infant mortality rate since 1958 and was reported last year by CDC.
Overall, there were 27,970 infant deaths in 2002 compared to 27,568 infant deaths in 2001. Provisional data for 2003 suggest that the increase noted in 2002 may not be continuing.
The number of extremely small babies (weighing less than 1 lb, 10.5 oz or 750 grams at birth) increased by almost 500 births from 2001 to 2002. The increase occurred primarily among mothers in the peak childbearing ages of 20-34 years and occurred across most racial and ethnic groups. While infant mortality rates had been declining for these vulnerable small babies, the majority of babies born at this weight still die within the first year of life. Multiple births may also contribute to the increase in low birth weight infants. About 3 percent of births in the United States were multiple births, yet they made up about 25 percent of the overall increase in infant mortality. However, most of the rise was due to an increase for babies born in single deliveries.
The data from CDC’s 2002 Linked Birth/Infant Death Data Set enables researchers to examine factors, in addition to birth weight, that may have contributed to infant mortality. The report looks at patterns by race/ethnicity, mother’s age, length of pregnancy, multiple versus single birth, and other factors.