Homicide is the leading cause of death due to injury among infants in the United States, say epidemiologists at the National Institute of Child Health and Human Development, and the children at greatest risk have young teen-age mothers.

Researchers analyzed birth certificates of the nearly 35 million babies born in the U.S. from 1983 to 1991, and the death certificates of those who died before their first birthdays. They determined that 2,776 of the infants were homicide victims -- although they believe such deaths are undercounted. They found several major risk factors for an infant becoming a homicide victim.

• Being the second- or later-born children of teen-age mothers less than 17 years old put an infant at 10 times the risk of being killed compared to the first-born children of women 25 and older.

• Being the second or later-born children of women 17 to 19 years old was a slightly smaller risk factor, followed by having a mother less than 15 years old.

• Other risk factors were the mother having no prenatal care (compared to having prenatal care) and, among women at least 17 years old, having less than 12 years of education compared to 16 years or more years of education.

The researchers also found the infant homicide rate increased to 8.9 per 100,000 births in the period from 1988 to 1991, up from 7.2 per 100,000 births in the period from 1983 to 1987.

Homicides accounted for more than one-third of the infant deaths due to injury in 1996, and children are more likely to be homicide victims in the first year of life, with similar or higher homicide rates only during later adolescence.

Source: Mary D. Overpeck, et al., "Risk Factors for Infant Homicide in the United States," and Lawrence S. Wissow, "Infanticide," both New England Journal of Medicine, October 22, 1998.

For text http://www.nejm.org/content/1998/0339/0017/1239.asp