The birth rate among American girls ages 10 to 14 has fallen to its lowest level since 1946, the government reported Monday.
The Centers for Disease Control and Prevention said the number of births among girls in this age group dropped 38 percent from 1994 to 2002 alone, even though the number of girls 10 to 14 climbed 16 percent during the same period.
CDC researchers attributed the decline to sex education.
"The message is getting across to them. Teens are behaving more responsibly when it comes to sex," said Fay Menacker, at the CDC's National Center for Health Statistics.
The birth rate among girls this young has been declining since 1994, when 12,901 babies were born to mothers ages 10 to 14.
In 2002, the most recent year with complete data, there were 7,315 babies born to this age group, a birth rate of 0.7 live births per 1,000 females -- about the same rate nearly 60 years ago.
The birth rate dropped among all racial groups, but it was still higher for black and Hispanic girls than for white and Asian ones. In 2002, the birth rate for black girls was 1.9 live births per 1,000 girls, and for non-Hispanic white girls it was 0.2 live births per 1,000 girls.
Between 2000 and 2002, Maine had the nation's lowest birth rate among girls in the 10-to-14 group, at 0.2 live births per 1,000 girls. Washington, D.C., had the highest, at two births per 1,000 girls.
Mothers in this age group have infant mortality rates more than twice those of mothers ages 22 to 40. Very young mothers are also more likely to bear children with low birth weight and deformities.
"These births are a tragic situation for the babies and the mothers and their families," Menacker said. "One birth in this age group is too many."
Health experts said one reason for the decline is that adults are talking to their children about the facts of life at a younger age than in generations past.
"People are increasingly aware that sex doesn't wait until high school," said Sarah Brown, director of the National Campaign to Prevent Teen Pregnancy.
Brown said much more study is needed on the boys -- or men -- who father children of young girls.
"I'm not thinking that all these fellows are 10 to 14 years old," Brown said. "When you're talking about very young pregnancies, you're not talking about a 'Blue Lagoon' true-love story. This is something distressing to everybody."