Analysts point to a number of reasons for the drop. Surveys show fewer teens are having sex and they're using more reliable forms of birth control, including long-lasting implants and injections. Fear of AIDS has also increased use of condoms.
The sharpest drops in birth rates have been to black teens, with their numbers falling 26 percent since 1991, and to the lowest point since 1960, when data on black women first became available.
The rate for Hispanic women has fallen steadily since 1994, dropping by 13 percent in four years.
Between 1991 and 1997, teen-age birth rates fell in every state, the District of Columbia and the Virgin Islands. The drops were statistically significant in every area except Rhode Island and Guam. And the declines exceeded 20 percent in 10 states and the District of Columbia.
Overall, births to teens ages 15 to 19 dropped last year by 2 percent from 1997. They dropped 18 percent from 1991 through 1998, according to a report Monday by the National Center for Health Statistics, a branch of the Department of Health and Human Services.
Births to those in the 15-to-17 age group fell 5 percent last year to 30.4 births for every 1,000 teens. That rate has dropped 21 percent since 1991 when it was 38.7 births and is the lowest rate in at least four decades.
The birth rate among the youngest teens and preteens, ages 10 to 14, also fell 6 percent, to its lowest level since 1969. Still, there were 9,481 babies born to these very young moms last year.
To calculate the teen pregnancy rate, the birthrate numbers must be combined with data on abortions and estimates of miscarriages, and the report gave final calculations for 1996: There were 98.7 pregnancies for every 1,000 teens ages 15 to 19, the lowest rate since 1976, when these statistics were first reliably collected.
The new report also included state-by-state birth rates for 1997, and rates ranged significantly across the country. In Vermont, just 2.7 percent of teen girls gave birth; in Mississippi, the rate was almost three times as high, with nearly 7.4 percent of teens having babies.
In 1998 overall, there were 51.1 live births for every 1,000 women, ages 15 to 19, meaning 5.1 percent of them had babies last year.