Atlanta ? In a troubling reversal, the nation’s teen birth rate rose for the first time in 15 years, surprising government health officials and reviving the bitter debate about abstinence-only sex education.

The birth rate had been dropping since its peak in 1991, although the decline had slowed in recent years. On Wednesday, government statisticians said it rose 3 percent from 2005 to 2006.

The reason for the increase was not clear, and federal health officials said it might be a one-year statistical blip, not the beginning of a new upward trend.

However, some experts said they have been expecting a jump. They blamed it on increased federal funding for abstinence-only health education that doesn’t teach teens how to use condoms and other contraception.

Some key sexually transmitted disease rates have been rising, including syphilis, gonorrhea and chlamydia. The rising teen pregnancy rate is part of the same phenomenon, said Dr. Carol Hogue, an Emory University professor of maternal and child health.

“It’s not rocket science,” she said.

The new teen birth numbers are based on the 15-19 age group of women, which accounted for most of the 440,000 births to teens in 2006. The rate rose to nearly 42 births per 1,000 in that group, up from 40.5 in 2005. That translates to an extra 20,000 births to teen mothers.

In 1991, the peak year for teen births, there were nearly 62 births per 1,000.

The new report offers a state-by-state breakdown of birth rates overall. Many of those with the highest birth rates teach abstinence instead of comprehensive sex education, according to the Planned Parenthood Federation of America.

And research has concluded that abstinence-only programs do not cause a decrease in teenage sexual activity, Planned Parenthood officials added.