WASHINGTON — U.S. teen birth rates rose sharply in 2006, according to figures released Wednesday by the federal Centers for Disease Control and Prevention, ending a 14-year decline.

While U.S. teen birth rates remained the highest in the industrialized world, the long decline had amounted to a 45 percent reduction since 1991.

According to the figures for 2006, the latest year for which data are available, birth rates for teens aged 15-19 rose by 3.5 percent, the largest growth in teen birth rates since 1989-1990. About 435,000 of the nation's 4.3 million births in 2006 were to mothers ages 15-19. That was about 21,000 more teen births than in 2005.

Analysts at liberal and conservative teen-pregnancy awareness groups had begun to notice the declines leveling off in recent years. Though dismayed, they weren't surprised by the upward spike.

The increases in teen births were greatest through the South and Southwest, and lowest in the Northeast.

Mississippi now has the nation's highest teen birth rate, displacing Texas and New Mexico for that lamentable title, the federal report says.

Mississippi's rate was more than 60 percent higher than the national average. The teen birth rate for that year in Texas and New Mexico was more than 50 percent higher.

The three states have large proportions of black and Hispanic teenagers — groups that traditionally have higher birth rates, experts noted.

It's not clear why Mississippi, with 68 births per 1,000, surged into first place. The state's one-year increase of nearly 1,000 teen births could be a statistical blip, said Ron Cossman, a Mississippi State University researcher who focuses on children's health statistics.

The New Mexico rate was 64 per 1,000; Texas was 63.

New Hampshire, with a rate of 19 per 1,000, was the nation's lowest, behind Vermont and Massachusetts.

The only states with declines in teen birth rates from 2005 to 2006 were North Dakota, Rhode Island and New York.

Michael Carrera, the director of Adolescent Pregnancy Programs at the Children's Aid Foundation in New York City, blamed economic stagnation among low-income families, which, he said, led to indifference about contraception.

"It is one thing to know about contraception, but to want to use it, you must also have knowledge of a good life," he said.

David Landry, a researcher at the Guttmacher Institute, a New York-based organization which supports abortion rights and gathers research on sexual and reproductive health, blamed a combination of poverty, culture and racial demographics. Kids in mostly white New England would be more likely to delay child birth, he said, than those in the South.

"It's more costly for youth in the Northeast to have a teen birth than for youth in the South, in terms of opportunities they'll miss," Landry said.

Carrera and other teen-welfare specialists who favor sex education and contraception also think that the hundreds of millions of dollars that the Bush administration invested in abstinence-only programs would have been better spent on their approach.

Other factors include the escalating cost of some types of birth control and their unavailability in some communities, said Stephanie Birch, who directs maternal and child health programs for the Alaska Department of Health and Social Services.

Glowing media portrayals of celebrity pregnancies don't help, either, she said. "They make it out to be very glamorous," said Birch, who cited a calculation by Alaska officials that teen births were up 6 percent in that state in 2006.

Janice Crouse, the executive director of the Beverly LaHaye Institute, an alliance of conservative women, faulted an atmosphere of sexual tolerance, especially on campuses, where teens are "under the influence of peers, and under pressure to drink."

"College counselors see a very close connection between all the sexual activity and alcohol.

"Over the last decade, this whole business of 'hooking up' has been very injurious to our girls," Crouse continued, "not just in terms of pregnancy, but also in terms of STDs (sexually transmitted diseases) depression and a very alarming increase in sexual assault among college students."

Crouse also blamed American society for "glamorizing teen pregnancy."

"TV shows with pregnant mothers don't show the morning sickness, the swollen feet, the more uncomfortable sides of pregnancy," she said.

Carrera said the previous declines — since 1991— were impressive only by American standards.

"Fourteen years ago, the rates were so high that anything looked down from there," he said.

The Associated Press contributed to this report.