Fewer teens are getting pregnant now, than at any point in the last 40 years, says a new report.

Researchers at the Guttmacher Institute, a sexual and reproductive health think tank, say the pregnancy rate among teens is down 42 percent, from 116.9 pregnancies per 1,000 women in 1990, to 67.8 pregnancies per 1,000 women in 2008. This means about 7 percent of young women between the ages of 15 to 19 became pregnant in the United States in 2008.

"The 30-plus years of rates that we have, have been showing a very steady decline," said Kathryn Kost, a senior research associate at Guttmacher, and the lead author on the paper. "Rates now, from 2008 are at the lowest levels we ever seen since we started reporting them."

Kost also says the teen birth rate -- the number of actual babies born to teenage moms - was down 35 percent as well; and the abortion rate among teens dropped almost 60 percent from its peak in 1988.

"What seems pretty clear is that increasing use of contraception is preventing these kids from getting pregnant in the first place," said Kost.

The report did show that racial and ethnic disparities still exist among teenagers. Pregnancy rates among African-American and Hispanic teens were two to three times higher compared to white teens. Abortion rates among Hispanic teens were also twice the rate of abortions in whites, and abortion rates among black teens were four times higher compared to white teens.

"Providing contraception or at least being able to ensure that everybody has access to it may help to reduce these disparities," Kost says.

The researchers believe that although the number of teens having sex is not declining significantly, awareness about contraceptives has turned the tide in the teen pregnancy numbers.

"It's clear that the largest share of the decline was due contraceptive use," she said, "both an increase in use, and increase in use of the most effective methods."