The U.S. teen pregnancy rate has reached a 40-year low, a new study finds.

The study, by the Guttmacher Institute, found that the pregnancy rate declined 42 percent from its peak in 1990, according to the study released Wednesday.

The teen pregnancy rate in 2008 was 68 per 1,000 girls age 15-19, down from 117 per 1,000 in 1990. That means about 7 percent of girls in that age group became pregnant that year.

In addition, the survey showed the birthrate declined 35 percent between 1991 and 2008, from 61.8 to 40.2 births per 1,000 teens.

The reduced pregnancy rate also meant fewer abortions. The abortion rate declined 59 percent from its 1988 peak of 43.5 abortions per 1,000 teens to 17.8 per 1,000 in 2008.

"The declines in teen pregnancy have been nothing short of extraordinary," said Sarah Brown, CEO of The National Campaign to Prevent Teen and Unplanned Pregnancy. "Make no mistake, the credit for this remarkable progress goes to teens themselves who have, over the past two decades, adopted a less sex, more contraception strategy— one that is clearly working."

Other findings from the study:

-- There were nearly 750,000 pregnancies to women 20 and younger in 2008.

-- Teen pregnancy declined among all racial and ethnic groups since 1990 — down 50 percent for whites, 48 percent for black teens and 37 percent among Hispanic teens.

"The recent declines in teen pregnancy rates are great news,” said Kathryn Kost, lead author of the study. “However, the continued inequities among racial and ethnic minorities are cause for concern. It is time to redouble our efforts to ensure that all teens have access to the information and contraceptive services they need to prevent unwanted pregnancies.”