A health worker teaches women how to properly use a intra uterine device (IUD) during the World Population Day in Manila. (Jay Directo, AFP/Getty Images)

Peipert's group also found that rates of teen pregnancy were substantially lower among girls participating in the project. Among teen girls aged 15 to 19 enrolled in Contraceptive CHOICE, the number of pregnancies translated to a rate of 6.3 per 1,000. That compares to the national average for 15-19 year-olds of 34 out of every 1,000 girls.

The study cannot prove that improved access to birth control caused the drop in abortions and teen pregnancies.

But Peipert said he hopes that with the insurance coverage changes for birth control under the Affordable Care Act, long-acting contraceptives will become more accessible to women.

The healthcare law requires insurance companies to offer birth control without co-pays. Some women may have already seen this change to their benefits, but others will have to wait until their new insurance plan year.

"It is possible for us, with our current medical knowledge and evidence and clinical services, to address the unintended pregnancy rate in the U.S.," said Cynthia Harper, a professor at the University of California, San Francisco, who was not involved in the study.

Harper said that the program's focus not only on cost barriers but information barriers among health care providers and women made it successful.

In particular, women were counseled on the effectiveness of each birth control method, an approach Harper said isn't always taken in the doctor's office.

"Patient education is important, and women don't have a very good sense of the effectiveness of contraception," she told Reuters Health.

"The unintended pregnancy rate has been high for decades, and this shows we can make progress and it's not beyond our grasp," said Harper.

SOURCE: http://bit.ly/QWcLrV Obstetrics & Gynecology, online October 3, 2012.