Teenagers do just as well as adults when it comes to understanding the information on emergency-contraception labels, a new study suggests.

The findings, say researchers, argue for making emergency contraception available to minors over-the-counter, as it already is for adults.

The emergency contraceptive Plan B can prevent pregnancy if it is taken within 72 hours of having unprotected sex. However, the sooner it is taken, the better - after the first 12 hours the risk of pregnancy increases by 50 percent. Since 2006, adults in the U.S. have been able to get the contraceptive without a prescription.

The Food and Drug Administration (FDA) still requires minors to get a prescription, and this delay, critics say, lowers the chances of preventing pregnancy. They also charge that the regulation has more to do with politics than health.

In the new study, of more than 1,000 girls 12- to 17-year-old, researchers found that most understood the information on the emergency-contraception labeling. And their level of comprehension was comparable to that of adults reported in a similar study conducted in 2002, the researchers report in the journal Obstetrics & Gynecology.

“I believe the potential implications of our study are to help the FDA decide to make Plan B available over-the-counter without an age restriction,” lead researcher Dr. Miriam Cremer, of New York University School of Medicine, told Reuters Health.

Last week, a federal court ordered the FDA to allow over-the-counter sales of Plan B to 17-year-olds, and to consider expanding access to all ages.

Plan B contains the hormone progestin, which prevents pregnancy primarily by stopping the ovaries from releasing an egg. Pills must be taken with 72 hours of unprotected sex, ideally, within 12 hours.

Studies have shown Plan B to be safe and effective, Cremer said, noting that she believes the FDA restriction on sales to minors was based more on politics than clinical evidence.

For their study, Cremer and her colleagues had 1,085 New York City girls ages 12 to 17 read the Plan B labeling and then complete a survey of their emergency contraceptive knowledge.

Overall, 92 percent understood that the product is a method of preventing pregnancy after unprotected sex - comparable with the 93 percent of adult women who said the same in the 2002 study. Eighty- three percent of the teenagers knew they needed to take Plan B within 72 hours, similar to the 85 percent of women in the earlier study.

The large majority of girls also understood that Plan B is ineffective if you are already pregnant, should not be used as long-term birth control, and does not lower the risk of acquiring HIV.

The findings, Cremer and her colleagues conclude, show that teenagers “demonstrate comprehension equal to adults of the key points necessary for safe and effective use of emergency contraception.”

The study was funded by the Compton Foundation, which supports research on reproductive health.

SOURCE: Obstetrics & Gynecology, April 2009.