April 17, 2007 - So-called morning-after contraception works for individual women, but it isn’t working to lower unwanted pregnancy rates at the population level, an analysis of the research shows.
The analysis of eight studies involving more than 6,000 women revealed that pregnancy rates were the same for women who did and did not receive an advance supply of emergency contraception along with counseling about how to use the pills.
Late last summer the FDA agreed to over-the-counter sales of the emergency oral contraceptive sold as Plan B to women aged 18 and older.
Supporters of the move contended that easy access to Plan B would help reduce unintended pregnancy rates, while critics charged that it would encourage promiscuity and increase the likelihood of women having unprotected sex.
Neither conclusion is supported by the research, one of the authors of the analysis tells WebMD.
“The women who had the emergency contraception on hand did use it more often, but that didn’t translate into a decrease in pregnancy rates at a population level,” says Chelsea Polis of the Johns Hopkins Bloomberg School of Public Health.
Wasn’t Used When Needed
When used correctly, morning-after contraception is very effective for preventing pregnancy. The high-dose pills should be taken as soon as possible after unprotected sex, but the strategy can prevent pregnancy for up to five days after intercourse. Plan B must be used within 72 hours of intercourse.
Polis says it is clear that the study participants who had Plan B or another emergency oral contraceptive on hand were not using emergency contraception every time they had unprotected sex.
“A high percentage of women who became pregnant hadn’t used [emergency contraception] when they needed it,” she says.
Four of the eight studies included information on women who had the emergency contraception on hand but got pregnant anyway. In these studies, 64% to 79% of the women said they did not use emergency contraceptives in the cycle in which they became pregnant.
The studies included women living in the United States, India, and China.
Polis says the findings should not be interpreted as meaning that emergency contraception isn’t useful or that efforts to make it more readily available are not important.
And the research makes it clear that having emergency contraception on hand does not increase risky sexual behaviors, she says.
There was no difference in sexually transmitted infection rates between study participants who had advanced provision emergency contraception and those in the control arm of the study.
Lessons From France
Emergency contraception has been available without a prescription in France since 1999, longer than any other country. Princeton University researcher Caroline Moreau, PhD, was one of the first to study the effectiveness of the birth control method at a population level.
She found that a 72% increase in emergency contraceptive use among French women over a five-year period did not have a measurable impact on abortion rates.
When women seeking abortions were asked why they hadn’t used emergency contraception, most said they had not known they were at risk for pregnancy, Moreau tells WebMD.
“While enhanced availability of emergency contraception is certainly an important measure to promote its use in case the need arises, misrepresentations of pregnancy risk may prove to be the strongest barrier to its use, thus limiting the possibility of its effect on unintended pregnancy rates at the population level,” she notes.