But after an investigation, the European Medicines Agency (EMA) says that emergency contraceptives are effective for women of all weights.
Last year, the agency requested a warning on the label of Norlevo, the European equivalent of Plan B containing levonorgestrel, indicating that it might not be as effective in preventing pregnancy for women with a body mass index (BMI) greater than 25. This decision was based on a 2011 study that showed heavier women who took products containing levonorgestrel—which prevents pregnancy after intercourse—were four times as likely to become pregnant as those with lower BMIs.
After that recommendation, the regulatory agency conducted a review of other emergency contraceptives containing levonorgestrel or ulipristal acetate, and found that the data in the earlier studies was limited and not substantial enough to conclude that the contraceptives' effect was decreased with increased body weight. That doesn't mean that weight may not play a role in the drugs' effectiveness, but for now, the EMA's Committee for Medicinal Products for Human Use (CHMP) recommends that Norlevo remove the current warnings from its label. It also said emergency contraceptives should continue to include on their product inserts some study results showing potentially reduced effects in heavier women.
While the European health authorities took action on Norlevo last year, the U.S. Food and Drug Administration has not issued any similar warnings for Plan B. “I don’t necessarily think it’s inevitable that the FDA would act on this,” Dr. Carolyn Westhoff, professor of obstetrics and gynecology and public health at Columbia University and senior medical adviser at Planned Parenthood Federation of America, told TIME in November 2013 regarding the data at the time. “People in the field have been scratching their heads since [the 2011 study] was published, saying what sorts of studies could we do to get more data to help us understand this better. To my knowledge, nobody has done those additional studies.”
EMA also admits that such data isn't available yet, but says that there isn't enough data to support the previous warning to women about weight.