The XX Factor

If You Weigh More Than 176 Pounds, Plan B Might Not Work. What’s Plan C?

NorLevo gets a new package warning: Will not work in women who weigh more than 176 pounds.

Photo by Jasper Juinen/Getty Images

Big news in emergency contraception: As Mother Jones reports, new research on Europe’s version of Plan B has found that the pill doesn’t work in women who weigh more than 176 pounds and loses effectiveness at 166 pounds. The pill, a drug called NorLevo that’s manufactured by HRA Pharma, will soon come with a warning label:

HRA Pharma began investigating the need to change Norlevo’s label after Anna Glasier, a professor of obstetrics and gynecology at the University of Edinborough, published research in 2011 showing emergency contraceptive pills that use levonorgestrel are prone to fail in women with a higher body mass index. In an email, Karina Gajek, a spokeswoman for HRA Pharma, says that by December 2012, the company had reviewed clinical data and requested permission from a European Union governing body to update its product information.

So what does this mean for American Plan B? There’s no evidence that similar warnings will be popping up here, but our version is formulated with similar levels of the same kind of synthetic hormones as NorLevo, meaning there’s every reason to believe that women who weigh more than 165 pounds in the U.S. are just as prone to see a decrease in the pill’s effectiveness. Which is serious news indeed, because, as Mother Jones reports, it just so happens that 166 pounds is the average weight of American women over 20 years old. Twenty-three percent of American women of child-bearing age are considered obese by Centers for Disease Control and Prevention standards, putting most of them in the weight range that European regulators consider ineffective for emergency contraception. None of the manufacturers of American versions of the drug replied to Mother Jones’ request for comment.

It’s hard not to wonder what this news also says about the effectiveness of regular old birth control pills on heavier women, since these pills frequently use the same kinds of hormones to prevent pregnancy as their emergency cousins. Right now, though, there isn’t much research to know whether we should be concerned. In 2010, researchers published a review of seven different studies examining the question of weight and birth control and found some evidence that heavy women had more unintended pregnancies on hormonal birth control than other women.

Still, while the overall research is in its preliminary stages, the news from Europe suggests that women who weigh more than 165 pounds should seriously consider alternatives to pill-based emergency contraception if they need it. Experts routinely suggest getting a copper IUD inserted as an effective option. It not only works as emergency contraception if done up to five days after intercourse, but it also can stay in to give you 10 years of having your contraception situation figured out before you have sex.