The morning-after pill has helped countless women prevent pregnancy in a pinch. But there’s one factor that could render your emergency contraception less effective: your weight.
A new study published in the journal Contraception has resurfaced previous concerns that the most popular type of EC, which is made from the hormone levonorgestrel, isn't as successful in women with higher body weights.
Quick history lesson: Based on clinical research, HRA Pharma, the European manufacturer of the emergency contraption drug Norlevo, added a warning on its packaging in 2013 that states it starts losing effectiveness for women who weigh 165 pounds or more—and that the drug isn't effective at all for women above 175 pounds. Why that matters in the U.S.? Norlevo is chemically identical to the one- and two-pill versions of Plan B, as well as its generics like Next Choice and My Way, says Jessica Arons, president and CEO of Reproductive Health Technologies Project, a birth control advocacy group. However, in 2014, the European Medicines Agency reviewed the data and found that there wasn't enough evidence to support the label change. Their Committee for Medicinal Products for Human Use released a statement saying that women of all weight could continue to use emergency contraception as needed.
The U.S. Food and Drug Administration (FDA) also decided that a label change on Plan B was not warranted, citing inconclusive data and calling for more research. But a new study, led by Alison Edelman, M.D., professor in the department of obstetrics and gynecology at the Oregon Health and Science University, is bringing the issue back to light.
The study included 10 women between the ages of 18 and 35. Five of the study subjects were considered “normal weight” and five were considered “obese,” according to the body mass index (BMI) measure. When obese women were given one dose of levonorgestrel-based EC, the amount of the hormone measured in their bloodstream was 50 percent lower than that of the women with normal BMIs.
The research team wanted to see if they could reverse the effect of obesity on levels of levonorgestrel in the bloodstream, an indicator of whether or not the drug might work. So, they upped the dosage to see what would happen. When obese women were given two doses, they had a similar hormone level as women with normal BMIs who were only given one dose. “By doubling the dose, we doubled the level of levonorgestrel observed in the bloodstream,” says Edelman. “We were surprised and pleased to see that we were able to compensate for [the effect of obesity] by doubling the dose.”
But does that mean obese women should start taking two pills the next time they need EC?
“As a clinical provider, I would love to tell you yes,” says Edelman. “As a researcher, it’s not something we can recommend yet. Levonorgestrel is safe, so doubling the dose in studies is very safe, but we don’t know if normalizing the dose in the bloodstream will stop ovulation.” One next step is to observe what happens in the ovaries of obese women in response to a double dose of levonorgestrel, says Edelman.
Elizabeth Westley, director of the International Consortium of Emergency Contraception, agrees with Edelman. “What we need now are some bigger studies that look at whether the higher dose of levonorgestrel is effective at preventing ovulation in heavier women,” she says.
There are other forms of emergency contraception that might provide more peace of mind for women above 165 pounds. ParaGard, a copper IUD, is 99.9 percent effective at preventing pregnancy when inserted within five days of unprotected sex. And Ella, an EC pill made from a compound called ulipristal acetate, is thought to be effective in women with higher body weights. Ella may be taken up to five days after unprotected sex, but it’s available by prescription only.
The average American woman weighs 166 pounds, according to the Centers for Disease Control and Prevention. Edelman says she would like to see more easily accessible oral EC pills that work for women regardless of their weight. “It’s important we have a wide range of options because it might be difficult to get an IUD placed, and some women don’t want to get an IUD under those circumstances,” she says. “It’s good to have more options when you need something this important.” Hopefully, this info will spur researchers to help create something that fits the bill.