After former President Donald Trump won a second term in the White House last week, Kelly Cleland had two women in her neighborhood hit her up for Plan B. As the president of the American Society for Emergency Contraception, she’s always got a stash at home for free.
Americans have been stocking up on emergency contraception and abortion pills in the wake of the election, with reproductive health company Cadence OTC reporting purchases in a single day that were five times the amount it normally gets in a week. But amid this surge in interest, social media discourse has also been highlighting concerns about whether the drugs are less effective for people at higher weights.
“The science isn’t clear. There have not been any studies that have been big enough and properly designed to answer this question,” said Cleland.
That doesn’t mean people at higher weights shouldn’t take emergency contraception, she and other health experts clarify — but it’s a gap in knowledge that highlights the ways this population can get left behind.
“I think we are just now as a reproductive health rights and justice community starting to really acknowledge the fact that people with higher BMI have been historically excluded from clinical trials,” said Cleland.
The need for more robust research on this topic has never been greater. Thirty percent of women of reproductive age have used emergency contraception, and the American population has steadily been getting heavier for decades. A recent survey found that over 40% of Americans are obese, a condition that can change how drugs interact with the body. This population has been historically excluded from drug trials and is still underrepresented today.
“The stakes are extremely high, and preventing pregnancy is more important than it’s ever been,” said Cleland. “Post-Dobbs, that became true. With the election of Trump, I think it’s even more true.”
Why it’s hard to get answers on BMI and emergency contraception
Reproductive rights, particularly abortion, have been increasingly restricted in the United States in the aftermath of the Supreme Court’s decision to overturn Roe v. Wade. Emergency contraceptives like Plan B are not abortion — rather, they delay ovulation. But health care professionals worry the incoming administration will nonetheless target emergency contraception.
“I’m feeling uneasy,” said Alison Edelman, a professor and obstetrician-gynecologist at Oregon Health & Science University. “Contraception is incredibly important, including emergency contraception. Reproductive health has had a long history of being either ignored or under attack, so we’re very used to being in that state. We just have to continue to take one day at a time and hope that people recognize their rights and their need to access care.”
Reproductive health experts agree that emergency contraception is vital and safe. In the U.S., there are three available: levonorgestrel (also known as the morning-after pill and sold under the brand names Plan B and Julie) and ulipristal acetate (sold under the brand name ella and others), and a copper intrauterine device. While weight doesn’t factor into the efficacy of a copper IUD, this nonhormonal option requires a potentially painful procedure and the contraceptive effects typically last years.
More than a decade ago, researchers published an analysis of randomized control trials on levonorgestrel and ulipristal acetate. They found that the risk of pregnancy for anyone with a BMI over 30 — labeled “obese” — was three times as high as someone with what they called a “normal” BMI up to 25. Nearly 6% of obese participants who used levonorgestrel got pregnant, while those who took ulipristal acetate had a slightly lower risk of becoming pregnant at 2.6%. Only 1.3% of people with a “normal” or underweight BMI got pregnant. (Also worth noting is that the BMI is now broadly viewed as a flawed metric for capturing health.)
The paper shook the field. Clinicians had observed similar failures in women with obesity with non-emergency hormonal contraceptives, but this was the first study to demonstrate the reduced efficacy of emergency contraception at higher BMIs. Participants fell off the efficacy cliff at 155 pounds for levonorgestrel and at 195 pounds for ulipristal acetate.
“The lack of attention to people who are across the full spectrum of body types who are able to get pregnant is really shocking to me, especially given the reality of our country,” said Cleland. “The average weight in the U.S. is 170 pounds, so that’s like more than half the country for whom Plan B potentially doesn’t work.”
Some subsequent studies also showed an increased risk of pregnancy for people with obesity who use levonorgestrel. But other attempts at replication have proven trickier. For ulipristal acetate, a July study found no drop in the drug’s efficacy when given to people who weighed more than 175 pounds.
Social media users have suggested that a double dose of emergency contraception for someone with obesity can prove just as effective as a lighter person taking a single dose. A 2016 study seemed to show that a double dose of levonorgestrel could improve the efficacy of the drug for obese people, but a recent follow-up study refuted the finding. (The U.K. does advise it in some cases.)
Conflicting data aside, contraception experts agree that ulipristal acetate, or ella, is a more effective option for people who weigh more, even though it requires a doctor’s prescription and Plan B can be found in drug stores.
Edelman said it is unlikely that the field will be able to definitively answer some outstanding questions about weight and emergency contraception. People are less likely to enroll in a study when they can just buy Plan B from a drug store. The widespread use of long-term hormonal contraceptives also means that trial participants are often reducing their pregnancy risk before they enter an emergency contraception trial. Edelman herself faced such problems with a recent study that sought to provide answers as to the efficacy of levonorgestrel and ulipristal acetate in people who weigh more, but low enrollment number and few pregnancies across all treatment arms left them unable to meet its endpoints.
“We always like the best evidence available to us, to base our recommendations on. And unfortunately, in this instance, it’s going to be challenging to get that,” said Edelman.
Talking to patients about contraception and weight
Scientists aren’t fully sure why the efficacy of emergency contraception might differ in people at higher weights, though some studies suggest these drugs can dissolve more readily in fat tissues and disperse the emergency contraception throughout the body, reducing its concentration. Another possible reason is that if someone weighs more, their ovulation rates can change, which can muck up comparisons to someone who weighs less in these types of studies.
Though the data may not be definitive, pediatrician Ashley Ebersole is emphatic that doctors should not withhold these options from patients.
“I’m telling residents all the time that just because something is less effective doesn’t mean you say, ‘You can’t have this.’ It just means you make sure your patients are aware of that,” said the Columbus, Ohio, contraception expert.
Ebersole attributes some of the confusion around contraception and weight to the inherently sensitive nature of weight. When Ebersole prescribes these treatments, some patients aren’t ready to have that conversation, she said.
“Maybe the resident has gone in there and they’ve been like, ‘Oh, great. This patient wants to do the patch. They’re so excited, their friends on the patch.’ And then I go in and break the bad news like, ‘Hey, I need you to know these things about how effective it is.’” said Ebersole.
In the rush to provide people with emergency contraception in the wake of Trump’s reelection, health care professionals are preparing to have these types of complicated conversations more and more often. Beyond people at higher weights, Ebersole says there’s a great need for more research about effective contraception for another major population, too.
“We really do have a lot of contraceptive options,” she said. “What makes me mad is that we don’t have male contraception yet.”