"Shrill": Does the Morning-After Pill Have a Weight Limit? Doctors Say Yes

In Hulu’s funny and moving new series Shrill, Aidy Bryant of Saturday Night Live fame plays Annie, a writer working toward becoming the person she wants to be while facing daily micro-aggressions and indignities related to her weight. Dealing with forces like her mom, her boss, and the pharmaceutical industry, Shrill stays true to the reality of what it means to be seen as a fat woman.

More on that in a moment. First, a warning: Spoilers below for the first episode of Shrill.

In the pilot episode released Friday, Annie finds herself in a situation: She had unprotected sex, leading her to take a “morning-after pill.” But to her surprise, a subsequent pregnancy test reveals that she’s pregnant. She confronts the pharmacist, which you can see in the video at the top, about her “defective test.” In turn, the pharmacist asks Annie if she weighs over 175 pounds. When she confirms, the pharmacist bluntly says that the morning-after pill only works for women 175 pounds and under.

Annie is astounded, letting out a what-is-this-fresh-bullshit “What?!” But as surprising as it may seem, what the pharmacists tells her is based on some real-world truths.

“This is a real thing,” Aaron Lazorwitz, M.D., an assistant professor of obstetrics and gynecology at the University of Colorado tells Inverse. “Studies have shown that overweight and obese women have higher rates of failure with the traditional morning-after pill.”

The issue with the existing literature is that the parameters of the data isn’t consistent. A woman’s weight, her body mass index, and the type of emergency contraception she uses are all factors, but the degree to which they affect a morning-after pill’s efficacy changes across studies.

In the United States, there are several progestin-only emergency contraceptive products, each which contain a type of hormone that prevents pregnancy called levonorgestrel. Progestin-only pills are available over the counter; some brand names are Plan B One-step, Next Choice, and Take Action. Studies indicate they are most effective taken as soon as possible after sex, and not more than five days afterward.

Lazorwitz says that some data suggest that the progestin-only emergency contraceptive, known more popularly as the morning-after pill, may not work at all for women over 150 pounds. Meanwhile, other data indicate that the method is less effective for women who weigh more than 165 pounds or have a BMI over 25. More consistently than specifying an exact weight, studies conclude that levonorgestrel-based emergency contraception does not prevent pregnancy as efficiently for “obese women,” possibly because a single dose of the medication results in lower concentrations of levonorgestrel in this group.

It’s an area of science that needs more research and leaves manywomen feeling confused. Nowhere on the packaging for Plan B One-Step, the best-known brand of levonorgestrel emergency contraceptives, does it warn women who weigh over a certain amount that it might not work for them.

In 2013, a company that sells a European morning-after pill identical in formula to Plan B One-Step announced it would update its packaging to say it’s not an effective pill for women over 176 pounds and loses its potency for women over 165 pounds. But that decision was reversed after the pill was reviewed by the European Medicines Agency, which decided the available data were “too limited and not robust enough to conclude with certainty that the contraceptive effect is reduced with increased body weight.”

And yet in 2016, while acknowledging that the “data are limited and poor to fair quality,” scientists said in the journal Contraception that their “findings suggest that women with obesity experience an increased risk of pregnancy after use of LNG ECP compared to those normal/underweight.”

Defining “normal” is crucial here. According to the CDC, the average weight of an American woman is 168.5 pounds, so a pill marketed to “normal” women should work for a woman of that weight. Not much has changed since the pill was first introduced: Plan B was approved by the FDA in 1999, when the average weight of a woman was closer to 160 pounds.

Lazorwitz recommends that women over 150 pounds who need emergency contraceptive not use levonorgestrel pills and instead use pills with ulipristal acetate, another active ingredient that prevents pregnancy. The brand name for this pill in the United States is ella. He also recommends the copper intrauterine device as an emergency contraceptive method, which is 99 percent effective as an emergency contraceptive for all patients, regardless of weight.