Plan B One-Step is said to work for around 90 percent of women — as long as you don’t fit the description of the average American woman. According to the Centers for Disease Control and Prevention, the average woman in the US weighs in at just over 170 pounds, meaning their BMI is likely too high for morning-after pills to be as effective as advertised for an emergency contraceptive.

Even more suspicious is the fact that Plan B One-Step fails to disclose this information on their website and packaging, yet Planned Parenthood does warn potential users of the drug and recommends an IUD alternative that works regardless of weight.

Most morning-after pills such as Plan B One-Step, Next Choice, and generic brands contain a synthetic hormone called levonorgestrel that’s used to delay ovulation. Levonorgestrel is a common component of birth control pills, but is required in a much higher dosage when used within a short window after unprotected sex. This is, in theory, the preferred emergency contraceptive when it comes to price and accessibility as it’s sold over the counter and online for as little as $20. 

However, in 2013, Europe’s version of Plan B One-Step, called NorLevo, announced that after a review by pharmaceutical regulators they would be disclosing on packaging that their drug would not perform as advertised for an individual over 165 pounds. 

Erin Gainer, CEO of HRA Pharma (whose products include NorLevo, Ella, and an IUD contraceptive) told the New York Daily News that “when we became aware that there appeared to be an impact on efficacy (linked to weight), we felt it was our ethical duty as a drug manufacturer to report it and be transparent.” 

The following year the European Medicines Agency, despite multiple clinical studies suggesting that the drug was not sufficient for women over 165 pounds, claimed that the benefits were greater than the risk, and that the disclosure would be removed from NorLevo’s packaging. 

Although levonorgestrel may do no harm (and in some cases, no good), taking the drug without that knowledge can still hold significant consequences. The CDC confirms that there are definite links between obesity and socioeconomic status, meaning that some may not be able to afford the price and insertion of an IUD depending on government programs and health insurance (whether it be for general birth control or an emergency contraceptive after the fact). Levonorgestrel would be the first choice, and if it does prove ineffective, why are the majority of women in the US being neglected?

For now, the only other alternative (in a pill form) to levonorgestrel is ulipristal acetate, known as Ella. It’s more effective for women with higher BMI, yet more expensive and requires a prescription. It also shouldn’t be used in conjunction with other hormonal birth control, so again an IUD remains the most reliable option albeit far from the most straightforward.

A 2010 British Medical Journal study finds “…the rate of unplanned pregnancies is four times higher among single obese women than normal weight women,” based off of the claim that they are “less likely to seek contraceptive advice.” If these women are using oral contraceptives without consulting a professional, there is no clear warning issued by the pharmaceutical companies that their drug won’t work for them. If these aren’t available in an appropriate dosage for the average woman, and double dose studies haven’t yielded positive results, then Plan B really shouldn’t be womens’ Plan B.