Oct. 18, 2023 – For women who are obese, daily life is wrought with landmines. Whether it’s the challenges of air travel because plane seats are too small, the need to shield themselves from the world’s discriminating eyes, or the great lengths many will go to achieve better health and the promise of longevity, navigating life as an obese person requires a thick skin.

So, it’s no wonder so many are willing to pay more than $1,000 a month out of pocket to get their hands on drugs like semaglutide (Ozempic and Wegovy) or tirzepatide (Mounjaro). The benefits of these drugs, which are part of a new class called GLP-1 receptor agonists, include significant and rapid weight loss, blood sugar control, and improved life quality; they are unprecedented in a setting where surgery has long been considered the most effective long-term option.

On the flip side, the desire for rapid weight loss and better blood sugar control also comes with an unexpected cost. Many women living with obesity who take oral contraceptives are unaware that these drugs – especially Mounjaro – can interfere with the absorption of birth control pills and how well they work, making an unintended pregnancy more likely.

Neel Shah, MD, an endocrinologist and associate professor at the University of Texas Health Science Center at Houston, said he has had several patients become pregnant without intending to. 

“It was when Mounjaro came out on the market when we started using it,” he said of the drug the FDA approved for type 2 diabetes in 2022. “It [the warning] was in the product insert, but clinically speaking, I don’t know if it was at the top of providers’ minds when they were prescribing Mounjaro.”

When asked if he believed that we were going to be seeing a significant increase in so-called Mounjaro babies, Shah was sure in his response. 

“Absolutely. We will because the sheer volume [of patients] will increase,” he said.

It’s All in the Gut

One of the ways that drugs like Mounjaro work is by delaying the time that it takes for food to move from the stomach to the small intestine. Although data is still evolving, it is believed that this process – delayed gastric emptying – may affect the absorption of birth control pills. 

Shah said another theory is that vomiting, which is a common side effect of these types of drugs, also affects the pills’ ability to prevent pregnancy. 

And “there’s a prolonged period of ramping up the dose because of the GI [gastrointestinal] side effects,” said Pinar Kodaman, MD, PhD, a reproductive endocrinologist and assistant professor of gynecology at the Yale School of Medicine in New Haven, CT. 

“Initially, at the lowest dose, there may not be a lot of potential effect on absorption and gastric emptying. But as the dose goes up, it becomes more common, and it can cause diarrhea, which is another condition that can affect the absorption of any medication,” she said.

Unanticipated Outcomes, Extra Prevention

Roughly 42% of women in the U.S. are obese, 40% of whom are between the ages of 20 and 39. Although these new drugs can improve fertility outcomes for women who are obese (especially those with polycystic ovary syndrome, or PCOS), only one – Mounjaro – currently carries a warning about birth control pill effectiveness on its label. Unfortunately, it appears that some doctors are unaware or not counseling patients about this risk, and the data is unclear about whether other drugs in this class, like Ozempic and Wegovy, have the same risks. 

“To date, it hasn’t been a typical thing that we counsel about,” said Kodaman. “It’s all fairly new, but when we have patients on birth control pills, we do review other medications that they are on because some can affect efficacy, and it’s something to keep in mind.”

It’s also unclear if other forms of birth control – for example, birth control patches that deliver through the skin – might carry similar pregnancy risks. Shah said some of his patients who became pregnant without intending to were using these patches. This raises even more questions, since they deliver drugs through the skin directly into the bloodstream and not through the GI system. 

What can women do to help ensure that they don’t become pregnant while using these drugs? 

“I really think that if patients want to protect themselves from an unplanned pregnancy, that as soon as they start the GLP receptor agonists, it wouldn’t be a bad idea to use condoms, because the onset of action is pretty quick,” said Kodaman, noting also that “at the lowest dose, there may not be a lot of potential effect on gastric emptying. But as the dose goes up, it becomes much more common or can cause diarrhea.” 

Shah said that in his practice, he’s “been telling patients to add barrier contraception” 4 weeks before they start their first dose “and at any dose adjustment.”

Zoobia Chaudhry, an obesity medicine doctor and assistant professor of medicine at Johns Hopkins School of Medicine in Baltimore, recommends that “patients just make sure that the injection and medication that they take are at least 1 hour apart.”

“Most of the time, patients do take birth control before bedtime, so if the two are spaced, it should be OK,” she said.

Another option is for women to speak to their doctors about other contraceptive options like IUDs or implantable rods, where gastric absorption is not going to be an issue. 

“There’s very little research on this class of drugs,” said Emily Goodstein, a 40-year-old small-business owner in Washington, DC, who recently switched from Ozempic to Mounjaro. “Being a person who lives in a larger body is such a horrifying experience because of the way that the world discriminates against you.”

She appreciates the feeling of being proactive that these new drugs grant. It has “opened up a bunch of opportunities for me to be seen as a full individual by the medical establishment,” she said. “I was willing to take the risk, knowing that I would be on these drugs for the rest of my life.”

In addition to being what Goodstein refers to as a guinea pig, she said she made sure that her primary care doctor was aware that she was not trying or planning to become pregnant again. (She has a 3 year-old child.) Still, her doctor only mentioned the most common side effects linked to these drugs, like nausea, vomiting, and diarrhea, and did not mention the risk of pregnancy.

“Folks are really not talking about the reproductive implications,” she said, referring to members of a Facebook group on these drugs that she belongs to. 

Like patients themselves, many doctors are just beginning to get their arms around these agents. “Awareness, education, provider involvement, and having a multidisciplinary team could help patients achieve the goals that they set out for themselves,” said Shah. 

Clear conversations are key.