Kathryn started taking Ozempic “off label” in April 2023 on her doctor’s advice. The Illinois native was diagnosed with gestational diabetes while pregnant and struggled with her weight after the birth of her daughter. After a short break from the drug in July due to side effects, she started taking it again in August. In September, she found out she was pregnant.
Although Kathryn was not using birth control, the pregnancy still came as a surprise. She was told by doctors that she was unlikely to conceive naturally, and had gone through several unsuccessful rounds of intrauterine insemination (IUI) before giving birth to her first child via IVF. “It was completely unexpected,” Kathryn tells me. “We didn’t really plan to grow our family so soon – my first daughter was only 13 months old.”
Ozempic is a type 2 diabetes medicine, not a fertility treatment. But stories like Kathryn’s are not rare. In fact, there is a whole register dedicated to monitoring women who became pregnant while using Wegovy, a weight loss drug containing the same active ingredient as Ozempic. Other women share their stories on X under the hashtag #OzempicBabies.
The weight loss caused by this class of drugs is likely to drive these surprise pregnancies, says Adam Balen, consultant in reproductive medicine at Leeds Teaching Hospitals. Carrying extra weight negatively affects women’s fertility in several ways, including inhibiting ovulation and reducing the quality of their eggs and uterine lining, he explains. So when overweight or obese women lose weight, their chances of conceiving tend to improve.
But there is also another theory that claims that drugs like Ozempic can interfere with the effectiveness of birth control pills. This new diabetes and weight loss drug mimics a natural gut hormone called GLP-1 that has three main functions – boosting insulin, slowing stomach emptying and working in parts of the brain that regulate hunger. It is the second function that can hinder the body’s absorption of oral contraceptives, leading to surprise pregnancies.
One major pharmaceutical company, Eli Lilly, advises women to switch to non-oral contraception or a barrier method when starting its drugs Mounjaro or Zepbound, or when switching to a higher dose. Both Mounjaro and Zepbound contain the GLP-1 agonist tirzepatide.
However, there is no evidence that this theory also applies to Ozempic and Wegovy, which are made by Novo Nordisk and contain another compound called semaglutide. A spokeswoman for Novo said its drugs did not change overall exposure to the active ingredients in the combined pill “to a clinically relevant extent” in the company’s clinical trials.
“The whole birth control pill issue is still a bit uncertain in terms of the degree to which it affects these pregnancies,” says Balen. The absorption factor may have some influence, but weight loss is probably the biggest reason, he adds.
This phenomenon has led some researchers to speculate that GLP-1 drugs may improve fertility in relation to the most common cause of anovulation in women – polycystic ovary syndrome (PCOS). The condition affects around one in 10 women and symptoms include irregular periods, excess body hair and weight gain. This was one of the reasons why Kathryn struggled to conceive with her first child.
PCOS patients are often prescribed the birth control pill to regulate their periods, but this does not address the root mechanisms of the condition and it certainly does not help with fertility.
Melanie Cree, director of the University of Colorado’s PCOS Multidisciplinary Clinic, is the principal investigator on a clinical trial tested semaglutide in 80 obese girls and women with PCOS between the ages of 12 and 35. She explains how GLP-1 drugs are thought to encourage ovulation in the condition.
In about 80% of people with PCOS, the finely tuned system of hormone secretions needed for ovulation is out of sync, says Cree. This hormonal imbalance is driven by two mechanisms – problems with the brain’s hypothalamus and insulin resistance. The latter occurs when the body’s cells do not respond well to the hormone that regulates blood sugar.
Insulin resistance can improve if patients lose weight, which is why women with PCOS are often advised to do so at diagnosis. The idea is that the weight loss caused by GLP-1 drugs can improve insulin sensitivity and thus restore the proper hormonal balance for egg release.
There may also be another mechanism at play, according to Cree. In pilot MRI studies, her team noticed changes in brain connectivity in women with PCOS taking semaglutide. “The part of the brain that senses calories, the hypothalamus, was better connected to the parts of the brain that do decision-making,” she tells me. “We don’t know exactly what it is neurologically – is it just related to appetite or is there something more there?”
For the most part, though, weight loss seems to be the main driver, Cree says. Based on her earlier research on the syndrome, she says semaglutide is unlikely to have an effect on patients who are at an ideal weight. While 80% of women with PCOS have BMI values above normal or high, the rest present with what is known as a lean phenotype, according to research published in the Journal of Diabetes and Metabolic Disorders.
This begs the question: do GLP-1 drugs do something special in women with PCOS that they do not in overweight or obese women in general?
There is probably more of an effect on insulin levels in women with PCOS than in overweight or obese women who do not have PCOS, says Colin Duncan, principal investigator at the MRC Center for Reproductive Health at the University of Edinburgh, who is not involved in the study. Colorado trial. The fertility improvement can therefore be more dramatic in women with PCOS, he says.
Furthermore, PCOS patients may benefit more from a medicinal approach to weight loss because they have metabolism issues that make shedding pounds more challenging. In a process known as postprandial thermogenesis, a woman with PCOS burns about 75% of the calories a weight-matched healthy woman burns after eating a meal, says Duncan.
“This means that every day, [women with PCOS] for example, have to exercise 20% more or eat 4% less to be the same as anyone else,” he says. “I think it can be very discouraging for women who struggle with their weight, so having something that helps with weight loss along with lifestyle changes, from a psychological and well-being point of view, can better enable people to lose weight,” Balen says.
Afua, who lives in the UK, also struggled with her weight and fertility. Her first son was conceived a year and a half into her journey with PCOS-specific nutritionists to optimize her diet to help her ovulate. Although she didn’t lose any weight, she did manage to get pregnant naturally in 2020. “I found out on my birthday – it was a good present,” she says.
Two years later, Afua started taking Ozempic on the recommendation of her private endocrinologist and lost 30 kg in less than nine months “like it was nothing”. When she was ready for another child, Afua stopped using the drug and found herself pregnant with her second son just four months later. “Ozempic completely changed my life,” she says.
The problem is that GLP-1 drugs are not recommended for women trying to conceive because of safety concerns about the potential for abnormal development of the baby, Balen says.
The US Food and Drug Administration advises women to stop taking Ozempic at least two months before a planned pregnancy. Kathryn, who became pregnant while taking Ozempic, was advised to come off it immediately – her second daughter is healthy.
But even when used correctly, access to GLP-1 drugs is still a challenge.
Novo recently got its supply of Ozempic and Wegovy back on track after several years of intermittent shortages in the US. More importantly, these drugs are only approved for a handful of conditions, and PCOS is not one of them.
The United Kingdom’s National Institute for Health and Care Excellence recommends Ozempic for patients with uncontrolled type 2 diabetes who have a BMI of 35 or more and another weight-related health concern, such as high blood pressure. It can also be given to people with a lower BMI if they cannot use insulin due to the risk of low blood sugar.
But GLP-1 drugmakers are working to unlock new indications for their drug in other weight-related conditions. In July, the UK’s Medicines and Healthcare products Regulatory Agency approved Wegovy to reduce the risk of serious heart problems or stroke in overweight and obese people.
“It would be nice to think that PCOS might be one of those things over and above obesity that would allow access to these medications,” says Duncan.
Meanwhile, the syndrome is taking its toll on health spending. An article published in July in the Journal of Clinical Endocrinology & Metabolism by researchers at Cardiff University shows more people are being diagnosed with PCOS. They estimated that the cost of treating the condition in the UK was more than £1.2 billion in 2019.
For Afua, Ozempic is a no-brainer. “Even my partner told me, once you’re done breastfeeding, if you’re ready, we’ll put you back on Ozempic because he could just see how much of a smile the benefits had on my face,” she says. “I think doctors, the NHS, everyone, just need to be more aware of what’s out there and what can really help.”
