More people are trying Ozempic and Mounjaro to improve their fertility chances – but is it safe?

Your body goes through a lot of changes during fertility treatments, pregnancy, and postpartum. Many of them can feel very unsettling if you look in the mirror and don’t see someone familiar looking back. Despite the gains of the body positivity movement over the past decade, there is still a normalization of slim body types. The pressure for women to maintain a certain weight heading into pregnancy and to "bounce back" after birth has led some to question the efficacy and safety of Ozempic, Wegovy, and other newly-available injectable drugs that induce weight loss. 

It’s not just celebrities who have reportedly turned to these medications. CNN reports that 373,000 prescriptions were filled for Ozempic in the last week of February, a 111 percent increase compared to the same time in 2022. Demand has become so great for Ozempic and Wegovy, for example, that the FDA is reporting ongoing shortages. The interest in these drugs has even reached the BabyCenter Community, where parents report taking them to treat their insulin-resistant polycystic ovarian syndrome (PCOS) and to lose weight they gained during pregnancy. 

Then there are parents taking these drugs with the goal to lose weight before trying to get pregnant. That trend concerns experts, because it’s unclear just how these drugs can impact fertility – or even a pregnancy.

But why would someone need to lose weight at all before getting pregnant? And should these new weight loss medications play a role? We asked experts to lay it out for us. 

Does body weight potentially impact fertility and pregnancy?

According to the American College of Obstetricians and Gynecologists (ACOG), there are a lot of different factors that can impact a person’s fertility chances, including their age, lifestyle, and existing health conditions – as well as the age, health, and lifestyle of their partner. 

One of those many complex factors that can play a role is body weight, experts say – which is why some women may be told by their doctors to lose weight before trying to get pregnant. 

"Obesity and higher BMI [body mass index] definitely impacts the menstrual cycle and ovulatory function, and as a result, just natural fertility," says Priyanka Ghosh, M.D., a fertility expert at Columbia University Fertility Center. Research has shown that people with BMIs between 25 and 29.9 (considered "overweight") and 30 or above (considered "obese") are less likely to ovulate in a given menstrual cycle compared to people with a BMI of 18.5 to 24.9 (what’s considered a "normal" BMI). And without regular ovulation – the releasing of an egg to get fertilized – it’s really hard to get pregnant. 

"There’s pretty good data that shows that women who have high BMIs can take longer to conceive [and] have higher miscarriage rates," adds Christina Boots, M.D., associate professor of obstetrics and gynecology specializing in reproductive endocrinology and infertility at Northwestern University Feinberg School of Medicine. She says that these patients have slightly lower success rates even with medical interventions like in vitro fertilization (IVF).

Having a higher body weight might also increase a person’s risk of health conditions during pregnancy, says Dr. Boots, including gestational diabetes, preeclampsia, and high blood pressure – all of which can make pregnancy more dangerous for mom and baby. 

For all of those reasons, Dr. Ghosh says, fertility patients who are of higher weight are often encouraged by their practitioners to lose weight via lifestyle interventions (exercise, supplements, etc.) and medical treatments. Some are even denied access to fertility treatment until they lower their BMI.

But as anyone who’s ever tried to lose weight can tell you, it’s rarely as simple as "calories in, calories out." And certain underlying conditions like polycystic ovarian syndrome (PCOS) or a thyroid disorder – which also affect fertility – can inherently make it even more difficult to lose weight, says Dr. Boots. 

How are Ozempic, Wegovy, and Mounjaro used for weight loss?

Enter this brand-new class of injectable medications, which are being positioned as a safer alternative to bariatric surgery – and thus have lots of appeal for people who have been told to lose weight before trying to conceive.  

There are a few different medications on the market, but the most popular right now are Ozempic, Wegovy, and Mounjaro. Ozempic and Wegovy are trade names for the drug called semaglutide, while Mounjaro’s active ingredient is called tirzepatide. These drugs are injected into a person’s upper arm, thigh, or stomach on a weekly basis, and work by mimicking certain hormones in the body to help lower blood sugar levels. These drugs also have effects on your intestinal tract that make you feel fuller for longer and reduce your appetite. (Side effects include nausea, diarrhea, vomiting, abdominal pain, and constipation.) 

Semaglutide and tirzepatide were initially created to treat type 2 diabetes. But research has shown they can also induce significant weight loss in a short amount of time. One clinical trial published in JAMA Network looking at semaglutide found that patients lost an average of 27 pounds (nearly 11 percent of their body weight) in six months. Another one published in the New England Journal of Medicine found that the average weight loss after taking tirzepatide for 72 weeks was 15 percent or more, depending on how high the dose was. (By comparison, people who undergo bariatric surgery lose as much as 13 to 31 percent of their baseline weight in 12 months, depending on what procedure they had – but that’s after undergoing a major surgery.)

The potential impact on body weight has created a huge demand for these medications from celebrities and regular people alike. "I personally have not prescribed it," says Dr. Ghosh, "but I am definitely seeing an increasing number of patients who are taking them." 

Only Wegovy is approved by the FDA for weight management, and that’s just for patients who have a BMI of 30 or above and weight-related health problems. But that doesn’t stop patients of all stripes from seeking out semaglutide or tirzepatide for the off-label purpose of losing weight – including people TTC. 

Is Ozempic safe for pregnancy? Can it impact fertility? 

Drs. Boots and Ghosh both say people should not take semaglutide or tirzepatide, the active ingredients in Ozempic, Wegovy, and Mounjaro, while pregnant. If you’re ready to try getting pregnant, experts say you should stop using these medications for at least two months before you have unprotected sex, since that’s about how long it takes the drugs to leave your system. It’s also really important to use some form of birth control consistently if you do take them. "You want to use something that is effective," says Dr. Boots, whether that’s oral contraceptives, an intrauterine device (IUD), or just really careful, stringent condom use. 

We have limited data telling us how safe these medications are for people of reproductive age. These drugs are relatively new to the market (Ozempic was approved by the FDA in 2017; Wegovy in 2021), meaning there isn’t a lot of long-term safety data available. Plus, they were developed to treat diabetes, so we have less clarity about how safe they are for people without that disease. Many existing studies on semaglutide and tirzepatide primarily focus on patients who are, on average, in their mid- to late- 40s.

"We don’t know what the drug does to a growing fetus," says Dr. Boots.

In fact, when you look at the prescribing information for Ozempic, Wegovy, and Mounjaro, you’re hit with a pretty glaring disclaimer: They are not recommended for people who are pregnant. In fact, all three drugs tell people of reproductive age to stop taking these medications for at least two months before trying to conceive. 

"We do not have clinical data evaluating the effect of Ozempic or Wegovy on fertility treatments," says a representative for Novo Nordisk (which manufactures the two drugs) in a statement emailed to BabyCenter. "We incorporate information about pregnancy into patient and healthcare provider advertisements for both products, along with other relevant safety information." (The company also states that it does not promote or recommend any off-label usage of its products.) 

Eli Lilly, which manufactures Mounjaro, tells BabyCenter that they do not promote or encourage the use of the drug outside of its FDA-approved indication for type 2 diabetes. “If any person has questions about their prescription, they should contact their healthcare provider who can assist in their treatment plan,” a brand representative adds. 

Beyond the immediate safety concerns of the drugs themselves, there are also some potential risks to losing a lot of weight right before getting pregnant. "Our body is very sensitive to dramatic fluctuations in our weight," Dr. Ghosh says. Your body may interpret significant weight loss as a sign that it’s not a safe time to be pregnant, she says, which can trigger menstrual cycle changes and disrupt fertility. 

Research also shows getting pregnant within a year of bariatric surgery (which also involve lots of weight loss) leads to an increased risk of miscarriages, preterm birth, or having a baby that is smaller than considered healthy. Some of those outcomes could be due to the fact that these patients are not getting enough nutrients or calories to support a healthy pregnancy, Dr. Boots says. While we don’t yet have any data looking at semaglutide and tirzepatide, Dr. Boots believes people who use these injectable drugs to lose weight immediately leading up to or during pregnancy may encounter similar potential risks. "You don’t want to be malnourished when you’re trying to grow a baby," Dr. Boots says. 

Can you use Ozempic and other similar drugs while breastfeeding? 

Both experts do not recommend using semaglutide or tirzepatide while breastfeeding. Currently there is no information on whether these drugs can pass through breast milk and impact your baby. Plus, excessive weight loss of any kind while breastfeeding can impact your milk supply and make it hard to feed your baby.

 "I would not recommend starting these until you’re all done nourishing [your] baby," says Dr. Boots.

Weight and BMI do not determine reproductive health

It’s also critical to remember amidst the Ozempic craze that there is a lot more to health (and fertility) than weight alone. 

Because BMI is so simple to calculate – just plug in a person’s gender, age, height, and weight into an online calculator – Dr. Boots says that focusing on weight loss often seems like an "easy target" for clinicians when treating infertility. "But I think it’s really flawed," she says. "BMI is an oversimplification about the health of somebody. It’s a predictor, but it’s not the only predictor of health."

In fact, research shows that BMI might even misdiagnose someone as metabolically unhealthy. (The index also doesn’t account for natural body differences that happen due to genetics, ethnicity, and other factors, making it less accurate for people of color.)

Dr. Ghosh says there are instances where weight loss may be helpful for infertility. For example, if someone is of a higher weight and they’re not ovulating, "weight loss has seemed to help restore ovulatory function," she says.

But in other cases, losing weight has not been proven to be universally beneficial to fertility. A 2022 PLOS Medicine study looked at hundreds of women who had a BMI over 30 and unexplained fertility issues, and randomly enrolled half in lifestyle modification groups, which focused on weight loss and physical activity before receiving fertility treatment. At the end of the study, there was no significant improvement in fertility or birth outcomes among the women who lost weight compared to those who didn’t before TTC.

However, Dr. Ghosh says that losing weight has been associated with better health outcomes during pregnancy itself, which is why doctors remain focused on it. "Pregnancy outcomes are impacted by obesity as well," she says. "This is kind of thinking more about long-term impacts [of weight] more than just the short term of achieving pregnancy." 

The bottom line: There remains much we don’t know about the safety or potential impact of semaglutide and tirzepatide. Both Drs. Boots and Ghosh tell patients who are on these medications to wait before trying to conceive (and be really careful about contraception in the meantime). 

"[Semaglutide and tirzepatide are] being prescribed very, very widely for a variety of indications," says Dr. Ghosh. "We just really need more data to be able to understand the safety profile of this medication."