Popular Weight-Loss Drugs Like Ozempic May Pose Hidden Risks for Women of Reproductive Age
A new Australian study has raised important concerns about the widespread use of GLP-1 receptor agonists—medications like Ozempic, Wegovy, and Mounjaro—among women of reproductive age. These drugs, while effective for weight loss and type 2 diabetes management, could carry significant risks during pregnancy, yet many women are using them without effective contraception.
Let’s break down what the research shows, what experts advise, and what you should know about these increasingly popular medications.
The Study: What Researchers Found
The study, published in the Medical Journal of Australia on September 1, 2025, analyzed data from 1.6 million Australian women aged 18 to 49 who attended general practices between 2011 and 2022. Within this group:
- 18,010 women began treatment with GLP-1 receptor agonists during that period.
- Only 21% of these women had documented use of contraception at the time of prescription.
- In 2022 alone, 6,954 women started GLP-1 therapy, and over 90% did not have type 2 diabetes—meaning most were taking these drugs primarily for weight loss.
The study also revealed that 2.2% of women became pregnant within six months of starting treatment. The rates were highest among younger women with diabetes and among women without diabetes in their early 30s. Women with polycystic ovary syndrome (PCOS) were twice as likely to conceive, which researchers believe may be linked to improved fertility after weight loss.
Why This Matters
GLP-1 receptor agonists are originally designed for type 2 diabetes, but their ability to suppress appetite and promote weight loss has made them incredibly popular worldwide. The concern arises because exposure during pregnancy is not considered safe. Human data is still limited, but animal studies have consistently shown reduced fetal growth and skeletal abnormalities when these drugs are taken during pregnancy.
That’s why regulators in different countries have issued strict recommendations: women should avoid pregnancy while taking GLP-1 drugs and use effective contraception.
Known Pregnancy Risks and Guidance
Animal and Human Evidence
- Animal studies show risks like delayed skeletal development and smaller fetuses.
- Human studies so far haven’t shown a clear, consistent pattern of birth defects, but the data is too limited to declare safety. Researchers stress that absence of evidence does not mean safety is guaranteed.
Official Recommendations
- UK guidance (MHRA): Women taking GLP-1 drugs should use contraception and stop treatment before trying to conceive.
- Semaglutide (Ozempic/Wegovy/Rybelsus): stop at least 2 months before pregnancy.
- Tirzepatide (Mounjaro/Zepbound): stop at least 1 month before pregnancy.
- Liraglutide (Saxenda/Victoza): avoid during pregnancy but no long wash-out period required.
- U.S. FDA: Labels for Wegovy and Ozempic also require discontinuation at least 2 months before planned pregnancy.
An Overlooked Problem: Fertility Boost
Interestingly, weight loss itself can increase fertility. For women with PCOS, who often struggle with irregular cycles and infertility, GLP-1 drugs may restore ovulation. This can lead to unplanned pregnancies if contraception is not in place. The study highlights this as a hidden risk: women may not expect to become pregnant, but treatment could make it more likely.
A Special Case: Tirzepatide and Birth Control Pills
Another important detail comes from the drug tirzepatide (Mounjaro, Zepbound). Unlike semaglutide, tirzepatide slows stomach emptying significantly, which can reduce how well the body absorbs oral contraceptives.
This means women taking tirzepatide need to:
- Use a non-oral form of contraception (like an IUD, implant, injection, patch, or ring), or
- Add a barrier method (like condoms) for at least 4 weeks after starting tirzepatide and after each dose increase.
This interaction doesn’t apply to semaglutide or liraglutide, but it makes contraceptive counseling especially important for tirzepatide users.
Why Contraception Is Not Being Addressed Enough
The Flinders University researchers behind the study, including Associate Professor Luke Grzeskowiak, argue that doctors often prescribe GLP-1 drugs without discussing contraception. The study shows contraceptive use was only documented in 21% of cases, which suggests many women may not even know about the risks.
This gap in care is concerning because these medications are being prescribed at record levels for women in their 20s and 30s—the very group most likely to become pregnant.
What Needs to Change
The study calls for:
- Clearer guidelines for doctors prescribing GLP-1s to women of reproductive age.
- Routine contraceptive counseling whenever these drugs are prescribed.
- Better education for women about pregnancy risks and planning ahead if they want children.
The authors also note that more human studies are needed to fully understand the impact of GLP-1 exposure during pregnancy.
What You Should Know About GLP-1 Drugs
Since these medications are making headlines worldwide, here’s some extra background you might find useful:
How GLP-1 Drugs Work
GLP-1 receptor agonists mimic the glucagon-like peptide-1 hormone, which stimulates insulin release, slows gastric emptying, and reduces appetite. This leads to:
- Better blood sugar control in people with type 2 diabetes.
- Reduced calorie intake, leading to significant weight loss.
The Big Names You Hear
- Ozempic (semaglutide): Approved for type 2 diabetes, widely used off-label for weight loss.
- Wegovy (semaglutide): Higher-dose version, specifically approved for obesity.
- Mounjaro / Zepbound (tirzepatide): Dual GIP and GLP-1 receptor agonist, showing even stronger weight-loss effects.
- Saxenda (liraglutide): An older GLP-1 drug used for weight loss.
Why They’re So Popular
- They can help patients lose 15–20% of their body weight, which is more than most other medications.
- Celebrities and social media have fueled demand.
- For many, it feels like the first truly effective weight-loss medication after decades of failed options.
What This Means for Women
The bottom line is clear:
- These drugs can be life-changing, but they are not risk-free, especially for women of reproductive age.
- If you’re a woman considering or already taking a GLP-1 drug, it’s essential to:
- Talk to your doctor about contraception and pregnancy planning.
- Use effective contraception while on treatment.
- Plan carefully if you want to conceive—stop treatment early enough (2 months for semaglutide, 1 month for tirzepatide).
- Know about tirzepatide’s interaction with birth control pills and use backup contraception as recommended.
Conclusion
The rise of GLP-1 drugs like Ozempic, Wegovy, and Mounjaro is transforming how we treat weight loss and diabetes. But with this popularity comes new challenges, particularly for women of childbearing age. This latest Australian study highlights a serious gap: contraception is not being consistently considered when these drugs are prescribed, despite the potential risks to pregnancy and fetal development.
The message is simple but crucial: these drugs and reproductive health must be discussed together. Women deserve clear guidance, safe prescribing practices, and the information they need to make informed decisions.
