Wegovy, Ozempic, and Mounjaro are now used by millions of people for weight management. But what happens if you are on one of these medications and want to get pregnant — or discover you already are? And can these medications actually affect your fertility?

These are questions that many women of childbearing age are asking, and the answers are important to understand. This article summarises what research and regulatory authorities currently recommend.

The clear message from the FDA, EMA, and the manufacturers is: stop GLP-1 medication before trying to conceive. These medicines are not approved for use during pregnancy, and animal studies have shown signs of harm to foetuses at high doses.

In animal studies with semaglutide (Wegovy/Ozempic) in rats and rabbits, high doses caused foetal death, structural malformations, and growth abnormalities. Similar findings were seen with tirzepatide (Mounjaro) in animal studies. Crucially, these studies used doses far higher than those given to humans — but out of caution, use during pregnancy is not recommended.

Human data are more reassuring: a large multicentre observational study published in eClinicalMedicine (2024), covering 168 pregnancies with first-trimester GLP-1 exposure, found no significant increase in congenital anomalies or pregnancy loss compared to controls. A further observational study (2025) involving 1,094 semaglutide-exposed pregnancies reached similar conclusions.

Important caveats apply: these are observational studies, not controlled trials, and the data remain limited. The official regulatory recommendation remains: avoid GLP-1 medications during pregnancy and when planning a pregnancy.

When should you stop the medication?

Both semaglutide and tirzepatide remain in the body long after the last injection — a detail many people overlook.

These timeframes are designed to ensure the medication has fully cleared the body before conception takes place, particularly during the vulnerable early stages of foetal development.

What if you became pregnant while on the medication?

It happens: a pregnancy is discovered while still on treatment. This is not a crisis, but you should act promptly.

  1. Stop the medication immediately — no gradual taper is needed; discontinue right away.
  2. Contact your doctor within a few days — your doctor can advise on the specific risks based on when during the pregnancy the exposure occurred.
  3. Enrol in a pregnancy registry — Novo Nordisk runs a semaglutide pregnancy exposure registry (PREGNORDISK), and Eli Lilly has a similar one for tirzepatide. Your participation helps researchers better understand any risks.

Research suggests that inadvertent first-trimester exposure is likely not associated with a major increase in risk — but this is not a guarantee, and medical follow-up is always important.

Can GLP-1 medications actually improve fertility?

Here is something that surprises many people: for women with obesity and PCOS (polycystic ovary syndrome), GLP-1 medications may actually improve fertility — indirectly, through weight loss.

Excess body weight is one of the most common causes of irregular ovulation and reduced fertility in women. Studies show that even a modest 5–10% weight loss can restore regular ovulation and improve pregnancy rates in women with PCOS and obesity.

Since GLP-1 medications promote significant weight loss, they can — over time — improve fertility prospects. However, the medication must of course be stopped well before any conception attempt.

Researchers are also exploring whether GLP-1 receptors directly influence ovarian function. Early studies (2024–2025) suggest semaglutide may have direct effects on follicle maturation and hormonal balance, but this remains unresolved and requires more research before clinical recommendations can be made.

Contraception and GLP-1 medications — an important detail

Tirzepatide (Mounjaro) may affect the absorption of oral contraceptives. Because the medication slows gastric emptying, oral contraceptive pills may be absorbed more slowly and potentially less completely. The prescribing information recommends using a barrier method (e.g. condoms) or switching to a non-oral contraceptive (e.g. IUD or implant) for 4 weeks after starting and after each dose increase.

Semaglutide works by the same mechanism — slowing gastric emptying — so similar precautions apply in practice, even if the product label does not specify this as explicitly.

In 2024, the EMA clarified that women of childbearing potential should use effective contraception throughout treatment with semaglutide.

What about breastfeeding?

Neither semaglutide nor tirzepatide is recommended while breastfeeding. It is not known whether either medication is excreted in breast milk, and potential effects on infants have not been studied. Manufacturers recommend choosing either breastfeeding or medication — not both.

What to do if you are planning a pregnancy

A practical checklist for anyone on GLP-1 medication who is considering pregnancy:

Summary

GLP-1 medications are powerful tools for weight management, but they require careful planning if you want to have a child. The regulatory message is clear: stop the medication in good time, use contraception during treatment, and speak with your doctor if in doubt. The good news is that inadvertent early-pregnancy exposure is likely not a major risk — but it is not something to rely on.

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