Can you take Mounjaro if you're pregnant?

Can you take Mounjaro if you're pregnant?

No. Mounjaro (tirzepatide) isn't used in pregnancy, and if you find out you're pregnant on it, the UK product information, the NHS and the MHRA agree: stop the injections and contact your GP or midwife straight away.¹²³ This is a clear "don't use it" position, based on a lack of human safety data rather than proof of harm. That distinction matters, so this guide covers what's known, what's assumed out of caution, and what to do when planning a pregnancy, using contraception, or finding out you're pregnant on it.

Pregnancy and contraception are one chapter of living well on Mounjaro, and the wider questions women ask, including periods and HRT, are in Mounjaro side effects in women.

Why isn't Mounjaro used in pregnancy? The honest nuance

Two things sit behind the guidance. First, pregnant women are essentially never included in drug trials, for good ethical reasons, so there is no solid human data on tirzepatide's safety in pregnancy, and regulators are cautious by default. Second, animal reproduction studies showed reduced fetal growth in rats and rabbits, and skeletal and other malformations in rats, at exposures below the maximum human dose; all of these occurred at doses also toxic to the mother animals.¹ The nuance that matters: researchers aren't fully sure whether these effects come from the drug acting directly on the developing fetus, or indirectly, from the mother eating substantially less and losing weight rapidly, which is risky in pregnancy whatever the cause. In a pooled analysis of obese women who lost weight during pregnancy instead of gaining within the guideline range, the odds of a small-for-dates baby were about three-quarters higher, and NHS advice is not to try to lose weight while pregnant.⁴⁵ So part of the caution is less "this molecule is dangerous" and more "nobody should be under-eating or losing weight fast during pregnancy, and this drug is designed to make that happen." Either way: don't use it while pregnant.

How long before trying to conceive should you stop Mounjaro?

Stop at least 4 weeks (one month) before you start trying.¹²³ This matches how the drug clears: with a half-life of around 5 days, tirzepatide takes around a month to largely leave your body after the last dose.¹ If you take Mounjaro for type 2 diabetes, this planning conversation matters even more: the NHS asks women with diabetes to keep using contraception until their glucose is under control and to take a higher 5 mg dose of folic acid, and your GP or diabetes team will want to review your whole treatment plan, not just the timing of stopping one drug, well before you start trying.⁶

What if you find out you're pregnant while taking Mounjaro?

Stop the injections and contact your GP or maternity team as soon as you find out.²³ Beyond that, the realistic picture is more reassuring than the animal data above. Many people have found out they were pregnant after weeks or months on a GLP-1 medication like Mounjaro or Ozempic, often because periods were already irregular, and the reported outcomes so far are reassuring: a European cohort of 168 first-trimester exposures found no rise in major birth defects, a multinational study of 938 exposed infants found no excess beyond the background risk that comes with type 2 diabetes itself, and the UK teratology service's leaflet, drawing on studies of about 47,000 women, says the information does not raise concern.⁷⁸⁹ That isn't a guarantee, and the researchers call for larger studies. The routine detailed scan at around 20 weeks checks your baby's development; UK advice is that no extra monitoring for birth defects is needed after early exposure, though you may be offered more regular checks if you have type 2 diabetes or a high BMI.⁹ Follow up with your care team, not forums.

Does Mounjaro affect fertility?

There's no direct evidence that tirzepatide itself improves or harms fertility in men or women: the product information says its effect on human fertility is unknown, and animal studies showed no direct harm.¹ The more relevant point is indirect. Excess weight reduces fertility for some people, particularly with PCOS, and in a systematic review of 40 studies, diet and exercise programmes that produced weight loss improved ovulation and made pregnancy more likely, although a later meta-analysis of randomised trials found the effect on pregnancy rates uncertain.¹⁰¹¹ Any such effect comes from the weight change, not from the drug acting on reproductive biology. The practical consequence: losing significant weight on Mounjaro may make you more fertile than before you started, which is why the contraception guidance below matters more, not less, once treatment is working.

Does Mounjaro affect the contraceptive pill?

Yes, and this catches people out. Mounjaro slows stomach emptying, which can reduce how well the pill's hormones are absorbed. In the one pharmacokinetic study, a single dose given with a combined pill cut the peak level of the pill's hormones by roughly 55 to 66 per cent and overall exposure by about a fifth.¹¹² The UK product information, the NHS and the MHRA are specific: use condoms, or switch to a non-oral method, for 4 weeks after starting Mounjaro and for 4 weeks after every dose increase, not just once at the start.¹²³ Data are limited in women with overweight or obesity, which is why the MHRA applies the advice to that group. Each dose increase reopens the window. The caution is specific to tirzepatide: the UK sexual and reproductive healthcare college notes that pharmacokinetic studies of semaglutide found no clinically relevant change in pill hormone levels, which points to how strongly tirzepatide slows gastric emptying rather than a class effect.¹²¹³

What's the safest contraception option while on Mounjaro?

Methods that don't rely on gut absorption sidestep the issue: the contraceptive implant, an IUD or coil (hormonal or copper), the contraceptive injection, or condoms used consistently.²³¹³ If you'd rather stay on the pill, condoms as well during the four weeks after starting and after each dose increase cover the higher-risk windows. A GP or sexual health clinic can talk through the options.

Can you breastfeed while taking Mounjaro?

UK sources currently differ, so this is a conversation rather than a rule. The NHS and the MHRA say tirzepatide is not used while breastfeeding, because it isn't known whether it passes into breast milk or what effect it might have on a breastfed baby.²³ The manufacturer's product information, revised in August 2026, now describes a study of 11 women in which tirzepatide in breast milk was undetectable or very low after a single dose, expects any trace to be broken down in the baby's gut rather than absorbed, and says it "could be considered" during breastfeeding, while noting it isn't known whether a mother eating less affects the milk's nutrient content.¹ If you're breastfeeding and considering Mounjaro, talk to your GP or maternity team, who can weigh the timing against the most current advice.

Frequently asked questions

Can you get pregnant while on Mounjaro?

Yes. Mounjaro isn't a contraceptive, and weight loss on it can make pregnancy more likely for some people than before they started, which is why reliable contraception matters throughout treatment if pregnancy isn't the goal.¹¹⁰

What happens if I get pregnant on Mounjaro?

Stop taking it and contact your GP or maternity team promptly.²³ Early exposure in others has generally shown reassuring outcomes, and the routine detailed scan at around 20 weeks is the standard next step, not a sign that something is wrong.⁷⁹

How long do you have to be off Mounjaro before having a baby?

At least 4 weeks before trying to conceive, based on how long the drug takes to clear.¹²³ If you're managing diabetes, your wider pre-conception care plan matters just as much, so involve your GP or diabetes team well before you start trying.⁶

Does the contraceptive pill still work while taking Mounjaro?

It can be less reliable, particularly in the four weeks after starting or after any dose increase, because delayed stomach emptying can reduce how well the hormones are absorbed.¹¹² Condoms alongside the pill during those windows, or a non-oral method, covers the gap.²³

Does Mounjaro affect male fertility or a male partner's role in conceiving?

There's no specific evidence either way, and the UK teratology service says there is no evidence that a father's use of a GLP-1 medicine harms the baby through effects on sperm.¹⁹ If either partner takes Mounjaro and you're planning a pregnancy, raise it with a GP.

If you're planning a pregnancy, standard UK pre-conception advice, including folic acid, still applies regardless of Mounjaro use, and is worth discussing with your GP or pharmacist rather than guessing at supplements.¹⁴ For nutrient gaps while taking Mounjaro, see our guide to which vitamins to take on Mounjaro.

Sources

1. Tirzepatide Summary of Product Characteristics, sections 4.5, 4.6, 5.2 and 5.3, emc, date of revision of the text 29 August 2026. medicines.org.uk.
2. NHS. Tirzepatide. Page last reviewed 15 May 2026. nhs.uk.
3. MHRA. GLP-1 medicines for weight loss and diabetes: what you need to know. Last updated 5 February 2026. gov.uk.
4. Kapadia MZ, et al. Weight loss instead of weight gain within the guidelines in obese women during pregnancy: PLoS One, 2015. Meta-analysis of observational studies, publicly funded. PubMed 26196130.
5. NHS. Overweight and pregnant. Page last reviewed 17 February 2023 (review overdue); checked 17 October 2026. nhs.uk.
6. NHS. Diabetes and pregnancy. Page last reviewed 28 May 2024. nhs.uk.
7. Dao K, et al. Use of GLP1 receptor agonists in early pregnancy and reproductive safety: BMJ Open, 2024. Prospective cohort, 168 exposed pregnancies, no competing interests. PubMed 38663923.
8. Cesta CE, et al. Safety of GLP-1 receptor agonists and other second-line antidiabetics in early pregnancy. JAMA Internal Medicine, 2024. Population cohort, 938 exposed infants, publicly funded. PubMed 38079178.
9. UK Teratology Information Service (Bumps). GLP-1 receptor agonists, September 2026, version 2.0; linked from nhs.uk/medicines/tirzepatide. medicinesinpregnancy.org.
10. Best D, et al. How effective are weight-loss interventions for improving fertility in women and men who are overweight or obese? Human Reproduction Update, 2017. 40 studies, 14 randomised, publicly funded. PubMed 28961722.
11. Boyle BR, et al. The effect of weight loss interventions for obesity on fertility and pregnancy outcomes. International Journal of Gynaecology and Obstetrics, 2023. Meta-analysis of 27 randomised trials, 5,938 women, publicly funded. PubMed 36440496.
12. Skelley JW, et al. The impact of tirzepatide and glucagon-like peptide 1 receptor agonists on oral hormonal contraception. Journal of the American Pharmacists Association, 2024. Review of six pharmacokinetic trials, no conflicts declared. PubMed 37940101.
13. Faculty (now College) of Sexual and Reproductive Healthcare. Statement: GLP-1 agonists and oral contraception, February 2025; linked from nhs.uk/medicines/tirzepatide. cosrh.org.
14. NHS. Trying to get pregnant. Page last reviewed 2 June 2026. nhs.uk.

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This guide is for general information and isn't a substitute for personal medical advice. Always speak to your GP, midwife or prescriber about pregnancy, contraception, or breastfeeding while taking Mounjaro.