Mounjaro and pregnancy — 7 important things to know before TTC.

Mounjaro and pregnancy is a conversation every woman of childbearing age taking tirzepatide needs to have with herself and her healthcare provider — whether trying to conceive is an active goal right now or simply a future possibility. The MHRA issued a significant public safety update in June 2025 confirming that GLP-1 medicines, including Mounjaro, Wegovy, and Ozempic, must not be used during pregnancy, while trying to get pregnant, or while breastfeeding. This guide covers the seven most important things to know — the official washout period, why contraception needs special attention on this medication, what happens if you fall pregnant unexpectedly, and how weight loss itself can change your fertility picture.

All guidance in this article reflects the most current regulatory position, including the MHRA’s June 2025 safety update and the GOV.UK patient guidance on GLP-1 medicines and pregnancy, last updated in February 2026, alongside the NHS guidance on medicines in pregnancy. This is general information, not a substitute for individual medical advice — always discuss your specific circumstances with your GP, prescriber, or fertility specialist.

7 important things to know about Mounjaro and pregnancy

1. Mounjaro must be stopped before trying to conceive

The clearest and most important fact about Mounjaro and pregnancy: tirzepatide must not be taken while actively trying to get pregnant. The MHRA’s June 2025 safety update reinforced this directly, stating that GLP-1 medicines must not be taken during pregnancy, while trying to get pregnant, or during breastfeeding. This is a firm clinical recommendation, not a precaution to be weighed against personal preference.

2. The recommended washout period is at least one month

When it comes to Mounjaro and pregnancy timing specifically, tirzepatide has a half-life of approximately 5 days, meaning it takes roughly 25 to 35 days for the medication to clear almost completely from the body. The GOV.UK patient guidance, last updated February 2026, sets out the washout periods clearly: tirzepatide needs at least one month before trying to conceive. Some doctors and fertility clinics recommend a more cautious 2 to 3 month washout, particularly ahead of IVF treatment, where clinics often prefer a wider safety margin around embryo transfer.

3. Mounjaro can significantly reduce contraceptive pill effectiveness

One of the most clinically important and frequently overlooked aspects of Mounjaro and pregnancy is the medication’s effect on oral contraception. Tirzepatide slows gastric emptying, which can reduce oral contraceptive pill absorption by 20 to 66%. The MHRA issued specific guidance on this in June 2025 after receiving over 40 pregnancy reports across all GLP-1 medications. If you are on the pill and taking Mounjaro, you need to use an additional barrier method of contraception, particularly during dose escalation when gastric slowing is most pronounced.

4. Accidental pregnancies on Mounjaro happen more often than expected

As of June 2025, the MHRA had received 26 pregnancy reports specifically related to tirzepatide, with at least one or two explicitly reported as unintentional — and this is likely an undercount, since not every incident gets reported. The combination of reduced contraceptive pill absorption and improved fertility from weight loss (covered below) means accidental pregnancy is a real and underappreciated risk for women on Mounjaro who are not using additional precautions.

5. Stopping Mounjaro before pregnancy is linked to weight regain

A 2025 study found that stopping GLP-1 medications before pregnancy is associated with significant weight regain during the washout and pregnancy period — those who switched to placebo in trial data regained an average of around 14% of their body weight over the following 88 weeks, while those who remained on treatment continued to lose weight. This does not mean you should stay on Mounjaro during conception attempts — you should not — but it does mean planning support for weight maintenance during the washout period and the months of trying to conceive is genuinely important, since higher pre-conception weight is associated with increased pregnancy risks including gestational diabetes, gestational hypertension, pre-eclampsia, and macrosomia.

6. There is currently no proven direct effect on fertility

There are no dedicated human studies examining tirzepatide’s direct effect on reproductive function in either women or men. The considerations around Mounjaro and pregnancy relate primarily to weight changes, contraception requirements, and the precautionary washout period — not to any established direct impairment of fertility itself. If you have specific fertility concerns, particularly involving PCOS or irregular cycles, these are worth discussing directly with your prescriber or a fertility specialist.

7. If you do fall pregnant, stop the medication and contact your doctor immediately

If you discover you are pregnant while taking Mounjaro, stop the medication right away and contact your healthcare provider. Do not panic — the data so far from accidental exposures has not shown a clear, consistent pattern of harm, but human safety data remains genuinely limited, so close monitoring with your doctor for the remainder of the pregnancy is the appropriate and necessary next step.

Mounjaro and pregnancy — the washout period explained

Understanding why the washout period for Mounjaro and pregnancy planning is set where it is comes down to basic pharmacokinetics. Tirzepatide has an elimination half-life of approximately 5 days — meaning every 5 days, the amount of medication remaining in the body roughly halves. After about 5 half-lives (around 25 days), more than 95% of the medication has cleared. This is why the MHRA and GOV.UK guidance lands on a minimum of one month before trying to conceive.

Fertility clinics in particular tend to favour the more cautious end of this range — a 2 to 3 month washout is a widely accepted baseline ahead of IVF treatment or embryo transfer, prioritising a clear margin of safety over the strict pharmacokinetic minimum.

Why contraception needs special attention on Mounjaro

The interaction between Mounjaro and pregnancy risk is amplified by a specific mechanical issue: tirzepatide slows gastric emptying as part of its core appetite-suppressing action, and this same mechanism can interfere with how well an oral contraceptive pill is absorbed. Studies show this can reduce pill absorption by 20 to 66% — a substantial enough reduction that the MHRA issued specific public guidance on it in June 2025.

Practical steps recommended for women on the contraceptive pill while taking Mounjaro: add a barrier method of contraception (such as condoms) for at least 4 weeks after starting treatment or after each dose increase, consider switching to a non-oral contraceptive method (such as an IUD or implant) if pregnancy prevention is a firm priority, and discuss your specific contraceptive plan directly with your prescriber rather than assuming your existing method remains fully effective.

Mounjaro and fertility — the surprising connection

One of the more striking aspects of the Mounjaro and pregnancy conversation is that the medication can indirectly improve fertility in some women, even though that is not its intended use. Weight loss and improved insulin sensitivity are known to help restore ovulation in women with conditions such as PCOS — research has shown that weight reduction using a structured diet can recover menstruation in obese patients with ovulatory disorders, and University of Oxford research found that women with obesity seeking IVF were 47% more likely to conceive naturally after weight loss.

This is genuinely good news for many women — but it is precisely why accidental pregnancies on Mounjaro happen more often than expected. A woman whose cycles become more regular as she loses weight, combined with reduced contraceptive pill absorption, faces a meaningfully increased chance of unplanned pregnancy if additional precautions are not taken.

What to do if you fall pregnant on Mounjaro

If you discover you are pregnant while taking Mounjaro, the steps are straightforward: stop the medication immediately, contact your GP or prescriber as soon as possible, and arrange the monitoring your doctor recommends for the remainder of the pregnancy. The only data available about pregnant women who have taken Mounjaro comes from women who fell pregnant during treatment, generally accidentally — and while this data has not shown a clear, alarming pattern, the sample size remains small and human safety data is genuinely insufficient to give firm reassurance. This is why close medical supervision matters, not because there is established evidence of harm, but because the uncertainty itself needs to be actively managed by a professional.

Mounjaro and IVF treatment

For women considering or undergoing IVF, Mounjaro and pregnancy planning takes on an additional layer of coordination — understanding Mounjaro and pregnancy timing matters even more in a clinical fertility setting. Fertility clinics usually recommend a clear washout period before embryo transfer or trying to conceive, generally focused on reducing any risk of early pregnancy exposure rather than concerns about ovarian response itself. Because tirzepatide acts on two metabolic receptors and has a slightly longer clearance time than semaglutide, your fertility provider may adjust the recommended timing specifically for your treatment plan. Coordination between your GLP-1 prescriber and your fertility team is the safest way to plan both optimal metabolic health and a safe pregnancy attempt.

Browse our full product range, read our verified customer reviews, and see our complete Mounjaro side effects guide for everything else you need to know about treatment. For specific guidance on your own pregnancy planning, always speak directly with your GP or prescriber.