Mounjaro and pregnancy should not overlap: the UK product information says tirzepatide, the medicine in Mounjaro, should not be used during pregnancy and should be stopped at least 1 month before a planned pregnancy because of its long half-life. The advice for Wegovy is to stop at least 2 months before. Effective contraception is recommended while you are taking either medicine, and if you use the oral contraceptive pill with Mounjaro the advice is to add a barrier method or switch to a non-oral method for 4 weeks after starting and after each dose increase. If you think you may be pregnant, stop the injection and speak to your GP or prescriber promptly, and discuss breastfeeding with your prescriber before using or restarting treatment.
The Summary of Product Characteristics and patient leaflet for Mounjaro give clear advice about reproduction.
- Mounjaro should not be used during pregnancy, because the effects on an unborn child are not known.
- It should be stopped at least 1 month before a planned pregnancy, because tirzepatide has a long half-life of about 5 days and stays in the body for several weeks.
- If you are pregnant, think you may be pregnant or are planning a baby, you should ask your doctor for advice before using it.
- Using contraception while taking the medicine is recommended.
- Women who use oral contraceptives are advised to consider also using a barrier method, such as a condom, or switching to a non-oral method, for 4 weeks after starting Mounjaro and for 4 weeks after each dose increase.
The reason for the contraceptive advice is that Mounjaro slows how quickly the stomach empties, which may reduce the absorption of oral contraceptives. Our guide to Mounjaro and the contraceptive pill explains the practical steps in more detail. The pregnancy advice itself reflects the limited safety information in pregnancy rather than a proven harm in people, and the medicine is deliberately kept out of pregnancy as a precaution.
Mounjaro and Wegovy Compared| Mounjaro (tirzepatide) | Wegovy (semaglutide) | |
|---|---|---|
| Use in pregnancy | Should not be used | Should not be used |
| Stop before planned pregnancy | At least 1 month before | At least 2 months before |
| Reason given | Long half-life of tirzepatide | Long half-life of semaglutide |
| Breastfeeding | Discuss with your prescriber (see below) | Product information says it should not be used |
| Contraception | Recommended; extra steps with the oral pill | Recommended while on treatment |
Drawn to scale. These are minimums set out in the UK product information; your prescriber will advise on your own plan.
The difference between 1 and 2 months reflects the different half-lives of the two medicines. If you take a different GLP-1 medicine, such as an oral tablet, follow its own product information and ask your prescriber.
Planning a Pregnancy While on TreatmentGood planning reduces uncertainty. A sensible sequence looks like this.
| Step | What to do | Why |
|---|---|---|
| 1. Talk early | Tell your prescriber and GP that you are planning a pregnancy, ideally several months ahead | So a safe stopping plan and weight plan can be made together |
| 2. Keep contraception going | Continue effective contraception until you have stopped the medicine and your prescriber advises otherwise | The medicine should not be used in pregnancy |
| 3. Stop on schedule | Stop at least 1 month before (Mounjaro) or 2 months before (Wegovy) trying to conceive | Allows the medicine to clear |
| 4. Prepare your body | Start folic acid, review other medicines, and discuss vaccinations and general health | Standard pre-conception care |
| 5. Plan nutrition and weight | Agree a plan for diet and activity to maintain progress without crash dieting | Weight can return after stopping |
| 6. Attend pre-conception review | Check blood pressure, blood sugar, and any other conditions | Optimise health before conception |
Folic acid and pre-conception care
The NHS advises all women trying to conceive to take 400 micrograms of folic acid daily from before conception until the twelfth week of pregnancy. A higher 5 mg dose, available on prescription, is advised for some women, including those with diabetes and, according to NHS guidance, some women with a BMI of 30 or above. Ask your GP which applies to you. Pre-conception care also includes avoiding alcohol and smoking and reviewing any other medicines.
Will I regain weight while I wait?
Stopping GLP-1 treatment commonly leads to appetite returning and some weight regain, as our guide on what happens when you stop explains. This is important to plan for, but it should not push anyone to continue the medicine while trying to conceive. Many people succeed by building a structured eating and activity routine before stopping, with protein-rich meals, regular movement and follow-up with their prescriber or a dietitian.
Weight Loss and Fertility: Why Contraception Still MattersFor some people, losing weight improves fertility. Excess weight can disturb ovulation, particularly in conditions such as polycystic ovary syndrome, and weight loss may restore regular cycles. This means that women who had difficulty conceiving, or irregular periods, may find that they ovulate again after losing weight, and unplanned pregnancies have been reported in women using these medicines. It is therefore sensible to assume you could become pregnant and to keep using effective contraception unless you are deliberately planning a pregnancy. Our guide to Mounjaro and PCOS covers a related question.
If you think you may be pregnant
Do not take your next injection. Take a pregnancy test and speak to your GP, midwife or prescriber promptly. Do not stop other prescribed medicines without advice. Most people who have been exposed to a medicine before they knew they were pregnant can be supported through a careful review; the key step is to stop and ask for advice early.
- Stop the injection and do not take any further doses.
- Contact your GP, midwife or prescriber as soon as possible and tell them which medicine you took, the doses and the dates.
- Remember that safety data are limited, so treatment is stopped as a precaution. Your clinicians will advise on monitoring.
- Do not try to lose weight rapidly or diet restrictively during pregnancy. The NHS advises a healthy balanced diet and does not recommend dieting while pregnant.
- Consider reporting the exposure through the MHRA Yellow Card scheme, which helps build safety information.
Breastfeeding information differs between GLP-1 medicines, so it is important not to apply the advice for one to another. The Mounjaro patient leaflet says tirzepatide passes into breast milk in very low amounts and is not expected to be absorbed by a breastfed newborn or infant, and advises talking to your doctor before using or continuing the medicine if you are breastfeeding or planning to. The Wegovy product information says semaglutide should not be used during breastfeeding.
In practice, decisions about restarting treatment after a baby are made individually. Factors include your baby’s age and feeding pattern, your own health, and whether weight management can safely wait. Deliberately restricting calories while breastfeeding can affect energy and milk supply, which is another reason to discuss timing with a prescriber and to prioritise nutrition and fluids first.
After Pregnancy: Restarting or Starting Treatment- Wait for your postnatal checks and speak to your prescriber before restarting or starting any weight-loss medicine.
- If you stopped for pregnancy, you will probably not restart at your previous dose. A prescriber will advise on the starting dose.
- Think about contraception, because weight loss can restore fertility, and because the medicine should not be taken if you become pregnant again.
- Focus first on sleep, nutrition and recovery, and build up activity gradually.
- “I can stop the week I start trying.” The product information advises stopping at least 1 month earlier because the medicine stays in your system.
- “If I got pregnant on Mounjaro, something has definitely gone wrong with my baby.” Not necessarily. The advice is precautionary because information is limited, and you should get advice promptly.
- “Mounjaro works as contraception.” It does not, and it may reduce the effectiveness of the oral contraceptive pill.
- “Breastfeeding advice is the same for every GLP-1.” It is not; check the specific medicine.
- When should I stop my medicine if I want to conceive?
- Which contraception should I use until then?
- What plan can we make to keep weight stable while I wait?
- Should I take 400 micrograms or 5 mg of folic acid?
- What do I do if I have a positive pregnancy test?
- Is it appropriate to restart treatment after the baby, and when?
The bottom line
Mounjaro and pregnancy should not overlap. Stop at least 1 month before a planned pregnancy (2 months for Wegovy), use effective contraception while on treatment, remember that the oral pill may need back-up on Mounjaro, and stop the injection and seek advice straight away if you think you may be pregnant. Breastfeeding decisions are made individually with your prescriber. Plan early, so that your weight, your nutrition and your safety are all part of the conversation.
General information only
This guide is for general information and is not a substitute for personal medical advice. Weight-loss medicines are prescription-only and are not suitable for everyone. If you are pregnant, may be pregnant, are planning a pregnancy or are breastfeeding, speak to your GP, midwife or prescriber before using or continuing any medicine.
Planning a Pregnancy or Unsure About Contraception?
Our GPhC-registered pharmacy team can talk through your medicines and the steps to take.
Start Your Free Online Consultation Use code SWITCH10 if you're switching from another provider Happy Pharmacy is a GPhC-registered pharmacy (No. 9013192). Superintendent Pharmacist: Palvinder Deol. Rated 4.8★ Excellent on Trustpilot- Mounjaro (tirzepatide) KwikPen: UK Summary of Product Characteristics, sections 4.5 and 4.6, and patient information leaflet. electronic Medicines Compendium (emc).
- Wegovy (semaglutide) FlexTouch: UK Summary of Product Characteristics, section 4.6. emc.
- NHS. Vitamins, supplements and nutrition in pregnancy: folic acid.
- NHS. Trying for a baby: planning a pregnancy.
- NHS. Breastfeeding and medicines.
- MHRA. Guidance on contraception and GLP-1 and dual GIP/GLP-1 receptor agonist medicines (2025).
- MHRA. Yellow Card scheme: reporting suspected side effects.