GLP-1 Medication, Pregnancy and Fertility

GLP-1 medicines such as Mounjaro (tirzepatide) and Wegovy (semaglutide) should not be used during pregnancy or just before trying to conceive. That is the clear position of the MHRA and the UK product information, because there is not enough safety data in human pregnancy and animal studies have shown harm. If you are planning a baby, the medicine needs to be stopped in advance: at least one month before for tirzepatide and at least two months before for semaglutide. Weight loss on these medicines can also increase fertility, so effective contraception matters during treatment. This guide explains the guidance, what to do after an unplanned pregnancy, and how to plan ahead.

Why GLP-1 medicines are not recommended in pregnancy

The UK Summaries of Product Characteristics (SmPCs) for both Mounjaro and Wegovy state that:

• There are no or limited data from the use of these medicines in pregnant women
• Studies in animals have shown reproductive toxicity
• The medicine should not be used during pregnancy

The Mounjaro SmPC adds that tirzepatide is not recommended in women of childbearing potential who are not using contraception. The Wegovy SmPC recommends contraception for women of childbearing potential during treatment.

In June 2025, the MHRA published guidance urging people taking GLP-1 medicines to use effective contraception, and stressing that these medicines should not be used during pregnancy, while trying to conceive or while breastfeeding. The MHRA's patient guidance, updated in February 2026, explains that this is because there is not enough safety data to know whether a GLP-1 medicine could harm a baby.

Weight loss in pregnancy

Beyond the medicine itself, intentional weight loss is not generally recommended during pregnancy. Pregnancy is a time for healthy eating and appropriate weight gain under the guidance of your midwife and doctors, even for people who start pregnancy with a higher BMI.

Wash-out periods: stopping before conception

GLP-1 medicines stay in the body for some time after the last dose. Tirzepatide and semaglutide are long-acting, once-weekly medicines. To make sure the medicine has cleared before conception, the MHRA and SmPCs give minimum wash-out periods.

Keep using effective contraception throughout the wash-out period. If you take other GLP-1 medicines, ask your prescriber about the advice for your specific medicine.

GLP-1 medicines and fertility

Effects of weight loss on fertility

Excess weight can affect fertility in several ways, particularly by disrupting ovulation. NICE's fertility guideline (CG156) advises that women with a BMI over 30 are likely to take longer to conceive, and that losing weight can increase the chance of conception for those who are not ovulating.

As a result, some people find that their periods become more regular and their fertility improves as they lose weight on GLP-1 treatment. This is especially relevant for people with polycystic ovary syndrome (PCOS), where weight loss can help restore ovulation. Our guide to GLP-1 medication and PCOS explores this in detail.

"Ozempic babies"

The term "Ozempic babies" has been used in the media to describe unexpected pregnancies in people taking GLP-1 medicines. These are anecdotal reports rather than systematic evidence. Possible explanations include improved ovulation with weight loss and, for Mounjaro specifically, reduced reliability of oral contraceptives. There is no evidence that GLP-1 medicines directly increase fertility independent of these effects.

Effects of the medicines on fertility

According to the SmPCs:

• The effect of tirzepatide on human fertility is unknown. Animal studies did not show direct harmful effects on fertility.
• The effect of semaglutide on human fertility is unknown. In animal studies, semaglutide did not affect male fertility; in female rats, there were changes in the reproductive cycle and a small reduction in ovulations at doses associated with maternal weight loss.

Male fertility

There is little specific evidence on GLP-1 medicines and male fertility. Obesity is associated with reduced sperm quality and lower testosterone in some men, and weight loss may help. UK guidance on wash-out periods applies to the person who would carry the pregnancy, and there is no specific MHRA wash-out advice for men. If you are a man planning a family while taking a GLP-1, it is reasonable to discuss it with your prescriber.

Contraception during treatment

Because GLP-1 medicines should not be used in pregnancy, and because fertility may increase with weight loss, effective contraception is important.

• Mounjaro and the pill: the UK SmPC and MHRA advise that tirzepatide may reduce the effectiveness of oral contraceptives in people with overweight or obesity. Switch to a non-oral method, such as an implant or coil, or add a barrier method for four weeks after starting and after every dose increase.
• Other GLP-1 medicines: extra barrier protection is not considered necessary with semaglutide or liraglutide, but effective contraception is still advised.
• Vomiting and diarrhoea: severe gastrointestinal side effects can reduce absorption of any pill.

Read our full guide to Mounjaro, GLP-1s and contraception.

If you become pregnant while taking a GLP-1

Unplanned pregnancies happen, and finding out you are pregnant while taking a GLP-1 medicine can be worrying. Here is what to do:

1. Stop taking the medicine. Both SmPCs advise discontinuing treatment if pregnancy occurs.
2. Contact your GP or prescriber promptly to let them know. If you were prescribed privately, tell your GP as well.
3. Book antenatal care. You can usually self-refer to your local maternity service or ask your GP.
4. Start folic acid if you are not already taking it, and ask about the dose.
5. Report the pregnancy. You can report through the MHRA Yellow Card scheme. For Wegovy, the SmPC asks that pregnancies be reported to the Novo Nordisk pregnancy registry.

What does the evidence say about early exposure?

Human data are limited. One of the larger studies, published in JAMA Internal Medicine in 2024, used health records from several Nordic countries, the United States and Israel to compare pregnancies in women with type 2 diabetes who used GLP-1 receptor agonists around conception or in early pregnancy with those who used insulin. It did not find a higher risk of major congenital malformations with GLP-1 exposure. However, the number of exposed pregnancies was relatively small, so a small increased risk could not be ruled out. The study included older GLP-1 medicines and did not specifically assess tirzepatide.

This evidence is reassuring to a degree, but it does not mean GLP-1 medicines are safe in pregnancy. It does suggest that early, unintentional exposure is not a reason for panic. Your GP and maternity team can discuss your individual situation.

Planning a pregnancy after GLP-1 treatment

If you would like to have a baby, planning ahead can help you have a healthier pregnancy.

Talk to your prescriber and GP

Before stopping contraception, discuss:

• When to stop your GLP-1 to allow the wash-out period
• How to manage your weight once treatment stops
• Any long-term conditions such as type 2 diabetes, high blood pressure or PCOS, which may need different treatment in pregnancy
• Any other medicines you take that may need reviewing

Expect appetite to return

When GLP-1 treatment stops, appetite usually returns and many people regain some weight. In trials, weight regain after stopping was common. Planning nutrition and physical activity in advance can help. Our guide to weight regain after stopping GLP-1 medication explains what the evidence shows.

Folic acid and vitamin D

The NHS advises taking folic acid before you conceive and for the first 12 weeks of pregnancy. If your BMI is 30 or more, you may be advised to take a higher dose, which needs a prescription from your GP. Vitamin D supplements are also recommended in pregnancy.

Nutrition

If you have been eating very small amounts on a GLP-1, it is worth making sure your diet is nutritionally adequate before pregnancy. Our guide to vitamins and supplements on GLP-1 medication may help.

Fertility treatment

If you need fertility treatment, your clinic will advise on BMI and timing. Some NHS-funded fertility services have BMI criteria that vary by area. Weight loss beforehand may be recommended. If a GLP-1 is used to support this, the timing of stopping it before conception or embryo transfer must be planned with both your fertility team and your GLP-1 prescriber.

After pregnancy: breastfeeding and restarting treatment

Breastfeeding

UK guidance on breastfeeding is currently not fully consistent:

The Mounjaro SmPC also notes it is not known whether reduced food intake on tirzepatide affects the composition of breast milk. Because guidance differs and is evolving, discuss your options with your GP, health visitor or prescriber, and check the latest SmPC and MHRA advice.

Restarting treatment after pregnancy

If you want to restart a GLP-1 after having a baby, speak to your GP or prescriber. They will consider whether you are breastfeeding, your contraception plans, your weight and health, and how long it has been since the birth. Many people regain some weight during pregnancy, and postnatal weight management is part of routine care.

Myths and facts

Questions to ask before trying to conceive

Bringing a list to your appointment can help. You might ask your GP or prescriber:

• When should I take my last dose, given my medicine and the wash-out period?
• What contraception should I use until then?
• How can I limit weight regain once I stop, and is some regain acceptable before pregnancy?
• Do I need a higher dose of folic acid because of my BMI?
• Do any of my other medicines need to change before pregnancy?
• If I have diabetes or high blood pressure, when should I be referred to a specialist pre-pregnancy service?
• If it takes a while to conceive, at what point should we look at fertility investigations?

The emotional side of stopping treatment

Stopping a medicine that has helped you lose weight can feel daunting, especially if you have struggled with your weight for many years. Some people worry about regaining weight during pregnancy, or about how others will react. These feelings are understandable.

It may help to remember that the priority during pregnancy is a healthy pregnancy and baby, not weight loss. Your midwife and GP can support you with healthy eating and activity during pregnancy, and you can discuss weight management options again after your baby is born. If worries about food, weight or your body are affecting your wellbeing, tell your GP or midwife. Our guide to GLP-1 medication and mental health may also be useful.

Special situations

Type 2 diabetes

If you take a GLP-1 medicine for type 2 diabetes, planning a pregnancy needs specialist input. Good blood sugar control before and during pregnancy is important for both you and your baby. Your diabetes team will usually switch you to medicines considered suitable for pregnancy. See our guide to GLP-1 medication and type 2 diabetes.

PCOS

People with PCOS may find that weight loss restores ovulation. This can be helpful if you want to conceive, but means contraception is important if you do not. See our PCOS guide.

Perimenopause

Pregnancy is still possible in perimenopause. Contraception is generally advised until periods have stopped for a set time, which varies with age. Our guide to GLP-1 medication and menopause covers this stage of life.

Choosing a prescriber who asks the right questions

A responsible prescriber should ask about pregnancy, contraception and breastfeeding before starting treatment and at reviews. If you are comparing regulated online services, our provider comparison sets out how each approaches screening and follow-up. We do not rank providers, and only a prescriber can decide whether treatment is right for you. For more background, see our hubs on weight-loss injections and Mounjaro, and our guide to who should not take GLP-1 medicines.

Reporting side effects and pregnancies

You can report a suspected side effect, or a pregnancy that occurred while taking a GLP-1 medicine, through the MHRA Yellow Card scheme, online or via the app. These reports help build the evidence about safety in pregnancy.

When to speak to a professional

Speak to your GP or prescriber if:

• You are planning a pregnancy and need to plan when to stop your GLP-1
• You are breastfeeding and considering starting or restarting treatment
• You have diabetes, PCOS or another long-term condition and are thinking about pregnancy

Contact your GP or prescriber promptly if:

• You think you might be pregnant while taking a GLP-1. Stop the medicine and take a pregnancy test.
• You have had unprotected sex or a contraceptive failure. Emergency contraception is available from pharmacies, GPs and sexual health clinics and is more effective the sooner it is used.

Call NHS 111 or your maternity unit urgently if you are pregnant and:

• You have vomiting so severe that you cannot keep fluids down, or signs of dehydration such as dark urine, peeing very little or dizziness
• You have bleeding or tummy pain

Call 999 or go to A&E if:

• You are pregnant and have heavy bleeding, severe tummy pain, or one-sided pain with shoulder tip pain, dizziness or fainting, which could be an ectopic pregnancy
• You have severe, persistent abdominal pain, especially if it spreads to your back, which may be pancreatitis
• You have yellowing of the skin or eyes (jaundice) with pain or fever

If you are struggling with your mental health, including during or after pregnancy, or having thoughts of suicide, call NHS 111 (option 2 for mental health in many areas), contact Samaritans free on 116 123, or call 999 in an emergency.