GLP-1 Medications And Pregnancy: What You Need To Know About Contraception

Weight management is just one part of the picture when it comes to your health. If you’re considering starting GLP-1 weight loss medications such as Wegovy or Mounjaro, it’s important to know how they might affect your fertility or interact with your current birth control method.

Whether you’re planning to have a family or wanting to avoid pregnancy, here you’ll find all you need to know about GLP-1s, pregnancy and contraception in our expert guide.

Article Summary:

• GLP‑1s and GIP dual agonists like Mounjaro and Wegovy are once-weekly injections prescribed for weight loss and type 2 diabetes. They work by mimicking naturally occurring gut hormones that regulate appetite and blood sugar.
• These weight loss treatments slow digestion and can cause side effects, which can delay or reduce absorption of oral medicines including the contraceptive pill.
• GLP-1 medications should not be taken during pregnancy, when trying to conceive, or while breastfeeding, due to limited human safety data.

What are GLP-1 Receptor Agonists (GLP-1RAs)?

GLP‑1s and GIP dual agonists are injectable medications, prescribed for weight loss and type 2 diabetes. While various active ingredients are available, you may know them better as their brand names (Wegovy, Mounjaro and Ozempic being the most widely recognised).

They work by mimicking the naturally occurring GLP-1 and GIP hormones in your body that are released after you eat. This helps to stabilise blood sugar levels, reduce your appetite, and slow digestion to increase feelings of fullness. [1]

In clinical trials, these medications have been proven to be effective in managing obesity. Patients sustained an average weight loss of 15.2% of their body weight over two years with semaglutide (the active ingredient in Wegovy and Ozempic). [2] While patients taking tirzepatide (the active ingredient in Mounjaro) lost 22.5% of their weight in 72 weeks, when combined with diet and exercise changes. [3]

GLP-1s and Fertility: The "Ozempic Babies" Phenomenon

While they’re highly successful for weight management, the benefits of GLP-1 medicines are also having an unexpected side effect: increasing chances of conception.

Dubbed the ‘Ozempic baby boom’, reports of surprise pregnancies from those on the treatment have spread. The trend prompted the MHRA to issue an alert warning patients to use effective contraception while taking the medication.

Weight Management, Fertility, and Family Planning

Weight and fertility are closely connected. Being underweight or overweight can impact your chances of getting pregnant, so it follows that weight loss treatments can have implications for your reproductive health, too.

For instance, living with obesity (a BMI of 30 or higher) can directly impact fertility, whereas reaching a healthier weight by using GLP-1s could help improve your chances of conceiving. [4] And if you want to avoid pregnancy, it’s vital to understand how the treatment interacts with oral contraceptives and birth control to stay protected.

Here’s what you need to know depending on your reproductive goals:

If you’re planning to get pregnant

Talk to your healthcare provider about your plans, and do not use weight loss medications while trying to conceive. Your prescriber can advise on the safest time to start or stop your treatment.

It is recommended that you wait at least one month after your last dose of Mounjaro before trying to get pregnant. For Wegovy, the advice is to wait at least 2 months after your last dose.

If you’re using contraception to protect against pregnancy

GLP-1s can reduce the effectiveness of some contraceptives, including the pill. [5] If you’re taking Mounjaro, you must use an additional barrier form of contraceptive such as condoms, or to switch to a non-oral method to stay protected.

Wegovy does not impact the absorption of the oral contraceptive pill, but it can cause side effects. If you experience severe diarrhoea that lasts for over 24 hours, or vomiting within 3 hours of taking your oral contraceptive pill, you may need a repeat dose of your oral contraceptive pill. Contact your GP or call 111 for medical advice if this occurs.

If you’re pregnant or breastfeeding

Regulatory bodies, including the MHRA, advise that GLP-1 medications should not be used during pregnancy or while breastfeeding. While we don’t yet know how Wegovy and Mounjaro could affect a breastfed baby, a risk cannot be ruled out. [6]

Find out more about the guidance for Wegovy and pregnancy and Mounjaro and pregnancy.

How GLP-1 Agonists Can Help To Boost Fertility 

It’s all down to how the active ingredients work within your body, and the results they can achieve in getting you to a healthier weight.

Reducing obesity

Weight loss injections can help you reach a healthy BMI. This can improve insulin sensitivity and metabolic health, which can make pregnancy more likely over time. You’ll also likely be improving your sleep and exercise habits as part of your treatment to optimise your lifestyle for better weight loss.

Together, these can restore regular ovulation and increase fertility, especially in people whose infertility is related to obesity or polycystic ovary syndrome (PCOS). [7]

Slowing down digestion

One of the ways these medications work is by significantly slowing down the rate at which food leaves your stomach, helping you stay fuller for longer. This is great for appetite control, but Mounjaro can also alter the way oral contraceptives are absorbed, meaning they are less effective and a different form of protection is needed. However, Wegovy users can safely continue to use the oral contraceptive pill.

Side effects that can impact pill absorption

Some of the more common side effects (such as diarrhoea and vomiting) can affect the absorption of the contraceptive pill, just as a stomach bug would. If you experience any of these symptoms you would need to follow missed pill guidance or use a backup method to avoid unintended pregnancy.

If you experience persistent vomiting or diarrhoea, consider using a non-oral contraception method. Contact your GP to discuss your options.

How GLP-1s Interact With Contraception

Oral contraceptives

As explained above, some GLP-1 medications can impact the effectiveness of oral contraceptives (known as the ‘pill’). But there are differences depending on which one you’re taking.

Tirzepatide (the active ingredient in Mounjaro) has been found to affect how your body absorbs the contraceptive pill. You should therefore use a non-oral birth control method, or add a barrier method like condoms to avoid an unplanned pregnancy. [8]

Semaglutide (the active ingredient in Wegovy) does not affect the absorption of the oral contraceptive pill, so it can be used alongside your treatment. However, if you do experience any side effects such as an upset stomach that result in a ‘missed’ pill, you will need to take extra precautions.

Non-oral contraceptives

Fortunately, there is no evidence that GLP-1s reduce the effectiveness of non-oral hormonal contraceptives. This means alternatives like the coil, implant, injection, patch, and vaginal ring remain safe options.

Whichever method you choose, always use a form of birth control while taking GLP‑1/GIP dual agonists, as they should not be taken while pregnant.

Emergency contraceptives

It’s not yet known what effect GLP-1s can have on oral emergency contraception, commonly known as the morning after pill. To be on the safe side, the copper IUD is a recommended option, as it can be fitted by a doctor or nurse up to 5 days (120 hours) after unprotected sex. [9]

Always tell your healthcare provider about any GLP-1 medication use if you’re seeking emergency contraceptives.

GLP-1s and Pregnancy 

Weight loss injections should not be taken when pregnant, or when trying to conceive. Planning a family? Follow the below guidance to fully clear the medication from your system (known as ‘wash‑out periods’) to be safe.

• If you’re taking semaglutide (Wegovy): Stop taking it at least 2 months before a planned pregnancy
• If you’re taking tirzepatide (Mounjaro): Stop taking it at least 1 month before a planned pregnancy. We recommend waiting 1 month after your last dose before trying to conceive.
• If you suspect you are pregnant while on a GLP‑1: Stop the treatment and seek prompt medical advice about next steps and monitoring. Our team are always on hand to help.

Ready to start your weight loss journey? Check your eligibility and find out what treatment is suitable for you with MedExpress.

References

1. Solan M. Understanding new weight-loss drugs [Internet]. Harvard Health. 2023 [cited 2024 Jul 3]. Available from: https://www.health.harvard.edu/staying-healthy/understanding-new-weight-loss-drugs
2. Garvey WT, Batterham RL, Bhatta M, Buscemi S, Christensen LN, Frias JP, et al. Two-year effects of semaglutide in adults with overweight or obesity: The STEP 5 trial. Nature Medicine. 2022 Oct 1;28(10):2083–91.
3. Jastreboff AM, Aronne LJ, Ahmad NN, Wharton S, Connery L, Alves B, et al. Tirzepatide Once Weekly for the Treatment of Obesity. New England Journal of Medicine [Internet]. 2022 Jun 4;387(3):205–16. Available from: https://www.nejm.org/doi/full/10.1056/NEJMoa2206038
4. Ozcan Dag Z, Dilbaz B. Impact of obesity on infertility in women. Journal of the Turkish German Gynecological Association [Internet]. 2015 Jun 4;16(2):111–7. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4456969/
5. Shankar A, Sharma A, Vinas A, Chilton RJ. GLP-1 receptor agonists and delayed gastric emptying: implications for invasive cardiac interventions and surgery. Cardiovascular Endocrinology & Metabolism [Internet]. 2024 Dec 4;14(1). Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC11620716/
6. GLP-1 medicines for weight loss and diabetes: what you need to know [Internet]. GOV.UK. 2025. Available from: https://www.gov.uk/government/publications/glp-1-medicines-for-weight-loss-and-diabetes-what-you-need-to-know/glp-1-medicines-for-weight-loss-and-diabetes-what-you-need-to-know#glp-1-medicines-contraception-and-pregnancy
7. Kettner J, Donnelly E, Maes ML. Glucagon-like Peptide-1 Receptor Agonists and Reproductive Health: Current Evidence and Clinical Implications. Journal of Pharmacy Practice. 2025 Sep 4;
8. Mounjaro KwikPen 2.5mg solution for injection in pre-filled pen - Summary of Product Characteristics (SmPC) - (emc) [Internet]. www.medicines.org.uk. Available from: https://www.medicines.org.uk/emc/product/15481/smpc
9. GLP-1 agonists (e.g. Mounjaro) and Contraception or HRT - Brig Royd Surgery [Internet]. Brig Royd Surgery. 2025 [cited 2026 Jan 29]. Available from: https://www.brigroydsurgery.co.uk/2025/10/08/glp-1-agonists-e-g-mounjaro-and-contraception-or-hrt/