Before starting a GLP-1 medication for weight loss, it's important you're well-informed about their effects on your reproductive health. Some medicines aren’t suitable in pregnancy, or can affect your method of contraception — is this the case for medications like Mounjaro and Wegovy? In this post, our experts review their safety in pregnancy, whether they increase your risk of unexpected pregnancies and what to do if you become pregnant while taking weight loss drugs.
GLP-1 receptor agonists (often referred to as GLP-1s) such as Wegovy and Mounjaro work by mimicking glucagon-like peptide-1, a naturally occurring hormone in your gut. Let's break down how they promote weight loss:
Wegovy and Mounjaro should not be used during pregnancy. This is because research in animals has shown that they may harm the unborn baby. [4,5]
If you are trying to conceive, we recommend that you discontinue Wegovy at least two months before conception. For Mounjaro, we recommend you discontinue at least 1 month before conception. This leaves enough time for your medication to leave your body before a pregnancy may occur.
Research has shown that tirzepatide, the active ingredient in Mounjaro, may impact absorption of the oral contraceptive pill . [6] For this reason, we recommend that patients using Mounjaro switch to non-oral contraceptive methods such as an IUD or implant, or adding a barrier method like condoms for 4 weeks when starting treatment and 4 weeks after each dose increase.
However, research has shown that semaglutide, the active ingredient in Wegovy, does not impact the absorption of the oral contraceptive pill. [7,8] You should still bear in mind that this medication can cause side effects — like vomiting and diarrhoea — that could impact the efficacy of your oral contraceptives.
If you’re unsure on the best method of contraception for you while on a GLP-1 weight loss medication, we advise you to speak to your clinical team for advice.
If you fall pregnant while taking a GLP-1 medication, you should stop treatment immediately and speak to your doctor or clinical team. There's no need to taper yourself off your treatment, it's safe to just stop taking it.
No, you shouldn’t take GLP-1s while breastfeeding. There is a lack of evidence available on whether GLP-1 medications enter your breast milk, or their effects on breastfed infants or lactation, so the risk to a breast fed child can’t be ruled out. If you're breastfeeding, your doctor or clinical team won't prescribe a GLP-1 medication to you to minimise any potential risks.
Your clinical team is on hand to help you through every stage of your treatment. Don't hesitate to reach out if you have any questions about weight management, pregnancy and contraception.
Haven't started your weight loss journey yet? See if you're eligible to try medicated weight loss today.
1. Blundell J, Finlayson G, Axelsen M, Flint A, Gibbons C, Kvist T, et al. Effects of once‐weekly semaglutide on appetite, energy intake, control of eating, food preference and body weight in subjects with obesity. Diabetes, Obesity and Metabolism [Internet]. 2017 May 5;19(9):1242–51. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5573908/
2. Silveira SQ, da Silva LM, de Campos Vieira Abib A, de Moura DTH, de Moura EGH, Santos LB, et al. Relationship between perioperative semaglutide use and residual gastric content: A retrospective analysis of patients undergoing elective upper endoscopy. Journal of Clinical Anesthesia [Internet]. 2023 Aug 1 [cited 2023 Mar 3];87:111091. Available from: https://www.sciencedirect.com/science/article/abs/pii/S0952818023000417?dgcid=coauthor
3. 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 [Internet]. 2022 Oct 1;28(10):2083–91. Available from: https://www.nature.com/articles/s41591-022-02026-4
4. Electronic medicines compendium (emc) (2025) Mounjaro KwikPen 10mg solution for injection in pre-filled pen. Available at: https://www.medicines.org.uk/emc/product/15484/smpc#gref (Accessed: 18 March 2025).
5. Electronic medicines compendium (emc) (2025) Wegovy 0.25 mg, FlexTouch solution for injection in pre-filled pen. Available at: https://www.medicines.org.uk/emc/product/13799/smpc#gref (Accessed: 18 March 2025).
6. Skelley JW, Swearengin K, York AL, Glover LH. The impact of tirzepatide and glucagon-like peptide 1 receptor agonists on oral hormonal contraception. Journal of the American Pharmacists Association. 2023 Nov 1
7. Jordy AB, Albayaty M, Breitschaft A, et al. Effect of oral semaglutide on the pharmacokinetics of levonorgestrel and ethinylestradiol in healthy postmenopausal women and furosemide and rosuvastatin in healthy subjects. Clin Pharmacokinet. 2021;60(9):1171e1185.
8. Kapitza C, Nosek L, Jensen L, Hartvig H, Jensen CB, Flint A. Semaglutide, a once-weekly human GLP-1 analog, does not reduce the bioavailability of the combined oral contraceptive, ethinylestradiol/levonorgestrel. J Clin Pharmacol. 2015 May;55(5):497-504. doi: 10.1002/jcph.443. Epub 2015 Jan 14. PMID: 25475122; PMCID:
PMC4418331.
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