In the past 5 years, there has been a significant rise in patients accessing weight loss medications such as GLP-1 therapies (e.g. common brand names include Ozempic, Wegovy, Saxenda and Mounjaro).
Prescribers of GLP-1 therapies must take note of 2 important considerations in women of reproductive age:
1️⃣ There is a risk of unplanned pregnancy; a phenomenon referred to as ‘Ozempic babies’
– There may be a delay in gastric emptying, particularly during initial use or dose escalations of GLP-1 therapies. This may reduce absorption of oral contraceptives.
– Diarrhoea and vomiting are common side effects with GLP-1 therapies and reduce effectiveness of oral contraceptives.
– Weight loss may have a positive influence on reproductive physiology, e.g. in women with PCOS and anovulatory cycles.
2️⃣ There is a potential for fetal risks and adverse pregnancy outcomes. There is a lack of high quality studies in humans to re-assure women.
With this in mind, the following are 3 recommendations for prescribers of GLP-1 therapies in women of reproductive age:
1️⃣ Inform women that unplanned pregnancy may occur with the use of GLP-1 medications and that contraception is recommended.
2️⃣ Advise women to consider a switch to non-oral contraception
– Mounjaro (tirzepatide) is the only GLP-1 therapy found to have a clinically significant effect on the bioavailability of oral contraceptives.
– If using Mounjaro (tirzepatide) specifically, women on oral contraceptives must use non-oral contraception or barrier contraception for at least 4 weeks after initiation or dose escalation.
– Though there is no evidence to suggest the other GLP-1 therapies (aside from Mounjaro) reduce the effectiveness of oral contraceptives, I recommend that any GLP-1 therapy should prompt prescribers to have a conversation with women about non-oral contraception long-term (barrier, Patch, ring, Implanon, Depo-Provera, Kyleena/Mirena IUD, Copper IUD).
– If vomiting occurs within 4 hours of taking the contraceptive pill, or severe diarrhoea occurs for more than 24 hours, women should follow the standard guidance for missed pills. If diarrhoea or vomiting persists, women should consider an alternative non-oral method of contraception or barrier contraception.
3️⃣ Due to a lack of safety data, women using GLP-1 medications should avoid pregnancy, unless recommended by a fertility specialist as part of a study. GLP-1 therapies should be ceased for 3 months (‘washout period’) before trying to conceive, or before contraceptions is ceased.
GLP-1 and weight loss medications have entered the mainstream market in recent years. Research will accumulate and guidelines will be developed for prescribers. Until then, it is best for prescribers to remain cautious in women of reproductive age.
Useful resources:
https://www.cosrh.org/Public/Public/Documents/FSRH-statement-Glucagon-like-peptide-1-agonists-and-oral-contraception-Feb-2025.aspx
https://insightplus.mja.com.au/2025/36/contraception-is-crucial-when-prescribing-weight-loss-drugs/
https://www1.racgp.org.au/newsgp/clinical/unplanned-pregnancy-risks-flagged-for-glp-1s
The above information is the professional opinion of Dr Kiran Atmuri, Specialist Obstetrician & Gynaecologist (FRANZCOG, MBBS, BCom/BSc, GCertClinTeach). While every effort is made to ensure information is accurate and reasonable, the information does not take the place of guidelines from professional bodies, an individual’s own research and consultation with a healthcare professional. There is no acceptance of liability for any injury, loss or damage caused by use of the information provided on this website.