Women urged to take precautions as watchdog links GLP-1 drugs to unintended pregnancies
Women using popular weight-loss medications such as Ozempic, Wegovy and Mounjaro are being warned to use effective contraception, after a series of pregnancies were reported among those taking the drugs.
The Medicines and Healthcare products Regulatory Agency (MHRA) has issued its first public alert on the link between these medications and contraception concerns. The regulator revealed it has received 40 reports of pregnancy in individuals using weight-loss drugs containing semaglutide and tirzepatide — the active ingredients in Ozempic, Wegovy and Mounjaro.
Ozempic and Wegovy, which both contain semaglutide, work by mimicking a naturally occurring hormone called GLP-1. This hormone not only encourages insulin production but also slows digestion and curbs appetite. Mounjaro, on the other hand, includes tirzepatide, which acts on both GLP-1 and another hormone that helps regulate blood sugar and appetite.
Despite being popularly dubbed “weight-loss injections,” not all of these medications are formally licensed for that purpose.
The MHRA has highlighted a particular concern around Mounjaro, warning it may reduce the effectiveness of oral contraceptives such as the pill in people with overweight or obesity. Of the 40 reports received, 26 were linked to Mounjaro. The regulator is now advising that women using the drug should also employ barrier methods of contraception, such as condoms, to guard against unintended pregnancy.
Eight of the reports related to semaglutide and a further nine involved liraglutide, the active component in another weight-loss drug, Saxenda. While it is not a requirement for women to indicate whether their pregnancies were unplanned, two of the reports did specify this.
The agency has reiterated that these medications should not be taken during pregnancy, while trying to conceive, or during breastfeeding, citing a lack of sufficient safety data on the potential impact on unborn children. In some cases, women may need to wait up to two months after discontinuing treatment before attempting to become pregnant.
Dr Channa Jayasena, consultant in reproductive endocrinology and andrology at Imperial College Healthcare NHS Trust, explained:
“GLP-1 drugs copy the natural hormones made in the gut which make you feel full. This makes them powerful treatments to help women lose weight.
“Obesity reduces fertility in women. So, women with obesity taking GLP-1 drugs are more likely to get pregnant than before they lost weight.
“In addition, we think that the absorption of oral contraceptive pills may be reduced with GLP-1 drugs which slow down emptying of the stomach, though more research is needed to confirm this.
“The guidance produced by the MHRA is sensible, since it highlights that women could accidentally get pregnant when taking GLP-1 drugs.
“We don’t know how harmful GLP-1 drugs are during pregnancy; however, we know that other forms of weight loss like weight-loss surgery can increase chances of a miscarriage. So women are advised to do all they can to prevent pregnancy while taking GLP-1 drugs.”
Reports of a potential “baby boom” linked to the rising use of weight-loss injections began emerging last year. One Facebook group titled “I got pregnant on Ozempic” had more than 750 members, reflecting widespread anecdotal concern among users.
Dr Alison Cave, the MHRA’s chief safety officer, underscored the importance of using these drugs appropriately: “Skinny jabs are medicines licensed to treat specific medical conditions and should not be used as aesthetic or cosmetic treatments. They are not a quick fix to lose weight and have not been assessed to be safe when used in this way.
“Our guidance offers patients a one-stop shop for our up-to-date advice on how to use these powerful medicines safely.
“This guidance should not be used as a substitute to reading the patient information leaflet or having a conversation with a healthcare professional as part of the prescribing process.”
The MHRA’s advice is clear: while these medications offer significant benefits to those managing chronic health conditions, they must be used with caution — and always under appropriate medical supervision.
