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The weight loss drugs, by mimicking gut hormones, effectively reduce appetite and promote weight loss, which can in turn boost fertility in women with obesity
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British health authorities have issued a warning to women using weight-loss medications such as Ozempic, Wegovy and Mounjaro, urging them to use effective contraception after dozens of pregnancy reports linked to the drugs.
The Medicines and Healthcare products Regulatory Agency (MHRA) on Friday (May 6) released its first public safety alert addressing the use of weight-loss drugs and contraception. The agency said it had received 40 reports of pregnancies involving users of medications that include the active ingredients semaglutide or tirzepatide, The Guardian reported.
Ozempic and Wegovy, which both contain semaglutide, mimic a gut hormone called GLP-1 that helps reduce appetite by slowing digestion and increasing insulin production. Mounjaro, which contains tirzepatide, also targets a second hormone involved in blood sugar and appetite control.
Though often referred to as “weight-loss injections,” not all of the drugs are formally authorised for weight loss.
Drugs not advised during pregnancy or attempts to conceive
The MHRA said the drugs should not be taken during pregnancy, while trying to conceive, or while breastfeeding due to a lack of safety data. In some cases, the agency recommends that women continue contraception for up to two months after stopping the medication before attempting pregnancy.
Among the 40 reports, eight were associated with semaglutide and nine with liraglutide, which is found in the weight-loss drug Saxenda. Two cases were explicitly reported as unintended pregnancies.
Dr. Channa Jayasena, a reproductive endocrinologist at Imperial College Healthcare NHS Trust, said the drugs, by mimicking gut hormones, effectively reduce appetite and promote weight loss, which can in turn boost fertility in women with obesity.
“Obesity reduces fertility in women. So, women with obesity taking GLP-1 drugs are more likely to get pregnant than before they lost weight,” he said. He also noted that the medications may interfere with the absorption of oral contraceptives due to delayed stomach emptying, although further research is needed.
Officials stress responsible use
Dr. Alison Cave, the MHRA’s chief safety officer, warned that the medications should not be used as quick fixes for weight loss or for cosmetic purposes.
“Skinny jabs are medicines licensed to treat specific medical conditions and should not be used as aesthetic or cosmetic treatments,” Cave said. “They are not a quick fix to lose weight and have not been assessed to be safe when used in this way.”
The MHRA said it has published updated guidance to help patients use the medications safely but emphasized that the advice should not replace consultation with a healthcare provider.
Dr. Jayasena added that while the risks of GLP-1 drugs in pregnancy are not fully known, similar weight-loss interventions like surgery have been associated with higher miscarriage rates. “So women are advised to do all they can to prevent pregnancy while taking GLP-1 drugs,” he said.