It has been linked to an increased risk of preterm birth in women who mistakenly take weight loss drugs just before or during early pregnancy to treat pre-existing diabetes.
However, a large study of more than 750,000 pregnancies found no link between using the drug to lose weight and preterm birth or other obstetric complications.
The authors of the study published today (Wednesday) said: human reproductive open, The study, one of the world’s leading reproductive medicine journals, said the findings suggest that it is diabetes, rather than drugs, that may be contributing to the increased risk of preterm birth.
Weight loss drugs such as semaglutide (trade names: Ozempic, Wegovy) and liraglutide (Saxenda) belong to a class of drugs called GLP-1 receptor agonists (GLP-1 RAs) and were originally developed to treat type 2 diabetes. It was soon discovered that they work primarily by suppressing appetite and can also help people lose weight. However, there is no evidence to suggest that it is safe to consume during pregnancy.
Professor Henriette Svaar Nielsen, from the Department of Gynecology and Obstetrics at Copenhagen University Hospital in Bydovre, Denmark, who led the study, said: “GLP-1 rheumatoid arthritis treatment has become the fastest-growing drug in the world in recent years. Current guidance requires that treatment be stopped eight weeks before a planned pregnancy. However, this is based on early stage model organism studies and not real-world evidence. Nevertheless, because of its widespread use, inadvertent exposure in early pregnancy is inevitable, and there is little evidence to guide clinical counseling when it occurs.”
Researchers decided to investigate the association between women who mistakenly receive GLP-1 RA treatment during the preconception period and the risk of complications such as preterm birth (birth before 37 weeks), preeclampsia, gestational diabetes, large-for-gestational age delivery, stillbirth, and placental problems.
Researchers analyzed data from the Danish National Health Register on 756,636 singleton pregnancies among 480,231 women who gave birth between October 1, 2009 and December 31, 2023. If a woman redeemed a prescription for liraglutide or semaglutide within 8 weeks before or after her last menstrual period, this was defined as inadvertent drug exposure. This 16-week window records a period during which the mother may not have known she was pregnant and the early stages of organ growth in the fetus. A total of 529 pregnancies were exposed to GLP-1 RAs during the preconception period.
The researchers adjusted the results to account for maternal age, body mass index (BMI), smoking status, geographic region, education, pre-existing diabetes, and month and year of pregnancy to control for seasonal and other trends.
“We made some very important findings that will have implications for future research, including randomized controlled trials and clinical counseling, on the use of GLP-1 RAs during pregnancy,” said lead author of the paper, Dr. Kathryn Viid, a doctoral student in the department.
“We found that these drugs were associated with an increased risk of preterm birth, but that risk was only present when the drugs were used to treat diabetes rather than weight management. This suggests that the underlying diabetes condition, rather than the drugs, may be driving this association.”
The researchers found that women who took GLP-1 RAs had higher rates of several obstetric complications, but after adjusting for factors that could influence the results, they only found that women who took liraglutide or semaglutide for diabetes treatment had a higher risk of preterm birth. Compared to women who did not take GLP-1 RAs, the increased risk was 70% higher for liraglutide and 84% higher for semaglutide. This means that for women who have previously taken semaglutide, the drug is associated with an approximately 11% higher risk of preterm birth. Liraglutide showed a 9% increased risk.
Future research should consider why women were prescribed these drugs, as the risks are different for women who use GLP-1 RAs for diabetes and those who use GLP-1 RAs for weight management. This is one of the first studies to investigate GLP-1 RA exposure during early pregnancy according to prescribing reason. As more evidence accumulates, these findings will guide clinical counseling for women who are inadvertently exposed to GLP-1 RAs during early pregnancy. In Denmark, around 70% of people who use weight loss drugs are women, so it is inevitable that some people will take them without knowing they are pregnant. ”
Professor Henriette Svar Nielsen, Department of Obstetrics and Gynecology, Vidvia University Hospital Copenhagen
However, she said more research is needed and it is too early to change the recommendation to stop GLP-1 RAs or provide counseling before pregnancy, regardless of why women take them.
The strength of this study is its large scale. Limitations include the fact that the results cannot show that GLP-1 RA causes preterm birth, only that GLP-1 RA is associated with preterm birth. Furthermore, there was no data to show that the women actually took the drugs after redeeming their prescriptions. However, in Denmark, women have to pay for GLP-1 RA injections, but there is a state subsidy for diabetes treatment. For example, a 1mg injection of Wegovy or Ozempic (semaglutide) costs approximately 180 and 114 euros, respectively, including the diabetes treatment subsidy.
“Due to the high cost, compliance rates among women prescribed GLP-1 RAs appear to be very high,” Dr. Hviid said.
In an invited comment accompanying the paper, Yay Chiu, Ph.D., and Monique Hederson, Ph.D., of Kaiser Permanente Northern California and the Obesity and Diabetes Upstream Prevention Center in Pleasanton, Calif., wrote that the study results “complement and extend the emerging evidence base for the reproductive safety of GLP-1 RA.”
The researchers continued: “For clinicians, the study by Hviid et al. (2026) may be useful for preconception and early pregnancy counseling, as the increased risk of preterm birth is limited to women being treated for diabetes, and GLP-1 receptor agonists are recommended for weight management. The observation that it is not limited to women who use it supports a more balanced and individualized discussion with patients who may have experienced inadvertent hyperconception exposure.For patients with diabetes, this study reinforces the importance of: Recognize diabetes as an important risk factor for obstetric complications and prioritize metabolic health and glycemic control before and during pregnancy. ”
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European Society of Human Reproduction and Embryology
References:
- Video, KVR, Others. (2026) Perirectonal GLP-1 receptor agonist exposure and obstetric outcomes: a Danish national cohort study. human reproduction. DOI: 10.1093/hropen/hoag015. https://academic.oup.com/hropen/article/2026/2/hoag015/8526483
- Zhu, Y., & Hedderson, MM (2026) When drugs meet disease: Unraveling the safety of GLP-1 receptor agonists around diabetes, obesity, and the concept. human reproduction. DOI: 10.1093/hropen/hoag016. https://academic.oup.com/hropen/article/2026/2/hoag016/8526482
