Weight Loss Drugs in Pregnancy Tied to Preterm Births

Study finds increased risk of preterm birth only for women taking GLP-1 receptor agonists for diabetes, not for weight loss

Mar. 18, 2026 at 11:12am

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A large study of over 750,000 pregnancies found that there was no link between taking weight loss drugs like semaglutide (Ozempic, Wegovy) or liraglutide (Saxenda) and an increased risk of preterm births or other obstetric complications. However, the researchers did find a 70% higher risk of preterm birth for women taking these medications to treat pre-existing diabetes.

Why it matters

The findings suggest that it is the underlying condition of diabetes, rather than the weight loss medications themselves, that may be contributing to the increased risk of preterm births. This has important implications for how clinicians counsel women who are inadvertently exposed to these drugs in early pregnancy.

The details

The study analyzed data from the Danish nationwide health registries for 756,636 singleton pregnancies. If women had redeemed a prescription for liraglutide or semaglutide within eight weeks before or after their last menstruation, this was defined as inadvertent exposure. The researchers found that women who took GLP-1 receptor agonists for diabetes treatment had a 70% higher risk of preterm birth for liraglutide and an 84% higher risk for semaglutide, compared to women who did not take these medications.

  • The study analyzed pregnancies that resulted in deliveries between October 1, 2009 and December 31, 2023.

The players

Henriette Svarre Nielsen

Professor from the Department of Gynaecology and Obstetrics at Copenhagen University Hospital Hvidovre, who led the study.

Kathrine Hviid

PhD student in the same department as Professor Nielsen and the first author of the paper.

Yeyi Zhu

Researcher from Kaiser Permanente Northern California and the Center for Upstream Prevention of Adiposity and Diabetes Mellitus.

Monique Hedderson

Researcher from Kaiser Permanente Northern California and the Center for Upstream Prevention of Adiposity and Diabetes Mellitus.

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What they’re saying

“GLP-1 RA treatment has, within the last few years, become the medication with the sharpest increase in prescription worldwide. Current guidance suggests the treatment should be stopped eight weeks prior to planning a pregnancy. However, this is based on early-phase model organism studies, and not real-world evidence. Nonetheless, because of its widespread adoption, inadvertent exposure in early pregnancy is inevitable, and there is hardly any evidence to guide clinical counselling when it happens.”

— Henriette Svarre Nielsen, Professor

“We made some extremely important findings that have implications for future studies, such as randomised controlled trials of GLP-1 RA usage in pregnancy, and for clinical counselling. We found that these medications were associated with an increased risk of preterm birth, but the risk was only present when the medication was used for diabetes treatment, and not for weight management. This suggests that the underlying condition of diabetes, rather than the medication, may be driving this association.”

— Kathrine Hviid, PhD student

“For clinicians, the study by Hviid et al (2026) may inform preconception and early pregnancy counselling. The observation that elevated preterm birth risk was confined to women treated for diabetes, and not to those using GLP-1 receptor agonists for weight management, supports more balanced, individualized discussions with patients who may have experienced inadvertent periconceptional exposure. For patients with diabetes, the study reinforces the importance of recognizing diabetes as an important risk factor for obstetric complications and prioritizing metabolic health and glycemic management before and during pregnancy.”

— Yeyi Zhu and Monique Hedderson

What’s next

Further studies are needed, and it is too soon to change the recommendation to stop GLP-1 receptor agonists prior to pregnancy, or to implement counseling, regardless of the reason why women were taking them.

The takeaway

This study highlights the importance of understanding the underlying medical condition, rather than just the medication, when assessing the risks of inadvertent exposure to weight loss drugs during early pregnancy. The findings will help guide more nuanced clinical counseling for women in this situation.