Popular weight-loss medications raise pregnancy safety concerns for women

Women taking popular weight-loss medications during their reproductive years may be unaware of associated risks to pregnancy and unborn babies, warn Flinders University researchers. 

A new study has revealed that most Australian women of reproductive age prescribed GLP-1 receptor agonists-medications increasingly used for weight loss such as Ozempic-are not using effective contraception, despite known risks during pregnancy. 

Published in the Medical Journal of Australia, the research analyzed data from over 1.6 million women aged 18 to 49 who attended general practices between 2011 and 2022. Of the 18,010 women who were first prescribed GLP-1 receptor agonists during that time, only 21% had reported using contraception. 

Originally developed to manage type 2 diabetes, GLP-1 receptor agonists have gained popularity for their appetite-suppressing and weight-loss effects, with the study finding that most prescriptions are now issued to women without diabetes. 

Lead author and pharmacist, Associate Professor Luke Grzeskowiak, says that in 2022 alone, more than 6,000 women began treatment on GLP-1s, and over 90% of those did not have a diabetes diagnosis. 

We're seeing widespread use of these medications among women of childbearing age, but very little evidence that contraception is being considered as part of routine care.

These medications can be incredibly helpful, but they're not risk-free, especially during pregnancy." 

Luke Grzeskowiak, Associate Professor, College of Medicine and Public Health, Flinders University

The study found that 2.2% of women became pregnant within six months of starting GLP-1 treatment with pregnancy rates highest among younger women with diabetes, and among women without diabetes in their early thirties. 

Women with polycystic ovary syndrome were twice as likely to conceive, suggesting that weight loss may improve fertility, even when unintended. 

Importantly, women who were using contraception at the time of prescribing had a significantly lower risk of pregnancy. 

A previous review of animal studies from the University of Amsterdam linked GLP-1 exposure during pregnancy to reduced foetal growth and skeletal abnormalities, and while human data is limited, the potential risks remain concerning.

"Whilst the UK advises that women using GLP-1 receptor agonists should avoid pregnancy and use effective contraception, this advice is not being followed consistently in Australian clinical practice," says Associate Professor Grzeskowiak.

"We need to ensure that reproductive health is part of every conversation when these drugs are prescribed to any women of childbearing age. 

"It is also vitally important that we have clearer practice recommendations and guidelines for those prescribing GLP-1s to women to ensure their safe and effective use. 

"Our advice is to speak to your GP about the risks and benefits of GLP-1 medicines before taking them, and only take those prescribed by a healthcare professional." 

The authors say that further studies evaluating the impact of these medications on pregnancy and unborn babies are warranted.