Weight loss injections – new guidelines support safe decision making in pregnancy

Study provides guidance and support for health professionals and families
Weight loss injection

Weight loss injections – new guidelines support safe decision making in pregnancy

Study provides guidance and support for health professionals and families
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Weight loss injections are an increasingly popular way for people to manage their weight.
However, the injections’ impact on reproductive health – from fertility onwards – is relatively unknown. Manufacturers currently advise that they should be stopped before people try to get pregnant, and should not be used during pregnancy or whilst breastfeeding.
Now an international study led by the University of Plymouth has examined available research to understand what science tells us to date, and use that to form a set of evidence-based guidelines for families and health professionals seeking to understand if and when incretin-based medications – such as weight loss injections – could be used safely before and after pregnancy.   
The guidance covers everything from contraception (with strong encouragement for women to use reliable non-oral contraception if using tirzepatide medication) to the need to monitor intake of nutrients alongside using the injections before pregnancy.

How did the research work? 

The research searched through all existing studies related to incretin-based medications – such as weight loss injections – and reproductive health. It found over 30 studies altogether, and drew on that evidence to form the basis of guidelines.
However, the low number of studies meant there were many gaps in evidence, so the study authors – with expertise stretching across all healthcare disciplines – have provided additional guidance based on their own, extensive knowledge and experience. 

Obesity can have negative effects on women’s reproductive health, but there haven’t been any comprehensive, evidence-based guidelines on whether incretin-based medications – like the commonly used injections – are a safe way of managing weight before and after pregnancy.

This new research, conducted by an international group of experts, is the first step to bridging that gap. 
As a team, we sought to find scientific papers worldwide related to the medications’ impact on fertility, conception, nutrition and long-term health of mother and baby.
We found 34 altogether. However, there are a lot of gaps in evidence – for example, there are no studies that explore the long-term impact on mother and baby of using the medications.

Kate MaslinDr Kate Maslin
Associate Professor of Women's Health and Nutrition, and the study's lead author

 
 
 

Making recommendations

As a result, when evidence from existing papers was lacking, our international team of experts has made consensus recommendations based on expert clinical experience.

These recommendations, alongside the published evidence, have formed a set of guidelines for health professionals to use.
One key recommendation was that incretin-based medication therapy should not be deliberately continued throughout pregnancy. 
However, for those who may have used the injections without realising they were pregnant, the current data show no increased risk for congenital anomalies following exposure in early pregnancy – which we hope will be reassuring.

Kate MaslinDr Kate Maslin
Associate Professor of Women's Health and Nutrition, and the study's lead author

 
 
Guidelines for healthy pregnancy after using weight loss medication
The guidelines (previewed above) are now available in a print friendly version for healthcare professionals.
The study and guidelines were undertaken by an international team of co-authors including the University of Surrey, UK; KU Leuven, Belgium; Edith Wolfson Medical Center and Tel Aviv University, Israel; Erasmus MC University Medical Center, The Netherlands; University Medical Centre Ljubljana, Slovenia; and Royal College of Surgeons in Ireland.  

Why the guidelines matter

Alice Rafferty from Macclesfield, Cheshire has polycystic ovary syndrome – a genetic condition that makes it difficult to conceive – and needed to lose weight to be considered for IVF treatment with the NHS. 
She started using weight loss injections on a friend’s advice but did not know where to find information about them, or even whether to disclose to health professionals that she was starting to use them. 
After a successful round of IVF with a private clinic, Alice is now expecting her first child in October 2026. 
Alice Rafferty and husband, Jamie
Alice Rafferty and husband, Jamie 

I needed to lose weight to go onto IVF so I looked into using the injections on a recommendation from a friend who’s a former midwife.

But most information and stories about the injections came from rumours around whether celebrities were using them, not anything to do with how effective they might be, and whether they might affect chances of getting pregnant. It was really hard trying to work it all out. 
Ultimately I used the injections to keep my weight down, then made my own decision to stop using them two weeks before my IVF treatment started, but that was because I couldn’t find any other information. 

I also felt like I couldn’t tell health professionals I was on the injections – what if I told them, and they wouldn’t let me continue with IVF?

Thankfully, things have worked out. I can’t wait to have our baby, and I’m already looking into how I’ll manage my weight after giving birth, so these guidelines will be really good to have. 
For me, it’s really important to talk about issues related to women’s health and fertility more widely, as you never know what someone is trying to navigate.

Alice Rafferty 
 
 

Next steps  

Lead research author Dr Maslin is now leading a further study exploring women’s use of the weight loss injections in relation to their fertility, including understanding where they found their information, and how it affected their decision making around use of the medication.

I’m leading a study to explore how women access information about injectable weight loss medication, and how that influences their perception and use of them, in order to shape how we communicate the correct scientific information.

Weight loss medications are readily available through private providers, although less so through the NHS. We need to do more to ensure health professionals have the best available information to hand, and women and families are supported to make informed choices.
As well as providing evidence for guidelines, the main takeaway from this current study is that much more research needs to be done to understand how weight loss injections affect all aspects of reproductive health.

Kate MaslinDr Kate Maslin
Associate Professor of Women's Health and Nutrition

The full study, entitled Incretin-based medications in women and reproduction: A systematic scoping review and consensus guidelines for clinical practice, is available to view in the journal Obesity Reviews (doi: 10.1111/obr.70203). 

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