April 23, 2024

expert reaction to journalists’ questions about obesity drugs and fertility

Scientists react to questions raised about obesity drugs and fertility. 

Prof Ying Cheong, Professor of Reproductive Medicine and Honorary Consultant in Reproductive Medicine and Surgery, University of Southampton, said:

“GLP-1 agonists are being marketed widely, but the lack of safety profile in human pregnancy is often not widely known.  The drug is known to cause pregnancy complications and abnormalities in animal studies, and so women planning to be pregnant should be advised not take them.

“Whether GLP-1 agonists can help with the management of other conditions e.g. in PCOS, apart from weight loss is still a matter of research, hence doctors should not be prescribing these medications without the appropriate indications.”

Prof Adam Balen, Professor of Reproductive Medicine and Surgery, Leeds Centre for Reproductive Medicine, Leeds Teaching Hospitals NHS Trust, said:

“Many women who are overweight have reduced fertility, and those with PCOS may stop ovulating.  Losing weight improves fertility and the likelihood of ovulation.  The GLP-1 agonist drugs, used for the management of diabetes, enable weight reduction and have been used to help women with PCOS, however these women are advised not to conceive because of uncertainty about safety of these drugs in pregnancy.  Furthermore, conceiving when not nutritionally stable may be harmful for the developing baby and overweight women should be taking appropriate vitamin supplements, in particular high dose folate, in order to reduce the risk of their baby having a range of congenital anomalies (e.g. spina bifida, heart defects).  Pregnancies should therefore be planned in a healthy way.”

Prof Barbara McGowan, Professor of Endocrinology and Diabetes, King’s College London; and Guy’s and St Thomas’s Hospital, said:

“Weight loss by any means can improve fertility and regulate periods in ladies with PCOS.  Weight loss improves insulin resistance associated with PCOS, and in doing so regulates the menstrual cycle and hence fertility.

“However, women on GLP-1 agonists should take contraception whilst they take the medication, and stop at least 2 months before trying for fertility.  Healthcare professionals should include this advice when the medication is started.”

Prof Trisha Tan, Department of Metabolism, Digestion & Reproduction, Imperial College London, said:

“Women need to know that these drugs should not be used during pregnancy.  You can also see that most of the clinical trials have not included women who are intending to become pregnant.  Animal studies did show that the animal babies born to animals who were given these medications had problems.

“In my practice where we see many women with obesity and infertility, we do not prescribe these GLP-1 agents unless they are on contraception.  This does sometimes cause delays in management and disappointment.

“We do need research on this area to understand how we can deploy these drugs effectively and safely.  This will help us to address the needs of women with obesity who want to have babies, so that we can improve their health, help them to have a safe pregnancy and deliver healthy children.”

Dr Nerys Astbury, Senior Researcher – Diet & Obesity, Nuffield Department of Primary Health Care Sciences, University of Oxford, said:

“I’ve been working on weight loss in women before, during and after pregnancy for a while.  One of the reasons I became interested in this is that we often see women who take part in our weight loss trials “accidentally” become pregnant during the trials, and I was interested in exploring this further.

“Excess adiposity, known as overweight or obesity, can disrupt regular menstruation, ovulation, and implantation of fertilised oocytes, and women living with obesity are more likely to have problems in conceiving, to suffer miscarriage, and are less likely to deliver live infants.  Losing a modest amount of weight, equivalent to 5-10% of initial body mass, can correct anovulation due to obesity, and there is evidence that this increases chances of conception.

“It is possible, and even plausible that Semaglutide (Wegovy/Ozempic), because it causes weight loss in obese people, is improving their fertility – but because they lose weight.  When women taking the drug then start losing some weight, and (for various reasons) have not been using a reliable form of contraception – or because of some of the side effects of Semaglutide (vomiting and diarrhoea) contraceptives may not work as effectively – they find themselves “accidentally” pregnant or an “oops” baby.  It’s nothing special about the drug – but the effect the drug has on promoting weight loss.

“It is important to note that whilst some doctors are prescribing Semagluiatide off-label to women with PCOS is not clear whether it’s safe to use in women during pregnancy, and should not be used as a method to treat infertility until research demonstrating safety and effectiveness is available, and until regulatory approval for use in those before and during pregnancy.

“Alternatively, approaches to weight loss which are not subject to pharmacological testing and regulation, may be helpful in women with excess weight who are trying to conceive.”

Declared interests

Prof Ying Cheong: “No COI.”

Prof Adam Balen: “No CoI.”

Prof Barbara McGowan: “Grants or contracts from any entity: Novonordisk research grants.

Royalties or licenses: None.

Consulting fees: Lilly, Novonordisk, Pfizer, J&J, Astra Zeneca.

Payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events: Novonordisk, Amgen, Lilly, Sanofi.

Payment for expert testimony: None.

Support for attending meetings and/or travel: None.

Patents planned, issued or pending: None.

Participation on a Data Safety Monitoring Board or Advisory Board: None.

Leadership or fiduciary role in other board, society, committee or advocacy group, paid or unpaid: Board member ISE, Co-chair EASO OMTF.

Stock or stock options: Stockholder Reset Health.

Receipt of equipment, materials, drugs, medical writing, gifts or other services: None.

Other financial or non-financial interests: None.”

Prof Tricia Tan: “I do not have any direct CoI but would like to declare the following: I am a shareholder and consultant for Zihipp ltd a spinout from Imperial College London.

I have participated in a medical advisory board for Astra Zeneca.”

Dr Nerys Astbury: “I have no conflicts.”