Doctors are warning babies may be harmed by weight-loss drugs, amid an apparent rise in women struggling with fertility becoming pregnant while using the medication.
Weight-loss drug semaglutide - available in the UK under the brand Wegovy - was developed to help minimise the symptoms of type two diabetes or manage long term weight loss in people struggling with obesity.
It comes as a pre-filled injector pen, which patients inject themselves with once a week, and has been hailed as a “game-changer” in the fight against obesity.
It has been available in the UK since September, and is now available both through the NHS and via private prescription.
Ozempic - another brand name for semaglutide - is manufactured by the same company, but is available in the UK only for the treatment of diabetes.
In the US, where millions have been prescribed Ozempic prescriptions, women have shared their experiences of surprise pregnancies while on the drug.
But medics are warning the risks to babies are not yet clear, and have warned it is “not clear whether it’s safe to use in women during pregnancy”.
“I thought I was, like, infertile because it took us maybe four years just to have our first child,” one woman told in a video on TikTok, sharing her ‘Ozempic baby’ story.
“Our son is now six years old.
“We never had any contraception [but] never had any [more] babies. We just assumed we couldn’t.
“Then I get on this new medicine, Ozempic, and I get pregnant.”
Another woman with polycystic ovary syndrome (PCOS) told how she had tried to get pregnant for two years, before beginning Ozempic treatment and conceiving almost immediately.
“I was told I couldn’t have kids and went on Ozempic, and five months later was pregnant,” said another.
Wegovy’s manufacturer, Novo Nordisk, says studies in animals have shown “reproductive toxicity” and says there is limited data on how the drug affects pregnant women.
“Therefore, semaglutide should not be used during pregnancy,” it says.
“If a patient wishes to become pregnant, or pregnancy occurs, semaglutide should be discontinued.”
It recommends the drug “should be discontinued at least two months before a planned pregnancy” due to its long half-life.
In a study on lactating rats given semaglutide, the drug was found secreted in milk.
“A risk to a breast-fed child cannot be excluded,” says Novo Nordisk. “Semaglutide should not be used during breast-feeding.”
It adds that semaglutide’s effects on fertility in humans is “unknown”.
Ying Cheong, professor of reproductive medicine at Southampton University, told The Times: “The drug is known to cause pregnancy complications and abnormalities in animal studies, and so women planning to be pregnant should be advised not to take them.”
Professor Tricia Tan, a consultant in diabetes, endocrinology and metabolic medicine at Imperial College London, told the newspaper: “Women need to know that these drugs should not be used during pregnancy.
“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.
“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.”
It is well-documented that people with a BMI of 30 or more - classified as obese - can find it more difficult to become pregnant.
Dr Nerys Astbury, nutrition scientist and senior researcher in diet and obesity at the University of Oxford, told The Times it was “plausible” semaglutide injections, by reducing people’s weight, could help improve fertility.
“It’s nothing special about the drug,” she told the newspaper. “The effect the drug has is on promoting weight loss.
“It is important to note that whilst some doctors are prescribing semaglutide off-label to women with PCOS, it is not clear whether it’s safe to use in women during pregnancy.”
She added: “It 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.”
Semaglutide is known as a GLP-1 agonist. It helps to increase the production of insulin, and was originally developed for managing type 2 diabetes.
Wegovy is the brand name for semaglutide, which is licensed and approved in the UK for managing overweight and obesity.
It is manufactured by Novo Nordisk and is recommended by the National Institute for Health and Care Excellence (NICE) for managing overweight and obesity in some patients on the NHS.
NICE recommends it should generally be prescribed to adults with a BMI of at least 30, who have a weight-related health condition such as cardiovascular disease.Clinical trials indicate that when used alongside diet, physical activity, and behavioural support, Wegovy users can achieve up to a 15 per cent reduction in body weight after one year, the NHS says.
Ozempic is another brand name for semaglutide. Current guidance says Ozempic should only be prescribed for the treatment of type 2 diabetes, and should not be prescribed solely for weight loss, to protect supply for diabetes patients.
Ozempic was approved for type 2 diabetes in Britain in 2019, but posts on Reddit suggest people have been able to buy the drug for weight-loss from private online providers.
In the US, prescriptions for Ozempic and Wegovy surged by 300 per cent between early 2020 and the end of 2022, according to CNBC.
In the last quarter of 2022, more than nine million prescriptions for those and similar other drugs were written out in the US, said the news outlet last year.
Ozempic injections accounted for more than 65 per cent of those prescriptions, while CNBC reported it was primarily prescribed off-label for its weight-loss credentials.
