Claims that ‘skinny pricks’ are causing an unexpected baby boom have led experts to warn women against combining their use with effective contraception.
Drugs such as Wegovy and Ozempic, both of which contain semaglutide, have become extremely popular, not least because they can help people lose more than 10% of their body weight.
The drugs work by mimicking a hormone in the body called GLP-1, which causes an increase in insulin production, slows the rate at which food is digested in the stomach and reduces appetite.
But as their use has exploded, there have also been reports of women becoming pregnant while taking such drugs, known as GLP-1 receptor agonists.
The Facebook group “I got pregnant on Ozempic” has more than 750 members, while discussions on the social networking site Reddit are full of anecdotes about such experiences.
Although studies confirming a link are lacking, experts say a link is plausible.
“Obese women often have irregular or no periods because they do not ovulate. Once they lose some weight, ovulation becomes more regular and their fertility improves,” says Dr Karin Hammarberg from Monash University in Australia.
Research is underway to investigate whether semaglutide can help stimulate ovulation in women with obesity and polycystic ovary syndrome (PCOS) – a condition that can cause irregular periods, weight gain and infertility, among other symptoms.
However, concerns have been raised about the safety of pregnant women taking GLP-1 receptor agonists.
A spokesperson for Novo Nordisk, the company that makes Ozempic and Wegovy, said: “Pregnancy or intention to become pregnant were exclusion criteria in our studies of semaglutide in both obesity and type 2 diabetes. Therefore, there is limited clinical trial data on use of semaglutide in pregnant women.”
Although evidence in humans is lacking, animal studies have suggested that semaglutide may cause fetal abnormalities.
According to Novo Nordisk, when semaglutide was given to pregnant rats, the unborn offspring showed both structural abnormalities and growth changes.
The preclinical safety information for Wegovy adds: “In developmental toxicity studies in rabbits and cynomolgus In monkeys, increased pregnancy loss and a slightly increased incidence of fetal abnormalities were observed at clinically relevant exposures.”
Although the company is now conducting studies to investigate whether such drugs are safe for pregnant women, the company currently recommends that semaglutide should not be used during pregnancy because it is not known whether it can affect an unborn child.
“It is therefore recommended to use contraception while taking this medicine,” says Wegovy’s patient information leaflet. “If you want to become pregnant, you must stop taking this medicine at least two months in advance. If you become pregnant, think you may be pregnant or are planning to become pregnant while taking this medicine, contact your doctor immediately as your treatment should be stopped.
But some women have reported becoming pregnant while taking GLP-1 receptor agonists despite using hormonal contraception, leading to speculation that the drugs could interfere with such contraceptive methods.
Professor Sir Stephen O’Rahilly, co-director of the Wellcome-MRC Institute of Metabolic Science, said the question of whether GLP-1 receptor agonists can interfere with the effectiveness of oral contraceptives remains largely unanswered so far.
“People treated with these medications may develop gastrointestinal side effects, including diarrhea, so it is not unlikely that some women may find that their oral contraceptive pill, at least intermittently, is not absorbed as reliably as before,” he said.
“A pragmatic response to this situation might be to suggest that women on the pill who are very keen to avoid pregnancy while experiencing active weight loss with GLP-1 [receptor agonists]they may consider themselves at higher risk of pregnancy and use additional methods, such as barrier contraception, until their weight stabilizes, at which time it seems likely that contraceptive efficacy will return to normal.”
Hammarberg agreed. “Stories of women taking semaglutide becoming pregnant while on the pill are anecdotal and we must remember that this also happens among women who are not taking semaglutide. Some speculate that semaglutide could alter the absorption of the pill, but as far as I know there is no evidence that this is the case,” she said.
“To ensure that an unplanned pregnancy does not occur, it may be wise for women taking Ozempic and similar medications to use condoms and of course an IUD would also be a very safe option.”