Using weight loss jabs in pregnancy is safe, major study suggests
Women can safely use weight loss jabs when trying to conceive without putting their baby at risk, research has suggested.
A major study of more than two million pregnancies found expectant mothers who use the blockbuster injections are not at higher risk of complications including miscarriage and still birth – as has previously been suggested.
The findings are contrary to official guidelines that warn women not to take the medicines during pregnancy and two months before trying to conceive.
This is because ‘there is not enough safety data to know whether the medicine can cause harm to the baby’, reads Government advice.
Now, experts at City St George’s, University of London have found ‘reassuring’ evidence that the jabs – used to treat obesity and diabetes – are in fact safe for mothers and babies.
‘The message for patients is that if you discover you were taking one of these medicines before you knew you were pregnant, you should not panic,’ said Professor Asma Khalil, an expert in maternal fetal medicine and study lead author.
‘Healthcare professionals are seeing more women who become pregnant while taking medications such as Ozempic and Mounjaro.
Using weight loss jabs at the time of conception does not increase the risk of miscarriage, birth defects or excessive weight gain, experts say
‘For many women, discovering they were taking one of these drugs before they realised they were pregnant can be a source of enormous anxiety.
‘These findings are reassuring and will help clinicians provide evidence-based advice to women who find themselves in this situation.’
However Professor Khalil recommended that women continue to follow recommendations to stop the injections before a planned pregnancy while further data is collected.
The study – published in the journal Cell Press – is the largest systematic review of its kind.
Researchers analysed data from ten studies involving more than two million pregnancies.
Among them were 8,325 women who had used weight loss jabs in the six months before or after a positive pregnancy test.
The researchers found that use of the drugs around the time of conception was not linked to a significantly higher risk of miscarriage, stillbirth, birth defects, premature birth, gestational diabetes or excessive weight gain during pregnancy.
There was also no detectable increase in the risk of babies being born unusually small or large, compared with pregnancies in which mothers had not used the drugs.
However, the researchers stressed that these findings should not be interpreted as proof that the medications – known as GLP-1 agonists – are safe to use throughout pregnancy.
This is because the study was observational – meaning it cannot establish cause and effect – and does not take into account the risk of higher doses.
Most of the women involved in the study also did not use the jabs for their entire pregnancy, just around the time they got pregnant.
Professor Tricia Tan, an endocrinologist at Imperial College London who was not involved in the research, welcomed the findings but said more still needs to be done so that women can make informed choices.
She is now calling on the pharmaceutical industry to fund further research into how these medications affect pregnancy, particularly at higher doses – to provide women who are using these medications to treat obesity with the ‘reassurance they deserve’.
The drugs have previously been linked to increased fertility, with some doctors in the US prescribing them off-label to treat polyendocrine metabolic ovarian syndrome, one of the leading causes of infertility.
Fat cells produce oestrogen which can negatively affect fertility. Losing weight can help restore hormone levels and regulate menstruation, increasing the chances of conception.
However, there have also been reports of women gaining three times the normal pregnancy weight after coming off the jabs, putting them at risk of gestational diabetes, which can increase the risk of premature birth, still birth and other pregnancy complications.
GLP-1s, such as semaglutide – sold under brand names Ozempic and Wegovy – and tirzepatide, marketed as Mounjaro, were originally developed for controlling blood sugar levels for people with Type 2 diabetes.
