Weight Loss Jabs Safe for Conception, Large Study Suggests

Women using weight loss injections like Ozempic and Mounjaro while trying to conceive do not face an increased risk of miscarriage, stillbirth, or birth defects, according to a major study. The findings challenge existing official guidelines, which advise women to stop taking these medications two months before attempting to get pregnant due to insufficient safety data.

A comprehensive review of more than two million pregnancies, published in the journal Cell Press, analyzed data from ten studies. Among these, 8,325 women had used weight loss jabs in the six months leading up to or immediately following a positive pregnancy test.

Researchers at City St George's, University of London, found that the use of these drugs, known as GLP-1 agonists, around the time of conception was not associated with a significant rise in complications such as miscarriage, stillbirth, birth defects, premature birth, gestational diabetes, or excessive weight gain. The study also found no discernible increase in the risk of babies being born unusually small or large compared to pregnancies where the drugs were not used.

"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, lead author of the study and an expert in maternal fetal medicine. "Healthcare professionals are seeing more women who become pregnant while taking medications such as Ozempic and Mounjaro. 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."

Despite the reassuring evidence, Professor Khalil advised women to continue following current recommendations to stop the injections before a planned pregnancy while further data is collected. The study's observational nature means it cannot definitively establish cause and effect, and it did not account for the risks associated with higher doses. Additionally, most participants in the study used the injections only around the time of conception, not throughout their entire pregnancy.

Professor Tricia Tan, an endocrinologist at Imperial College London not involved in the research, called the findings welcome but emphasized the need for more comprehensive data to enable informed choices for patients. She urged the pharmaceutical industry to fund additional research into the effects of these medications during pregnancy, particularly at higher doses.

GLP-1 agonists, including semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro), were originally developed to manage blood sugar levels in individuals with Type 2 diabetes. The drugs have also been linked to improved fertility, with some U.S. doctors prescribing them off-label for conditions like polycystic ovary syndrome (PCOS), a common cause of infertility. Weight loss can help restore hormonal balance and regulate menstruation, potentially increasing conception chances. However, concerns remain about potential rapid weight gain after discontinuing the medication, which could pose risks such as gestational diabetes during pregnancy.