Study offers reassurance after unintended exposure, but states more safety data is needed.
Published
Exposure to GLP-1 weight-loss and diabetes drugs around conception is not linked to a clearly detectable increase in adverse outcomes for mothers or babies, according to the largest study of its kind involving more than 2.1 million pregnancies and led by researchers at City St George's.
GLP-1 receptor agonists are a class of medicines used to treat obesity and type 2 diabetes. They include semaglutide, sold under brand names such as Ozempic and Wegovy, and tirzepatide, marketed as Mounjaro. Their popularity has grown rapidly in recent years, with increasing numbers of women of reproductive age using these medicines.
Current clinical guidance recommends that women stop taking GLP-1 receptor agonists before a planned pregnancy because there is limited evidence about their effects during pregnancy. However, because many pregnancies are unplanned, women are often exposed to these medications before they know they are pregnant.
But this major study offers reassuring evidence for women who inadvertently become pregnant while taking GLP-1s before they realise they are pregnant.
The study, published today in the Cell Press journal Med, is the largest systematic review and meta-analysis on this topic to date.
Led by Professor Asma Khalil, researchers examined data from the ten studies that had investigated pregnancy outcomes among women who had been exposed to GLP-1 receptor agonists during the periconceptional period. This included before conception and in the very early stages of pregnancy before pregnancy was recognised.
The analysis included 2,118,215 pregnancies, including 8,325 pregnancies in which the mother had been exposed to a GLP-1 receptor agonist around the time of conception and within six months before a positive pregnancy test.
Following inadvertent GLP-1 exposure around conception, researchers found no clearly detectable increase in the risk of miscarriage, stillbirth, congenital anomalies, preterm birth, gestational diabetes, high blood pressure disorders of pregnancy, excessive maternal weight gain, or babies being unusually small or large at birth compared with pregnancies that had no exposure to GLP-1 receptor agonists.
Professor Asma Khalil, Professor of Obstetrics and Maternal Fetal Medicine in the School of Health & Medical Sciences, said:
"Healthcare professionals are seeing more women who become pregnant while taking these GLP-1 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. One of the questions we are most commonly asked is whether this exposure could have harmed their baby.”
The authors caution that these findings should not be interpreted as proof that GLP-1 receptor agonists are safe to use during pregnancy. The available evidence comes from observational studies, which can identify patterns and associations but cannot establish cause and effect.
Further research is needed before definitive conclusions can be drawn about the safety of these medications during pregnancy.
Professor Asma Khalil added:
"These findings are reassuring and will help clinicians provide evidence-based advice to women who find themselves in this situation. However, it is important to stress that our findings do not establish that these medications are safe during pregnancy. The evidence remains observational, and current recommendations to discontinue GLP-1 receptor agonists before a planned pregnancy should continue to be followed.
"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. Speak to your healthcare team, who can provide personalised advice and support.”
The authors say the findings have important public health implications and hope the study will help address uncertainty among both patients and healthcare professionals, while highlighting the need for further research into medication use during pregnancy.