Patients who stopped using semaglutide or liraglutide medications immediately before pregnancy or in the first weeks after pregnancy showed an average weight gain during pregnancy compared to those who did not use the medications.
On average, pregnant women who stopped using Ozempic, Wegovy, or Saxenda gained 13.7 kg, about 3 kg more than pregnant women who had not used them before, where the average weight gain was 10.5 kg.
In addition, there was also an increased risk of premature birth, development of gestational diabetes and high blood pressure during pregnancy after stopping treatment with molecules, known as GLP-1 receptor agonists (GLP1-RAs).
There was no significant difference in the size of babies by gestational age in the treatment discontinuation group compared with the control group, although mean birth weight was also higher in patients who used GLP1-RAs before pregnancy.
The data come from a study conducted on thousands of women in the United States coordinated by Jacqueline Maya, from the Department of Pediatrics, and Camille Bowie, from the Diabetes Research Center of Massachusetts General Hospital, and published on Monday (24) in the specialized journal JAMA (Journal of the American Medical Association).
There are few data on the effects of using so-called weight-loss pens, such as Wegovy (semaglutide 2.4 mg, intended for the treatment of obesity), Ozempic (semaglutide 1 mg, which is recommended for the treatment of type 2 diabetes), Saxenda (liraglutide 6 mg, intended for obesity) and Mounjaro (tirzepatide 10 mg, approved for both obesity and type 2 diabetes) on the developing fetus.
Preclinical studies in laboratory animals show a toxic effect of the molecules on embryos, with some congenital malformations in mouse embryos. However, data on humans are scarce and based on real-world studies on the use of molecules. The current medical recommendation is to suspend treatment to avoid potential risks to the fetus.
The research analyzed medical records of pregnant women from the Brigham and Women’s Mass Network, which includes Brigham and Women’s Hospital and Massachusetts General Hospital, in Boston (USA), from June 1, 2016 to March 31, 2025.
The analysis was divided into three groups: 1) gestational weight gain group; 2) Fetal size according to gestational age; and 3) assess the incidence of complications during pregnancy, such as gestational diabetes, preeclampsia (high blood pressure), and risk of prematurity. All analyzes were adjusted for the pregnant woman’s age, pre-existing conditions, and race.
In the overweight group during pregnancy, 448 pregnant women who used Wegovy, Ozempic and other medications before pregnancy were compared with 1,344 pregnant women who did not use these substances. The risk of weight gain during pregnancy was 32% higher among those with a history of treatment.
Regarding the size of the baby at birth, 442 pregnant women in the group exposed to the drug before pregnancy were evaluated compared to 1,326 unexposed women. As a result, the average size of the baby for gestational age was 3.6% higher in the treated group compared to the untreated group.
Finally, an analysis of complications during pregnancy showed a 34% higher risk of preterm birth, 30% higher risk of gestational diabetes, and 29% higher risk of high blood pressure problems in pregnant women who were exposed to the medications before pregnancy. About 23% of participants had pre-diabetes and the average body mass index (BMI) was 36.1 (considered to be a diagnosis of obesity equal to or greater than 27), compared with 26.9 in women who were not recommended treatment with weight-loss pens.
The researchers concluded that data on the risks of stopping treatment with these medications during pregnancy are scarce, but research findings suggest that, at least in women with pre-existing obesity, stopping treatment before or at the beginning of pregnancy was associated with gestational weight gain and an increased risk of preterm birth, diabetes, and problems associated with high blood pressure (eg, preeclampsia) during pregnancy.
Increase in postpartum prescriptions
Another study, also published on Monday (24) in JAMA, reported a significant increase in the use of weight loss pens in postpartum women (up to 182 days postpartum) in Denmark. Based on the National Medical Birth Register, researchers from the Institute of Public Health at the University of Southern Denmark observed an increase in the use of Ozempic and Wegovy in postpartum women from 2021 onwards.
According to the research, between 2018 and 2022 there was a split between liraglutide users (33%, mainly Saxenda) and semaglutide (67%, 36% Ozempic users), but from 2023 onwards, semaglutide began to respond to more than 97% of prescriptions, with nearly 9 out of 10 (89%) being for the drug. And goofy.
The research says that only 23% of pregnant women had a previous diagnosis of type 2 diabetes before birth, and 73% of users in 2023 and 2024 used the treatment for the first time, without prior indication.
Risks of uncontrolled use of weight loss pills
The data reinforce that there is little evidence on the use of medications before, during, and after pregnancy by women with or without a previous diagnosis of obesity or diabetes.
This is a conclusion also shared by Caroline Cesta, a physician and researcher at the Karolinska Institutet in Sweden, who wrote an editorial published in the same issue of the medical journal. According to her, the two studies provide alarming data and open the way to explore new areas.
“There is limited or no clinical guidance on the use of drugs such as Wegovy and Ozempic before pregnancy. Such studies provide valuable answers but there is no direct evidence for clinical advice before treatment with GLP-1RAs about their potential harms and benefits for future pregnancies. The absence of this last question is probably due to the paucity of pre-treatment BMI data in global databases and the significant effort required to link this information to prescriptions and pregnancy registries.”
The main recommendation, in the case of a previous diagnosis of obesity or diabetes, is to seek out a responsible healthcare professional who can provide information about the best way to control weight and blood glucose level during pregnancy, in order to reduce the risks for both mother and child.