, 2025-05-02 09:47:00
The use of glucagon-like peptide 1 (GLP-1) medications amongst women – particularly those of childbearing age – has risen dramatically in recent years. From 2020 to 2023, the rate of young women taking these medications increased by 594%.
Experts contend that certain GLP-1 agonists, specifically tirzepatide (Mounjaro), may decrease the effectiveness of oral contraceptives, which can lead to unplanned pregnancies. What’s more, these medications haven’t been formally tested on pregnant women, so it’s unclear if the drugs could impact the fetus.
Given the influx of younger women taking GLP-1 medications, it is critical to understand the potential impact on fertility and pregnancy.
Unplanned Pregnancies and GLP-1s
GLP-1 agonists can cause delayed gastric emptying, which can slow the absorption of certain medications, including oral birth control, said Jody Dushay, MD, an assistant professor of medicine at Harvard Medical School and an attending physician in the Division of Endocrinology and Metabolism at the Beth Israel Deaconess Medical Center in Boston.
Tirzepatide carries a warning on the label that during the first 4 weeks of using the drug, and during the 4 weeks after increasing the dosage, patients may experience reduced efficacy of their oral contraceptive (due to gastric emptying delaying the absorption of the medication). While semaglutide (Ozempic) does not carry a warning on the label, the mechanisms of both medications are likely similar.
“If someone does not want to get pregnant or cannot get pregnant for any number of reasons, I might suggest with both medications that they use a barrier contraception in addition to taking the pill,” said Dushay. This is particularly true at certain inflection points when gastric emptying is at its highest.
How GLP-1s Affect Fertility
Polycystic ovarian syndrome — a condition characterized by ovarian cysts which can cause an irregular menstrual cycle and potential infertility — is a common comorbidity that goes along with type 2 diabetes and obesity, said Rosa Drummond, MD, a maternal fetal medicine fellow at the University of Maryland Medical Center in Baltimore. The condition can also cause women to ovulate irregularly, which can reduce fertility.
“We see that people who experience weight loss through diet and exercise, or through these medications, return to more frequent ovulations,” said Drummond. So in some cases, it might be that women are becoming more fertile as they become healthier. Those who had trouble getting pregnant before may find it easier. “You can ovulate without even getting a period, so if they weren’t on a good form of birth control, women may conceive as a result of the weight loss,” Drummond said.
Fertility hormones work better when insulin is working more efficiently through the use of these medications, said John Norian, MD, a board-certified reproductive endocrinologist with HRC Fertility in Pasadena and Rancho Cucamonga, California. “The pituitary gland communicates better with the ovaries, which allows a mature dominant follicle to release a mature, healthy egg,” said Norian.
Risks of GLP-1s During Pregnancy
It can be difficult to study the impact of medications on pregnant women because of ethical concerns. No one is going to allow research that could possibly endanger a fetus, and pregnant rodent models aren’t the same as pregnant humans, said Courtney Younglove, MD, an Ob/Gyn and obesity medicine physician at Heartland Weight Loss in Lawrence and Overland Park, Kansas.
“We usually depend on registries where people report adverse events, and then overtime, the registry builds,” said Younglove. Obstetricians tend to only allow older-generation medications during pregnancy; these drugs have been used over time and registry data shows physicians a broader picture of how these medications may affect pregnancy.
Another issue is that GLP-1 agonists linger in your system for up to 2 months — an eternity in the development of a fetus. If a physician discovers a patient is pregnant and taking these medications, they should advise the patient to refrain immediately due to lack of data. “The consensus among physicians is that because we don’t know, patients should stop taking them,” said Younglove.
Additionally, if a patient is planning to get pregnant, Younglove recommends they stop taking GLP-1 medications at least 2 months before trying to conceive.
IVF and GLP-1s
If a patient is considering starting in vitro fertilization (IVF), there’s also a cause for concern about how the medications will affect the embryo. “We require that patients stop taking their GLP-1 agonists at least 10 days to 2 weeks prior to an egg retrieval,” said Norian.
Egg retrieval is the process during IVF when a needle, guided by ultrasound, is used to collect eggs from a woman’s ovaries. Egg retrieval happens under anesthesia, which isn’t safe for patients on GLP-1s due to the risk for aspiration and vomiting resulting from delayed gastric emptying.
Norian requires that his patients cease taking GLP-1s at least 1 month before the embryo transfer — the process in IVF where a fertilized egg is placed into a woman’s uterus in the hopes that she will become pregnant. “While the data is preliminary on this, early pregnancy is when all the fetal organs are being formed, so we wouldn’t want to risk it,” said Norian.
It’s also worth considering that women who took GLP-1s to lose weight and control blood sugar, and then suddenly stopped taking the drugs, risk comorbidities like developing diabetes unexpectedly and endangering the fetus. In these cases, more monitoring may be required. “Poor glycemic control is a disaster in the first trimester for a fetus,” said Younglove.
The bottom line: There is still a lot to learn about taking these medications during pregnancy. Women who are on GLP-1s should consider using another form of birth control in addition to their oral contraceptive. Women who are not taking birth control — but have had trouble ovulating while being overweight — may find that losing weight boosts their fertility.
Lastly, if a patient finds out they are pregnant unexpectedly, GLP-1 agonists should be stopped immediately.
“There’s pretty much no time when we would want a pregnant person to be losing weight, so there’s no reason to continue with these medications when you’re pregnant,” said Younglove.
