Semaglutide in pregnancy: first-trimester exposure risk and the counseling gap

TL;DR

A 2025 narrative review in Obstetric Medicine (PMC12141256) identifies a critical counseling failure in GLP-1 prescribing: women of childbearing potential are frequently not informed that semaglutide and other GLP-1 medications may reduce the absorption of oral contraceptives through delayed gastric emptying, potentially increasing unintended pregnancy risk. When pregnancy occurs, exposure during the first trimester carries a 2-month wash-out requirement (semaglutide has a 5-week half-life), and animal data showing developmental risks makes early discontinuation essential.

GLP-1 medications have become one of the most prescribed drug classes among women of childbearing age. Obesity itself increases pregnancy risk through polycystic ovary syndrome (PCOS), anovulation, and metabolic dysfunction - and GLP-1-mediated weight loss can restore fertility in women with obesity-related infertility. This creates a clinical paradox: GLP-1 medications may help some women become pregnant, but they need to be stopped well before conception, and the drug-contraception interaction may be undermining the protection intended to prevent unintended pregnancy.

The contraceptive absorption problem

Semaglutide and other GLP-1 receptor agonists significantly slow gastric emptying - the rate at which the stomach delivers its contents to the small intestine. Oral contraceptives (the pill) are absorbed primarily in the small intestine. Delayed gastric emptying means oral contraceptive pills spend more time in the stomach and reach the small intestine more slowly, potentially reducing peak hormone concentrations and overall bioavailability.

Novo Nordisk's prescribing information for oral semaglutide (Rybelsus) specifically warns about this interaction. For injectable semaglutide (Ozempic, Wegovy), the gastric emptying effect is also present - particularly in the first few months of treatment before the body partially adapts. The review authors note that counseling on this interaction is inconsistent: many prescribers do not discuss it, and many women on GLP-1 medications are not informed that their oral contraceptive may be less reliable than expected.

The fertility restoration effect

A compounding factor is that GLP-1 medications can restore ovulation in women with PCOS and obesity-related anovulation. PCOS is the most common cause of infertility in women of reproductive age and affects up to 10-15% of women globally. Weight loss reliably restores ovulatory cycles in many PCOS patients. As women lose 10-15% of body weight on GLP-1 therapy, cycles that were absent or irregular can normalise - sometimes before the woman or her prescriber has recognised that fertility has been restored.

The combination of restored fertility and potentially reduced oral contraceptive efficacy creates a significant unintended pregnancy risk that is specific to GLP-1 therapy - and that is not adequately flagged in current prescribing practice.

Animal data and the first-trimester risk

Human safety data on GLP-1 medications in pregnancy is limited because trials ethically exclude pregnant women. What exists is a mix of animal data, case reports, and registry data from inadvertent exposures. The animal picture is concerning: in rodent and rabbit studies, semaglutide at exposure levels comparable to human therapeutic doses caused increased embryo-fetal mortality, structural abnormalities, and growth retardation. The FDA labels all GLP-1 medications as contraindicated in pregnancy based on this animal data.

The challenge is semaglutide's long half-life. The half-life of weekly injectable semaglutide is approximately 5 weeks - meaning it takes 10-12 weeks (about 2 months) to clear from the body after stopping. A woman who discovers she is pregnant in week 5-6 of gestation has likely had semaglutide in her system throughout the critical early embryonic period. Most major organ systems begin forming between weeks 3 and 8 of gestation - precisely the window when most unintended pregnancies are discovered.

This is why the review authors emphasise stopping semaglutide at least 2 months before a planned pregnancy - not at the positive pregnancy test. For women who are not planning pregnancy but are sexually active, robust contraception from the start of GLP-1 therapy is essential, with awareness that oral contraceptives may be less reliable and that non-oral methods (IUD, implant, injection, barrier methods) may offer more reliable protection.

What the human pregnancy exposure data shows

Registry and spontaneous reporting data on inadvertent semaglutide exposure in early pregnancy is accumulating but remains limited. Novo Nordisk maintains a pregnancy exposure registry, and published case series have begun to appear. The available human data to date has not shown a definitive pattern of specific birth defects, but the case series are small and insufficiently powered to detect increased rates of uncommon malformations.

Importantly, first-trimester miscarriage rates appear potentially elevated in some reports of GLP-1 exposure in early pregnancy, but confounding by obesity-related pregnancy loss (which is independently elevated) makes interpretation difficult. The honest summary of available human data is: insufficient to establish safety, with animal data suggesting risk.

The PCOS and fertility dimension

Women with PCOS who are using GLP-1 medications specifically for weight loss and metabolic improvement deserve particular attention. They may believe they are at low pregnancy risk due to irregular cycles, when in fact GLP-1 therapy may have normalised those cycles. PCOS-related fertility loss is reversible with weight loss - which is exactly what GLP-1 medications deliver. Prescribers should specifically discuss this possibility with PCOS patients when starting GLP-1 therapy.

The nutritional picture for women on GLP-1 medications who are pregnant or planning pregnancy

If a woman discovers she is pregnant while on semaglutide, the recommended action is to stop the drug immediately and seek obstetric review. After stopping, the focus shifts to ensuring adequate nutritional status for a healthy pregnancy.

This is where GLP-1-specific nutritional considerations intersect with pregnancy nutrition. Women who have been on GLP-1 medications may have depleted folate, B12, iron, and zinc - all nutrients critical for fetal development in the first trimester. Folate deficiency in early pregnancy is associated with neural tube defects; B12 deficiency impairs neurological development; iron deficiency increases the risk of preterm birth and low birth weight.

Any woman who has been on GLP-1 medications and is considering pregnancy should have her nutritional status assessed before conception, with particular attention to B12 and folate, and begin pregnancy-specific supplementation that addresses both the pregnancy requirements and the GLP-1 depletion patterns. GLP-1 Shield addresses the GLP-1-specific nutrient gaps, and women transitioning to pregnancy planning should work with their prescriber on a comprehensive nutritional support plan.

Frequently asked questions

Is it safe to take Ozempic or Wegovy during pregnancy?

No. GLP-1 medications including semaglutide (Ozempic, Wegovy), tirzepatide (Mounjaro, Zepbound), and liraglutide are contraindicated in pregnancy. Animal studies show developmental risks at human-comparable doses. If you discover you are pregnant while taking a GLP-1 medication, stop it immediately and contact your prescriber and obstetrician. The long half-life of semaglutide (about 5 weeks) means it takes 10-12 weeks to fully clear.

Does Ozempic or Wegovy affect the birth control pill?

Potentially yes. GLP-1 medications slow gastric emptying, which delays the absorption of oral medications including oral contraceptives. This can reduce oral contraceptive hormone concentrations, potentially reducing their effectiveness. The prescribing information for oral semaglutide (Rybelsus) specifically notes this interaction. Injectable semaglutide also has gastric-emptying effects. Women on GLP-1 medications should discuss contraception with their prescriber - non-oral methods (IUD, implant, injection, barrier methods) are not affected by gastric emptying.

Can GLP-1 medications make it easier to get pregnant?

Yes, indirectly. GLP-1 medications cause significant weight loss, which can restore ovulatory cycles in women with obesity-related anovulation and polycystic ovary syndrome (PCOS). PCOS is the most common cause of infertility in reproductive-age women, and weight loss reliably restores fertility in many cases. This means women on GLP-1 medications may have higher fertility than expected - making contraception planning especially important.

How long do I need to stop Ozempic before getting pregnant?

Current guidance recommends stopping semaglutide at least 2 months before attempting to conceive. This accounts for the drug's long half-life of approximately 5 weeks - after 2 months (roughly 4 half-lives), plasma concentrations have fallen to very low levels. For women planning pregnancy, this means discussing the timing with their prescriber well in advance, not just at the point of starting trying to conceive.