Does GLP-1 Exposure in Early Pregnancy Increase Birth-Defect Risk?
RESEARCH UPDATE · HUMAN PREGNANCY DATA
New human studies of GLP-1 pregnancy exposure have not found a consistent, statistically significant increase in major congenital malformations. That is reassuring—but it is not proof that semaglutide, tirzepatide, or other GLP-1-based drugs are safe during pregnancy.
Human pregnancy studies can identify patterns after exposure, but observational data cannot by themselves prove safety or causation.
The concise answer
Short answer: A 2026 meta-analysis of seven cohort studies covering more than 40,000 exposed pregnancies did not find a statistically significant increase in congenital malformations overall or major malformations after first-trimester exposure. A newer 16-patient semaglutide case series also reported no major fetal anomalies.
Those results do not establish safety. Most available evidence is observational, different GLP-1 drugs and indications are often pooled, and underlying diabetes, obesity, hypertension, and other factors can affect pregnancy outcomes. Data on continued treatment throughout pregnancy—and tirzepatide-specific human pregnancy data—remain limited.
For weight reduction, current FDA prescribing information still says to discontinue Wegovy or Zepbound when pregnancy is recognized. This article explains the evidence; it is not individualized medical advice.
Last reviewed: September 18, 2026.
What did the 2026 meta-analysis find?
A July 2026 systematic review and meta-analysis in Scientific Reports combined seven cohort studies involving more than 40,000 pregnancies with maternal GLP-1 receptor agonist exposure.
The pooled analysis reported:
| Question | Pooled result | Careful interpretation |
|---|---|---|
| Any congenital malformation after exposure at any time in pregnancy | OR 1.11; 95% CI 0.82–1.51 | No statistically significant increase was detected |
| Major congenital malformation after first-trimester exposure | OR 1.39; 95% CI 0.73–2.65 | No statistically significant increase was detected, but the interval was wide |
An odds ratio above 1 does not automatically mean the drug caused an outcome. The confidence intervals crossed 1, meaning the pooled estimates were statistically compatible with no increase. At the same time, those intervals do not prove that every clinically important increase has been excluded.
The correct conclusion is narrower than “GLP-1 drugs are safe in pregnancy”: the available cohort evidence did not demonstrate a consistent increase in congenital malformations.
What did the newest semaglutide studies add?
A 429-pregnancy retrospective cohort
A 2026 retrospective cohort study used linked electronic medical record and pharmacy-dispensing data for people with prepregnancy overweight or obesity who delivered between January 2022 and January 2026.
The pregnancy-exposed group included 429 semaglutide users with a median of 44 days of exposure during pregnancy. Compared with nonusers, the adjusted analysis found higher odds of excessive gestational weight gain, gestational diabetes, excessive fetal growth, and cesarean delivery.
That finding needs context. Former semaglutide users—those who had used it before pregnancy but were not classified as exposed during pregnancy—also had higher odds of the same outcomes than nonusers. Similar patterns in both the pregnancy-exposed and former-user groups suggest that underlying metabolic health, treatment history, rebound weight change, or other residual differences may contribute. The study was not a randomized trial and cannot prove that semaglutide caused those outcomes.
A 16-patient first-trimester case series
A September 2026 open-access case series described 16 patients who conceived unexpectedly while using subcutaneous semaglutide and continued it during part of the first trimester. All had overweight or obesity.
The authors reported no major fetal anomalies. They also reported preeclampsia in 18.8% of the series and one medically indicated preterm birth at 35 weeks. The authors cautioned that the high preeclampsia prevalence was likely related to underlying obesity.
Sixteen pregnancies are far too few to estimate uncommon risks. A case series also has no matched control group and cannot separate drug exposure from diabetes, obesity, hypertension, clinical care, or chance.
Why the findings are reassuring—but not definitive
Human observational data are more directly relevant than animal findings, but they still have important limits:
- Confounding by indication: People receiving GLP-1-based drugs often have diabetes, obesity, or other conditions that can independently affect pregnancy outcomes.
- Exposure timing varies: Many exposures stop when pregnancy is recognized, so the literature largely reflects preconception or early first-trimester exposure—not continuous use throughout pregnancy.
- Different drugs are pooled: Semaglutide, liraglutide, dulaglutide, exenatide, and sometimes dual GLP-1/GIP agonists may be analyzed together even though they are not interchangeable.
- Outcome definitions differ: Studies use different databases, comparators, pregnancy windows, and definitions of malformation or obstetric outcomes.
- Rare outcomes need large samples: A study can miss a real but uncommon risk, especially when drug-specific exposure groups are small.
- Live-birth and documentation bias: Some datasets may not capture early pregnancy losses, terminations, medication obtained outside the recorded system, or every congenital finding.
A separate 2026 systematic review of GLP-1 and dual GLP-1/GIP agonists reached a similarly limited conclusion: adjusted observational studies did not consistently show increased major congenital malformations, fetal growth restriction, stillbirth, or neonatal mortality, but evidence for continued use throughout gestation remains sparse.
What do current FDA labels say?
The observational studies have not changed current U.S. product labeling.
The 2026 Wegovy prescribing information says available human pharmacovigilance and clinical-trial data are insufficient to establish a drug-associated risk of major birth defects, miscarriage, or other maternal or fetal outcomes. For weight reduction, it advises discontinuing Wegovy when pregnancy is recognized and, because of semaglutide’s long half-life, at least two months before a planned pregnancy.
The 2026 Zepbound prescribing information likewise says available tirzepatide data in pregnant patients are insufficient to evaluate drug-related risk. It advises discontinuing Zepbound when pregnancy is recognized and provides information about a pregnancy exposure registry.
Both labels also describe animal reproduction findings. Animal studies inform risk assessment, but they cannot be converted directly into a human birth-defect rate.
Do these studies prove semaglutide is safe during pregnancy?
No. “No statistically significant increase detected” and “proven safe” are different statements.
The 2026 human literature reduces some uncertainty about inadvertent early exposure. It does not establish the safety of ongoing treatment during pregnancy, exclude all uncommon risks, or override current prescribing information.
It also does not establish safety for compounded or research-use material. Published pregnancy studies involve defined pharmaceutical exposures. They cannot verify the identity, concentration, purity, formulation, or equivalence of a different material.
What about tirzepatide and other dual GLP-1/GIP agonists?
Tirzepatide activates both GIP and GLP-1 receptors and should not be treated as interchangeable with semaglutide. Some reviews discuss GLP-1 and dual GLP-1/GIP therapies together, but the newest drug-specific pregnancy evidence is much deeper for semaglutide than for tirzepatide.
FDA’s current Zepbound label says human pregnancy data are insufficient to evaluate major birth defects, miscarriage, or other maternal and fetal outcomes. The recent tirzepatide lactation studies answer a different question: milk transfer after birth does not establish fetal exposure or safety during pregnancy.
Frequently asked questions
Do GLP-1 drugs cause birth defects?
Current human observational studies have not demonstrated a consistent statistically significant increase in major congenital malformations after early exposure. The evidence remains incomplete and cannot prove zero risk.
What if exposure happened before pregnancy was recognized?
The published human literature primarily informs inadvertent preconception and early-pregnancy exposure. Anyone with a personal exposure question should contact a licensed prenatal or prescribing clinician, who can interpret the specific drug, timing, indication, and current label. This article cannot make an individual risk determination.
Were tirzepatide pregnancies included?
Some broad reviews include dual GLP-1/GIP therapies, but tirzepatide-specific human pregnancy evidence remains limited. Pooled GLP-1 findings should not be assumed to apply identically to tirzepatide.
Does “not statistically significant” mean there is no risk?
No. It means the analyzed data did not demonstrate a difference with the study’s statistical threshold. Sample size, bias, confounding, exposure classification, and confidence-interval width still matter.
The bottom line
The 2026 human evidence is more informative than headlines based only on animal studies. Across seven cohorts, early maternal GLP-1 exposure was not associated with a statistically significant increase in congenital malformations, and a small new semaglutide case series reported no major fetal anomalies.
But the honest conclusion keeps its limits: these are observational data, drug-specific evidence is uneven, and continued exposure throughout pregnancy remains poorly studied. The findings are reassuring about inadvertent early exposure—not a declaration that GLP-1 or GLP-1/GIP drugs are proven safe during pregnancy.
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Primary and authoritative sources
- Uysal N, et al. Pregnancy outcomes following maternal GLP-1 receptor agonist exposure: a systematic review and meta-analysis. Scientific Reports. 2026. doi:10.1038/s41598-026-61582-8.
- Gestational Weight Gain and Pregnancy Outcomes After Semaglutide Exposure. 2026 retrospective cohort study.
- Obstetrical and medical outcomes following GLP-1 receptor agonist exposure in pregnancy: a case series. Case Reports in Women's Health. 2026;51:e00831.
- Ozbek L, et al. Safety of GLP-1 and Dual GLP-1/GIP Receptor Agonists in Preconception, Pregnancy, and Lactation. Diabetes, Obesity and Metabolism. 2026;28(6):4503–4528.
- U.S. Food and Drug Administration. Wegovy prescribing information. Current 2026 label.
- U.S. Food and Drug Administration. Zepbound prescribing information. Current 2026 label.
Research-use and editorial disclaimer: This article summarizes published human observational research and current prescribing information for educational purposes. It is not medical advice, a diagnosis, or guidance about starting, stopping, or changing any medication. Pregnancy-related decisions require a licensed clinician who can review the specific exposure and medical context. JD BioWorks materials are intended solely for qualified laboratory research and are not for human or veterinary use. Review the full research-use disclaimer.