Semaglutide, tirzepatide, and liraglutide are pregnancy-contraindicated. Washout is ~2 months for semaglutide, ~4 weeks for tirzepatide. Tirzepatide reduces oral contraceptive absorption — barrier or non-oral backup required.
GLP-1 receptor agonists are contraindicated in pregnancy due to animal reproductive toxicity and the absence of adequate human safety data. The FDA labels recommend discontinuation at least 2 months (semaglutide) or 4 weeks (tirzepatide) before a planned pregnancy¹². The Mounjaro and Zepbound labels carry an additional warning that tirzepatide may reduce oral contraceptive efficacy during initiation and each dose escalation, requiring non-oral contraception or barrier method backup for 4 weeks².
Pregnancy category and labeling
All GLP-1 receptor agonists currently marketed in the U.S. carry a recommendation against use during pregnancy. Wegovy and Ozempic labels recommend discontinuation at least 2 months before a planned pregnancy due to the ~7-day half-life of semaglutide (5 half-lives = ~35 days plus safety margin)¹. Tirzepatide labels (Mounjaro, Zepbound) recommend at least 4 weeks given its ~5-day half-life².
Animal studies in rats and rabbits showed adverse developmental outcomes at clinically relevant exposures (embryofetal mortality, structural abnormalities, growth alterations). Human pregnancy data are insufficient to characterize drug-associated risk.
Oral contraceptive interaction with tirzepatide
Tirzepatide reduces rate and extent of oral medication absorption due to delayed gastric emptying. A drug-drug interaction study showed single-dose ethinyl estradiol/norelgestromin AUC reduced ~20% and Cmax ~55% following the first tirzepatide dose and subsequent escalations².
The Mounjaro and Zepbound labels recommend switching to non-oral contraceptive (IUD, implant, injection) or adding a barrier method (condom) for 4 weeks after initiation and after each dose escalation. Semaglutide labels do not carry this specific warning, though delayed gastric emptying is a class effect.
If pregnancy occurs on GLP-1 therapy
Discontinue immediately on confirmation of pregnancy and refer for routine prenatal care. There is no evidence brief first-trimester exposure mandates pregnancy termination, but documented exposure should be reported to the relevant pregnancy registry (Wegovy or Mounjaro Pregnancy Registry). Standard early pregnancy ultrasound and anatomic survey are appropriate.
Breastfeeding
Labels state that data are insufficient to characterize presence in human milk or effects on milk production or the breastfed infant. Animal studies showed transfer of semaglutide to milk. Clinical guidance is to consider developmental and health benefits of breastfeeding alongside the mother's clinical need¹. Many clinicians recommend deferring GLP-1 initiation during lactation.
Fertility and weight loss
Weight loss in patients with obesity and infertility (particularly PCOS) frequently improves ovulatory cycles and conception rates. Patients on GLP-1 therapy not actively trying to conceive should use effective contraception, since restoration of fertility may precede their intent to conceive. Patients planning conception should discontinue with the timing described above and use bridging interventions during washout.
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How long do I need to stop semaglutide before pregnancy?
FDA labels for Wegovy and Ozempic recommend at least 2 months. Based on the ~7-day half-life and clearance of 5 half-lives plus safety margin.
Does Mounjaro or Zepbound affect birth control pills?
Yes. Use a non-oral contraceptive (IUD, implant, injection) or add condoms for 4 weeks after starting or escalating tirzepatide.
What if I get pregnant on a GLP-1?
Stop immediately and contact your obstetrician. Report to the pregnancy registry. Standard early prenatal care.
Can I breastfeed on a GLP-1?
Current label guidance is that data are insufficient. Most clinicians recommend deferring GLP-1 until after weaning.
Can I use GLP-1 in PCOS if planning conception?
Yes for the weight-loss phase. Plan a washout (2 months semaglutide, 4 weeks tirzepatide) before active conception attempts.
References
U.S. Food and Drug Administration.Wegovy (semaglutide) injection — Prescribing Information.FDA Drug Approval Records. 2021 (updated 2024).View source
U.S. Food and Drug Administration.Mounjaro (tirzepatide) injection — Prescribing Information.FDA Drug Approval Records. 2022 (updated 2024).View source
Pi-Sunyer X, Astrup A, Fujioka K, et al.A Randomized, Controlled Trial of 3.0 mg of Liraglutide in Weight Management (SCALE).N Engl J Med. 2015;373(1):11-22.PMID: 26132939
U.S. Food and Drug Administration.Zepbound (tirzepatide) injection — Prescribing Information.FDA Drug Approval Records. November 2023.View source
Citations are peer-reviewed where available. PubMed (PMID) links resolve to NCBI's PubMed. FDA links resolve to fda.gov. All citations were last verified 2026-05-11.
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