GLP-1 washout before pregnancy: what the FDA labels + ACOG say + the honest half-life math

What the FDA labels actually say (in plain English)

Wegovy prescribing information, Section 8.1 (Pregnancy): 'Discontinue Wegovy in patients at least 2 months before a planned pregnancy because of the long washout period for semaglutide.' Ozempic label uses the same 2-month recommendation.

Zepbound and Mounjaro labels state: 'Advise patients of the potential risk to the fetus… Discontinue [drug] in patients when pregnancy is recognized.' No specific washout window is required on the tirzepatide labels as of mid-2026 — implied 4-week clearance from half-life math is the clinical rule of thumb.

The FDA warnings are based on animal-reproduction studies (semaglutide) that showed structural malformations at exposures 4-19× the maximum recommended human dose. Human data is limited to observational registry studies (e.g., MotherToBaby OTIS) that have not established a clear teratogenic signal, but the sample size is small.

• Sources for this section
• Wegovy FDA prescribing information (2024 revision) — US FDA
• Ozempic FDA prescribing information (2024 revision) — US FDA
• Zepbound FDA prescribing information — US FDA

The half-life math — where the 2 months comes from

Semaglutide half-life ≈ 1 week (7 days). Standard pharmacology defines 'washout' as 5 half-lives, at which point plasma concentration is ~3% of steady-state. That is 5 weeks for semaglutide.

The FDA rounds up to 2 months (8 weeks) because (a) real-world adherence varies, so steady-state before discontinuation may be higher than the label pharmacokinetic model, (b) the conservative window covers early-pregnancy exposures that could pre-date a positive pregnancy test.

Tirzepatide half-life ≈ 5 days (dual GIP + GLP-1 agonist). 5 half-lives = ~4 weeks. The label does not specify a fixed washout because the clinical guidance is discontinue-when-pregnancy-recognized, but a 4-6 week window before planned conception is the clinical rule of thumb most obesity-medicine specialists follow.

Rybelsus (oral semaglutide 3, 7, 14 mg daily) has the same 1-week semaglutide half-life. The 2-month FDA guidance applies.

ACOG guidance on obesity + pregnancy

The American College of Obstetricians and Gynecologists Committee Opinion #762 on obesity in pregnancy (2016, reaffirmed 2021) does not recommend anti-obesity pharmacotherapy — GLP-1 or otherwise — during pregnancy or lactation. Preconception weight optimization is encouraged, but the medication must be discontinued before conception.

ACOG endorses preconception counseling that specifically covers weight-loss medication discontinuation timing, coordination with the prescribing clinician, and expected weight-regain during the washout window. Realistic expectation-setting is part of the standard-of-care visit.

• Sources for this section
• ACOG Committee Opinion No. 762 — Prepregnancy Counseling — Obstetrics & Gynecology, 133(1), 2019

If you are planning a pregnancy — the practical timeline

3+ months before planned conception: Discuss with your prescriber and OB. Confirm the discontinuation window (2 months for semaglutide, 4-6 weeks for tirzepatide). Expect weight-regain during and after the washout period — 2-6% of body weight in the first 3 months is typical.

2 months before planned conception (semaglutide) / 4-6 weeks (tirzepatide): Stop the drug. Continue lifestyle intervention (protein, resistance training, sleep). Restart folate 400 mcg daily if not already on prenatal vitamin.

During the washout window: Track menstrual cycles. Some patients experience cycle changes as GLP-1 exposure declines — often a return to a more predictable cycle after the anovulation that unmedicated obesity can drive.

After conception: Do not restart the GLP-1 while pregnant or breastfeeding, unless a specialist explicitly re-approves postpartum based on individual circumstances (rare).

If you are already pregnant on a GLP-1

Stop the medication the same day you have a positive pregnancy test. Notify both your prescriber and OB within 24-48 hours — they will coordinate ongoing care.

This is not a reason to consider pregnancy termination. Registry data (MotherToBaby OTIS, EPIC/EHR studies) have not established a clear teratogenic signal for semaglutide in humans as of mid-2026, though the datasets are small. Early first-trimester exposure to Wegovy/Ozempic has been reported in observational studies without a clear malformation signal above baseline.

Your OB will likely order an early-anatomy ultrasound (18-20 weeks) with attention to skeletal-development markers, given the animal-study signal. Enroll in the manufacturer's pregnancy registry if invited — this is how the safety database grows for future patients.

For Zepbound / Mounjaro specifically: same guidance. Stop, notify, and follow OB monitoring — same rationale.

• Sources for this section
• MotherToBaby OTIS Semaglutide Pregnancy Registry — Organization of Teratology Information Specialists

Breastfeeding on a GLP-1

Both Wegovy and Ozempic labels do not recommend GLP-1 use during breastfeeding — the drug's transfer to breast milk in humans has not been definitively characterized, but animal studies show detectable presence in milk.

ACOG and the Academy of Breastfeeding Medicine both recommend deferring GLP-1 restart until breastfeeding is complete or transitioned. If you plan to breastfeed exclusively for 6+ months, plan for weight-regain during that window and restart the GLP-1 (or a similar medication) afterward with your prescriber.