How long to stop a GLP-1 before trying to get pregnant

The short answer: how long to stop a GLP-1 before pregnancy

Both Novo Nordisk and Eli Lilly point people planning a pregnancy to stop their GLP-1 roughly two months before trying to conceive. That window is not picked at random. It maps loosely to two menstrual cycles, enough time for your body to fully clear the drug and for your prescriber to confirm your cycle has settled into something predictable again before you start timing anything.

The two drugs do not leave your system at the same speed, though. Semaglutide has a half-life of about one week, so five half-lives, the rough point at which a drug is considered essentially cleared, lands around five to six weeks. Tirzepatide's half-life is closer to five days, putting full clearance closer to four weeks. Two months covers either one with room to spare, which is likely why both companies converged on roughly the same number instead of publishing drug-specific windows.

If your cycle is irregular, or you have not had a period in a while on the drug, add a month. You want at least one confirmed normal cycle before you start counting toward a pregnancy, otherwise you are guessing at timing on top of everything else.

The birth control interaction that only affects one of these drugs

This is the part most general advice pages skip entirely, and it matters if you are actively avoiding pregnancy while you decide when to start trying. Tirzepatide, sold as Zepbound and Mounjaro, slows gastric emptying enough to measurably cut how much of an oral contraceptive dose actually gets absorbed. In the trial that established this, a single 5 mg dose of tirzepatide reduced oral contraceptive drug levels by about 20%. The FDA label responds accordingly: anyone on an oral contraceptive should switch to a non-oral method or add a barrier method, condoms in addition to the pill, for four weeks after starting tirzepatide and for four weeks after every dose increase.

Semaglutide does not carry this warning. Its label has no equivalent language about oral contraceptive interaction, and the mechanism that causes it in tirzepatide, delayed gastric emptying strong enough to blunt drug absorption, is milder with semaglutide. If you are choosing between the two and you rely on the pill, that difference belongs in the conversation, not as the deciding factor on its own, but as one more thing your prescriber should know you are weighing.

What the FDA labels actually say about pregnancy

Neither drug has been tested for safety in human pregnancy, and neither is approved for use during one. The labels are built on animal data: pregnant rats given semaglutide during the period of fetal organ formation showed embryofetal mortality, structural abnormalities, and growth changes at maternal exposures below the maximum recommended human dose. Tirzepatide's animal data shows a similar pattern. Neither company is claiming these effects are confirmed in humans. They simply have not ruled them out, which is why the standard instruction is to discontinue the drug once a pregnancy is recognized rather than continue and monitor.

Both manufacturers run pregnancy exposure registries, Novo Nordisk's for semaglutide and Lilly's for tirzepatide, that track outcomes in people who were exposed during pregnancy, intentionally or not. Enrolling is voluntary and is how the safety picture for human pregnancy eventually gets built, since no company is going to run a randomized trial that deliberately exposes a fetus to test the question directly.

If a pregnancy test comes back positive while you are still on it

Stop the medication and call your prescriber. That is the full instruction on every label, and it is worth saying plainly because a lot of people panic and assume a few weeks of exposure before a positive test means something has already gone wrong. It does not automatically mean that. No drug label or medical society recommends ending a pregnancy solely because of GLP-1 exposure in the early weeks. What you should do is stop the drug, tell whoever is managing your prenatal care, and consider enrolling in the relevant exposure registry so your outcome adds to what is known.

Can a GLP-1 actually help you get pregnant?

For a specific group, maybe, and the early data is more concrete than most people expect. A 2025 pilot study followed women with obesity, prediabetes, and PCOS-related infertility who were given semaglutide alongside metformin. Over the follow-up period, average weight dropped by roughly 13 kg, and 60% of the women in the study became pregnant. The proposed mechanism fits what is already known about PCOS: excess insulin drives the ovaries to overproduce androgens, which disrupts ovulation, and improving insulin sensitivity tends to let normal cycles resume.

Treat that number carefully. It is one small, uncontrolled pilot study, not a randomized trial, and semaglutide has no FDA approval for fertility or PCOS. Larger studies, including an ongoing NIH-adjacent trial referred to as RESTORE, are working through the same question with more rigor. If you have PCOS and are struggling to conceive, this is a real conversation to have with a reproductive endocrinologist, not a reason to start a GLP-1 on your own.

Breastfeeding: a thinner but reassuring picture

Postpartum, the question shifts to breastfeeding. A study measuring semaglutide concentrations in breast milk found only minimal transfer to nursing infants, well under the level generally treated as a safety concern. That is encouraging, but it is not the same as an official recommendation. The current Ozempic, Wegovy, Mounjaro, and Zepbound labels do not endorse use while breastfeeding, mostly because the studies behind that reassurance are still small. Most prescribers decide case by case, weighing how far postpartum you are and whether type 2 diabetes management is also part of the picture.

Restarting after pregnancy

Whenever you do restart, expect to begin back at the starting dose, not wherever you left off. The same titration schedule that applied the first time applies again, partly for tolerability and partly because the tirzepatide contraceptive interaction resets with every dose increase, so the four-week backup-contraception window comes back into play if you restart while still avoiding a second pregnancy soon after. Weight regain after stopping any GLP-1 is common and well documented; our guide on preventing GLP-1 weight rebound covers what actually slows that down during the months you are off the drug, pregnancy or not.