GLP-1, birth control and pregnancy: what the labels and research say

Does tirzepatide affect birth control pills?

Yes, according to its FDA labels. GLP-1 medicines slow how fast the stomach empties. That can change how well pills are absorbed. For tirzepatide, the effect on oral contraceptives was measured directly.

In a study described in the Zepbound and Mounjaro labels (section 12.3, Pharmacokinetics), people took a combined pill with ethinyl estradiol and norgestimate alongside a single 5 mg dose of tirzepatide.¹

The labels say this delay is largest after the first dose and gets smaller over time. Under section 8.3, "Females and Males of Reproductive Potential," both labels advise patients on oral hormonal contraceptives to switch to a non-oral method, or add a barrier method, for 4 weeks after starting and for 4 weeks after each dose escalation.^1,2 Section 7.2, "Oral Medications," adds that hormonal contraceptives that are not taken by mouth should not be affected.

The current Wegovy (semaglutide) label does not include the same oral contraceptive advice.³ If you take the pill with any GLP-1 medicine, ask your prescriber or pharmacist which method fits you, especially around dose changes.

Where do "Ozempic babies" come from?

"Ozempic babies" is a social media term for unplanned pregnancies in people taking semaglutide (Ozempic, Wegovy) or tirzepatide. These are personal reports, not study results. There are two plausible explanations, and neither has been measured well.

• Less reliable pills. For tirzepatide, the label data above show lower hormone levels after a dose.
• Weight loss itself. Losing weight can make periods and ovulation more regular in some women. A 2026 review found early signs of better ovulation and pregnancy rates with GLP-1 medicines in women with polycystic ovary syndrome (PCOS), mostly from small trials of older drugs such as liraglutide.¹⁰

No large study has yet measured how often unplanned pregnancies happen on these medicines.

What do the labels say about pregnancy?

All three labels say the medicine may cause fetal harm, based on animal studies, and that human data are insufficient to judge the risk of birth defects or miscarriage.^1,2,3 Section 8.1, "Pregnancy," in the Zepbound label says weight loss offers no benefit during pregnancy and advises stopping when a pregnancy is recognized.

The Wegovy label gives the 2-month window in section 8.3.³ The current Zepbound label does not set a number of weeks before a planned pregnancy. The Mounjaro label, which is for type 2 diabetes, says it should be used in pregnancy only if the benefit justifies the risk, because poorly controlled diabetes also carries risks.² These differences are one reason pregnancy plans need a conversation with your prescriber, not a one-size rule.

Zepbound and Wegovy both have pregnancy exposure registries listed in section 8.1. If you were exposed during pregnancy, your doctor can help you join.^1,3

Do GLP-1 medicines cause birth defects? What the studies found

All of the studies below are observational. They follow pregnancies that happened while people were taking a medicine. No one is randomly assigned to take a drug while pregnant, so these studies can show a link or the lack of one, but not prove cause.

The big picture is cautiously reassuring. The Cesta study found that type 2 diabetes itself raised the rate of malformations (5.3% vs 3.7% in all infants), and GLP-1 exposure did not add a large risk on top of that.⁴ But the Brown study's authors say their results are compatible with both no added risk and a clinically relevant one.⁶ Most data come from older GLP-1 medicines and from women with diabetes, not from people using semaglutide or tirzepatide for weight loss.

A Danish national study of 529 exposed pregnancies looked at other complications. Preterm birth was more common in women taking liraglutide or semaglutide for diabetes (semaglutide adjusted odds ratio 1.84), but not in women using them for weight management (0.71). The authors suggest the diabetes, not the drug, may explain the difference.⁷

Can you take semaglutide or tirzepatide while breastfeeding?

The evidence is small. In a study in the Zepbound label (section 8.2, "Lactation"), 11 breastfeeding women got one 5 mg dose. Tirzepatide was undetectable in 164 of 171 milk samples, and the total amount found was less than 0.02% of the dose.¹ A 2024 study of milk from 8 women on semaglutide injections found no detectable drug, with a worst-case estimated infant dose of 1.26%.⁹

The Wegovy label says breastfeeding is not recommended with Wegovy tablets, because of an ingredient called SNAC that does pass into milk. For the injection, it says there are no data on milk levels or effects on the infant.³ Neither label has data on effects on the breastfed baby, so this is a decision to make with your doctor.

What isn't known yet

• How safe semaglutide and tirzepatide are in pregnancy when used for weight loss, in larger groups.
• Whether the rapid weight loss itself, or lower food intake, affects early pregnancy.
• How often contraception fails on these medicines in real life.

For related reading, see GLP-1 nausea and stomach side effects and what happens to weight after stopping, which matters for anyone pausing treatment before a pregnancy.