The short answer: Nobody knows, and that is a reason to avoid it. Retatrutide is investigational and not FDA approved as of October 2026, so it has no label and no pregnancy guidance. No published study reports pregnancy outcomes after retatrutide exposure. The labels of related approved drugs say to stop them when pregnancy is recognized, and the same caution fits retatrutide until data exist.

What do we actually know about retatrutide and pregnancy?

Almost nothing, and no source can honestly say more. Retatrutide has no approved label, so it has no pregnancy section, no lactation section and no official stopping advice.

On September 29, 2026, Eli Lilly described retatrutide as "an investigational molecule that cannot be legally sold or marketed for human use." Lilly also said it plans to submit a Biologics License Application to the FDA in the first quarter of 2027. Formal pregnancy wording would come only after FDA review. Our post on when retatrutide could be approved covers that timeline.

The published trials do not fill the gap. The abstract of the phase 2 obesity trial reports weight, heart rate and stomach side effects in 338 adults. It reports no pregnancy outcomes. The TRIUMPH-2 phase 3 paper enrolled 1,152 adults with a mean age of 55.1 years, and its abstract reports no pregnancy outcomes either. Animal reproduction studies for retatrutide have not been published in a label, because there is no label.

What did the retatrutide trials require for pregnancy and contraception?

The clearest public statement is in the phase 2 record. The ClinicalTrials.gov entry for NCT04881760 says female participants "must not be pregnant, breast-feeding, or intend to become pregnant." It also excluded women of childbearing potential who were not using an adequate contraceptive method.

The phase 3 records say less. The public eligibility lists for TRIUMPH-1, TRIUMPH-2 and TRIUMPH-3 do not mention pregnancy, breastfeeding or contraception at all. That does not mean pregnant people could enrol. Registry entries are summaries, and the full protocols can hold more criteria than the public page shows.

The practical point is simple. The researchers who know retatrutide best kept pregnancy out of the phase 2 study. So the trial results tell us nothing about how the drug behaves in pregnancy.

Two approved drugs act on some of the same receptors. Tirzepatide (Zepbound, Mounjaro) acts on GIP and GLP-1. Semaglutide (Wegovy, Ozempic) acts on GLP-1. Retatrutide adds a third target, the glucagon receptor, which neither approved drug has. The label text below is comparator information and not retatrutide data.

  • Zepbound (tirzepatide): the label on DailyMed, revised August 2026, says "weight loss offers no benefit to a pregnant patient and may cause fetal harm." It says to stop the drug when a pregnancy is recognized. It also says human data are "insufficient" to judge the risk of birth defects or miscarriage. In rats, fetal growth reductions and fetal abnormalities occurred at clinical exposure.
  • Wegovy (semaglutide): the label on DailyMed, revised June 2026, says to stop Wegovy in pregnant patients who use it for weight reduction. Animal studies found embryofetal death, structural abnormalities and growth changes at clinically relevant exposures.

Both labels note that the animal findings came with marked weight loss in the mother. That matters for retatrutide. In TRIUMPH-2, the 12 mg dose produced a mean weight loss of 18.8% at 80 weeks, according to the Lancet abstract. Whether that degree of weight loss changes the risk in pregnancy has not been studied.

What do human studies of GLP-1 drugs in early pregnancy show?

The human data are for older GLP-1 drugs, and they are cautiously reassuring. They do not cover retatrutide.

  • A 2024 cohort study in JAMA Internal Medicine followed 938 infants exposed to GLP-1 receptor agonists around conception. All were born to women with type 2 diabetes. Compared with insulin, the adjusted relative risk of major birth defects was 0.95 (95% CI, 0.72 to 1.26).
  • A 2026 meta-analysis pooled six studies with 43,577 exposed women. The relative risk of major birth defects was 1.02 (95% CI, 0.96 to 1.08). The authors wrote that the findings "should not be interpreted as proof of safety."
  • A Danish nationwide cohort studied 529 pregnancies exposed to liraglutide or semaglutide. Preterm birth was more common only in women who took the drugs for diabetes. The authors suggest the diabetes, and not the drug, may explain it.

Three limits apply. These studies cover exposure near conception, not use through a whole pregnancy. They cover drugs that act on GLP-1 alone. And none included a drug that also activates the glucagon receptor. A 2025 review in the American Journal of Obstetrics and Gynecology concluded there is not enough evidence to predict harm or its absence. The review authors recommend contraception for all patients taking these drugs.

How long before trying to conceive should retatrutide be stopped?

No primary source states a washout period for retatrutide, so this article does not give one.

Here is what is known. In a phase 1b trial published in the Lancet, the half-life of retatrutide was about 6 days. A drug with a half-life that long stays in the body for weeks after the last dose.

For comparison only, the Wegovy label says to stop semaglutide at least 2 months before a planned pregnancy. It explains that semaglutide has a half-life of about 1 week and stays in the circulation for about 5 to 7 weeks after the last dose. It cannot be copied to a different molecule.

If you are in a retatrutide trial and want to conceive, tell the study team before you start trying. They hold the full protocol, which may set a stopping rule that the public record does not show. If you become pregnant during a trial, report it to the study team right away.

Does retatrutide affect birth control pills or breastfeeding?

Neither question has been answered for retatrutide. No published interaction study with oral contraceptives exists, and no lactation study exists.

The tirzepatide label gives a reason for care. It says Zepbound "may reduce the efficacy of oral hormonal contraceptives due to delayed gastric emptying." It advises a non-oral method, or an added barrier method, for 4 weeks after starting and for 4 weeks after each dose increase. Retatrutide also causes stomach side effects, as our side effects guide explains. Whether it changes how well the pill is absorbed has not been reported. Vomiting or severe diarrhea can lower pill absorption with any cause, so ask your clinician about a backup method.

Fertility can also change. The review above notes that many women who had irregular periods conceived without planning to after losing weight on GLP-1 drugs.

On breastfeeding, the Zepbound label describes a single-dose study in 11 women. Tirzepatide in breast milk was undetectable or low. No such study exists for retatrutide.

For a drug with approved pregnancy guidance, see the ozempic.md guide to pregnancy and trying to conceive.

Why do "research peptide" vials add risk in pregnancy?

Outside a trial, there is no legal supply of retatrutide. The FDA page on unapproved GLP-1 drugs, current as of October 1, 2026, says retatrutide "cannot be used in compounding under federal law." It says the ingredient has "not been found safe and effective for any condition."

The FDA also says it has warned companies that sold unapproved retatrutide falsely labeled "for research purposes" or "not for human consumption." It describes these products as "of unknown quality." In pregnancy, that adds a second unknown to the first: an untested drug, in a vial with untested contents. Our post on gray-market retatrutide has more detail.

The bottom line

Retatrutide has not been studied in pregnancy, and it has no approved label. The phase 2 trial excluded women who were pregnant, breastfeeding or planning a pregnancy. Related approved drugs carry label advice to stop when pregnancy is recognized, and their human data are limited. No source gives a stopping time for retatrutide before conception. If you are pregnant, planning a pregnancy or breastfeeding, talk to your obstetric clinician or study team before any dose.

Last updated: October 2026. This article is for informational purposes only and does not constitute medical advice. Retatrutide is an investigational drug. Talk to your clinician or study team about pregnancy, contraception and breastfeeding.