Peptides, GLP-1s and Pregnancy or Breastfeeding: What the Labels and the Data Say

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This page sets out what the approved labels say, word for word in substance, and what has been measured since. It is not advice, and it cannot be: pregnancy decisions depend on why someone is taking a drug, what the alternative is, and their own history. If you are pregnant, trying to conceive, or breastfeeding and taking any of these compounds, the conversation to have is with the clinician who prescribed it or your maternity team, and sooner rather than later.

Two things are worth knowing before the detail. First, "peptide" tells you nothing about pregnancy safety. Insulin is a peptide and is the mainstay of treating diabetes in pregnancy; oxytocin is a peptide given during labour. The question is always about the specific molecule, not the category. Second, the labels are revised, so the date on the version matters. Every section quoted below carries the effective date of the label it came from.

What the labels say about pregnancy

The three widely used GLP-1 and dual-agonist labels agree on the central instruction and differ in their framing.

Semaglutide (Wegovy label effective June 18, 2026): the label states that weight loss offers no benefit to a pregnant patient and may cause fetal harm, that the drug should be discontinued when a pregnancy is recognised, and that available pharmacovigilance and trial data are insufficient to establish a drug-associated risk of major birth defects, miscarriage or adverse maternal or fetal outcomes. The animal findings are stated plainly: in pregnant rats given semaglutide during organogenesis, embryofetal mortality, structural abnormalities and growth alterations occurred at maternal exposures below the maximum recommended human dose; early pregnancy losses and structural abnormalities were seen in rabbits and monkeys.¹ The current label adds a second case: where Wegovy is being used for MASH with advanced liver fibrosis rather than for weight reduction, it says the drug should be used in pregnancy only if the potential benefit justifies the potential risk, and that whether treating during pregnancy reduces the risks of the underlying liver disease is unknown.¹

Tirzepatide for weight management (Zepbound label effective August 28, 2026): the same core instruction — weight loss is not recommended during pregnancy, discontinue when a pregnancy is recognised — with available data in pregnant patients described as insufficient, and fetal growth reductions and abnormalities reported in rats and rabbits at clinically relevant exposures.²

Tirzepatide for type 2 diabetes (Mounjaro label effective August 27, 2026) frames it differently, because the alternative is different. It says the drug should be used in pregnancy only if the potential benefit justifies the potential risk, and it puts the comparison in numbers: the estimated background risk of major birth defects is 6 to 10% in women with pre-gestational diabetes and an HbA1c above 7%, and has been reported as high as 20 to 25% with an HbA1c above 10%.³ Poorly controlled diabetes is itself a risk to a pregnancy, which is why the weight-loss and diabetes labels read differently.

Both manufacturers run pregnancy exposure registries that monitor outcomes in women exposed during pregnancy, and both labels encourage patients and clinicians to enrol.^{1 2}

The stop-before-conception line, and where it does and does not appear

This is the detail most often garbled, so it is worth quoting carefully.

Semaglutide's weight-management label, in section 8.3, instructs that because of the potential for fetal harm the drug should be discontinued in patients at least two months before they plan to become pregnant, to account for its long half-life.¹ That is a specific, written instruction with a stated reason.

Tirzepatide's weight-management label does not carry an equivalent pre-pregnancy interval in section 8.3. What it carries instead is the contraception instruction below.² The absence of a stated washout is not permission to conceive on the drug — the same label says to stop when a pregnancy is recognised and that weight loss may cause fetal harm — but it does mean anyone repeating "stop two months before" as a general rule for this class is applying semaglutide's label to a drug whose label does not say it. Planning a pregnancy is a conversation with a prescriber, not an interval to copy from an article.

The instruction most people never hear

Tirzepatide delays gastric emptying, and that can reduce the absorption, and therefore the effectiveness, of oral hormonal contraceptives. Both tirzepatide labels say so and give a specific instruction: switch to a non-oral contraceptive method, or add a barrier method, for four weeks after starting the drug and for four weeks after every dose escalation. The delay is largest after the first dose and lessens over time, and contraceptives that are not taken by mouth are not affected.^{2 3}

Dose escalation is the part that gets missed. The four-week window reopens with each step up, which on a standard titration means several separate windows over the first months of treatment.

This matters beyond contraception. The same delayed gastric emptying affects other oral medicines, and the labels advise caution with drugs that depend on threshold concentrations or have a narrow therapeutic index. Our interaction checker covers that ground in more detail.

Breastfeeding: what has been measured, drug by drug

Here the labels differ in substance, not just wording, because different things have been measured.

Tirzepatide: a single-dose clinical lactation study gave 5 mg to 11 healthy lactating adults and found the concentration in breast milk either undetectable or low compared with the maternal dose. The label is explicit about what that does not establish: there are no data on the effects on the breastfed infant or on milk production.²

Semaglutide — and here the formulation changes the answer. The current Wegovy label covers both an injection and an oral tablet, and says different things about them. For the tablets, a clinical lactation study found semaglutide itself below the limit of quantification in human milk, but the absorption enhancer SNAC and its metabolites are present in human milk; because the enzymes that clear SNAC may be less active in infants than adults, and because semaglutide formulations without SNAC exist, the label advises that breastfeeding is not recommended during treatment with Wegovy tablets. For the subcutaneous injection, there are no data on the presence of semaglutide in human milk, on effects on the breastfed infant, or on milk production; semaglutide was present in the milk of lactating rats.¹

That distinction is new enough to be worth flagging. An older version of this label, still being served by some data feeds, said only that there were no human milk data — with no tablet section at all. A reader checking a summary written against the earlier text would miss a specific instruction about a specific formulation.

Liraglutide: the same position as semaglutide — no human milk data, present in the milk of lactating rats.⁴

All three labels then say the same thing, which is the actual guidance: the developmental and health benefits of breastfeeding should be weighed against the mother's clinical need for the drug and any potential adverse effects on the infant or from the underlying condition. That is a judgement for a clinician who knows the case, and it is deliberately not a yes or a no.

What the studies have found so far

Label language describes what is known at the time of writing. Several cohort studies and reviews have reported since, and the picture they give is consistent and limited in the same way.

A 2024 cohort study of second-line diabetes drugs in early pregnancy compared infants exposed to GLP-1 receptor agonists with those exposed to insulin and found an adjusted relative risk for major congenital malformations of 0.95 (95% CI 0.72 to 1.26). The authors concluded their results did not indicate a large increased risk above that conferred by maternal type 2 diabetes requiring second-line treatment, while noting some estimates were imprecise.⁵

A 2026 study of unintentional periconceptional exposure reported adjusted risks against insulin of 0.64 for malformations, 2.05 for stillbirth, 1.09 for preterm birth and 0.86 for small-for-gestational-age infants, all with confidence intervals crossing one, and concluded that periconceptional exposure was not associated with increased risks — while stating that intentional use in a planned pregnancy is not advised.⁶

A 2026 systematic review and meta-analysis found no statistically significant association with major congenital malformations, stillbirth, spontaneous abortion, small-for-gestational-age or preterm birth, with one signal for urinary malformations (OR 1.24, 95% CI 1.05 to 1.47) based exclusively on unadjusted data.⁷ A second 2026 systematic review covering preconception, pregnancy and lactation concluded that preconceptional or early-pregnancy exposure is not consistently associated with increased risk, while noting that data on continued use through gestation remain limited.⁸

A 2025 review in an obstetrics journal states the position most directly: there is not enough evidence to predict adverse effects or their absence from periconceptional exposure, and its authors recommend contraception to prevent unintended pregnancy while taking these drugs.⁹

Read together, these are reassuring about accidental early exposure and silent about deliberate use. Nobody has studied taking a GLP-1 drug through a pregnancy on purpose, and the labels tell you not to.

Research peptides: there is nothing to report

Everything above exists because these are approved drugs. An approved drug has a label, and a label has sections 8.1, 8.2 and 8.3 that a regulator required somebody to write and support. A research peptide has none of that.

For BPC-157, TB-500, CJC-1295, ipamorelin, GHK-Cu, epitalon, MOTS-c and the rest, there is no pregnancy section, no lactation study, no exposure registry and no cohort. The honest statement is not that they are risky in pregnancy and not that they are safe: it is that the question has never been asked. Our entries for each compound record what human evidence exists at all, and for most of these it is thin enough that pregnancy was never going to be studied.

Two features of this group deserve naming rather than implying. Many of these compounds are growth factors or act on growth-factor pathways, and pregnancy is the one state in which the body's own growth signalling is doing something very specific — which is a reason for caution by mechanism, not a finding. And the products themselves are unregulated: independent testing has collapsed, purity certificates frequently do not cover sterility, and what is in a vial is not established by its label. Our verification guide covers that.

If you are pregnant or breastfeeding and have been taking a research peptide, that is worth telling your clinician plainly, including the compound name and dose, even though there is no literature for them to consult. What they can act on is the exposure, not the evidence.

Peptides that are used in pregnancy

It is worth closing the loop on the category confusion, because it cuts both ways.

Insulin is a peptide hormone, and insulin is the standard treatment for diabetes in pregnancy — the comparator the GLP-1 cohort studies above measured against. Oxytocin is a peptide and is given during labour. Several other approved peptide medicines are used in pregnant patients where the indication requires it.

So the word peptide carries no information about pregnancy safety in either direction. What carries information is whether a specific molecule has been studied in pregnancy, what the label says, and what the alternative to taking it is. For the compounds sold as research peptides, all three of those are blank.

Frequently asked questions

Can you take semaglutide while breastfeeding?

The label distinguishes the formulations. It advises that breastfeeding is not recommended during treatment with Wegovy tablets, because the absorption enhancer SNAC is present in human milk and may accumulate in infants, and because semaglutide formulations without it exist. For the subcutaneous injection there are no human milk data at all, and the decision is framed as weighing the benefits of breastfeeding against the mother's clinical need.

Can you take tirzepatide while breastfeeding?

The label does not say yes or no. It reports a single-dose study in 11 lactating women in which tirzepatide in breast milk was undetectable or low compared with the maternal dose, and states there are no data on effects on the breastfed infant or on milk production. The decision is explicitly framed as weighing the benefits of breastfeeding against the mother's clinical need, which is a conversation with a clinician.

How long before pregnancy should you stop semaglutide?

Its weight-management label says to discontinue at least two months before planning to become pregnant, because of the drug's long half-life. That instruction is specific to that label; tirzepatide's weight-management label does not carry an equivalent interval.

Do GLP-1 drugs affect birth control?

Tirzepatide can. Because it delays gastric emptying it may reduce the effectiveness of oral hormonal contraceptives, and the label instructs switching to a non-oral method or adding a barrier method for four weeks after starting and for four weeks after each dose increase. Non-oral hormonal contraceptives are not affected.

What happens if you get pregnant while taking one?

Both labels say to discontinue when a pregnancy is recognised, and to tell your clinician. Cohort studies of accidental early exposure have not found increased risks of major malformations, stillbirth or preterm birth compared with insulin, though estimates are imprecise and no study covers deliberate use through a pregnancy.

Are research peptides like BPC-157 safe in pregnancy?

There is no evidence either way. No research peptide has a pregnancy section, a lactation study or an exposure registry, because none is an approved drug. That is an absence of information, not a safety finding.

Is it safe because peptides are natural?

The category means nothing here. Insulin and oxytocin are peptides used in pregnancy and labour; semaglutide is a peptide whose label says weight loss may cause fetal harm. What matters is the specific molecule and what has been studied.

Related on Grey Peptides

• Peptides and women's health: approved, studied, thin evidence
• Semaglutide
• Tirzepatide
• Interaction checker
• Peptide encyclopedia

Sources

1. Wegovy (semaglutide) prescribing information, sections 8.1 Pregnancy, 8.2 Lactation and 8.3 Females and Males of Reproductive Potential (DailyMed SPL version 19, effective June 18, 2026; read October 1, 2026). FDA
2. Zepbound (tirzepatide) prescribing information, sections 7.2, 8.1, 8.2 and 8.3. (DailyMed SPL version 40, effective August 28, 2026; read October 1, 2026). FDA
3. Mounjaro (tirzepatide) prescribing information, sections 8.1, 8.2 and 8.3 (DailyMed SPL version 40, effective August 27, 2026; read October 1, 2026). FDA
4. Saxenda (liraglutide) prescribing information, section 8.2 Lactation. (DailyMed SPL version 22, effective February 25, 2026; read October 1, 2026). FDA
5. Cesta, C. E. et al. (2024). Safety of GLP-1 Receptor Agonists and Other Second-Line Antidiabetics in Early Pregnancy. JAMA Internal Medicine, 184(2), 144-152. PMID: 38079178
6. Chou, Y. C. et al. (2026). Unintentional periconceptional exposure to glucagon-like peptide-1 receptor agonists and adverse pregnancy outcomes. Diabetes, Obesity and Metabolism, 28(2), 1420-1430. PMID: 41346258
7. Uysal, N. et al. (2026). Pregnancy outcomes following maternal GLP-1 receptor agonist exposure: a systematic review and meta-analysis. Scientific Reports. PMID: 42420519
8. Ozbek, L. et al. (2026). Safety of GLP-1 and Dual GLP-1/GIP Receptor Agonists in Preconception, Pregnancy, and Lactation: A Systematic Review. Diabetes, Obesity and Metabolism, 28(6), 4503-4528. PMID: 41885132
9. Drummond, R. F. et al. (2025). Glucagon-like peptide-1 receptor agonist use in pregnancy: a review. American Journal of Obstetrics and Gynecology, 232(1), 17-25. PMID: 39181497

This article reports what approved labels and published studies say, as of October 1, 2026. It is not medical advice and it is not a substitute for your own clinician. If you are pregnant, trying to conceive or breastfeeding and taking any compound discussed here, speak to your prescriber or maternity team.