Pregnancy and Breastfeeding: What the GLP-1 Labels Say, and Where They Admit They Don't Know

Answer first: the shared sentence and the shared gap

The weight-management labels in this group state the same thing in nearly identical words. Weight loss offers no benefit to a pregnant patient and may cause fetal harm. Each instructs that the drug be discontinued when a pregnancy is recognized.

That is a statement about the goal of the treatment, not only about the molecule. The purpose of a weight-management drug is weight reduction, and the labels say weight reduction is not a thing to pursue during pregnancy.

The shared gap is equally plain. Every one of these labels says that available human data are insufficient to evaluate a drug-related risk of major birth defects, miscarriage, or other adverse maternal or fetal outcomes. The risk statements rest on animal reproduction studies.

There is one exception to the discontinue-on-pregnancy pattern in this set, and it is narrow and specific. It is described further down, because it is easy to over-generalize and it applies to one indication on one label.

The animal data, and why it differs so much between molecules

The tirzepatide labels describe studies in rats and rabbits. In pregnant rats given the drug during organogenesis, the labels report increased incidences of external, visceral and skeletal malformations, developmental variations and decreased fetal weights. In rabbits, they report maternal mortality or abortion in a few animals and reduced fetal weights.

Both labels attach an important qualifier to those findings: the adverse embryo and fetal effects coincided with pharmacologically mediated reductions in maternal body weight and food consumption. That is the labels raising, in their own text, the question of whether the effect on the fetus follows from the drug or from the mother eating less.

The semaglutide labels report embryofetal mortality, structural abnormalities and alterations to growth in rats, and early pregnancy losses and structural abnormalities in rabbits and monkeys, at clinically relevant exposures. The Wegovy label adds the same qualifier, noting these findings coincided with marked maternal body weight loss in both animal species.

The orforglipron label is different again, and for a structural reason. Because orforglipron is not pharmacologically active in rats or rabbits, the usual rodent reproduction studies could not answer the question, and the label's primary animal data come from monkeys, where administration during organogenesis at doses lower than the maximum recommended human dose did not produce embryofetal effects.

That label is also candid about a limit in its own design. Higher doses could not be evaluated in monkeys because of dose-limiting effects on body weight, which means the study could not reach the exposures that would have made a negative result most informative.

A case study in why one animal result is not a conclusion

The orforglipron label reports two rabbit studies that point in opposite directions, and it prints both.

In a dose-range finding study, administration to pregnant rabbits during organogenesis at exposures fourteen times the clinical exposure produced external malformations and decreases in fetal and placental weights, in the absence of maternal toxicity.

In the definitive rabbit study, administration during organogenesis at exposures up to six times the clinical exposure did not produce embryofetal effects.

Those two results are compatible — a finding at fourteen times exposure and no finding at six times is a fairly ordinary dose picture — but the pairing shows something useful about how labels work. A dose-range finding study is a preliminary experiment, the definitive study is the designed one, and a reader who saw only the first would draw a much more alarming conclusion than one who saw both.

The phrase in the absence of maternal toxicity is also doing work, because it removes the explanation that the other labels lean on. Where the tirzepatide and semaglutide labels can point to maternal weight loss as a possible cause of fetal effects, this particular result cannot be explained that way.

None of this tells anyone anything about their own pregnancy. It is included because these are the actual contents of the section people are told to consult, and because the section is more equivocal than its summary usually is.

Which labels run a pregnancy registry, and which do not

Three of the five labels open section 8.1 with a pregnancy exposure registry. Two do not — they begin directly with the risk summary.

The Zepbound label describes a registry that monitors pregnancy outcomes in women exposed during pregnancy, and gives a phone number and an email address for enrollment along with a Lilly registry web address.

The Wegovy label describes its own registry and directs patients and providers to contact Novo Nordisk by phone or through a dedicated pregnancy registry website.

The Foundayo label states that there will be a pregnancy exposure registry, in the future tense, and directs contact to Eli Lilly by phone. That single word is worth reproducing accurately: the label promises a registry rather than describing one already enrolling.

The two diabetes labels, Mounjaro and Ozempic, carry no registry section at all. Their 8.1 begins with the risk summary. That is not an oversight in the reading — both labels carry full lactation sections and full pregnancy risk summaries, so the extractor was reading the same documents; the registry simply is not there.

The pattern tracks indication rather than manufacturer. The three weight-management labels have registries; the two labels indicated for type 2 diabetes do not. That makes sense: the drug is discontinued on recognized pregnancy for weight management, so exposures happen early and unintentionally, and a registry is how anyone learns what happened next.

The exception: one label that contemplates continuing

The Wegovy label carries an indication the others do not, for MASH with advanced liver fibrosis, and its pregnancy section handles that indication separately.

For weight reduction, the instruction is the familiar one: discontinue in pregnant patients who are using it for weight reduction.

For the liver indication, the label says something different. There may be risks to the mother and fetus related to underlying MASH with advanced liver fibrosis, and whether treatment during pregnancy reduces those risks is unknown. It states that the drug should be used during pregnancy for that indication only if the potential benefit justifies the potential risk to the fetus.

That is the standard benefit-risk formulation, and it appears here because the underlying disease itself carries risk. The label names some of those risks: gestational diabetes, hypertensive complications, preterm birth and postpartum hemorrhage.

This is the only place in the set where a GLP-1 label contemplates continuing during pregnancy, and it is tightly scoped to one indication on one product. It is not a general softening of the pregnancy position, and reading it as one would be a mistake.

Breastfeeding: three different answers

The lactation sections diverge more than any other part of these labels, and they diverge because the underlying evidence is genuinely different.

The tirzepatide labels are the only ones in this set with an actual human lactation study. Following a single dose given to eleven healthy lactating adults, the concentration of tirzepatide in breast milk was undetectable in 164 of 171 samples assayed, and the cumulative amount detected in the remaining seven samples over a twenty-eight day window was equivalent to less than 0.02% of the maternal dose. Both labels then give the standard weighing: the developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for the drug and any potential adverse effects on the infant.

The Ozempic label has no human data. It reports that semaglutide was present in the milk of lactating rats at levels three to twelve-fold lower than in maternal plasma, and adds a caution that is easy to skip past: due to species-specific differences in lactation physiology, the clinical relevance of these data is not clear. It then gives the same benefit-weighing statement.

The Foundayo label goes furthest. It reports no human data, states that orforglipron was present in the milk of lactating rats, and notes that when a drug is present in animal milk it is likely to be present in human milk. Its rat data run the other direction from Ozempic's: milk concentrations three-fold higher than in plasma. That label states plainly that the drug is not recommended for nursing women.

The breastfeeding statement that is not about the GLP-1 at all

The Wegovy label splits its lactation section by formulation, and the tablet half contains the most easily misread statement in this entire set.

For the tablet, the label reports that a clinical lactation study found semaglutide concentrations below the lower limit of quantification in human milk. That is a reassuring result about the active drug.

It then advises that breastfeeding is not recommended during treatment with the tablet. The reason is not semaglutide. It is SNAC, the absorption enhancer that makes an oral peptide work, which is present in human milk along with its metabolites.

The label's reasoning is specific. Enzymes involved in clearing SNAC may be less active in infants than in adults, so higher levels could occur in neonates and infants; and because alternative formulations of semaglutide exist that do not contain SNAC, the label advises against breastfeeding on the tablet rather than accepting an unknown.

The last clause is the interesting one, because it shows the recommendation resting on the availability of an alternative rather than on demonstrated harm. For the subcutaneous injection, the same label reports no human data on semaglutide in milk and gives the ordinary benefit-weighing statement instead of a recommendation against.

Anyone summarizing this as semaglutide being unsafe while breastfeeding has inverted the label. The active drug was below the limit of quantification; the caution attaches to an excipient in one specific formulation.

What to ask, and who to ask

Ask which molecule and which formulation you are being prescribed, generically. The pregnancy and lactation sections differ enough between tirzepatide, semaglutide and orforglipron — and between the injection and the tablet of the same molecule — that a program's brand name does not answer this question.

If you are or might become pregnant, raise it before starting rather than after. The weight-management labels instruct discontinuation when a pregnancy is recognized, which means this is a question that changes the plan rather than one that adjusts it.

If you are breastfeeding, ask specifically about the formulation. One label in this set advises against breastfeeding for the tablet and not for the injection of the same molecule, for a reason that lives in the excipient rather than the drug.

If a pregnancy happens during treatment, ask about the registry. Three of these labels run or promise one, and they publish contact details in section 8.1 precisely so that outcomes get recorded. That is how the human data everyone is currently missing eventually gets collected.

Then take the whole question to an obstetric clinician and a pharmacist rather than to a comparison site. Nothing on this page is specific to any individual, and pregnancy and lactation are the two areas where general information is least adequate.