Trulicity (Dulaglutide) Pregnancy & Lactation Safety

What Is Dulaglutide and How Does It Work?

Dulaglutide is a long-acting glucagon-like peptide-1 (GLP-1) receptor agonist injected once weekly for type 2 diabetes. It binds the GLP-1 receptor on pancreatic beta cells, gut enteroendocrine cells, and neurons, producing glucose-dependent insulin secretion, suppressed glucagon release, and slowed gastric emptying. The result is lower postprandial glucose with a relatively low intrinsic hypoglycemia risk when used without a sulfonylurea or insulin.

Molecular Structure and Half-Life

Dulaglutide is a fusion protein consisting of two modified GLP-1 analogue peptide chains linked to a human IgG4 Fc fragment. The Fc linkage extends its half-life to roughly 4.7 days, allowing once-weekly dosing at either 0.75 mg or 1.5 mg (with higher doses of 3 mg and 4.5 mg approved in the U.S. Following the AWARD-11 data). Because the molecule is a large protein, it does not cross cell membranes freely, but GLP-1 receptors are expressed in placental tissue, which carries biological significance for fetal development.

Clinical Efficacy Context

The REWIND trial (N=9,901) published in The Lancet in 2019 showed dulaglutide 1.5 mg once weekly reduced the composite of major adverse cardiovascular events (MACE) by 12% versus placebo over a median 5.4 years in adults with type 2 diabetes (HR 0.88, 95% CI 0.79-0.99, P=0.026). [1] This cardiovascular benefit shaped prescribing patterns, making dulaglutide a common agent in women of reproductive age with T2D and comorbid cardiovascular risk.

FDA Labeling and Pregnancy Classification

The current FDA-approved prescribing information for dulaglutide lists pregnancy as a situation in which the drug should be used only if the potential benefit justifies the potential risk. In practice, given strong animal teratogenicity signals and zero human controlled-trial data, most guidelines and the manufacturer's own guidance advise against use throughout pregnancy. [2]

What the Label Actually Says

The prescribing information states: "Based on animal reproduction studies, there may be risks to the fetus from exposure to dulaglutide during pregnancy. Available data with Trulicity in pregnant women are insufficient to establish a drug-associated risk for major birth defects, miscarriage, or adverse maternal or fetal outcomes." [2] This language reflects the absence of data rather than demonstrated safety.

Pregnancy Exposure Registry

Eli Lilly maintains a pregnancy exposure registry for dulaglutide (1-800-545-6962). Clinicians should enroll any patient inadvertently exposed during pregnancy to contribute post-marketing safety data, which remain sparse.

Animal Reproductive Toxicology Data

Animal studies form the primary evidence base for dulaglutide's pregnancy risk classification. These findings are not simply regulatory formalities. They reflect mechanistic concerns about GLP-1 receptor activation during fetal organogenesis.

Embryo-Fetal Development Studies

In rats and rabbits given dulaglutide during the period of organogenesis, doses producing exposures approximately 11 times (rat) and 4 times (rabbit) the maximum recommended human dose of 1.5 mg weekly produced fetal growth restriction, reduced fetal body weight, and skeletal malformations including wavy ribs and skull bone malformations. [2] These effects occurred at doses that also produced maternal toxicity, but the skeletal changes are consistent with GLP-1 receptor-mediated interference with normal embryonic signaling.

Peri- and Postnatal Studies

When rats received dulaglutide from gestation day 6 through postnatal day 20, offspring showed reduced body weight during lactation and early postnatal life. Some effects persisted into adulthood in the rodent model. The biological plausibility rests on GLP-1 receptor expression in developing bone, kidney, and the central nervous system, tissues that depend on tightly regulated growth factor signaling.

Why Animal Data Matter Here

Rodent and rabbit reproductive toxicology data, while imperfect predictors of human outcome, are the only prospective controlled data available for dulaglutide in pregnancy. The FDA considers these data meaningful enough to support the contraindication language in the current label. Until a human prospective cohort produces reassuring data, the precautionary approach remains standard of care.

GLP-1 Receptor Expression in Placenta and Fetal Tissue

Understanding whether dulaglutide could reach or affect the fetus requires knowing where GLP-1 receptors are expressed during gestation. This is an area of active investigation.

Placental GLP-1 Receptor Biology

GLP-1 receptors are expressed in human placental tissue, specifically in syncytiotrophoblasts and cytotrophoblasts. [3] A study published in Endocrinology (2016) confirmed GLP-1 receptor mRNA in first-trimester human placenta, raising the question of whether exogenous GLP-1 agonists could alter trophoblast invasion or placental vascular development. At this point, no human study has quantified the effect of therapeutic dulaglutide concentrations on these placental functions.

Fetal Exposure via Placental Transfer

Dulaglutide is a large protein (approximately 59 kDa). Large proteins can cross the placenta via neonatal Fc receptor (FcRn)-mediated transport, the same mechanism that transfers maternal IgG to the fetus for passive immunity. Because dulaglutide contains an IgG4 Fc domain, FcRn-mediated transfer is biologically plausible. Animal studies have not definitively measured fetal drug concentrations, and no human pharmacokinetic data in pregnant women exist. This gap is clinically significant.

Human Pregnancy Data: What We Know (and Don't)

No randomized controlled trial has studied dulaglutide in pregnant women, and none is likely to be conducted given ethical constraints. The available human data are limited to case reports, spontaneous adverse event reports submitted to the FDA, and the pregnancy exposure registry.

Post-Marketing Case Reports

A small number of inadvertent first-trimester exposures have been reported through the FDA adverse event reporting system (FAERS) and in the published literature. These reports describe no consistent pattern of specific birth defects, but the case numbers are too small to draw conclusions. Spontaneous abortion and fetal growth restriction appear in some reports, but confounding by the underlying diabetes, obesity, and other exposures makes attribution impossible.

The Problem of Confounding in Diabetic Pregnancies

Women with type 2 diabetes face elevated baseline rates of congenital anomalies (approximately 2 to 3 times the general population rate), miscarriage, preeclampsia, and large-for-gestational-age infants independent of any medication. [4] Separating a drug signal from the disease signal requires large, well-characterized cohorts. No such dataset exists for dulaglutide. This does not mean the drug is safe. It means the data to evaluate safety do not exist.

Comparison With Other GLP-1 Agonists

Semaglutide (Ozempic, Wegovy) and liraglutide (Victoza) carry similar pregnancy warnings. Liraglutide data from the Novo Nordisk pregnancy registry (published in Diabetes Care, 2020) showed no unexpected pattern of anomalies in a small cohort (N=80 exposed pregnancies), but the sample lacked power to detect modest risk increases. [5] These data should not be extrapolated to dulaglutide given structural differences between agents.

Breastfeeding and Lactation Safety

Dulaglutide's lactation safety profile is, in a word, unknown. The prescribing information states that it is not known whether dulaglutide is present in human milk, and that the potential effects on the breastfed infant or on milk production have not been established. [2]

Pharmacokinetic Considerations in Breast Milk

As a large protein, dulaglutide would be expected to have limited excretion into breast milk compared with small-molecule drugs. If secreted, it would likely undergo proteolytic degradation in the infant's gastrointestinal tract before systemic absorption. This theoretical reasoning provides some reassurance, but it is not a substitute for measured pharmacokinetic data. The American Academy of Pediatrics and LactMed (NCBI's drug-lactation database) list dulaglutide as having insufficient data to recommend use during breastfeeding. [6]

Clinical Decision-Making During Lactation

Because uncontrolled postpartum hyperglycemia poses real risks to maternal health, and because many GLP-1 agonists are initiated postpartum in women with gestational diabetes transitioning to overt T2D, the clinical team must weigh theoretical infant risk against documented maternal benefit. Current consensus from the American Diabetes Association (ADA) 2024 Standards of Care recommends insulin as the preferred agent for both gestational diabetes and type 2 diabetes during breastfeeding, deferring GLP-1 agonist restart until the mother has weaned. [7]

Preconception Counseling and Washout Planning

Women of reproductive age on dulaglutide who are considering pregnancy need a structured preconception discussion well before discontinuation, not at the time of a positive pregnancy test.

When to Stop Dulaglutide Before Conception

Dulaglutide's half-life of approximately 4.7 days means that five half-lives (roughly 23-24 days) are needed to reach near-complete elimination. The prescribing information advises stopping dulaglutide at least 2 months before planned conception, which provides a generous buffer and time to stabilize glucose on an alternative regimen. [2] Some endocrinologists recommend a minimum of 4 weeks, but 8 weeks provides more margin given inter-individual pharmacokinetic variability.

Transitioning to Insulin Before Conception

The transition from dulaglutide to insulin before conception requires careful planning:

• Start insulin overlap. Begin basal insulin (NPH or insulin detemir, both with established pregnancy safety data) while still on dulaglutide to allow dose titration before discontinuing the GLP-1 agonist.
• Target preconception HbA1c. The ADA recommends an HbA1c <6.5% before conception in women with preexisting diabetes to reduce the risk of congenital anomalies. [7]
• Monitor weekly after switch. Glucose patterns shift substantially when GLP-1-mediated gastric slowing resolves, often requiring rapid insulin dose adjustments in the first 2-4 weeks post-discontinuation.
• Folic acid. Start 400-800 mcg of folic acid daily at least 3 months before conception. Women with diabetes and obesity may benefit from 5 mg daily per some national guidelines.

Unplanned Pregnancy While on Dulaglutide

Unplanned pregnancies do occur. If a patient presents with a positive test while still on dulaglutide, the drug should be stopped immediately and insulin initiated. The patient should be referred urgently to maternal-fetal medicine or a high-risk obstetrics team. First-trimester HbA1c measurement helps quantify the degree of glycemic exposure during organogenesis and informs counseling about anomaly risk. [4]

Safe Alternatives for Diabetes Management in Pregnancy

Insulin remains the reference standard for glycemic management throughout pregnancy. Several regimens have decades of human safety data.

Insulin Options With Established Pregnancy Data

• NPH insulin. The most extensively studied basal insulin in pregnancy. Data span more than 40 years. Once or twice daily dosing.
• Insulin detemir (Levemir). The INSIGHT trial (N=310, published in Diabetologia 2012) demonstrated non-inferior glycemic control versus NPH in pregnant women with type 1 diabetes, with lower rates of nocturnal hypoglycemia. [8]
• Insulin lispro and aspart. Both rapid-acting analogues have established pregnancy safety records and are preferred over regular human insulin for postprandial coverage because of their pharmacokinetic profile.
• Insulin glargine. Used off-label in pregnancy based on growing cohort data, though NPH and detemir retain guideline preference.

Metformin in Pregnancy

Metformin crosses the placenta and reaches fetal concentrations comparable to maternal concentrations. The MiG trial (N=751, NEJM 2008) showed metformin was non-inferior to insulin for gestational diabetes outcomes, but a follow-up study at 7-9 years found children exposed to metformin in utero had higher body fat percentage compared with insulin-exposed children. [9] Given these concerns, metformin is not preferred as monotherapy for preexisting T2D in pregnancy, though some guidelines accept its use as an adjunct to insulin.

Managing Cardiovascular Risk in Pregnant Women With T2D

The REWIND trial established that dulaglutide reduces MACE by 12% in T2D (HR 0.88, 95% CI 0.79-0.99) over a median 5.4 years. [1] Stopping dulaglutide before or during pregnancy removes this cardiovascular protection. For women with established atherosclerotic cardiovascular disease, the transition period requires attention to other risk factors.

Maintaining Cardiovascular Protection Without GLP-1 Agonists

Blood pressure control, statin therapy (noting that statins are typically held during pregnancy itself), and low-dose aspirin (recommended by ACOG for women at high risk of preeclampsia) become the primary tools. [10] The maternal-fetal medicine team should document cardiovascular status at the first prenatal visit and establish a postpartum plan to restart dulaglutide or an equivalent cardiovascular-protective GLP-1 agonist after weaning.

Postpartum Restart and Contraception Counseling

Postpartum glucose management is often overlooked. Women with T2D who deliver may face insulin resistance changes, breastfeeding effects on glucose, and the desire to restart effective weight-managing therapy.

When to Restart Dulaglutide Postpartum

Dulaglutide can be restarted once breastfeeding has completely ceased. There is no mandatory delay beyond cessation of nursing. Given the drug's 4.7-day half-life, steady state is reached in approximately 4-5 weeks after restart. During this period, insulin doses may need tapering as the GLP-1 effect reestablishes itself.

Contraception During and After Transition

Women restarting dulaglutide who do not wish to become pregnant again should discuss reliable contraception. GLP-1 agonists can alter gastric emptying in ways that may theoretically reduce oral contraceptive absorption, though pharmacokinetic studies with dulaglutide have not shown a clinically significant interaction with oral contraceptives. Intrauterine devices or implantable progesterone devices provide highly reliable contraception without this theoretical concern.