GLP-1 Safety in Pregnancy

Taking a GLP-1 medication like Wegovy or Ozempic has become very in vogue and I have been working with a lot of non-pregnant women in clinic in my role as a Nutritionist who have starting taking them for both type 2 diabetes control and weight loss. So I thought it pertinent to look into its safety in the preconception period, pregnancy and breastfeeding.

A literature search only bought up 5 studies related to this topic due the relatively new use of this medication and it was all from 2023-2025. As you can imagine, the ethical boundaries of any research conducted in pregnancy also restricts the methods of research conducted.

Here is a summary of the research, for those like me that prefer the evidenced based answers (yes I am a girly swot who loves a bit of researching to find answers!):

1) Cesta et al., 2024 — “Safety of GLP-1 receptor agonists and other second-line antidiabetics in early pregnancy”

Design / scope: Large, international observational cohort (InPreSS-type analysis) including pregnancies in people with pregestational type 2 diabetes from multiple countries (overall dataset >50,000 pregnancies).
Main findings: Periconceptional exposure to GLP-1 RAs and other non-insulin, second-line antidiabetics was not associated with a higher risk of major congenital malformations (MCMs) compared with insulin in this cohort. The authors describe increasing periconceptional use of these agents.
Limitations noted: observational design → potential confounding by indication and incomplete capture of early pregnancy losses; limited data on outcomes other than major malformations (e.g., fetal growth, neonatal complications, long-term metabolic outcomes).
Implication: Provides important, large-scale human data that are somewhat reassuring for major structural malformations, but does not prove safety across all pregnancy outcomes. PubMed

2) Dao et al., 2024 — multicenter observational study of GLP-1 RA exposure in early pregnancy

Design / scope: Multicentre prospective/observational cohort comparing outcomes of women exposed to GLP-1 RAs in early pregnancy vs comparators (insulin/other). (Paper is available open access.)
Main findings: No clear signal for increased rates of major congenital anomalies after early exposure in the cohorts analysed; authors report small numbers of exposed pregnancies for some agents and emphasise need for more data.
Limitations noted: limited numbers for some drug-agent/time windows, potential reporting bias, and inability to robustly evaluate less common outcomes or long-term child effects. Implication: Adds additional observational human data consistent with the larger cohort — reassuring for major malformations but not definitive for overall safety. PubMed Central

3) Muller et al., 2023 — Systematic review: “Effects of GLP-1 agonists and SGLT2 inhibitors during pregnancy and lactation on offspring outcomes”

Design / scope: Systematic review of available human and animal data for offspring outcomes after exposure to GLP-1 RAs and SGLT2 inhibitors during pregnancy/lactation.
Main findings: Human data are very limited (case reports, small series, and a few observational studies). Animal toxicology studies have reported fetal growth restriction, delayed skeletal ossification and other developmental signals at exposures comparable to human therapeutic levels for some agents. Human case reports/series do not provide enough evidence to rule out effects on fetal growth, pregnancy loss, or neonatal outcomes.
Limitations noted: heterogeneity of sources; much of the evidence for risk comes from animal studies and case reports rather than high-quality prospective human trials.
Implication: Biological plausibility and animal safety signals justify continued caution; more human data needed before declaring safety. PubMed Central+1

4) Harris, Emily — JAMA piece (2024) “First large study of GLP-1 receptor agonists during pregnancy”

Type: JAMA news/summary highlighting the new large cohort results (and placing them in clinical context).
Main points: Reports the large multinational cohort and notes that results are “reassuring” with respect to major birth defects when compared to insulin; emphasises limits of observational data and the need for further research on other outcomes.
Implication: A concise, peer-reviewed news synopsis — useful context but not new primary data. JAMA Network

5) Khan, Grobman, Kazi — JAMA Cardiology viewpoint (2025) “Periconceptional GLP-1 RA use and discontinuation”

Type: Expert viewpoint / commentary.
Main points: Discusses timing of discontinuation before conception, gaps in evidence about how long to stop GLP-1 RAs prior to conception, and practical counselling (contraception while on therapy, individualized discontinuation timing). Calls for data-driven guidance on washout intervals and monitoring.
Implication: Professional opinion supporting precaution (use contraception while on treatment; stop before trying to conceive) and need for prospective research. PubMed+1

BTW: yes, unashamedly, I did put all of the articles from my traditional research review into chatgpt to summarise - voila its amazing!

So what is this in plain speak saying?

Are GLP-1 medications safe in pregnancy?

No. At this stage, GLP-1 medicines are not recommended during pregnancy.

Here’s why:

• Human studies are still limited. A few recent large studies show no increase in major birth defects, but they do not tell us enough about miscarriage, fetal growth, or long-term baby development.

• Animal studies show effects on fetal growth and development.

• Because of this uncertainty, medical and regulatory bodies recommend stopping GLP-1 medications before trying to conceive.

If you become pregnant while taking a GLP-1 medication:

• Stop the medication.

• Contact your GP, midwife, or obstetrician to discuss next steps.

• You may be referred for additional monitoring (e.g., ultrasound).

 Trying to get pregnant?

• Use reliable contraception while taking GLP-1 medication.

• Most GLP-1 medications should be stopped at least 2 months before trying to conceive, depending on the specific drug.

• Talk with your doctor or nutritionist about a safe plan for weight, metabolic health, and fertility.

Are GLP-1 medications safe while breastfeeding?

We do not currently know.

• There is almost no high-quality human research on how GLP-1 medications affect breast milk or babies.

• Animal studies show that the drug can pass into milk and affect growth.

• Because of this, health organisations advise avoiding GLP-1 medications while breastfeeding.

If you are breastfeeding and considering restarting:

• Speak with your GP or specialist.

• Safer alternatives are available depending on your goal (weight, blood sugar, appetite, etc.).

 Why stopping is important

Even though early research is encouraging, we do not yet have enough information to guarantee safety during pregnancy or breastfeeding. Protecting your baby’s early development is the priority

FOR MIDWIVES: Download a patient information sheet https://www.victoriakate.co.nz/s/GLP-1-in-pregnancy.pdf