The 30-second summary
- The largest review yet. A meta-analysis in Med, published on 29 September 2026, pooled 2,118,215 pregnancies. 8,325 were exposed to a GLP-1 medicine in the six months before a positive pregnancy test.
- No clearly detectable increase in miscarriage, stillbirth, congenital anomalies, preterm birth, gestational diabetes, high blood pressure in pregnancy or abnormal growth.
- A French study the same day of 19,092 pregnancies in women with type 2 diabetes found no overall rise in major birth defects, but could not rule out a small rise in heart defects.
- The advice has not changed. GLP-1 medicines are not for use in pregnancy, and the stopping window before a planned pregnancy still applies.
Why this question keeps coming up
More women of childbearing age take semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound) every year. Many pregnancies are unplanned, and weight loss can make a pregnancy more likely, as our piece on GLP-1s and fertility explains. So a growing number of women find out they are pregnant after weeks on a medicine their label says to avoid.
Until now the answer to "is my baby at risk?" rested on small studies. This review pulled them together.
What did the Med meta-analysis find?
The team, led by Professor Asma Khalil at City St George's, University of London, with colleagues in Italy, Sweden and Norway, searched for observational studies that compared pregnancies exposed and unexposed to a GLP-1 receptor agonist within six months before a positive pregnancy test.
Ten studies met the bar. Between them they held 2,118,215 women: 8,325 exposed and 2,109,890 unexposed.
| Outcome | What the pooled data showed |
|---|---|
| Miscarriage or stillbirth | No clearly detectable increase |
| Congenital anomalies | No clearly detectable increase |
| Preterm birth | No clearly detectable increase |
| Gestational diabetes | No clearly detectable increase |
| High blood pressure in pregnancy | No clearly detectable increase |
| Baby too small or too large | No clearly detectable difference |
| Pre-eclampsia | Slightly lower odds (OR 0.87), from only two datasets |
The results looked the same whether women were taking the medicine for diabetes or for weight. The authors' conclusion is careful: the evidence "did not identify a clearly detectable increase" in harm, and it does not establish safety.
Speaking to The Pharmaceutical Journal, Professor Khalil said that women who find they took one of these medicines before knowing they were pregnant "should not panic" and should speak to their healthcare team.
What did the French study add?
On the same day, Diabetologia published a nationwide study from the French National Health Data System. It followed 19,092 pregnancies between 2011 and 2024 in women aged 18 to 50 with type 2 diabetes treated with medication (Collier et al.).
Compared with insulin alone, first-trimester exposure to newer diabetes medicines, GLP-1s included, was not linked to more major birth defects overall. But when the researchers used stricter definitions of exposure, they saw a possible small increase in heart defects with GLP-1 medicines and with sulfonylureas. Their words: teratogenicity "cannot be excluded".
Two honest readings sit side by side. The big picture is reassuring. A small risk to the baby's heart has not been ruled out.
What these studies cannot tell us
2.1 million is not the number that matters. Only 8,325 pregnancies were exposed, and each outcome drew on fewer. Dr Marie Spreckley of the University of Cambridge, commenting through the Science Media Centre, pointed out that the miscarriage analysis rested on two datasets with 1,138 people in total, and its result was compatible with both lower and higher odds.
The studies looked at past prescribing. Professor Tricia Tan of Imperial College London noted that women now often use higher doses for weight loss than were common in the studies pooled.
Observational data cannot prove safety. Women who took a GLP-1 differ from those who did not in weight, diabetes and care. The researchers adjusted for this, but cannot remove it. The French study had no BMI or HbA1c values at all.
Individual drugs were not separated. We cannot yet say whether semaglutide, tirzepatide and liraglutide differ.
Does this change the advice if you take a GLP-1?
No. As of October 2026, UK guidance from the MHRA says GLP-1 medicines should not be taken in pregnancy, while trying to conceive or while breastfeeding. Before a planned pregnancy it asks for at least two months off semaglutide and at least one month off tirzepatide. Liraglutide clears faster and can be stopped just before trying. Our longer guide to GLP-1s and pregnancy covers the reasoning.
What the review changes is how to feel about an exposure that has already happened. If you find out you are pregnant while on a GLP-1:
- Contact your GP, midwife or prescriber straight away. UK guidance says to stop the medicine as soon as possible, and they will plan that with you.
- Do not assume the worst. The best data available found no clear increase in harm.
- Say which medicine, which dose and the date of your last dose. That shapes the advice and helps future research.
If you are taking tirzepatide with the pill, there is a separate issue with how well oral contraception works, set out in GLP-1s and birth control.
What to do with this
When a GLP-1 stops, appetite tends to come back, sometimes at the same time as early pregnancy nausea. Regular small meals with some protein and fibre at each, and enough fluid, are a sensible base. Your midwife can tailor it to you.
Sources
- D'Antonio F, Flacco ME, Manzoli L, Samara A, Khalil A. GLP-1 receptor agonist exposure in the periconceptional period and adverse obstetric outcomes: A systematic review and meta-analysis. Med 2026. PubMed
- Collier M, Chouchana L, Kaguelidou F, Treluyer JM, Bérard A. Safety of glucagon-like peptide-1 receptor agonists and other new-generation glucose-lowering agents for the management of type 2 diabetes in pregnancy: a French nationwide population-based study. Diabetologia 2026. PubMed
- Medicines and Healthcare products Regulatory Agency. GLP-1 medicines for weight loss and diabetes: what you need to know. GOV.UK, updated February 2026. GOV.UK