Could GLP-1 Weight Loss Drugs Affect Fertility in Women Without PCOS? What Animal Studies Suggest | Research

The takeaway

GLP-1 receptor agonists show contradictory effects on female reproduction in animal studies — both stimulating and suppressing ovarian and uterine function — raising important unanswered questions about fertility in the millions of non-PCOS women using these drugs for weight loss.

Contradictory effects
Native GLP-1 in the brain stimulated ovarian function and reproductive hormones, but GLP-1 agonist drugs (Exendin-4, liraglutide) produced opposite inhibitory effects — and virtually no human data exist in non-PCOS women

What the researchers found

Animal studies revealed contradictory GLP-1 effects on female reproduction:

Stimulatory effects (intracerebroventricular GLP-1):

• Increased luteinizing hormone surge amplitude

• Increased FSH secretion

• Elevated serum progesterone

• Up-regulated Kiss-1r expression in hypothalamus

• Increased ovarian Graafian follicles and corpora lutea

Inhibitory effects (GLP-1 RA drugs):

• Intracerebroventricular Exendin-4 and subcutaneous liraglutide produced opposite effects to native GLP-1

• GLP-1 suppressed FSH-induced progesterone synthesis in granulosa cells despite up-regulating FSH receptor expression

Uterine effects (controversial):

• Some studies: beneficial antifibrotic effect, reducing collagen deposition in intrauterine adhesion models

• Other studies: destruction of luminal epithelium and shrinkage of muscle fibers

Why it matters

This is potentially one of the most important unanswered safety questions about GLP-1 drugs. Millions of reproductive-aged women without PCOS are using these medications for weight loss, but virtually all reproductive research has focused on women with PCOS. The contradictory animal data — where native GLP-1 stimulates reproduction but GLP-1 agonist drugs suppress it — is concerning and demands human studies before we can reassure women about fertility safety.

How the study worked

Narrative review critically analyzing published data on GLP-1 receptor agonists in non-PCOS females, covering both human and animal studies. The review focuses on effects on the hypothalamic-pituitary-ovarian (HPO) axis and uterine function.

What this study cannot tell us

Most evidence is from animal models with different species, doses, routes, and GLP-1 agonists, making comparison difficult. Human data in non-PCOS women are essentially absent. The review acknowledges that animal findings are contentious and may not translate to humans. Intracerebroventricular drug delivery in animals doesn't replicate subcutaneous injection in humans. The specific GLP-1 drugs and doses causing different effects are not fully reconciled.

How to read the evidence

This is a narrative review of predominantly animal studies with acknowledged contradictory findings. Human data in the target population (non-PCOS women) are essentially absent. The evidence is preliminary and insufficient to draw safety conclusions, which is precisely the review's point — more research is urgently needed.

When this study was published

Published in 2025, this review addresses one of the most timely safety questions about GLP-1 drugs as their use expands dramatically among young women for weight management.

The bigger picture

The 'Ozempic baby' phenomenon — unexpected pregnancies in women on GLP-1 drugs — has been widely reported anecdotally, while simultaneously animal data suggest possible reproductive suppression. This contradiction mirrors the broader confusion in the literature: native GLP-1 and GLP-1 agonist drugs can have different effects, and brain vs peripheral routes produce opposite outcomes. Resolving this is urgent as GLP-1 prescriptions in young women continue to surge.

Questions still open

Do GLP-1 drugs at standard clinical doses affect ovulatory function or fertility in women with normal reproductive systems?
Why do native GLP-1 and synthetic GLP-1 agonists produce opposite reproductive effects in animal models?
Should women trying to conceive discontinue GLP-1 therapy, and if so, how far in advance?

Common questions

Can GLP-1 drugs like Ozempic affect fertility?

The honest answer is: we don't know yet for women without PCOS. Animal studies show confusing, contradictory results — GLP-1 can both stimulate and suppress reproductive function depending on the specific drug, dose, and how it's given. For women with PCOS, GLP-1 drugs appear to improve fertility. But for the millions of women without PCOS using these drugs for weight loss, there's almost no human data on reproductive effects. If you're planning pregnancy, discuss timing of GLP-1 therapy with your doctor.

What about 'Ozempic babies' — unexpected pregnancies on GLP-1 drugs?

Anecdotal reports of unexpected pregnancies in women on GLP-1 drugs have been widely discussed, though not rigorously studied. This could be explained by improved ovulation from weight loss rather than a direct drug effect on fertility. However, the contradictory animal data mean we can't rule out direct reproductive effects. The review emphasizes that studying this relationship is urgent given how many reproductive-aged women are now taking these medications.

Read the original research

Impact of dramatic weight loss with the new injectable medications on reproduction in healthy non-polycystic ovary syndrome obese women.

F&S reports, 6(1), 4-9

View on PubMed ↗Publisher’s paper ↗

Citation

Merhi, Zaher. (2025). Impact of dramatic weight loss with the new injectable medications on reproduction in healthy non-polycystic ovary syndrome obese women.. F&S reports, 6(1), 4-9. https://doi.org/10.1016/j.xfre.2024.12.003