Girls born to mothers who took paracetamol during pregnancy had smaller ovaries, fewer ovarian follicles, smaller uteruses and lower reproductive hormone levels at three months old, according to a new Danish study — though the researchers stress the findings are observational, do not establish that paracetamol caused the changes, and should not change current clinical guidance on its own.
A study published on 8 September 2026 in Human Reproduction Open, one of the field’s leading journals, has found that infant girls whose mothers took paracetamol (acetaminophen) during pregnancy showed measurable differences in reproductive organ development at three months of age, compared with girls whose mothers did not. Led by Dr Margit Bistrup Fischer, the Danish research team examined 685 mother-daughter pairs, with a second, larger group of 1,210 girls used to test whether the pattern held up independently. Daughters of paracetamol-exposed pregnancies had smaller ovaries, fewer ovarian follicles — the structures in which immature eggs are stored — smaller uteruses, and lower levels of reproductive hormones than daughters of mothers who had not taken the drug.
What the study does and does not show
The researchers and outside commentators were notably careful about the limits of what an observational study of this kind can establish. Dr Fischer emphasised that women “should not be alarmed” by the findings, since the study does not demonstrate that paracetamol caused the observed differences — an association is not proof of causation, and pregnant women who took paracetamol may differ from those who did not in other ways that independently affect infant development. The mothers in the study took relatively low doses; none exceeded the standard recommended daily maximum of 4,000 milligrams, and most used the drug for common complaints such as headaches or musculoskeletal pain rather than for treating serious illness or high fever. Current clinical guidance in Europe and the UK continues to recommend paracetamol as the first-choice medication for pain and fever in pregnancy specifically because untreated severe pain or high fever can themselves pose risks to both mother and foetus — a trade-off the study’s authors explicitly acknowledge rather than dismiss.
What lends the finding weight, however, is that it is not an isolated result. In an accompanying commentary in the same journal, Professor Christian De Geyter of the University Hospital of Basel — who was not involved in the study — wrote that the findings “fits well with the already-published animal research data” and that the specific pattern of a dose-response relationship, where larger or longer paracetamol exposure corresponded to larger effects, is “a common principle in toxicology” that strengthens the case for a genuine biological effect rather than mere statistical noise. De Geyter called for follow-up research extending into the daughters’ adulthood and up to menopause, to establish whether the organ and hormone differences observed at three months old persist and translate into any measurable effect on fertility later in life — a question this study, by its nature, cannot yet answer.
Part of a wider, unsettled evidence picture
This finding adds to an already active and somewhat contested body of research on prenatal paracetamol exposure. Separate epidemiological work has looked at possible links between prenatal paracetamol and outcomes including cryptorchidism (undescended testes) in boys and neurodevelopmental conditions such as autism spectrum disorder, with results across that broader literature described by researchers as genuinely mixed — some studies find associations, several others do not, and a large systematic review and meta-analysis published in January 2026 specifically on neurodevelopmental outcomes found the evidence base still inconclusive enough to warrant further synthesis rather than a policy change. The reproductive-organ findings reported this week are a new and more specific data point within that same broader, unresolved research area, rather than a first or final word on paracetamol’s safety in pregnancy.
Why it matters
Paracetamol is the most widely used over-the-counter analgesic in pregnancy worldwide, used by a majority of pregnant women in most countries where it has been studied, precisely because it has long been considered one of the safer options relative to alternatives such as NSAIDs, which carry their own well-established pregnancy risks. A credible, dose-responsive signal affecting reproductive organ development — even one that stops well short of proving causation — is the kind of finding that warrants serious attention from obstetricians and regulators without justifying alarm or a sudden change in individual clinical practice. For India, where paracetamol is similarly the default analgesic recommended in pregnancy and where India’s own maternal and reproductive health research infrastructure is expanding, this is a genuine candidate for longer-term Indian cohort research rather than an immediate cause for guidance changes — precisely the kind of measured, “watch and study further” framing the study’s own authors and commentator are urging.
– Rithvisha Kiran
Key facts
– Danish study, 685 mother-daughter pairs (validated against a further 1,210 girls), published in Human Reproduction Open, 8 September 2026
– Daughters of paracetamol-exposed pregnancies had smaller ovaries, fewer ovarian follicles, smaller uteruses and lower reproductive hormone levels at 3 months old
– Findings were dose-responsive; none of the mothers exceeded the recommended maximum daily dose (4,000mg)
– Study is observational — does not establish causation; current European/UK guidance continues to recommend paracetamol as first-choice pain/fever relief in pregnancy
– Accompanying commentary by Prof. Christian De Geyter (University Hospital of Basel) calls the dose-response pattern consistent with prior animal research and urges long-term follow-up into adulthood
