Study links prenatal Tylenol use to smaller ovaries and uteri in newborn girls
Researchers found that daughters of mothers who took Tylenol during pregnancy had reduced ovarian and uterine size at three months old, though the study does not prove causation or predict future fertility.
In a new investigation, 302 three-month-old girls were assessed after their mothers' acetaminophen (Tylenol) intake was monitored throughout pregnancy via urine samples. Infants whose mothers used the drug, especially before 17 weeks, displayed about 40% smaller ovarian volume, 13% smaller uterine volume and 23% fewer ovarian follicles, along with lower anti-Müllerian hormone levels. The mothers’ consumption stayed within the 4,000 mg daily limit and was typically for headache or musculoskeletal pain.
A separate follow-up of over a thousand girls linked prenatal exposure to smaller reproductive organs at puberty and adolescence. Researchers caution that the study does not establish causality, nor does it forecast fertility or menopause timing, and they note that many exposed girls had measurements similar to unexposed ones. Current medical guidelines continue to deem Tylenol safe for pain and fever in pregnancy, emphasizing that untreated fever or severe pain also pose risks.
Why it matters
The findings could influence guidance on pain-relief medication use during pregnancy and prompt further long-term research.
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