Key facts
- A study found that infants exposed to Tylenol in utero had smaller ovaries, fewer ovarian follicles, smaller uteruses, and lower reproductive hormone levels on average.
- Early exposure to Tylenol before 17 weeks of pregnancy was associated with lower Anti-Müllerian hormone levels.
- Longer-term follow-up of girls from infancy to adolescence showed fetal Tylenol exposure linked to smaller uteruses at puberty and smaller ovaries during adolescence.
- Researchers emphasize the study does not prove Tylenol is to blame and does not indicate effects on future fertility.
- Current medical guidelines continue to recommend Tylenol as safe for pain and fever treatment during pregnancy.
- U.S. President Donald Trump's claim linking Tylenol use in pregnancy to autism has been widely dismissed by the medical community.
A study published in Human Reproduction Open suggests a potential link between maternal use of Tylenol (acetaminophen) during pregnancy and developmental differences in the reproductive organs of infant daughters. Researchers observed that infants exposed to Tylenol in utero had, on average, smaller ovaries, fewer ovarian follicles, smaller uteruses, and lower levels of reproductive hormones compared to those not exposed.
These differences were more pronounced in infants exposed earlier in pregnancy, before 17 weeks, who also showed lower levels of Anti-Müllerian hormone, an indicator of egg quality and quantity. A separate, larger group of girls followed from infancy to adolescence also showed associations between fetal Tylenol exposure and smaller uteruses at puberty and smaller ovaries during adolescence.
However, study leader Margit Bistrup Fischer emphasized that the findings do not prove Tylenol is to blame and do not indicate any effect on the girls’ future fertility. She advised women who used Tylenol during pregnancy not to be alarmed, noting that untreated fever or pain can also pose risks to mother and fetus. Current medical guidelines continue to recommend Tylenol as safe for use during pregnancy.
In an accompanying commentary, Dr. Christian De Geyter suggested that recommendations on Tylenol use during pregnancy should be reconsidered, noting the findings align with animal studies. The study also referenced U.S. President Donald Trump's claim linking Tylenol use in pregnancy to autism, a statement widely dismissed by the medical community for lacking scientific backing.