What Did the Study Find?
A new study published in the journal Human Reproduction Open found that some girls born to mothers who took acetaminophen (also known as paracetamol or Tylenol) during pregnancy developed changes in their reproductive organs. Specifically, compared to girls whose mothers didn't take the medication, these girls had on average 40% smaller ovarian volume, 13% smaller uterine volume, and 23% fewer ovarian follicles — the structures containing immature eggs — at 3 months of age. They also showed lower levels of a hormone linked to ovarian reserve.
Does This Mean the Drug Caused the Problem?
Dr. Margit Bistrup Fischer, co-author of the study and a postdoctoral researcher in the Department of Growth and Reproduction at Rigshospitalet in Copenhagen, Denmark, emphasized that the research does not prove acetaminophen caused these reproductive changes, and women should not be "alarmed" by the findings. "But it's definitely something we need as a society to talk about and inform pregnant women more about, so they can make an informed decision," she noted.
Is Acetaminophen Still Safe During Pregnancy?
Acetaminophen has long been known as the safest over-the-counter option to treat fever or pain during pregnancy, although doctors advise using it in moderation and only when necessary. An untreated fever can endanger both mother and fetus, potentially leading to birth defects or miscarriage. The American College of Obstetricians and Gynecologists (ACOG) stated that the findings "do not indicate that current clinical recommendations should change," and acetaminophen remains one of the only safe medications that can be used during pregnancy when indicated. Patients should consult their obstetric care professional before making any changes to medication use.
Background and Controversy
Last year, former President Donald Trump controversially told pregnant women to "tough it out" and avoid acetaminophen, blaming the medicine and certain vaccines for autism without evidence. The FDA also initiated a label change suggesting potential neurological risks, despite decades of evidence to the contrary. This new study focused specifically on girls' reproductive organs and did not examine any links to autism.
Expert Advice: Weigh Benefits and Consider Alternatives
Dr. Fischer noted that many women in the study took acetaminophen for headaches and musculoskeletal pain, and women should weigh alternatives before reaching for an over-the-counter pill. Heat therapy, for example, may help with certain types of back pain. Dr. Christian De Geyter, a retired senior scientist at the University of Basel who studies fertility and reproductive toxicology, wrote in an accompanying commentary that the "eminent importance" of the findings "cannot be stressed enough!" He advised: "It is still safe, to some extent; take it if you need it, but consider alternatives when possible."
Future Research Needed
Researchers emphasize that much more study is needed to determine whether the medication itself or other factors caused the reproductive organ changes. The current study only captured a snapshot in time and did not follow the girls long-term to determine future fertility. ACOG also noted that the "clinical significance of these findings is uncertain or unknown."
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