Study Finds Prenatal Acetaminophen Linked to Smaller Reproductive Organs in Girls
Research involving Danish mother-child pairs observed reduced ovarian and uterine size in girls whose mothers used acetaminophen during pregnancy, though experts say the findings do not warrant changes to current medical guidance.
A Danish study published in Human Reproduction Open reported that girls whose mothers took acetaminophen in the first trimester had, on average, 40% smaller ovarian volume, 13% smaller uterine volume and 23% fewer ovarian follicles compared with peers whose mothers did not use the drug. The researchers measured drug exposure through maternal urine samples and self-reported use, and they evaluated 302 girls at three months of age.
The study’s co-author, Dr. Margit Bistrup Fischer of Rigshospitalet, emphasized that the results do not establish a causal relationship and should not prompt pregnant women to stop using acetaminophen when needed. “Women shouldn’t be alarmed by the findings because the research does not establish cause and effect,” she said, adding that the medication remains the safest over-the-counter option for fever or pain during pregnancy when used responsibly.
The American College of Obstetricians and Gynecologists (ACOG) issued a statement affirming that current clinical recommendations remain unchanged, noting that the clinical significance of the observed differences is uncertain and that long-term fertility outcomes were not assessed.
Commentary from other experts highlighted the study’s exploratory nature. Dr. Gavin Stewart of Newcastle University warned that the small sample size and multiple comparisons could produce false-positive results, and Dr. Hugh Taylor of Yale School of Medicine cautioned that underlying conditions prompting acetaminophen use, such as fever or infection, might also influence fetal development.
While the findings suggest a possible association between prenatal acetaminophen exposure and reduced reproductive organ size, researchers stress that further large-scale, longitudinal studies are needed before any revisions to treatment guidelines are considered.