Danish Study Links Prenatal Paracetamol Exposure to Smaller Reproductive Organs in Female Infants
A new study published in Human Reproduction Open suggests that prenatal exposure to paracetamol may be associated with smaller ovaries and uteruses in female infants, though researchers emphasize the findings do not prove causation or immediate fertility impacts.
Researchers from a Danish study have suggested that maternal use of Tylenol or generic paracetamol during pregnancy may impact the development of female reproductive organs in daughters. The study, led by Margit Bistrup Fischer of Rigshospitalet in Copenhagen and published in Human Reproduction Open, analyzed data from three-month-old girls to examine potential associations between drug exposure and organ size.
The primary study group consisted of 302 three-month-old girls whose mothers' drug use was tracked via questionnaires and urine samples. Among these infants, 92 were first exposed to the medication before 17 weeks of pregnancy, 67 were exposed after 17 weeks, and 143 were born to mothers who did not use the drug. The results indicated that infants exposed to paracetamol in utero had, on average, 40-per-cent smaller ovarian volume, 13-per-cent smaller uterine volume, and 23-per-cent fewer ovarian follicles compared to unexposed infants. Additionally, babies exposed early in pregnancy (before 17 weeks) had lower average levels of Anti-Müllerian hormone, an indicator of egg reserve quality and quantity.
To assess longer-term trends, researchers examined a separate longitudinal group of 1,210 girls. This cohort showed similar associations between fetal paracetamol exposure and smaller uteruses at puberty as well as smaller ovaries during adolescence.
Despite these statistical links, the study's authors caution against drawing definitive conclusions. Margit Bistrup Fischer stated that the findings do not prove the pain medicine is to blame and do not indicate any effect on future fertility. Current medical guidelines continue to recommend paracetamol or acetaminophen as safe for treating pain and fever during pregnancy, with a recommended daily maximum dose of 4,000 milligrams.
Dr. Christian De Geyter, a reproductive medicine specialist at the University Hospital of Basel in Switzerland, commented that the findings align with animal research data. He suggested that recommendations on use during pregnancy should be reconsidered based on this alignment. However, Kenvue, which owns the Tylenol brand, issued a statement noting that the study has methodology limitations and does not support a causal relationship. Following the report, Kenvue shares dropped more than 3 per cent.