Researchers in Denmark have observed notable patterns in girls whose mothers used paracetamol during pregnancy. Findings indicate changes in several markers related to ovarian development that persist from infancy to adolescence.
Paracetamol (commonly known as Tylenol) is widely used by pregnant women. Despite its prevalence, the study does not confirm causation but complements a body of evidence from animal studies indicating potential long-term impacts on female reproductive health. Dr. Margit Bistrup Fischer from Rigshospitalet highlights that these observations demand a more nuanced view of paracetamol usage during pregnancy.
The study, published in Human Reproduction Open, tracked 302 girls, assessing reproductive development indicators during infancy. Detailed questionnaires and urine samples documented the maternal usage of paracetamol. Results showed that daughters exposed to the drug in utero exhibited smaller ovaries and differences in ovarian activity compared to unexposed peers. Early exposure linked to reduced ovarian and uterine volumes, while late exposure affected the number of ovarian follicles.
Moreover, lower levels of anti-Müllerian hormone (AMH)—a marker often associated with ovarian reserve in adults—were detected in some girls exposed early in pregnancy. However, the long-term significance of these infancy-stage differences remains uncertain.
Further analysis involved an independent group of 1,210 girls, confirming similar outcomes. Prenatal paracetamol exposure correlated with diminished uterine volume at puberty and reduced ovarian volume during adolescence.
The widespread use of paracetamol in pregnancy—utilized by more than half of pregnant women—paired with past rodent studies indicating diminished ovarian follicles and reduced reproductive lifespan, raises concerns. The translation of these findings to human fertility outcomes remains an open question.
Dr. Lucy Hooper, unaffiliated with the study, noted measurement limitations and emphasized maintaining current medical guidance: using paracetamol at the lowest effective dose for the shortest feasible duration. She highlighted that many women in the study relied on paracetamol for conditions where alternative treatments might suffice.
While Fischer acknowledges no immediate changes to medical guidelines are necessary, the study advocates for careful consideration of when paracetamol is employed during pregnancy.
“Ultimately, the decision should be based on an individual’s symptoms and made in consultation with a healthcare professional,” Fischer noted.