Full Breakdown
Prenatal Paracetamol Exposure Linked to Smaller Reproductive Organs in Infants
9/9/2026, 9:24:34 AM
Study Findings
A prospective observational study in Denmark found that infants whose mothers used paracetamol during pregnancy had reduced ovarian and uterine size, fewer ovarian follicles, and lower reproductive-hormone levels at three months. The same group later reported smaller uterine volume at puberty and smaller ovaries during adolescence in a separate cohort of girls.
Study Design & Cohorts
The Copenhagen Analgesic Study (COPANA) enrolled 685 pregnant women in their first trimester (March 2020 – November 2022). Participants reported medication use every two weeks and provided urine samples for paracetamol quantification. Of the 302 daughters examined at three months, 92 had first exposure before 17 weeks gestation, 67 after 17 weeks, and 143 had no reported exposure. A second cohort comprised 1,210 girls from the Copenhagen Mother-Child Cohort, whose mothers reported any paracetamol use in the third trimester.
Key Measurements
- Exposed girls had, on average, 40 % smaller ovarian volume, 13 % smaller uterine volume, and 23 % fewer ovarian follicles than unexposed peers.
- Early-gestation exposure was associated with lower anti-Müllerian hormone levels, a marker of egg quantity and quality.
- In the adolescent cohort, fetal exposure correlated with reduced uterine size at puberty and smaller ovaries during teenage years.
These findings are reported in *Human Reproduction Open*.
Expert Commentary
Study leader Margit Bistrup Fischer of Rigshospitalet emphasized that the observations are population-level associations and do not predict outcomes for any individual child. She noted that current guidelines continue to endorse paracetamol as the first-line medication for pain and fever when medically indicated.
Professor Christian De Geyter of the University Hospital of Basel said the results align with animal research and suggested the precautionary principle should guide use, especially in the first trimester.
Cautionary Perspectives
Statistical expert Brian Lee of the University of Pennsylvania warned that the association could arise from chance or residual confounding, stating, “I would not jump to the conclusion that the statistical association observed is a causal association.”
Fischer added, “We cannot say anything about the reproductive consequences for these girls.”
Gaps & Need for Long-Term Follow-Up
Because the study is observational, it cannot establish a direct cause-and-effect relationship between prenatal paracetamol exposure and later fertility or age at menopause. Longitudinal monitoring into adulthood is required to determine whether early-life differences translate into clinically meaningful outcomes.
Verbatim Quotes
- “We still recommend that pregnant women should use paracetamol with high fever or strong pain,” — Margit Bistrup Fischer, Rigshospitalet
- “We cannot say anything about the reproductive consequences for these girls,” — Fischer
- “I would not jump to the conclusion that the statistical association observed is a causal association,” — Brian Lee
What’s Next
Researchers plan to continue tracking the COPANA cohort through adolescence and into the menopausal years to assess any lasting reproductive impact. Professional societies are expected to review guidance on paracetamol use in pregnancy in light of the emerging evidence.
