Fetal exposure to paracetamol is associated with altered markers of ovarian development and reduced uterine volume in girls: the COPANA study.

study questionIs fetal exposure to paracetamol associated with markers of ovarian function in infancy? SUMMARY ANSWER: Mild to moderate doses of prenatal paracetamol exposure, assessed by detailed maternal reports and urinary measurements, are associated with ovarian morphology and activity as well as reduced size of estrogen-responsive tissues in infant girls. WHAT IS KNOWN ALREADY: Maternal use of paracetamol is widespread. Across multiple independent animal studies, fetal exposure consistently impairs the formation of primordial ovarian follicles, causing subfertility and premature estropause in female offspring. STUDY DESIGN SIZE DURATION: The Copenhagen Analgesic study (COPANA) is a single-center, prospective, observational cohort study conducted at a university hospital (March 2020 to November 2022). From 3425 eligible participants, 685 healthy singleton pregnant women of Caucasian origin, were enrolled in the first trimester of pregnancy, and 302 infant daughters were examined at follow-up. Exclusion criteria included maternal diabetes or thyroid disease, pre- or post-term delivery, or severe infant illness. PARTICIPANTS/MATERIALS SETTING

methodsPregnant women reported paracetamol use biweekly and provided first-trimester urinary samples which were analyzed for paracetamol levels (LC-MS/MS) and adjusted for urinary osmolarity (n = 299). Girls were classified by timing of initial exposure: early fetal life (<17 weeks, n = 92), mid-late fetal life (≥17 weeks, n = 67), or unexposed controls (n = 143). Of the 92 girls initially exposed in early fetal life, a subgroup was exposed exclusively in early fetal life (n = 22).In an independent confirmatory cohort, 1210 girls were followed from infancy to adolescence. Their exposure was maternal self-reported (any) use of paracetamol during pregnancy and reported early in the third trimester (yes/no). MAIN RESULTS AND ROLE OF CHANCE: Early fetal exposure was associated with reduced ovarian volume (-0.11 cm LIMITATIONS REASON FOR CAUTION: The observational design of the study allows evaluation of exposure outcome associations, while the causality interpretation is supported by consistency with experimental models demonstrating comparable effects. Residual confounding by indication for paracetamol use cannot be completely excluded, although the results were robust after accounting for fever and other maternal factors. The analytic design of the current study limited our ability to evaluate whether frequency or patterns of paracetamol use influenced the observed associations. WIDER IMPLICATIONS OF THE

findingsIn this prospective cohort study of infant girls, prenatal exposure to paracetamol was associated with differences in several markers of ovarian development, including ovarian volume, follicle number, and circulating AMH, as well as uterine volume and breast tissue diameter. The associations with reduced ovarian and uterine size were also observed in a confirmatory cohort followed to adolescence. Whether these early-life differences have long-term clinical relevance, including effects on reproductive lifespan, remains uncertain and requires analyses in studies with extended follow-up.

fundingThis research was supported by Rigshospitalets Research Council under grant (E-22717-21), Læge Sofus Carl Emil Friis og hustru Doris Friis'Legat (F-23936-01), Aase og Ejnar Danielsens Foundation (20-10-0367), Helsefonden (20-B-0388), Axel Muusfeldt Foundation (2020-0385), and The Danish Centre for Endocrine Disrupting Substances (CeHoS) (2022-23219). The funders had no role in considering the study design or in the collection, analysis, interpretation of data, writing of the report, or decision to submit the article for publication. The publication was completed as part of the MERLON project under grant agreement No. 101137411. The MERLON project is funded by the European Union. Views and opinions expressed are, however, those of the authors only and do not necessarily reflect those of the European Union or the European Health and Digital Executive Agency (HADEA). Neither the European Union nor HADEA can be held responsible for them. DISCLOSURES: All authors declare no support from any organization for the submitted work, no financial relationships with any organizations that might have an interest in the submitted work in the previous 3 years, and no other relationships or activities that could appear to have influenced the submitted work. One author (MA) is a government official. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov ID: NCT0436922.