Comment from Anonymous

This 2026 review in The Journal of Physiology is attached because it addresses a key threshold issue for prenatal acetaminophen safety: maternal acetaminophen does not remain confined to the mother. The authors summarize evidence that acetaminophen readily crosses the placenta, that fetal circulating levels can closely mirror maternal levels, and that acetaminophen can cross fetal brain barriers and enter the developing brain. The review also summarizes animal and mechanistic studies showing potential neurodevelopmental effects, including oxidative stress, endocrine modulation, gene/protein changes, and behavioral changes, while acknowledging that human epidemiologic evidence remains mixed and causality has not been definitively established. In my view, this makes the study directly relevant to the petition because it supports biological plausibility and shows why pregnant women should receive clear warning language and informed-consent guidance to use acetaminophen only when truly necessary, at the lowest effective dose, for the shortest duration.