A new study from Copenhagen Analgesic (COPANA) found that young girls exposed to Tylenol’s active ingredient in utero had abnormal organ development.
The study, which assessed 685 pregnant women in Denmark during their first trimester, went on to analyze 302 healthy three-month-old girls. The study found that the infants’ exposure to the ingredient paracetamol was linked to smaller ovaries, fewer ovarian follicles, differences in reproductive hormone levels, and smaller uterine size.
“Maternal urinary paracetamol concentrations were inversely associated with ovarian and uterine volume as well as breast tissue diameter,” the study read. “In the independent confirmatory cohort, fetal paracetamol exposure was associated with reduced uterine volume at puberty and smaller ovarian volume during 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,” researchers concluded.
Researchers also explained that their findings reflect the “first human study specifically designed to investigate whether prenatal paracetamol exposure is associated with markers of ovarian development in daughters. While this study cannot prove that paracetamol directly caused these differences, the findings are consistent with results from animal studies.” They again emphasized that more research is “needed to determine whether these early-life differences have consequences for reproductive health later in life and to inform recommendations on paracetamol use during pregnancy.”
Paracetamol is known as acetaminophen in the United States and has come under scrutiny for its associations with autism development in children.
Standing alongside Health and Human Services Secretary Robert F. Kennedy Jr. last year, President Trump said, “Tylenol taken during pregnancy can be associated with a very increased risk of autism.” He called the development part of “historic steps to confront the crisis of autism” and urged women to limit use unless absolutely necessary.
Following the announcement, the FDA began the process of changing the labeling for Tylenol to reflect the risk of developing neurological conditions. The agency sent letters to physicians nationwide to inform them of the accumulation of evidence “suggesting that the use of acetaminophen by pregnant women may be associated with an increased risk of neurological conditions such as autism and ADHD in children.”
