Tejal Somvanshi
A new study links prenatal acetaminophen to reproductive changes in girls, with researchers finding 40% smaller ovarian volume, 13% smaller uterine volume, and 23% fewer ovarian follicles among girls exposed in the womb. The research, published in Human Reproduction Open, enrolled 685 women in Denmark during the first trimester and evaluated 302 girls at 3 months old.
Dr. Margit Bistrup Fischer, co-author and postdoctoral researcher at Copenhagen’s Rigshospitalet, said the findings should drive future research but should not yet change clinical practice. “It’s definitely something we need as a society to talk about and inform pregnant women more about, so they can make an informed decision,” she told CNN.
The study also analyzed data from 1,210 girls in the Copenhagen Mother-Child Cohort followed from infancy to adolescence, confirming smaller ovaries during adolescence and smaller uteruses at puberty. Girls are born with all the eggs they will ever have, so fewer eggs may mean harder conception and earlier menopause.
ACOG issued a statement saying the findings “do not indicate that current clinical recommendations should change.” Acetaminophen remains one of the only safe medications for pregnancy pain and fever. An untreated fever can endanger both mother and fetus.
But not all experts agreed the take-home message was caution. Dr. Christian De Geyter, a retired senior scientist at the University of Basel, wrote in an accompanying commentary that recommendations about acetaminophen use “should be reversed.” He told CNN: “There are many, many things that can be avoided, rather than just always taking medicine.”
Dr. Hugh Taylor at Yale School of Medicine warned the study cannot answer whether the drug itself or the reason for taking it caused the changes. “What are the other things they took the Tylenol for? Did they have a fever during pregnancy? Was an infection at play,” Taylor asked. “Tylenol is the safest drug we have when it’s needed.”
Dr. Gavin Stewart at Newcastle University flagged the small sample size and multiple measurements as raising false positive risk. “When you hunt really hard for a pattern, you inevitably find one,” he said.
The study comes amid heightened scrutiny of acetaminophen safety. Last September, President Trump urged pregnant women to avoid the drug over an unproven autism link, and the FDA initiated a label change suggesting fetal neurological risk despite decades of evidence to the contrary.
