A new Danish study links paracetamol use during pregnancy to smaller reproductive organs in infants, and the researchers behind it call the finding concerning.
Researchers at the Department of Growth and Reproduction at Rigshospitalet followed 589 mothers who logged their medicine use during pregnancy. DR reports that the children were examined at three months of age, including ultrasound scans of ovaries and testicles.
On average, the boys had eight percent smaller testicles. The girls had 41 percent smaller ovaries, fewer eggs and a smaller uterus than children whose mothers did not take paracetamol.
Gylli Mola, a doctor and PhD student responsible for the part of the research concerning the boys, told DR the women had taken only one to two days of the recommended maximum dose during the entire pregnancy. She said it is notable that an association appears at such a small dose.
Consultant Casper Hagen, research leader on the study, said in a press release from Rigshospitalet that the exposure appears to disturb fetal development so fundamentally that it can be measured long after birth. He noted that most people, including doctors, consider the medicine harmless to the fetus within recommended doses.
Observational study, no proof of cause
The researchers stress that the work is an observational study. It cannot establish that paracetamol directly caused the differences, and the long-term meaning for individual fertility was not examined.
The results were published in the journal Human Reproduction Open on September 9, 2026. Reuters reported the study the same day, writing that the data point to possible changes in reproductive development without establishing causation. TV 2 also covered the findings on September 9, reporting that they do not change current guidance.
DR notes that the results are consistent with findings from several independent animal studies. Those studies indicate that paracetamol can affect the development of ovaries and testicles in the fetus. Paracetamol is the active ingredient in tablets sold in Denmark under names including Panodil, Pinex, Pamol and Pinemol.
Mola emphasized that paracetamol remains the recommended medicine for pain, including during pregnancy. Women with high fever or strong pain should still take it, she said, adding that the study should not be read as a scare campaign.
Most women in the study took paracetamol for headaches or mild muscle, joint or back pain. For those cases, Mola said the new knowledge allows pregnant women to make a more informed choice. She pointed to alternatives such as rest, a walk, water or massage.
CNN reported the international angle, including that doctors said pregnant women should not stop using acetaminophen when it is needed.
