In August 2025, a research project published in Human Reproduction attracted media attention by showing that paracetamol may impair the development of the fertilized egg in the very first days after conception. Paracetamol is the active compound in commonly used headache medication like Panodil and Pinex.
The study showed that paracetamol inhibit cell division in the fertilized egg with a negative impact on its viability and the potential to establish and sustain a pregnancy. The research was based on a variety of human cell types, donated human tissue from fertility treatments and mice.
“Our results suggest that women trying to conceive may benefit from being cautious with their use of paracetamol,” said first author Morten Rønn Petersen, Laboratory Director at the Fertility Clinic, Rigshospitalet, in a press release.
From laboratory findings to clinical evidence
Building on these findings, a follow-up study funded by the Independent Research Fund Denmark (DFF) will, for the first time, examine whether paracetamol exposure is associated with fertility treatment outcomes in 300 women from the ReproUnion Biobank & Infertility Cohort (RUBIC).
“With the RUBIC cohort, we now have a unique opportunity to investigate whether paracetamol exposure is associated with fertility outcomes in a clinical context. This is the natural next step after the laboratory studies have shown how paracetamol can impair early embryo development,” says Marie Louise Grøndahl, Laboratory Director at the Fertility Clinic, Herlev-Gentofte Hospital.
RUBIC’s unique contribution
The collaborative DFF study will benefit from the RUBIC Cohort by making use of samples and data that have been collected from more than 1000 Danish women before and during their fertility treatment.
“Based upon paracetamol concentrations in the blood sample, we will categorize the 300 women in levels of exposure in the treatment period. Our overall aim is to investigate whether paracetamol exposure during IVF treatment influences key outcomes such as the rate of good quality embryos, live birth rate, and miscarriage rate per embryo transfer,” explains Marie Louise Grøndahl. Secondary endpoints will include cumulative (per egg retrieval) live birth rate and follicular development.
Implications for reproductive health
Between 10-40% of all pregnancies are lost in the very earliest stages, when the fertilized egg is dividing. Genetic errors account for roughly half of these early losses, but the other causes remain largely unexplained.
If the laboratory-based findings are confirmed in the DFF study, it could have important implications for clinical counselling of women undergoing fertility treatment. At the same time, it may help raise awareness that even widely used over-the-counter medicines may have unintended consequences for reproductive health.
The study is led by David Møbjerg Boslev Kristensen, Professor, Rigshospitalet, Roskilde University and based on a DKK 3.165.254 DFF grant from 2024.
