Led by Bernard Jegou, the study was performed by researchers from the University of Copenhagen, together with the Rennes University Hospital and the Laboratory for the Study of Residues and Contaminants in Food (Laberca). Results from the study, “Ibuprofen results in alterations of human fetal testis development”, were published in Scientific Reports, and was supported by the French National Agency of Medicine and Health Products Safety (ANSM).
The experiments included xenografting, a process by which cells or organ fragments (tissue) from a living organism are transferred onto other species in order to understand their development. In the study's case, they used laboratory-cultured testes tissue to graft onto mice. Data collected from the first trimester of fetal development showed a sharp drop in testosterone production by the Leydig cells when ibuprofen was administered to the grafted mice. Ibuprofen also affected the production of antimüllerian hormone by the Sertoli cells, which plays an important role in genital tract masculinization. Ibuprofen apparently reduced expression of the genes needed for germ cells, the progenitors of spermatozoa. Also notable is that the production of prostaglandin E2 was inhibited by the drug. Results also showed that reduced production of hormones and gene suppression are dose-dependent, and are associated. Side effects of ibuprofen in the first trimester were not present during the second trimester of fetal development.
The research found that there is a window of sensitivity in the first trimester of fetal development where ibuprofen presents a risk for genital and reproductive system development. Prior studies only showed the significant risk of paracetamol and aspirin in the endocrine system of the fetus, resulting in cryptorchidism, or the failure of the testes to descend. The recent study found that the drug suppresses the production of various hormones including testosterone, which controls the primary and secondary sex characteristics and descent of the testes. While ibuprofen does not directly affect the fetus in the second trimester, it does not give leave for pregnant women to take the drug during that period. Of all the drugs tested during the experimentation stage, ibuprofen contributed to the most damage on the endocrine system.
Researchers found that three out of 10 pregnant women self-medicate with ibuprofen, or any other analgesic. Many studies have already shown the adverse effects of analgesics and other non-steroidal anti-inflammatory drugs (NSAIDs) on the fetus, including low birth weight, asthma, and premature birth. While these NSAIDs are known to be effective medications, most people including pregnant women self-medicate to relieve migraines, pain, fever, and inflammatory conditions. Drugs such as paracetamol (acetaminophen), aspirin, and ibuprofen can cross the placenta, and can also be found in meconium (prenatal infant stool), neonatal urine, and breast milk. While analgesics can easily be bought without a prescription, these drugs have teratogenic potential.
Pregnant women should take more precaution due to the fact that they are carrying another individual. Whatever harms the mother harms the baby as well.