Women who take painkillers during pregnancy could be negatively affecting the future fertility of the unborn child and their descendants, according to UK researchers.
They said their laboratory findings added to a growing body of evidence that certain medicines, including paracetamol, should be used with caution during pregnancy.
“We would encourage women to think carefully before taking painkillers in pregnancy”
However, the researchers stressed that current advice for pregnant women remained unchanged, with paracetamol used, where necessary, at the lowest possible dose for the shortest possible time and that ibuprofen should be avoided.
The team, from the University of Edinburgh, looked at the effects of paracetamol and ibuprofen on samples of human foetal testes and ovaries.
They found similar effects using several different experimental approaches, including lab tests on human tissue samples and animal studies.
In addition, human tissues exposed to either drug for one week in a dish had reduced numbers of cells that give rise to sperm and eggs, called germ cells.
Ovaries exposed to paracetamol for one week had more than 40% fewer egg-producing cells. After ibuprofen exposure, the number of cells was almost halved.
The study also indicated that painkiller exposure during development could have effects on unborn boys too. They found testicular tissue exposed to painkillers in a culture dish had around a quarter fewer sperm-producing cells after exposure to paracetamol or ibuprofen.
Lastly, the team tested the effects of painkiller treatment on mice that carried grafts of human foetal testicular tissue. After one day of treatment with a human-equivalent dose of paracetamol, the number of sperm-producing cells in the graft tissue had dropped by 17% and by around 30% after a week.
Dr Rod Mitchell, who led the research at the University of Edinburgh, said: “We would encourage women to think carefully before taking painkillers in pregnancy and to follow existing guidelines – taking the lowest possible dose for the shortest time possible.”
The study, published in Environmental Health Perspectives, was funded by the Medical Research Council, Wellcome and the British Society of Paediatric Endocrinology and Diabetes.