Taking ibuprofen in the first three months of pregnancy could cause harm to the future fertility of the unborn child, a new study has shown.
The drug, which is used to treat pain and inflammation, was found to cause a reduction in germ cells, which eventually develop into eggs.
About 30% of women are thought to use ibuprofen in the first 24 weeks of pregnancy.
Doctors recommend that the painkiller not be taken after that time as it is known to increase the risk of foetal abnormalities.
However, at the moment there are no real guidelines on whether or not it is safe for women to use it in the early weeks, The Journal reports.
"We found there were fewer cells growing and dividing, more cells dying and a dramatic loss of germ cell numbers, regardless of the gestational age of the foetus," said Dr Severine Mazaud-Guittot, a researcher at Inserm in France.