Pregnant women expecting boys should not take paracetamol for long periods.
Scientists in Edinburgh have said that it could increase the risks of reproductive disorders in their sons.
They said that long term use of the painkiller could affect the child's ability to produce testosterone.
"Our advice would be to firstly consider whether it is necessary to take paracetamol, and if it is felt to be necessary then only take it for the shortest possible time, in the lowest possible dose," said
Rod Mitchell from the centre for reproductive health.