Concerning new research suggests taking paracetamol during pregnancy could reduce testosterone production in unborn baby boys.

Paracetamol is commonly used for reducing pain and fever during pregnancy, but this new research suggests it could have some previously-unknown effects on the baby, the University of Edinburgh reported. The study's researchers recommend expecting mothers should follow current guidelines and only take the drug at the lowest does possible.

"This study adds to existing evidence that prolonged use of paracetamol in pregnancy may increase the risk of reproductive disorders in male babies," said Rod Mitchell, Wellcome Trust Intermediate Clinical Research Fellow, University of Edinburgh.

A reduced exposure to testosterone in the womb has been linked to serious conditions such as infertility, undescended testicles, and even testicular cancer. Researchers gave mice that had grafts of human testicular tissue a typical dose of paracetamol over the course of 24 hours or seven days. They measured the amount of testaterone produced by the human tissue after taking the final dose of paracetamol, and found there was no effect after 24 hours. On the other hand, after seven days of exposure testosterone levels were reduced by 45 percent.

The researchers noted further studies are required to determine the mechanism by which paracetamol reduced testosterone exposure.

"We would advise that pregnant women should follow current guidance that the painkiller be taken at the lowest effective dose for the shortest possible time," Mitchell concluded.

The findings were published in a recent edition of the journal Science Translational Medicine.