The study tested women in Denmark and Finland and found that Dutch women who took a combination of one or more painkiller, such as aspirin and acetaminophin, had a seven-fold increased risk of giving birth to sons with undescended testicles.
The condition is known to be a risk factor for poor semen quality and testicular cancer later in life.
Studies in rats have also linked analgesics to insufficient levels of testosterone during a crucial period of gestation when male organs are forming.
The group of Finnish women did not show the same strong correlation, though whether this was the result of how they were interviewed is unclear. The reproductive disorders studies are almost four times more common in Denmark than Finland.
Doctors urged women to restrict their intake of such painkillers as much as possible during pregnancy.
