A cheap and widely available drug could save the lives of 1 in 3 of the 100,000 new mothers who bleed to death after childbirth every year, mostly in poorer countries, according to the first study of its use in postpartum hemorrhage.

In a trial of 20,000 women, researchers found that the drug, called tranexamic acid (TXA), cut the number of deaths due to postpartum bleeding by 31 percent if it was given within three hours. The treatment costs about $2.50 in most countries, they said.

As TXA works by stopping blood clots from breaking down, the researchers also found that it reduced the need for urgent surgery to control bleeding by more than a third.