CAIRO — The girl did not know whether it was night or day when she plotted her escape from a house in Yemen. Her husband had locked the girl in a windowless room.

“He was mean to me because I didn’t want to touch him,” she said.

He was 35. She was 14.

But the girl, Mohsina, was not only a victim of child marriage. She was a casualty of a war that has plunged her country into a humanitarian catastrophe. For Mohsina’s family, marrying off their underage daughter earned a $1,300 dowry — enough to feed them for a year.

Yemen is a country in crisis. After more than two years of war, its infrastructure has been badly damaged and its people impoverished, with hundreds of thousands sickened with cholera. But hidden among the numbing statistics of death and destruction is another insidious scourge: Desperate families are increasingly selling their daughters off as child brides or letting their boys be recruited as child soldiers.

“It is impossible to say how many kids are being pulled out of school now to be married off or sent to fight, but we know that more and more parents are doing this,” said Meritxell Relano, the United Nations Children’s Fund representative in Yemen. “The lack of livelihood and unemployment is forcing them to do this.”