“You’ll be surprised at the lack of knowledge among the community about the devastating health consequences of early marriage,” said Fasel Shammout, a psychologist who has done training for the refugees. “By the time they reach us, they are in a dire state — legally, mentally, physically.”

Even among those who end up in loving marriages, the risks can be severe. Hana Mohammad, 16, was married in Syria during the war to a young man who professed his love, but whom she would have married later had the fighting not given her few good choices. Her parents, who remained in Syria, thought she would be safer living with his family, which was planning to leave the country, than staying in Dara’a, where so many missiles fell on the wedding day the families held no party.

By the time the husband’s family left Syria, she was eight months pregnant. Soon after they arrived at the Zaatari camp, she collapsed. “She turned blue, she became stiff as stone, she was having seizures and there was blood coming out of her mouth,” said her husband, Mohammad Ghazawi, 26, who said he had known he wanted to marry her since catching glimpses of her in their hometown.

It is unclear whether the arduous 12-day journey through the desert caused her collapse and the coma that followed, but teenage mothers are considered at risk for the condition she eventually learned she had: eclampsia.

In the end, doctors were able to deliver her baby, a girl, safely, but Hana continues to have seizures.

Although she is still a believer in early marriages, her anxious husband and her mother-in-law have begun warning other girls to wait until they are past 18.

“I almost lost my wife,” said Mr. Ghazawi. “She paid the price for being pregnant too early in her life.”