According to statistics from the Syrian Ministry of Justice, the proportion of child marriages in has risen from seven percent to 14 percent over the past six years.
In refugee camps, the figure is even higher: 35 percent of marriages in Jordanian refugee camps involve somebody under the age of 18, in Lebanon the figure is 32 percent.
In half of all cases, the average age of marriage for women is now ten years younger than it was before the war.
Under Syrian law, the minimum age to get married is 18 for men and 17 for women. In some cases, however, a judge may give permission for a 15-year-old boy or a 13-year-old girl to get married.
"Another factor is religion. The parents may have a mistaken belief that by marrying off their under-age daughter, they are observing Sharia law. This can be seen in some distant regions of Syria," al Hadj said.
Earlier this year, the UN conducted a survey of Syrian refugee populations in Lebanon, which found an "alarming rise in child marriages."
In Western Beka, more than a third of refugee women and girls surveyed between the ages of 20 and 24 had been married before reaching age 18. Some 24 percent of refugee girls currently between ages 15 and 17 were married.
Iman, a Syrian refugee, told the UN Population Fund that she married off her 15-year-old daughter because as a widow and the sole breadwinner for her family, she has trouble supporting her three children and ageing father.
"For this, reason my cousin, out of his good heart, wanted to help out by getting engaged to my daughter and supporting us financially," Iman said.