AMMAN, Jordan (AP) — The U.N. agency for children said Sunday that 85 percent of Syrian refugee children in Jordan live in poverty, 38 percent are not in school and almost half of those under the age of five don't have access to proper health care.

The findings by UNICEF are based on responses from about 1,000 families among Jordan's 660,000 registered refugees. Some 5.5 million Syrians have fled civil war in their homeland since 2011, most settling in neighboring countries where they struggle to survive, and millions more have been uprooted inside Syria.

The UNICEF study is the latest of six to be conducted among refugee families at six-month intervals and reflects a continued deterioration in the lives of Syrian children, said Robert Jenkins, the agency's Jordan representative.

"The overwhelming message of this study is that Syrian refugee families are becoming increasingly vulnerable in Jordan," he told The Associated Press. He called on donor countries to step up at a time of growing need. In Jordan, UNICEF has a $145.7 million funding shortfall for child and youth programs in 2018.

The study found that 94 percent of Syrian refugee children under the age of five lack at least two of the five basics, such as access to health care and preschools. In this group, 45 percent don't have access to proper health care, including vaccinations. Among those of school age, 38 percent are not enrolled in schools and four out of 10 are food insecure.

After years in exile and with savings depleted, refugees are increasingly resorting to "negative ways" of coping to survive, including permitting daughters to get married before age 18 and sending teen boys to work, said Maha Homsi, the agency's chief of child protection in Jordan.

She said that Jordan's economic downturn, including rising prices and unemployment, will further harm refugees.