Freezing temperatures and the lack of medical care have killed at least 15 displaced Syrian children in recent weeks, the United Nations reported on Tuesday.
The UN Children's Fund (UNICEF) said eight of them had died as a result of the cold in the Rukban camp in southeastern Syria and seven others during the displacement from the jihadist bastion of Hajin, further north.
"Freezing temperatures and harsh living conditions in Rukban... are increasingly putting children's lives at risk," UNICEF regional director Geert Cappelaere said.
"In just one month, at least eight children -- most of them under four months and the youngest only one hour old -- have died," he said.
Cappelaere explained that the cold in the isolated desert camp on the Jordanian border, where 80 percent of the 45,000 residents are women and children, was increasing infant mortality.
The cold snap that has hit the region is also having dire consequences on the people fleeing the fighting in the so-called Hajin pocket in eastern Syria.
The area near the Iraqi border has seen intense fighting between Islamic State group defending the last remnants of their "caliphate" and Kurdish-led forces backed by US air strikes.
According to the UN, more than 10,000 people have fled the area since December.
"Families seeking safety face difficulties leaving the conflict zone and wait in the cold for days without shelter or basic supplies," Cappelaere said.
"The dangerous and difficult journey has reportedly killed seven children -- most of them under one-year-old" in Hajin, he said.
According to the Kurdish-dominated Syrian Democratic Forces battling the jihadists and to the Syrian Observatory for Human Rights, significant numbers of IS members have attempted to blend in with fleeing civilians.
A Syrian child stands out in the open in Abu Al-Khashab camp for the displaced from the eastern province of Deir Ezzor, northwest of the city of Deir Ezzor. AFP