Aid officials say those dying were part of a group of 2,000 women and children who arrived at the camp fleeing Daesh's last enclave, Baghouz. Separately, Russian air strikes in Idlib killed four children and their father, reports say.
At least 12 people died overnight after arriving at a camp in northeastern Syria from Daesh's final enclave at Baghouz, the International Rescue Committee (IRC) said on Thursday.
"Last night, another 2,000 women and children arrived at Al Hol camp in northeast Syria from Baghouz. Up to 60 arrivals needed immediate hospitalisation and there were another 12 deaths recorded," IRC said in a statement.
"These women and children are in the worst condition we have seen since the crisis first began. Many have been caught up in the fighting and dozens have been burnt or badly wounded by shrapnel," Wendy Taeuber, IRC's Iraq and northeast Syria country director, said in the statement.
"There have now been at least 138 deaths on the way to Al Hol or soon after arriving at the camp since early December. The deaths have overwhelmingly been of babies and infants," IRC said.
Since April 2017, the US-backed YPG/PKK terror group fighting Daesh terrorists in Baghouz has placed civilians fleeing the fighting in crammed Al Hol camp.
Russian air strikes in Idlib
Meanwhile, Russian warplanes launched an overnight air strike in Idlib province, killing at least five people, according to pro-opposition observatory.
Air strikes that continued until Thursday morning claimed the lives of four children and their father in Al Faqie village, with the mother being rescued from debris, according to sources with the White Helmets civil defence agency.
The attacks taking place at dawn also targeted the villages of Frikeh, Sheikh Mustafa, Al Hamidiyah, Hbit and the outskirts of the town of Kafr Rumah.
According to a pro-opposition warplane observatory, the attacks were carried out by six Russian warplanes that took off from Khmeimim airbase in the country’s western Latakia province.
Attacks carried out by the Syrian regime and Iran-backed terrorist groups in Idlib's de-escalation zone are estimated to have killed at least 152 civilians – and injured more than 445 others – since the beginning of 2019.
Violation of Idlib deal?
In September 2018, Turkey and Russia agreed to turn Idlib into a de-militarised zone.
Ankara and Moscow signed a memorandum of understanding calling for the stabilisation of the situation in Idlib's de-escalation zone, in which acts of aggression are prohibited.
Syria has been locked in a vicious civil war since early 2011, when the Bashar al Assad regime cracked down on pro-democracy protests with unexpected ferocity.
Since then, hundreds of thousands of people have been killed and more than 10 million others displaced, according to UN officials.