The 'leaked' images shared on social media show the women hold pieces of paper on which their names and a date - July 27, 2015 - are written.
It is feared this means they will be sold to IS fighters if their families or charities do not pay ransom for their release, although no figure appears on the signs they hold.
A source at The Assyrian Federation of Sweden told MailOnline: "The names resemble the family names of people in a nearby village - Tel Jazire - so it is possible that these women could be from Assyrian villages but we cannot confirm that the women's surnames resemble those of families who lived in the region, although they cannot completely verify they are Christians. These names are names you find in Assyrian villages."
On Tuesday, ISIS released 22 of more than 220 Christians who were abducted from several Assyrian farming communities it raided in Iraq's north-eastern Hassakeh province, Syria, earlier this year.
Last week, IS militants kidnapped 230 Christians and Muslims in Syria, according to the Syrian Observatory for Human Rights. At least 60 of them are thought to be Christian and could face the prospect of a life of slavery.
Meanwhile, Syrian government warplanes have attacked a busy market in a rebel-held suburb of the capital Damascus, killing at least 67 people and wounding more than 200.
The attack is one of the deadliest incidents involving government air strikes since the crisis began nearly five years ago.
Syrian government air raids on rebel-held areas throughout the country have killed thousands over the past few years.
The air raids on the market in Douma occurred during rush hour when people were out shopping on the first working day of the week in Syria, the activists said.
Rami Abdurrahman, who heads the British-based Syrian Observatory for Human Rights, said four missiles were fired at the market, killing 70 and wounding more than 200. He said the death toll is expected to rise because many of the wounded are in critical condition.
The Local Coordination Committees, another activist group, said the air raids killed 67 and wounded 200, adding that rescue workers are digging through the rubble in search of survivors.
"The situation is catastrophic," a Douma-based activist called Mazen al-Shami said, adding clinics in the area are full and many of the wounded are being rushed in civilian cars to other medical facilities since ambulances are overwhelmed.
Al-Shami said mosque loudspeakers are issuing calls for residents to donate all types of blood, and hundreds of people were in the busy market when the first missile struck the area, inflicting heavy casualties.
Syria's civil war, now in its fifth year, has killed more than 250,000 people and wounded at least a million.