Shamima Begum's lawyer says her baby son has died
"We have strong but as yet unconfirmed reports that Shamima Begum's son has died," Tasnime Akunjee tweeted on Friday. "He was a British citizen."
Begum's baby, named Jarrah, was born on 16 February, at a camp for IS family members controlled by the Syrian Democratic Forces in northern Syria.
Questions over the citizenship of Jarrah emerged after the UK Home Office stripped Shamima Begum of her British nationality.
Begum fled her home in East London at the age of 15 to join Islamic State in Syria. Four years later, she emerged in a Syrian refugee camp with a newborn son, asking the UK government to let her back into the country.
Begum's family have said they are appealing the decision by the British government to ban her re-entry and were exploring measures to bring Shamima's newborn son to England.
The home secretary, Sajid Javid, said "children should not suffer, so if a parent loses their British citizenship it does not affect the rights of their child".
The Home Office revoked Begum's citizenship on the grounds that her heritage claim to Bangladeshi citizenship would not render her stateless. Bangladesh have said there is no question of her being allowed into the country.
"I would like them (British politicians) to re-evaluate my case with a bit more mercy in their heart, you know," Begum told Sky News on Thursday. "I am willing to change".
Begum had two other children while in Syria, but both died.
She ended up in a refugee camp after fleeing the village of Baghouz in eastern Syria. It is the last square mile of IS territory and currently besieged by the Kurdish-led Syrian Democratic Forces.
While living in Syria, Begum married a Dutch IS fighter who is currently being held by Kurdish fighters. He told the BBC a week ago that he wished to return to the Netherlands with his wife and son.
Her case highlights the challenges faced by Western governments as IS recruits - some considered dead - re-emerge and ask to return to their home countries.
The British authorities estimate around 900 Britons travelled to Syria and Iraq to join the conflict, of whom around 300-400 have since returned - and 40 have been prosecuted.
Sajid Javid is vehemently opposed to IS members returning to the UK. "My message is clear - if you have supported terrorist organisations abroad I will not hesitate to prevent your return," he told The Times.