"Please find enclosed papers that relate to a decision taken by the Home Secretary, to deprive your daughter, Shamima Begum, of her British citizenship", the letter read.
"We are considering all legal avenues to challenge this decision", the statement added.
Shamima Begum, 19, has appeared unrepentant in a series of interviews despite announcing her desire to return to her family home in Bethnal Green, east London.
Despite her fears, she says she still wishes to return home and for her child to be brought up by her family, who said her child had "every right as a total innocent to have the chance to grow up in the peace and security of this home".
Mr Javid's decision will nearly certainly face legal scrutiny, as the United Kingdom is presently unable to render citizens born in the country stateless, and the revocation of citizenship is usually used against those with dual citizenship, or who became naturalised British citizens.
Her remarks come as a report suggests that numerous girls who have travelled to join Isil are far from vulnerable and naive.
A Home Office spokesman said he could not discuss individual cases, but added: "We don't leave people stateless".
In an interview with the Times, published on 13 February, Ms Begum said she was heavily pregnant and wanted to come home to the United Kingdom for her baby's health.
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"With any foreign fighter, as a starting point, an admission of guilt for supporting or belonging to a proscribed terrorist organization should allow authorities to immediately begin the process of ensuring that ISIS returnees receive the justice they deserve", he said. "I just was hoping that maybe for me, for the sake of me and my child, they let me come back".
While it is unclear whether Begum committed any crimes, many have focused on her apparent lack of remorse. The teenager, who is now heavily pregnant, married a Daesh fighter and said that seeing a severed head "didn't faze me at all".
But her claim has been highlighted as a cause for concern by some, who say her claims sound "unrepentant and cynical". She said she had two other children during her time in Syria, who died in infancy from malnutrition and illness.
If Ms Begum is ready to reach a British consulate in a recognised country, it's miles assumed security chiefs would possibly possibly "arrange" her return.
Writing in the newspaper on Tuesday, he said: "As a Christian, I can not help reflecting that if Jesus had thought like that he would never have told the parable of the Prodigal Son, which neatly marks out his teaching both from Islam and from the cold logic of secularism".
"We must remember that those who left Britain to join Daesh were full of hate for our country", he said, according to Sky News.
Akunjee told AFP the family had learned about the birth from a translator in an eastern Syria refugee camp where Begum is now staying.
What can Shamima Begum do now?
However, the looming U.S. departure has created a deadline for those governments whose citizens joined IS and have now been captured by the US-backed, Kurdish-led Syrian Democratic Forces (SDF).