Shamima Begum has lost an initial bid to challenge the removal of her British citizenship at the Supreme Court.
The 24-year-old had requested permission from the Court of Appeal to take her case to the UK's highest court.
The government stripped her citizenship on national security grounds in 2019, leaving her stateless.
Ms Begum left London nine years ago aged 15 to travel to Syria and join the Islamic State group, or IS.
Earlier this year, three judges at the Court of Appeal unanimously dismissed her bid to regain her citizenship.
She now has the option to ask the Supreme Court directly for permission to have her case heard.
Delivering the Court of Appeal's rejection in February, Lady Chief Justice Baroness Carr said: "It could be argued the decision in Ms Begum's case was harsh. It could also be argued that Ms Begum is the author of her own misfortune.
"But it is not for this court to agree or disagree with either point of view. Our only task is to assess whether the deprivation decision was unlawful. We have concluded it was not, and the appeal is dismissed."
Her lawyers have argued that the Home Office's decision to remove her citizenship was unlawful, in part because British officials failed to properly consider whether she was a potential victim of trafficking.
Ms Begum, born in the UK to parents of Bangladeshi heritage, was one of three east London girls who travelled to Syria in 2015 to support the IS group. She left with her friends Kadiza Sultana and Amira Abase.
Ms Sultana is thought to have died when a house was blown up. The fate of Ms Abase is unknown.
Ms Begum lived under IS rule for more than three years. She married a Dutch member of IS, who is currently held in a Kurdish detention centre, and lived in Raqqa, once a stronghold of the group. She had three children, all of whom have died.
She was found in al-Roj camp in northern Syria in 2019 following the defeat of IS, and remains there to this day.
Her lawyers say conditions in the camp have reached a "critical point", with "near starvation" and disease now seen daily.
"The fact of the matter is this - that Shamima, as with other British women and children, is arbitrarily detained in a prison camp in north east Syria," her lawyers said in a written statement on her behalf.
"It is not a refugee camp - those detained are unable to leave and the conditions have, with ever greater urgency, been categorised by every international body as well as by the UK courts in Shamima's case itself, as constituting torture and inhuman treatment."
Ms Begum has admitted knowingly joining a proscribed organisation. She said that she was "ashamed" to have done so and regretted it.
