The 23-year-old loses her appeal on national security grounds, which means she cannot return to the UK.
In extensive BBC interviews, Shamima Begum also reveals the detailed planning before she joined IS at 15.
Lawyers defending stripping Shamima Begum's citizenship say her age at the time does not matter.
Decision to remove UK citizenship from woman who went to Syria when schoolgirl is being challenged.
Her UK citizenship was unlawfully stripped, lawyers say, as a five-day appeal hearing begins.
PM Justin Trudeau will examine accusations that Shamima Begum was smuggled into Syria by a Canadian spy.
Mohammed Al Rasheed says he shared her passport details with Canada as UK police hunted for her.
