The family of Shamima Begum have told ITV News they want the Government to step in and bring the so-called Islamic State bride and her baby home from Syria.
In a statement they accept the heavily pregnant 19-year-old should face justice, but say that should be here in Britain.
Begum, who ran away to join so-called Islamic State when she was 15, and later escaped, is currently being held in a refugee camp.
Also on Friday, the head of MI6 said that while returning IS fighters and brides are "potentially dangerous", the authorities cannot stop British nationals coming home.
Alex Younger's comments came after the Home Secretary said he would try to stop Begum returning home.
In a statement issued exclusively to ITV News, Shamima Begum's family pleaded with the Government to treat the case as a "matter of urgency".
They continued that the "welfare of Shamima’s unborn baby is of paramount concern to our family, and we will do everything within our power to protect that baby who is entirely blameless in these events".
The child is expected to be born any day.
The family added that Begum's baby is "a total innocent" and has "every right" to "grow up in the peace and security" of the UK as it will "be British".
As well as the unborn child's right to live in the UK, the family continued that "as a British citizen, Shamima has every expectation to be returned to the UK and be dealt with under the British justice system.
"We welcome an investigation in what she did while she was there under the principles of British justice and would request the British government assist us in returning Shamima and her child to the UK as a matter of urgency."
Their plea came after MI6 chief Alex Younger said that while returning former IS fighters and brides "are likely to have acquired both the skills and connections that make them potentially very dangerous".
However, Mr Younger - also known as C - acknowledged that "British nationals have a right to come to the UK".
Yet those who return "can expect to be investigated and questioned and potentially prosecuted if they return to our jurisdiction", he said.
Earlier this week, Begum spoke to The Times at a refugee camp in northern Syria, telling the newspaper she would "do anything required just to be able to come home and live quietly with my child”.
Despite wanting to return home, the teenager said she had "no regrets" about travelling to Syria.
Begum's family said they were "utterly shocked" by what they heard in the interview.
"But to us, those are the words of a girl who was groomed at the age of 15; we are also mindful that Shamima is currently in a camp surrounded by IS sympathisers and any comments by her could lead directly to danger to her and her child," they added.
They said: "Given Shamima’s four-year ordeal, we are concerned that her mental health has been affected by everything that she has seen and endured.
"Now, we are faced with the situation of knowing that Shamima's two young children have died – children that we will never come to know as a family."
Their message to the Government follows a warning from Home secretary Sajid Javid who said he "will not hesitate" to prevent the return of Britons who travelled to join so-called Islamic State.
The Home Secretary said those who left the UK to join so-called Islamic State were "full of hate for our country".
"My message is clear — if you have supported terrorist organisations abroad I will not hesitate to prevent your return," Mr Javid said.
"If you do manage to return you should be ready to be questioned, investigated and potentially prosecuted."
While Security Minister Ben Wallace warned that runaways who now want to come back must realise that "actions have consequences", and that the lives of Britons would not be put in danger returning people from Syria.
Any hopes of a rescue mission by British officials were swiftly quashed on Thursday as the Government ruled out an effort inside Syria to assist Ms Begum.
- ITV News Security Editor Rohit Kachroo explains what the options for Shamima Begum are
Outlining what the consequences could look like for those returning from Syria, the head of Counter Terrorism Policing, Assistant Commissioner Neil Basu said: "British nationals who want to return from Syria or Iraq, can expect to be investigated, and anyone allowed to come back will have to live under stringent limitations.
He added: "Any investigation is carried out with an open mind and based on the evidence available.
"This is to determine if individuals have committed any terrorist or other criminal offences, regardless their motivation, and to ensure that they do not pose a danger to the public or the UK's national security."
Former Foreign Secretary David Miliband, who is now the chief executive of the International Rescue Committee, says humanitarian organisations will focus on helping those caught up in the caliphate, rather than those who chose to fight for IS.
Mr Miliband told ITV News: "Obviously the vast majority of people we're helping both in Iraq and in Syria, but also, frankly, where extremist groups are in control in north-east Nigeria or elsewhere, humanitarian agencies are helping people who have effectively been imprisoned by these terrorist groups not those who are volunteering to go and fight for them [IS], that raises a whole host of different issues.
"What we do know is that you don't tackle the burning sense of insecurity and injustice by domestic populations, not by foreign fighters who are going there, but by domestic populations then you're incubating trouble for the future."
- The family's statement in full