If she's allowed to return to UK but is convicted of a crime (and we can't be sure she has actually committed any) and sent to prison, she will be allowed to have her baby with her in one of the mother-and-baby units in UK women's prisons until it is 18 months old.

I don't agree with separating babies from their mothers, unless Social Services find the mother to be 'unfit', or that she is living with a violent/abusive/paedophile etc 'unfit' partner.

I think it would be perfectly possible for her to be monitored by MI6 or something to make sure she wasn't in touch with IS or engaging in any nefarious activities.