The problem is bureaucracy. SS have no access to things like CB records. You should see the hoops that have to be jumped through to get to see the criminal record of someone who has committed a crime. If you ask the NHS for details on someone, it takes them a fortnight just to confirm that they are aware of their existence.
We have two members of staff permanently based in our small Court which runs three Court rooms. There is no way you could run checks on the 40-50 people who come through the door each day, so you would have to wait until after sentencing, to see who was going to jail. Then you would need a staff member in each Court room to do the actual checks, which would be time consuming - first to get a hold of someone who was able to access the CB register, and was free to do so, then to establish where the children actually were and who they were with, then to check if that person was suitable, do a home check, criminal background check etc. All this does happen when someone tells us that they have children, and it can take hours, and can require two staff members to do a home visit if there are concerns. All this on top of all the other work needing done in the Court. It would require the formation of a whole new team to do this for all the female prisoners going through all the Courts in a local authority, and you would still miss all the children cared for by male prisoners.
Given the massive cuts to our budgets, we are struggling to cover our basic duties. There is absolutely no chance of this being funded. If the children are already known to SS, then the social worker involved should have organised care in advance. If they are not, we are reliant on the prisoner being open and honest.