A mystery doctor.
Perhaps an angel? Who is to say?
Something similar happened to a friend of mine as his wife was in labour a number of years ago at a Toronto teaching hospital.
The nurses didn't believe that the baby was ready to be born. She kept insisting "it's time".
Anyway-all the nurses disappeared, and they were calling for help and some doctor-a female, just happened to be walking by and walked into the room and delivered the baby, and eased the cord from around the baby's neck. She told them she wasn't an OB/GYN from the department, and then disappeared after she cut the umbilical cord. The nurses came in a few minutes after the mystery doctor left.
They never found out who she was. The nurses didn't recognize her by their description.
If it weren't for her, their baby could have been strangled by the umbilical cord. Still a mystery all these years later.