Police holding a man suspected of stabbing a pregnant woman multiple times in the street have been granted an extra 12 hours to question him.
A 41-year-old man was arrested on suspicion of attempted murder and taken into custody after a woman was stabbed in Sutton Coldfield on Friday afternoon.
Passers-by flagged down officers on Trinity Hill after the stabbing in the busy town centre, and several members of the public attempted to intervene, two of whom were treated for minor injuries.
The 40-year-old victim was taken away from the scene by air ambulance at around 4pm and her unborn child was later safely delivered.
The baby girl is doing well although her mother remains in a critical but stable condition, West Midlands Police said.
In a statement on Saturday afternoon the force said officers would be able to continue questioning the man until the early hours of Sunday morning.
Detective Inspector Ian Ingram from the Public Protection Unit added: "We have launched a major investigation and are working hard to understand the circumstances that led up to the assault.
"I am appealing to anyone who was in the area yesterday afternoon and who may have seen something to come forward and speak to my officers."
On Friday, Chief Inspector Julian Harper told reporters: "They (the man and woman) are believed known to each other so this was what we call a domestic-related situation.
"As such, no other members of the public should be alarmed and should be reassured that we have what we believe is the only person involved in this incident."
He praised the members of the public for "bravely" intervening, saying: "What is clear at this early stage is that two members of the public bravely stepped into what was a dangerous and volatile situation, with complete disregard for their own safety and I commend them for their actions.
"Fortunately, they suffered only minor injuries."
He added the investigation could become a murder probe if the mother does not pull through, but said: "Obviously our wishes are with her and we hope that she will recover."
Anyone with information is asked to call police on 101 or Crimestoppers anonymously on 0800 555 111.