The girls – aged 12, 10, eight and four – were saved from the arson-hit property on Round Road in Erdington in the early hours of Friday morning.
A 37-year-old has since been arrested on suspicion of attempted murder and a 29-year-old woman has been arrested on suspicion of child neglect.
Meanwhile a car has been recovered after crashing into a stationary fire engine at the scene.
A total of 20 firefighters were sent to the blaze which broke out at around 2.30am.
The fire affected 80 per cent of the ground floor with all of the property engulfed by smoke, West Midlands Fire Service said.
Investigators later confirmed the cause of the blaze was arson.
A West Midlands Ambulance Service spokesman added: "We were called by the fire service at 2:30am to a house fire at a property just off Tyburn Road in Erdington.
"We sent two ambulances, three paramedic officers and the Hazardous Area Response Team (HART) to the scene.
"Crews treated four patients, all girls, for the effects of smoke inhalation and they were conveyed to Birmingham Children’s Hospital for further treatment."
Both suspects remained in custody on Friday afternoon.
Anyone with any information about the fire should contact West Midlands Police between 8am and midnight or by calling 101 anytime. Quote crime reference 20BE/265248E/20.
Crimestoppers can be called anonymously on 0800 555 111.