A 15-year-old boy has been charged with manslaughter after a heavily pregnant woman was killed in a crash involving an allegedly stolen car in central Hobart.

Key points: Pregnant woman, 24, dies in two-vehicle crash in central Hobart

Pregnant woman, 24, dies in two-vehicle crash in central Hobart Baby delivered at Royal Hobart Hospital

Baby delivered at Royal Hobart Hospital Teenager charged with manslaughter and motor vehicle stealing

The woman, who was 32 weeks pregnant, died at the scene and her baby was delivered at the Royal Hobart Hospital.

The 24-year-old woman had dropped her partner off at work and was driving with her two-year-old son inside the car when the crash happened about 1:00am on the corner of Davey and Argyle Street.

Her son received minor injuries and police said specialists were treating the newborn.

The teenager, who is alleged to have been the other driver, was questioned while under police guard in hospital.

He has been charged with one count of manslaughter and one count of motor vehicle stealing and is due to appear at the Hobart Youth Justice Court.

Police have alleged the car was seen speeding across the Tasman Bridge shortly before the crash.

The two cars ended up on either side of the one-way arterial street and the allegedly stolen car was badly burnt.

Three teenagers, including a 12-year-old girl, were taken to hospital with non-life threatening injuries.

They are all from the Hobart area and police said they were likely to be charged with stealing a motor vehicle.

Fundraising campaign launched for family

Floral tributes have been left at the sight of a crash that claimed the life of a pregnant mother on Hobart's Davey Street. ( ABC News: Edith Bevin )

The employer of the dead woman's husband has started a fundraising campaign to "assist the family as much as they can".

The campaign, which has been started on a crowd funding website, aims to raise $10,000.

Tasmanian financial group MyState has also opened an account for people who want to donate money to the family.

"In the wake of the horrific car crash which took the life of a 24-year-old pregnant mother, MyState have begun accepting cash donations to provide to the family," it said.

Dozens of bunches of flowers and cards with messages of shock and grief have been left at the side of the road.

Passerby Kurt Collins said he came across the crash scene was "probably one of the worst I've seen".

"To see the effect of the cars and the power lines down ... it's devastating," he said.

High-speed chase ban policy observed by police

Commander Glenn Frame said police did not engage in a high-speed chase, as per policy.

"It never followed or chased the vehicle but it turned around and travelled in the same direction but quite some distance behind," he said.

"It's about protecting the public. The last thing we want is police vehicles pursuing those vehicles and putting the public at more risk.

"It's about reducing the risk to the public, and this is an absolute tragedy, but it is avoidable."

Traffic was diverted around the accident scene for more than seven hours.

Commander Frame said support was being offered to the woman's partner and other people impacted by the incident.

"This has been a traumatic experience for all of us; police officers involved, the family, the young people involved in the accident and the witnesses who were there and saw it," he said.