A triple zero operator heard an argument, screaming and then silence during a call from a pregnant woman killed when flung from a ute allegedly driven by her partner, according to police.

Helena Broadbent, 32, suffered a “catastrophic brain injury” when she fell backwards out of the Mitsubishi Triton in suburban Melbourne on Saturday and died in hospital after delivering a baby girl by caesarean.

In court on Wednesday police said she was on the phone to emergency services, reporting that her partner had a hammer, as the tragedy unfolded at Keilor Downs.

Police allege Broadbent and William Wilson, 35, had gotten into an argument at their shared home and he left in the ute.

After he returned some time later, Det Sgt Darryl Out said, Broadbent called triple zero claiming Wilson had a hammer and was threatening to kill her.

Wilson took some items from the home and left again, believing police were on the way. Broadbent followed him to remove child seats from the vehicle but Wilson drove off.

Security footage shows the ute approach a corner, the rear passenger door open, and a person fall.

Wilson told police he thought Broadbent had been running alongside the ute but had stopped when he made a right turn.

But police don’t agree.

“Investigators believe the accused ought to have known Ms Broadbent was at risk of being seriously injured while driving the car, with her being in close proximity, and should not have driven further once she had opened the door,” Sgt Out said.

The incident was captured on an emergency call, police say, in which Broadbent was heard saying “he’s going to take off with the kids’ seats” and “go on you fucking idiot, wreck your car”.

“Then there’s a scream, then silence,” he said.

Broadbent “suffered a catastrophic brain injury” and was flown to hospital but died after delivering her baby.

Wilson sobbed loudly and at times put his head in his hands as he faced Melbourne magistrates court on Wednesday charged with causing her death by dangerous driving.

His lawyer made an application for bail, stressing the potentially long wait until his next appearance and that he has a job to return to and family to support.

A prosecutor argued against bail, adding Wilson was a flight risk, particularly as he had family based in Queensland.

Magistrate Charlie Rozencwajg refused bail, noting Wilson was facing a serious charge, and without “compelling reason why his detention is not justified”.

Broadbent’s baby remains in intensive care.

Wilson is scheduled to next appear on 6 January.