A driver accused of causing a fatal crash that killed two women, including one who was pregnant with twins, could face another manslaughter charge if an autopsy finds one of the unborn children drew breath in the moments after the collision.

Key points: Richard Moananu faces manslaughter charges for his alleged role in a crash which killed two women, one who was pregnant

Richard Moananu faces manslaughter charges for his alleged role in a crash which killed two women, one who was pregnant An autopsy is determining whether one of Katherine Hoang's unborn twins actually drew breath, which would result in further charges

An autopsy is determining whether one of Katherine Hoang's unborn twins actually drew breath, which would result in further charges The prosecution said Mr Moananu was driving despite being about "four times" over the legal alcohol limit

Richard Moananu, 29, appeared in the Penrith Local Court on Friday charged with 10 offences over the September 28 crash in western Sydney that killed the pregnant 23-year-old Katherine Hoang and a 17-year-old.

In court on Friday, prosecutor Lisa Graham said at the time of the crash the body of one of the twins — a boy — was taken to Melbourne to undergo an autopsy to determine whether the baby did draw breath.

She said if it was found the baby did breathe Mr Moananu could face a further charge of manslaughter and dangerous driving causing death.

She said Ms Hoang was about eight months pregnant at the time.

The court was also shown a video captured by security cameras close to the crash site, showing the impact of the collision.

The crash scene on the night of the incident captured by the ABC ( ABC News )

Ms Graham said Mr Moananu had been drinking at a hotel in St Marys for almost nine hours before he got in his car.

She said he was about "four times" over the legal blood alcohol limit and witnesses said he was driving erratically in the lead up to the impact.

She told the court Mr Monananu's car was travelling at about 140kmh in a 60kmh zone at the time.

"They (the Hoang family) had no hope of avoiding a collision," Ms Graham said.

She said the incident showed a "complete abandonment of any level of responsibility by the accused".

Ms Hoang's husband Bronco was taken to hospital in a critical condition after the crash. The court heard he now has a brain injury.

Mr Moananu, a New Zealand citizen, appeared by video link from Long Bay Prison Hospital.

A large family group were in court offering support with some who openly showing emotion during his appearance.

The court heard he was also allegedly driving under the influence of cannabis and that a note was also found in his car at the crash site from his partner, which read: "You like to drink, gamble, and be with your friends 80 per cent of the time."

Ms Graham told the court: "The accused clearly has an unresolved major problem with alcohol, your honour. That was apparent on the night."

Mr Moananu is yet to enter a plea over the charges and his application for bail was refused.