Shane David Bausch admitted dangerous driving last year over a crash at Bannockburn, near Geelong, when he drove through a give-way sign and slammed into the side of Amanda Davies' car.

She was 31-weeks pregnant and suffered serious injuries in the crash, after which she was airlifted to hospital where her baby was delivered stillborn.

Ms Davies' two other children in the back seat were uninjured.

Bausch appealed his maximum three-year sentence and in a decision handed down "with reluctance" on Tuesday two Court of Appeal Justices reduced the term.

"This is a case of disastrous misjudgment at an intersection rather than one of protracted dangerous driving," they said of Bausch's slowing down before a give-way sign but speeding up to go through it.

He had drugs in his system at the time, including ice and prescription diazepam.

But the court also heard he had cognitive impairments as a result of an acquired brain injury.

His appeal was successful after his lawyer Paul Smallwood argued the sentencing judge had erred in concluding Bausch knew of the presence of the drugs in his body at the time of the crash.

The judges said there was an absence of evidence as to when the drugs had been consumed and around their probable effect on Baushch.

It could not be concluded beyond reasonable doubt that he had disregarded the probable risk of driving with the drugs in his system, and such disregard could not be linked to the crash, they found.

Bausch was originally sentenced in March to up to three years prison, which has been reduced to two years and one month.

He'll be eligible for parole after 15 months.

The reduced sentence came with an increased driving ban - up to nine years starting Tuesday, almost double the five-year band he was handed in March.

Australian Associated Press