A pregnant driver who seriously injured a cyclist while overtaking a school bus made a small but devastating mistake, a judge says.

Jessica Louise Collins, 21, was 10 weeks pregnant when she slammed into cyclist Stuart Day in Gladstone's Longbush Rd in March.

She had tried to overtake a school bus on a left-hand bend, but lost control and skidded into him, catapulting him over the car.

The crash left the 48-year-old engineer lying unconscious on the roadside with multiple injuries to his face, including seven fractures to his jaw, bleeding on his brain and kidney damage.

He also lost the use of his right arm, and was flown to Wellington Hospital, where he spent five weeks recovering.

Yesterday, Mr Day said that eight months after the crash he still had limited use of his right arm.

"I reckon it's at about 30 per cent. I'd like to think I will be back how I was, but realistically I won't be. If I can get 80 per cent use of my arm back, then I'll be lucky."

He had recently started working again part-time, but could not "swing a hammer" or do other physical work.

In Masterton District Court yesterday Collins, who now has a 6-week-old baby, wiped away tears as her lawyer, Ian Hard, described her "despair and complete remorse".

After the crash, she placed Mr Day, who was not wearing a helmet, in the recovery position, before driving to a neighbouring property to get help.

"It's a case where a small amount of negligence can cause a huge amount of damage," Mr Hard said.

Judge Stephen Harrop said Collins had made an error of judgment that had devastating consequences for the victim.

Collins had pleaded guilty in August to careless driving causing injury. The judge sentenced her to 40 hours' community work and ordered her to pay reparations of $2500 to the victim.

He disqualified her from driving for six months.

- © Fairfax NZ News