Baby Nate's mum angry at WA jail release

The WA mother of a baby boy, who was killed when a heavily drunk woman smashed her car into his bedroom, says she should stay behind bars longer.

Nate Dunbar was just eight months old when Melissa Ann Waters ploughed her ute into his Merriwa home in January 2013, crushing him in his cot.

The District Court of Western Australia heard her friends had told her not to drive and attempted to hide her keys, to no avail.

Waters was sentenced in September 2013 to three years and eight months in jail, eligible for parole after one year and 10 months.

Nate's mother Stacey says she's angry Waters will be released in coming weeks.

"I'm not particularly happy about that," Ms Dunbar told ABC radio on Thursday.

"What message does this send to all those other drink drivers?

"You can go and kill somebody in their own home with your car after your decision to drive drunk, after being told multiple times by your friends (not to) and having keys hidden from you."

Ms Dunbar said Waters should have been made to serve her full jail term.

"I've never said I want her to rot in jail for the rest of her life. "I was expecting more around the five year mark, the five, maybe to seven year, mark. I think that is a much more appropriate sentence."