The paternal grandparents of a one-year-old boy whose mother sexually violated him for money deny they fought for her name suppression to be lifted out of revenge.

The woman, who now has renewed name suppression, pleaded guilty to filming herself sexually violate her baby son, then selling that video to a man for $300.

Her son is now being cared for by his paternal grandparents, who fought in court to have the woman's name suppression lifted.

The woman was intially allowed to be named before a court subseqently reversed that decision.

"People saying that we may be doing it out of revenge, but that's not the case. It is just because we wanted people out there to know who (cannot be named) really is," the boy's paternal grandmother told ONE News.

The mother of two was sentenced to eight months home detention, 100 hours community service and 20 months of judicial monitoring, with the judge saying the Manukau District Court prison could have a negative impact on the 23-year-old.

Webpages have been setup calling for her to go to jail and police are investigating online death threats made against her.

But her lawyer says home detention will be more effective than jail because she will recieve counselling and rehab while at home.

She'll also be monitored for an extra 12 months after completing her home detention and if she was jailed the authorities couldn't monitor her as closely, the lawyer said.

Her mother says her daughter "got away with far too much".

"I think it's disgusting. My grandson would not have known what was going on. He was so vulnerable and she's meant to love him and take care of him, not use him as a sex object."

It was also revealed in court that the woman was put into state care at an early age because her mother was in an abusive relationship at the time.

"The reason why I didn't leave him because he threatened if I left him he'd kill me and the kids. So I tried to protect my girls as much as I could. And that was the only way - for me to get a hiding to protect the girls."

The boy's grandparents say he's doing well.

"I bought him a Thomas the Tank Engine train set, sun hat, schoolbag and everything for Christmas. And he just loves it, apparently.

His paternal grandmother said: "When I tuck him into bed at night and I give him a kiss and I think this is something that a mother should be doing, not me."