The woman's husband, David, told Australian TV show 3rd Degree that he walked in to find his wife attempting to kill their newborn daughter last year.
"The baby's throat was cut and [she] was cutting her [own] wrists"
He revealed: "She was hearing things and seeing things that didn't exist and was saving the baby by killing it.
"The baby's throat was cut and [she] was cutting her [own] wrists."
Thankfully, despite the fact her trachea was severed and an artery cut, their little girl's life was saved - and the mother was taken to a local mental health unit.
Tragically she had no recollection of what she had done - and David was forced to explain to his wife how she almost murdered their child.
"She will never forgive herself."
The woman was found not guilty of attempted murder because the attack happened during an episode of temporary insanity, diagnosed later as post-natal psychosis.
A forensic psychiatrist told the court that ‘her psychotic mental state would ... have rendered her unable of knowing that the act was morally wrong’.
After receiving psychiatric treatment, the mother was reintroduced to her four-month-old little girl for the first time at a hospital.
She has been given permission to return to her family home under the condition she is never alone with the child, The New Zealand Herald reported.
3rd Degree's Phil Vine has been staying with mother, father and baby since last September as they gradually com to terms with what's happened - and come back together as a family.
It will air tonight.
**Puerperal (post-natal) psychosis is a very rare, but severe, mental health condition that is experienced by one or two in 1,000 women in the weeks after having a baby. **
Symptoms can include sleeplessness, full of energy, restlessness and irritability.