An Otago woman who poisoned her son with eye drops and nasal sprays while in hospital will never see the child again, the boy's father hopes.

The woman, aged in her 30s, was yesterday sentenced before the High Court at Auckland to 11 months' home detention after pleading guilty to two counts of ill-treating a child and one of theft.

The charges were representative, meaning the crimes happened repeatedly and the horrifying extent of the defendant's efforts to harm her son were divulged in a lengthy court summary.

It included details of dozens of internet searches and articles accessed by the woman in August 2019 while her baby was languishing in intensive care.

One article she read was entitled "Drugs that can kill toddlers because of accidental ingestion". Another was called "Just an (eye) drop of poison".

Her former partner told the Otago Daily Times he only found out about the woman's online activity when she pleaded guilty a few months ago.

"I was like 'holy crap'," he said.

The victim's father felt "absolutely betrayed" and was devastated the woman had evaded a prison sentence and been granted name suppression.

"Me and the kids are just moving on. The less we have to do with her the better.

"The best thing for them would be to have nothing to do with her. She's a very crafty sort of person."

He believed the defendant's crimes came down to a craving for attention that began when she set up a Givealittle page following her son's premature birth in 2018.

While the couple legitimately needed the nearly $1000 raised, the woman appeared to thrive on the outpouring of sympathy, he said.

During their son's stay in Dunedin Hospital's neonatal intensive care unit, the man said his then partner became "obsessed" with a couple in the ward whose baby died.

They stayed in contact until the news of the defendant's crimes broke.

"They were really gutted when they found out what she'd done," the victim's father said.

It began on August 12, 2019 when the defendant took the boy to her local medical centre, reporting that he had been coughing and vomiting.

Three days later he was transferred to Dunedin Hospital.

When the victim's condition improved and clinicians cleared him for discharge, the woman requested another night's stay because she was tired.

But rather than sleeping she spent hours scouring various web pages about the ingestion of a range of chemicals.

The next day she administered a toxic concoction to her son — a combination of non-prescription eye drops and her own anti-depressants.

The boy became "unresponsive and floppy" and had a life-threateningly low heart-rate, combined with high blood pressure.

Doctors fought to stabilise the child, putting him in an induced coma and later airlifting him to Starship Children's Hospital in Auckland.

- Robb Kidd, ODT

There the pattern repeated, though now the defendant began stealing eye drops from the hospital pharmacy.

Every time the boy's condition improved, the woman would make more internet searches about poisoning him before secretly administering the harmful chemicals.

But this time her online activity appeared to expose her fear of being caught.

She searched: "toxicology analysis" and "Starship policy when suspected child abuse".

The final search she made was "Abuse and neglect".

On August 27, toxicology results revealed her ongoing actions over the preceding two weeks.

An MRI scan that month showed tissue damage to three areas of the boy's brain, confirmed by another five months later.

"At this stage, it is not possible to determine whether [he] will experience any long-term effects from his brain damage," court documents said.

But miraculously, since being in his father's care, the now 3-year-old had suffered no further medical issues.

He had just been discharged by the child development team and was "going good", the man said.

He was left rocked by the experience though.

"There's such a range of emotions you feel, like you failed at protecting your child, but absolutely betrayed by your partner and his mum.

"I felt like an absolute fool," he said.

At court yesterday, The New Zealand Herald reported, defence counsel Julie-Anne Kincade stressed her client's genuine remorse.

There was no greater punishment than living without her children and knowing it was due to her own actions, the lawyer said.

Justice Christine Gordon acknowledged the defendant's abusive upbringing and mental disorders.

"It is abundantly apparent you have a complex psychiatric history."

A family member of the defendant wrote a letter to the court saying the woman often sobbed for hours, praying for her children.

While serving the sentence, she will need permission from Probation and Oranga Tamariki if she wished to contact her victim, and was barred from contact with under-16s unless supervised.

Justice Gordon imposed a protection order in favour of the boy.

Final suppression of the defendant's identity will be decided at a future hearing.