A Hamilton mum was found breastfeeding her baby while high on P during a Waikato drug operation, shocking veteran detectives.
Waikato police acting district crime services manager, Detective Inspector Chris Page, said the woman appeared oblivious to the risk to her baby.
Children were found in nearly 20% of homes raided by police during the month-long methamphetamine operation, dubbed Operation Share.
Page said the breastfeeding incident was a first for his 27-year policing career.
"I think members of the community will be shocked by this, and it reinforces for us how important it is to continue to target and work on the methamphetamine trade and industry," he said.
"We have come across children in drug-dealing houses and methamphetamine labs previously, but this is the first occasion I'm aware of where we've actually come across breastfeeding."
The drugged mum was among 32 arrests made by the team of about 50 police throughout the operation. Her baby was placed in Child, Youth and Family care.
Police searching the Hamilton East house early last month found a meth bag and pipe next to baby formula in the kitchen.
"Two children were found in the house, including a special needs child who requires regular treatment."
Other Hamilton parents face charges after forensic scientists found methamphetamine traces in the cot of a one-year-old baby. Samples taken from the hair of the baby and its sibling showed they had been exposed to methamphetamine for at least six months.
While cases of children being exposed to drugs - including P - were not unusual, the circumstances of the mother were new territory. Page described the operation as a "bittersweet" success.
"Whilst we're very pleased to be able to catch and prosecute drug dealers, it's tainted significantly by the finding of children in the condition they're in, in these houses.
"That's what causes investigators real concern because no-one else is looking after those kids."
Page said anyone under the influence while caring for a child, "is in my view not taking into consideration the risks and the care of that child".
The case is also uncharted territory for the country's leading researcher who is profiling prenatal drug exposure and infant mental health. Dr Trecia Wouldes, developmental psychologist and lecturer at University of Auckland, said there was no research on the effects of breastfeeding a baby while on P.
"As you can imagine it's a very tricky study to do ethically. You can't really encourage someone to take P and then breastfeed and then say 'hey, give me some of that breast milk'. But one study carried out has shown that P is present in the breast milk."
The breast milk study was carried out by Professor Anne Bartu, of the Curtin University school of nursing and midwifery in Perth. She gained samples from two breastfeeding mothers, and found that the drug was still in their breast milk after 24 hours.
Waikato District Health Board director of nursing and midwifery Sue Hayward said it was not appropriate for anybody, especially babies, to ingest or be exposed to illegal drugs.
"While I may not have come across any mother who has been high on P while she has been breastfeeding, I have come across mums who have been on medication or addictive drugs where it crosses through breast milk."
She was also concerned about the "conscious or cognitive" state of the mum. "And the baby being exposed to levels of (medication/drugs) that they should have no exposure to at all because they're such fragile little bodies, systems and brains."
Page said anyone who noticed suspicious behaviour that could be linked to drug use should contact police or the Crimestoppers line on 0800 555111.
Waikato meth raids
32 properties searched
10 grams of methamphetamine found
$10,000 cash seized
Six weapons uncovered