Many of the 44 babies who died of cot death in 2015 were living in damp, cold conditions - including converted garages and even cars.
A report released todayshows rates of sudden unexpected death in infancy (SUDI) have dropped drastically, but not for everyone.
Maori babies are still almost seven times more likely to die unexpectedly in their sleep than non-Maori, non-Pacific Island babies. Pacific Island babies are almost four times more likely to die, according to the Child and Youth Mortality Review Committee's report.
The committee is calling for the Government to do more to look after these at-risk families.
Sudden infant death rates in New Zealand dropped from about 250 a year in the 1980s to 44 in 2015, the review found. It estimated 37 of those deaths were preventable.
"While New Zealand has made clear strides to reduce the number of SUDI deaths, too many of our babies are still dying," committee chair Dr Felicity Dumble said.
The review found many of the families were living in poor quality or overcrowded homes, which often leads to bed-sharing.
Mother and baby sleeping in the same bed is a major risk factor for SUDI as the mother can accidentally suffocate her child.
Some whanau and families were staying with others in crowded situations, some were living in temporary or emergency accommodation, and "a few" were living in cars or converted garages, the report said.
"Many of these living situations were damp and cold, with many babies having ongoing physical health problems prior to death."
Making safe sleep devices widely available would help improve babies' safety, whatever their environment, the report found.
Health Minister Jonathan Coleman decided to fund the sleep devices, known as pepi-pods, for at-risk families after a 2016 investigation by the Herald.
In announcing the funding last week he said he was aiming to reduce the SUDI rate to 0.1 in every 1000 births by 2025, which would cut the number of deaths from 44 a year to six.
Dumble said that news was "heartening".
"The CYMRC knows whanau and families living in higher deprivation areas often face significant challenges in providing their babies with a warm, dry home and a safe sleep space, so this is a very positive step."
The combination of bed-sharing and having a mother who smoked while pregnant is "extremely hazardous", the report says.
Such babies are 32 times more at risk of dying unexpectedly in their sleep compared to a baby who does not bed-share and is raised in a smoke-free household.
The committee wants stop-smoking services and more funding to house families at risk of SUDI in warm, uncrowded homes.
Rates of SUDI are highest in Gisborne, Whanganui and Northland. Within Auckland they are disproportionately high in Counties Manukau, which has the city's highest Maori and Pacific Island population.
As Maori and Pacific Island families are most likely to lose a baby through SUDI, the committee also wants to ensure everyone from police to pathologists and funeral directors know how to offer culturally appropriate support to grief-stricken whānau.