The rate of sudden unexplained death in infants (SUDI) has been steadily rising in New Zealand, despite major efforts to reduce it.
Coroners' figures show there were 51 cases of SUDI last year, up from a low of 42 in 2012.
Now, it's prompted Chief Coroner Judge Marshall to speak out, saying many of the deaths are preventable.
"It's heartbreaking," Judge Marshall said.
"As coroners, we don't like to see these preventable deaths coming across our desks time after time, and we're talking about vulnerable babies. The message is quite simple – every sleep should be a safe sleep."
The Shoemark family, who lost baby Addison at just four month old, hopes the coroner speaking out will prevent other families from going through the "absolute hell" they've been through.
Craig Shoemark says: "If we can find a solution to what is still a problem for 50 families every year - to stop those 50 families going through the absolute hell of losing a baby - then it's worth it".
The numbers had previously been trending downwards, after The New Zealand Cot Death Study in the 90s helped identify several risk factors.
They include co-sleeping with the baby, the baby's sleeping position, smoking while pregnant, and the temperature during sleep.
"The fact that we had 51 deaths last year indicates that the message isn't getting through."
The Ministry of Health says it's recently started working with the Ministry of Justice to better track SUDI incidents as part of a national SUDI prevention programme launched in August last year.
The goal is to reduce SUDI rate to 0.1 per 1000 babies born by 2025.
The current rate is about 0.7 per 1000 babies born.
As part of the programme, $3.3 million goes to DHBs each year to support SUDI prevention activities, such as providing safe sleeping devices like PepiPods and Wahakura.
However, NZ College of Midwives advisor Jacqui Anderson is concerned that the safe sleeping devices are not "universally accessible for everybody in every area".
"I think that's something that's really important for the Ministry of Health to be considering," Ms Anderson said.
Hāpai te Hauora, the national SUDI prevention coordination centre, says it's working to better connect DHBs to Wahakura weavers to ensure the devices are available to more families.
Fay Selby-Law, the general manager for SUDI Prevention, says, "If they've got their Wahakura with them, and they know to keep baby sleeping face up - face clear in that Wahakura - then baby will be safe".
Ms Selby-Law believes the increase in deaths is also down to socio-economic factors, as some parents are unable to afford a cot or bassinet.