New Zealand Coroner Chris Devonport has reiterated a warning against some parents' practice of putting their babies to sleep with them in their bed.

In his report, he said a 1-month-old baby boy from Gisborne died tragically from asphyxiation while co-sleeping in an adult's bed with his mother.

The New Zealand Herald said an autopsy found the death of baby T - an "anatomically normal male infant with no evidence of injury and no evidence of infection to satisfactorily explain the cause of his death" - was Sudden Unexpected Death in Infancy (SUDI).

The mother's 12-year-old son was with them that night, according to Herald, but the young boy had no statements as to what transpired the night before baby T died.

The report said baby T's mother had been drinking with neighbours on the evening before he died.

The mother, in reporting the death, said she found baby T with a pillow covering his face and someone had struck her with a hammer. Authorities found no evidence to support her claims.

In Australia last month, Victorian Coroner's Prevention Unit data shows 72 children aged between seven days and one year died suddenly as they slept. Of those, 33 had been sharing a bed, or other sleep surface, with an adult.