A seven-week-old baby who died four years ago at her southern Tasmanian home suffocated while sleeping in bed with her parents, a coroner has found.
The girl, known only as MH, was brought into the bed by her dad during the early hours of September 1, 2016.
She was found unresponsive around 7am.
Her breathing was most likely restricted by her father or the adult bedding, coroner Olivia McTaggart wrote in findings published on Wednesday.
"MH would not have died if she had been placed on her back in her own cot to sleep," Ms McTaggart wrote.
At two assessments with Child Health and Parenting Service prior to MH's death, her mother, aged 20 at the time, indicated that she provided a safe sleeping environment.
Ms McTaggart wrote she was fully satisfied MH's mother was aware of safe sleeping practices and "based upon all of the evidence in the investigation ... neither parent did any deliberate act with an intent to harm MH".
Child Safety Services were involved with MH's two older siblings before her birth, and received four notifications from 2012-14 around neglect, general parenting concerns and family violence.
Ms McTaggart said there were no, or no significant, failings in the CSS responses to the notifications.
She said CSS actions and decisions were not sufficiently connected to MH's death to require extended investigation and had been covered in an extensive review published in 2018.
However, Ms McTaggart wrote with the hindsight of a coronal investigation "it is apparent that the risks to (the) children did not diminish to any significant degree after CSS ceased involvement two years before MH died".
"Those risks included poor parenting skills. (The mother's) worsening mental health issues, dirty and unhygienic home conditions and smoking within the house," she added.
On the morning after MH's death, emergency services noted the house appeared dirty, the bedrooms in disarray and ashtrays with used cigarette butts were in several rooms.
MH's cot mattress was stained and dirty, as was the bedding on the main bed in the lounge room, they described in an affidavit.
MH's mother said her daughter was "the happiest she had ever been" the night before she died.