Isaac Newton's lifeless body was found in the double bed he was sharing with his dad, Brooklyn Newton, and older sister on the morning of September 6 2019.
An inquest last week heard that Mr Newton, of Egerton Road, North Shore, had put his son in the bed, surrounded by pillows, at around 10pm the night before.
At 12.30am he went to check on Isaac and give him his bottle. He then smoked some cannabis before getting into bed between his two children at around 1.30am.
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At 5.55am he awoke to find Isaac cold and unresponsive with blood around his nose.
A postmortem carried out later by Dr Alison Armor found the baby had been dead for some time and had been face down on the bed, as blood had pooled at the front of his body.
She said: “The cause of death was due to overlaying, which occurs when the weight of an adult body overlays the body of the baby. The effects of this on the chest and abdominal region prevent the baby from breathing.
“It is an unsafe practice to take a child into a double bed with an adult. This is exacerbated by the presence of alcohol or drugs. In this case, the cannabis levels in the father indicated previous cannabis use.”
She said it was unlikely that Isaac had rolled into a face down position on his own, as his family said he was not able to roll over yet.
After finding his son, Mr Newton ran through the house he shared with his parents shouting for help, and attempted to perform CPR.
An ambulance was called and Isaac was taken to Blackpool Victoria Hospital, where he was pronounced dead.
Police attended Mr Newton’s house and found drugs paraphernalia in the bedroom along with a cot that did not appear to have been slept in.
Evidence of prescribed medication and cannabis were found in Mr Newton’s system. However, Det Insp James Lillystone said the levels were too low to warrant criminal charges.
He told the hearing: “Brooklyn was very distressed and shaking, but did not appear impaired. When Brooklyn was told his son had died, he replied ‘it’s my fault’.”
In a statement after the hearing, Lancashire Police said: “An investigation established that no criminal offences had taken place. No arrests were made.”
The court heard that Isaac often co-slept with both his father and his mother - who lives in Preston - despite both parents being warned that it was dangerous.
Handing down a conclusion of accidental death, coroner Alan Wilson said: “This is a very upsetting set of circumstances.
“On Thursday, Isaac appears to have been bottle fed and has fallen asleep at 10pm and he was placed in a double bed by his father. During the course of the evening his father has smoked some cannabis. Police would go on to find a cannabis grinder and some cannabis.
“He has gone on to get into bed between Isaac and his sister.
“At the hospital Brooklyn did not present as impaired or under the influence. But at that point it had been a number of hours from the point at which Brooklyn first put Isaac to bed. It’s possible that having one joint of cannabis did impair him.”
Mr Wilson said he planned to write to the Department of Health and local children’s services to raise his concerns over unsafe sleeping.
He added: “Today we have heard about a young child who has been sleeping in his parents’ bed. This has been the fourth inquest I have done this year in which a child has died lying in or on a parent’s bed, and all seem to involve relatively young parents. Clearly, messages are not being followed.”