Sharing a bed with a newborn increases the risk of sudden infant death syndrome fivefold, research claims.
The risk applies even if parents avoid tobacco, alcohol and drugs - other factors firmly linked to cot deaths.
The BMJ Open research compared nearly 1,500 cot deaths with a control group of more than 4,500 parents.
Current guidance in the UK is that parents should decide where their baby sleeps, but says the safest option is in a crib or cot in the same room.
/BBC/