Bed sharing between adults and young babies multiplies the child's risk of Sudden Infant Death Syndrome five times, even if the parent is a non-smoker and hasn't consumed drugs and alcohol.
The finding comes from a University of Auckland study, looking at adults who share a bed with their breastfed baby in the child's first three months.
While there is a general consensus that sleeping with a baby increases the risk of SIDS if the parents smoke or if the mother has been drinking alcohol or taken drugs, previously there have been conflicting opinions about whether bed sharing represented a risk when these factors were not present.
The researchers found the risk of SIDS was fivefold in comparison to when a baby slept in a cot in the parents' room, even without these other factors, said Professor Mitchell, said University of Auckland paediatrician Professor Ed Mitchell.
"Sudden Infant Death Syndrome (SIDS) is a major cause of death among babies aged under one in New Zealand and other high income countries.