A report into the nature of child deaths in NSW over a 10-year period found that children in the child protection system were 9.8 times more likely to die from Sudden Unexpected Death in Infancy, which includes deaths from Sudden Infant Death Syndrome (SIDS).

While the deaths are categorised as unexpected, Barnardos chief executive Louise Voigt believes abuse or neglect could be a contributing factor in the SIDS deaths of 179 children known to the department.

''SIDS deaths are more likely to happen when a child's birth history shows, for example, the mother's alcoholism or drug use,'' she said.

''I'm sure some of those children in utero had a pretty difficult experience. Children who are seen by the department come from a population with a whole range of issues, alcohol above all else.

''The automatic and rapid conclusion is that these are SIDS deaths, but they really could be child abuse.''

The report from the NSW Ombudsman found that one in five of the 6,152 young people who died between 2002-11 were known to child protection services.

Children known to the department were almost three times more likely to die from unnatural causes than children who had not come into contact with the protection system.

They were almost 24 times more likely to die in a fire, 6.3 times more likely to be killed in an assault, 5.5 times more likely to die from accidental poisoning and 4.1 times more likely to take their own lives.

NSW Ombudsman Bruce Barbour said the deaths were correctly classified but acknowledged that many of the SUDI deaths involved babies being exposed to tobacco smoke or being put to sleep in unsafe situations such as on a couch or in a bed with an alcohol or drug-affected parent.

State Labor health spokesman Andrew McDonald said families at risk need to be targeted early.

''If governments are serious about reducing these rates, then universal, long-term visiting is the only way.

''We're not doing it for long enough. It can't be six-month visits, it needs to be done over five years.''

While some families have greater risk factors for accidental and non-accidental child deaths, he said, many of the causes are outside parental control.

''Smoking, drug and alcohol use and over-crowded housing are often beyond the control of parents.''

He said high mortality rates from fire were because of smoking and inadequate heating which could lead to fires from bar radiators.

''Most of these deaths are accidental. Trying to tease out where poverty ends and where neglect and abuse begins is often extraordinarily difficult.''

smh.com.au