The Child and Youth Mortality Review Committee says figures shows fewer babies and young people are dying.
The committee's latest figures on deaths for those aged between 28 days and 24 years were released on Thursday. In 2012, 600 in that age group died compared with 699 in 2008.
It said one of the reasons for the fall was that there were fewer car crashes involving people aged between 15 and 24.
Committee chairman Nick Baker said young people's behaviour had changed substantially, in part because of police's zero tolerance to offending by young drivers, and advertising had also made people realise alcohol and driving do not mix.
Dr Baker said there were also fewer cases of sudden unexpected death in infancy because of improved safe-sleep policies by district health boards, greater community awareness and better access to safe-sleep resources and equipment.