1.Making sure that all relevant cases of SIDS had been identified reliably
2.Comparing the cases with controls matched for risks of SIDS.
3.Appropriate investigations to ensure that the diagnosis of SIDS was accurate, including an autopsy, tests for familial causes of unexplained death and determining possible homicide.

However, all eight studies failed to meet these three criteria. This failure, the researchers state would have resulted in the risk of SIDS recurrence being overestimated.

'All eight studies failed to meet these three criteria, which would have resulted in the risk of recurrence being overestimated," the British Medical Journal quoted the authors, as stating.

"We conclude that, although an increase in risk is probable on theoretical grounds, the risk cannot be quantified from the available evidence," they said.

"Families whose initial death was fully investigated and who have no major risk factors can be advised that, although the risk of a second death might be slightly increased, it remains very small," they added.

"But my main intention is to get the message across to those parents who have lost their first child that they do not have a significant risk of losing a second," said co-author of the study Dr Christopher Bacon.

The study is published online ahead of print in Archives of Disease in Childhood.

Source: ANI
LIN/S