Epidemiological investigation of sudden infant death syndrome infants--recommendations for future studies.

In recent years the study of infant care practices within the sleeping environment has proved to be the single most important set of observations for reducing the risk of Sudden Infant Death Syndrome (SIDS). To further reduce the number of deaths and resolve the debate on safe infant care practice, a closer scrutiny of this environment is required. However, anecdotal observation from uncontrolled death-scene investigations and a reluctance to diagnose SIDS because of adverse social conditions or circumstantial evidence at the time of death is undermining future research. To investigate SIDS now means investigating the wider umbrella of all Sudden Unexpected Deaths in Infancy (SUDI) because of the potential for misdiagnosis. In trying to find out why SIDS infants die we have increasingly been forced to search for why infants survive in the first few months of life and it is this comparative component of epidemiological observation that has saved so many lives. A death-scene investigation is vital to any planned future investigation of SIDS but equally essential is a sleep-scene investigation of surviving infants to put any findings into context. SIDS infants are no longer scattered across the social strata and the cot is not the only environment in which they are found, social deprivation and use of the parental bed are now more discernable. Future studies should therefore reflect these changes with a second control group of surviving infants more closely matched to the type of environment in which SIDS infants might be found.