A team of Australian researchers have identified a biochemical marker in the blood that could help identify newborn babies at risk for sudden infant death syndrome (SIDS), a breakthrough they said creates an avenue to future tragedy-preventing interventions.

In their study, babies who died of SIDS had lower levels of an enzyme called butyrylcholinesterase (BChE) shortly after birth, the researchers said. BChE plays a major role in the brain's arousal pathway, and low levels would reduce a sleeping infant's ability to wake up or respond to its environment.

The findings are...