A new study from Australia may have revealed the cause of sudden infant death syndrome (SIDS), which typically happens to babies less than a year old.

It has been years since parents whose infants died unexpectedly were unable to get a concrete answer to what was causing the syndrome among infants.

Parents were advised that taking certain precautions, such as placing babies on their backs, preventing them from overheating and keeping cribs free of clutter, to reduce the chances of SIDS.

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The Centers for Disease Control and Prevention reported earlier that there are about 3,400 sudden unexpected infant deaths in the U.S. each year.

Dr. Carmel Harrington, a lead researcher on the study, said the discovery is part of “a very exciting journey ahead.”

“We are going to be able to work with babies while they are living and make sure they keep living,” Harrington said.

According to the study, the enzyme was significantly lower in babies who died from SIDS than those who died causes. The enzyme plays a key role in waking babies from sleep.

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“Babies have a very powerful mechanism to let us know when they are not happy,” lead researcher Dr. Carmel Harrington told The Sydney Children’s Hospitals Network. “Usually, if a baby is confronted with a life-threatening situation, such as difficulty breathing during sleep because they are on their tummies, they will arouse and cry out. What this research shows is that some babies don’t have this same robust arousal response.”

Harrington lost her 2-year-old son Damien to SIDS in 1991.

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“Does this shine light on what we can screen for in terms of looking for reasons why babies are vulnerable and what we can do in terms of treatment for that?” asked Riley Hospital for Children Pediatrician Dr. Melissa Klitzman. “We know it could be something with their heart or their breathing but is there something going on in terms of their nervous system that puts these babies really at increased risk for sudden infant death syndrome?”