For decades, parents and doctors have had no way to know which newborns were most vulnerable to sudden infant death syndrome. A team of Australian researchers has now identified the first measurable blood biomarker linked to SIDS risk — a discovery that could one day allow doctors to flag at-risk infants at birth and tailor protective measures before tragedy strikes.
At a glance
- SIDS biomarker: Researchers found that infants who died of SIDS had significantly lower levels of an enzyme called butyrylcholinesterase (BChE) in blood samples taken at birth, compared to infants who survived or died of other causes.
- Newborn blood screening: The study drew on dried blood spot samples collected from 722 babies at birth — a routine procedure in many countries — meaning a future test could slot into existing newborn screening programs with minimal disruption.
- Brain arousal deficiency: BChE plays a role in the brain’s arousal system; researchers believe low levels may prevent some infants from waking or crying out when they face a life-threatening situation during sleep.
What the study found
The research, published in the journal eBioMedicine and led by Carmel Harrington of the Sydney Children’s Hospital Network, analyzed dried blood spot samples from 722 babies taken at birth. Of those babies, 67 died suddenly and unexpectedly between one week and two years of age. Twenty-six deaths were classified as SIDS-related; 41 were non-SIDS sudden unexpected infant deaths.
When researchers compared BChE levels across the groups, SIDS cases showed significantly lower levels of the enzyme at birth than infants in the healthy control group or those who died of other causes. It was the first time a specific physiological marker had been measurably linked to SIDS vulnerability in a blood sample.
“Babies have a very powerful mechanism to let us know when they are not happy,” Harrington said. “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.” Her team’s finding suggests that infants with low BChE levels may lack that robust arousal response.
Why this matters after decades of mystery
SIDS has long been understood through what researchers call the “triple risk model.” For SIDS to occur, three factors must converge: a physiologically vulnerable infant, a critical developmental window, and an external stressor. Environmental stressors — sleeping face down, exposure to tobacco smoke, soft bedding — have been well documented for years, and public health campaigns around safe sleep have meaningfully reduced SIDS rates in many countries.
But the physiological piece — what makes one infant more vulnerable than another — has remained stubbornly out of reach. SIDS still accounts for around 50 percent of all sudden unexpected infant deaths in Western countries. This study addresses that gap directly.
“What this research shows is that some babies don’t have this same robust arousal response,” Harrington said. “This has long been thought to be the case, but up to now we didn’t know what was causing the lack of arousal. Now that we know that BChE is involved we can begin to change the outcome for these babies and make SIDS a thing of the past.”
A path toward intervention
The practical potential of this finding is significant. Dried blood spot collection is already a routine part of newborn care in Australia and many other countries — the same heel-prick test used to screen for metabolic disorders. Incorporating a BChE assay into that existing protocol could, in principle, identify high-risk infants early and prompt closer monitoring or enhanced safe-sleep precautions.
Harrington has also signaled interest in developing interventions that could directly address the enzyme deficiency itself — potentially giving infants with low BChE additional protection beyond environmental safeguards. “This discovery has opened up the possibility for intervention and finally gives answers to parents who have lost their children so tragically,” she said.
The researchers at the Sydney Children’s Hospital Network are calling for further studies to validate their findings across larger and more diverse populations. The journal eBioMedicine, which published the study, is a peer-reviewed open-access publication from The Lancet group. Broader validation will be essential before BChE screening could be recommended for clinical use — the cohort of 26 SIDS cases, while meaningful as a discovery study, is relatively small, and replication in independent populations is a necessary next step.
That honest caveat sits alongside a genuine milestone. For the first time, a biochemical signal present at birth appears to distinguish infants at elevated SIDS risk from those who are not — giving researchers a concrete target to study, and giving grieving families, for the first time, something approaching an answer. The U.S. National Institute of Child Health and Human Development estimates that roughly 3,400 sudden unexpected infant deaths occur in the United States each year, a figure that underscores why a reliable screening tool would matter at scale. Organizations like the Lullaby Trust have long advocated for safer sleep environments; a biomarker test would complement, not replace, those behavioral safeguards.
Read more
For more on this story, see: New Atlas
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