Sudden Infant Death Syndrome (SIDS), also known as "cot death," is a rare condition where an apparently healthy baby suddenly dies.

It typically occurs during the baby's sleep, but there have been instances where it happened while the baby was awake. Babies born prematurely or with low birth weight are at a higher risk.

There were about 3,400 sudden unexpected infant deaths (SUID) reported in the United States in 2020, with approximately 1,389 of those cases attributed to SIDS, according to the Centers for Disease Control and Prevention.

In a new study, researchers tried to understand the underlying causes of SIDS and found that it is linked to biological abnormalities.

Researchers gathered tissue samples of infant fatalities that occurred between 2004 and 2011 from the San Diego Medical Examiner's Office. They analyzed the brain stems of 70 infants to determine the presence of any consistent abnormalities.

The study showed that abnormalities in the serotonergic system specifically reduced serotonin binding to 5-HT2A/C receptors, which may be the root cause behind the condition. A previous study on rodents showed the 2A/C receptor played a role in promoting arousal and autoresuscitation, which helps protect the brain's oxygen supply during sleep.

Researchers say there could be three possible factors – the infant is in a critical stage of cardiorespiratory development during their first year, there were some external stressors like the baby was sleeping on its stomach or sharing the bed with someone else (experts say the best way to safeguard a child from SIDS is to make them sleep on their back) and the infant may have a biological abnormality that increases their vulnerability to breathing difficulties while asleep.

"The work presented builds upon previous research by our laboratory and others, which has demonstrated abnormalities in the serotonergic system of some SIDS infants," study lead author Robin Haynes told Science Blog.

Haynes noted that more work is required to understand the relation between these abnormalities and the cause of death. Researchers said the abnormalities when combined with other environmental and biological factors, including an infant's sleeping position, lead to an increase in the risk of SIDS.

The findings of the study were published in the Journal of Neuropathology & Experimental Neurology.

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An infant’s first year of life is filled with many changes that occur at a rapid pace. Photo courtesy of Pixabay