Lower levels of the hormone serotonin may help explain why some infants succumb to sudden infant death syndrome (SIDS), according to a new study.
In the U.S., SIDS deaths have declined by more than 50% since 1990. Experts say that's partly due to practices believed to minimize the risk, such as putting infants to sleep on their backs rather than their stomach and avoiding soft bedding, which could lead to asphyxiation.
But SIDS is still the leading cause of death among infants age 1-12 months, accounting for about 2,750 U.S. deaths annually. It's defined as the death of an infant before his or her first birthday that can't be explained even after a complete autopsy, investigation of the death scene and circumstances, and a review of the medical history of the child and family.
Now, the new research suggests that a deficiency of serotonin in the brain stem (which controls vital functions during sleep, such as breathing, heart rate, and blood pressure) may help explain most of the deaths, says study researcher Hannah Kinney, MD, a professor of pathology at Harvard Medical School and a neuropathologist at Children's Hospital Boston, WebMD reports.
The researchers say the low levels of serotonin may inhibit a baby's ability to deal with breathing challenges like low oxygen levels or high carbon dioxide levels. Carbon dioxide may accumulate when babies rebreath air while sleeping face down.
Doctors recommend placing babies on their backs for sleeping, AHN reports.
Researcher Dr Jhodie Duncan, of the Melbourne-based Florey Neuroscience Institutes also provides a new insight into another of SIDS known risk factors - women who smoke during pregnancy or smoking in a home with a newborn.
Exposure to nicotine was also known to affect serotonin levels in the body, Dr Duncan said.
It is hoped the research could result in a new regime of testing, monitoring and treatment that could intervene to stop babies dying from SIDS.
"The ultimate test would be able to identify these infants and then monitor them as a high-risk infant, and intervene to alter their serotonin levels," Dr Duncan said, AAP reports.
US President Joe Biden and Iraqi Prime Minister Mustafa Al Qadimi signed an agreement on July 26 to formally end the USA's military presence in the country by the end of the year