Children's Health Newborns and Toddlers

A Step Closer to Understanding SIDS

There may be some new clues into understanding a mysterious cause of death that affects the youngest and most helpless among us. Researchers from Children’s Hospital Boston have discovered a brain abnormality that may make some infants more prone to sudden infant death syndrome (SIDS).

SIDS is the leading cause of death of infants in America, affecting more than 2,000 babies every year. While the cause for the most part had not been understood, experts believed that SIDS, which strikes babies as they sleep, is tied to breathing difficulties that leads to a baby suffocating during the night.

It is for that reason, that the Centers for Disease Control recommends that a baby under the age of one always be put to sleep on his or her back on a firm mattress, cradle, etc, without fluffy pillows or stuffed animals that could possibly fall on a baby’s face.

These preventative measures have helped to lower the rate of SIDS by more than 60 percent between the years of 1980 and 2000, but researchers still never understood why SIDS affects some children.

However, in a review of autopsies from infants that died of SIDS between 1997 and 2005, researchers have found that these babies all had a commonality. Compared to their peers, those who died from SIDS tended to have an abnormality in their brain stem, in cells that make serotonin, a chemical that helps nerve cells communicate with each other. The study was published in the Journal of the American Medical Association.

It is believed that serotonin helps to coordinate breathing, blood pressure and temperature during sleep. When a baby sleeps face down or with his or her face covered by a blanket or pillow, they are more likely to re-inhale the carbon dioxide that they just exhaled, not fresh, oxygenated air. “A normal baby will wake up, turn his or her head and start breathing faster when carbon dioxide levels rise,” said Dr. Hannah Kinney, study author in a press release. However, in a child with abnormal serotonin levels, his body may not react at all, the researchers theorize. In fact, 65 percent of the children in the study who died of SIDS were found sleeping on their side or stomach.

These abnormalities begin to develop in the womb, said Kinney, and may be caused by smoking or alcohol use by the mother while she is pregnant. The findings also explain why SIDS tends to affect children under six months of age, a time when their body is still developing to function independently outside of the womb. So, in an older child various mechanisms may be able to monitor breathing during sleep, but a baby may rely on this section of the brain stem.

“We think that these control systems reach full maturity only towards the end of the first year of life,” said Kinney.

Kinney hopes that her work will lead to the development of screening tests to identify those babies at risk for SIDS. She also believes that a treatment to protect children with this abnormality is a possibility.

“We provide strong evidence that SIDS is a biological problem, and that the brainstem serotonin system isn a good place to focus continued research efforts,” said Kinney.