New Clue Into Cause of Sudden Infant Death Syndrome (SIDS)

By BEA KARNES, News First 5, Colorado Springs, Colorado

Sudden Infant Death Syndrome is the leading cause of death for babies under a year old with most SIDS deaths occurring between the ages of 2 and 4 months.

The deaths come without warning, and for a long time without any known cause. Parents these days are told to put their newborn babies to sleep on their backs to reduce the risk for SIDS. The "Back To Sleep" campaign has been successful, reducing the number of crib deaths by about half since it began in the early 90's.

Still, thousands of seemingly healthy babies die in their sleep each year.

"You cannot tell a living baby is going to die of SIDS that night. There's no marker," said Dr. Hannah Kinney of Children's Hospital Boston.

But now doctors at Children's Hospital Boston have uncovered a big clue leading them to a likely cause for SIDS.

"We've come to focus on serotonin," said Dr. Kinney.

Dr. Kinney, along with a team of doctors and scientists has found that SIDS babies have low levels of serotonin in their brainstems.

Serotonin helps regulate breathing, heart rate and blood pressure. Too little could impair those functions especially during sleep.

"Something about sleep unmasks the defect when the baby is stressed," said Kinney.

Stress, like re-breathing carbon dioxide when they're sleeping on their tummies makes affected babies vulnerable.

Researchers say infants with normal brainstem serotonin levels would be able to wake up long enough to turn their heads and breathe fresh air.

The long-term goal is to develop a test to identify which babies have this serotonin defect and then try to prevent it altogether.Some pregnant women take antidepressant drugs called SSRIs that affect serotonin levels in the mother.

But there is no conclusive research on whether those drugs impact developing brainstems.

Doctors say pregnant women prescribed such medication should not stop taking it based on this study.

What expecting mothers should forego, are alcohol and cigarettes.

Experts say both greatly increase the risk for SIDS.