Sudden Infant Death Syndrome is considered the most common cause of death among babies younger than one year old. The reason for these deaths is often a mystery.  Now researchers have discovered something unusual in the brains of many of these babies. 

Sudden infant death can occur without warning.  The parent puts the baby to bed, only to return and find it has stopped breathing.  Doctors do not really understand why, but there are some common factors associated with what is also called 'crib death.' 

A majority of these deaths occur in the first six months of life, often during the winter months, and frequently while the baby sleeps on its stomach or on its side.  There are no symptoms or signs of struggle.

Thirteen years ago Steve and Katie Scully of suburban Washington, D.C. lost their baby Carolyn to SIDS.  Katie Scully still feels the pain: "Yeah, it was such a shock.  You know, I had read about SIDS, but that wasn't going to happen to me.  That's one in a thousand."

Researchers from Children's Hospital of Boston, Massachusetts and Harvard Medical School think they may have discovered a cause for crib death.  What they found were abnormalities in the brainstems of 31 babies and 10 infants who had died of SIDS.  Their study indicates an imbalance in the neurotransmitter called serotonin that influences the baby's breathing, temperature and ability to wake up.  The danger occurs when babies born with too much serotonin are placed on their stomachs to sleep. 

Dr. Marian Willinger of the National Institute of Child Health and Development explains why the findings are so important.  "What's so important about this paper -- and exciting -- is the fact that there is an actual structural and biochemical problem in the part of the brain that controls life sustaining functions that we think are affected in SIDS babies."

At present it is not possible to confirm a diagnosis of Sudden Infant Death Syndrome in a living child.   But scientists hope to develop a test in the future that can identify those babies at risk, as well as a means of correcting the defect before it is too late. 

If that happens, Katie Scully says, it might save other parents from the grief she and her husband have endured. "You know, babies aren't [supposed] to die, and when one does, it's so shocking, it's so tragic, it's so what's not supposed to happen.  So, if even just one little life is saved today, then every effort that all these people have done is so worthwhile."