Sudden Infant Death Syndrome - Causes

While the exact cause or causes of SIDS are still unknown, one important factor may be infection of the respiratory (breathing) tract. Some studies show that many babies who die of SIDS had recently been treated for a cold or other respiratory illness. Most SIDS deaths occur during the winter and early spring. These seasons are the peak times for respiratory infections. Research suggests that the following factors may increase the risk of SIDS for a baby:

• The baby sleeps on his or her stomach.
• The baby's mother smoked during pregnancy.
• The mother was under the age of twenty at pregnancy.
• The mother abuses drugs.
• The mother received little or no prenatal (before birth) care.
• The baby was born prematurely (early) or with a low birth weight.
• The baby lives in house where someone smokes.
• The baby is male (SIDS is more common for infant boys that girls).
• Baby is a member of a minority or low-income family.
• Baby's family has a history of Sudden Infant Death Syndrome.

Theories about SIDS

Researchers have long been puzzled as to the actual cause of SIDS. While there are a number of theories to explain the condition, none of them have been proven. Doctors are often unable even to determine whether a baby died because of a heart problem or because it suddenly lost the ability to breathe.

Generally the theories focus on either medical disorders or the baby's physical surroundings.

MEDICAL DISORDERS. One theory about the cause of SIDS is that the baby's upper airway gets blocked. The baby suffocates because it can not get oxygen. Another theory is that the baby's blood has the wrong composition and may not contain enough of certain chemicals needed to keep the brain functioning.

A third theory is that SIDS babies have a faulty nervous system. Normally, infants have a mechanism that wakes them up when their oxygen supply is low. It could be that SIDS babies don't have that mechanism. Other theories blame SIDS on a faulty immune system or the buildup of certain chemicals called fatty acids in the baby's blood.

PHYSICAL SURROUNDINGS. Some researchers think SIDS may be caused by the way a baby sleeps. For example, it may be that a baby sleeps with its face in soft bedding or that the baby may be wrapped too tightly in blankets. Either of these situations can stop the baby from breathing properly or getting enough oxygen.