What causes sids?

Sleeping on belly: Recent studies have shown that belly sleeping can be major cause of sids, causing decreased oxygen to brain. Nowadays, the recommendations by the aap is for all kids to sleep on their back for that reason.

True cause unknown: Although studied in detail for years, the true origin of sids is unknown. Population studies have shown factors that increase the risk: belly sleeping or side sleeping(they fall on their belly), multiple birth, smoker in home, poverty, etc. The "back to sleep " program that started in ~1992 has resulted in a 40% drop in sids in some populations in the us.

Brain Abnormality: Some of the leading thinking with SIDS is that a brain abnormality is the cause of an abnormal breathing response when more oxygen is necessary. The hippocampus is a focus of much of this research. http://www.medicinenet.com/script/main/art.asp?articlekey=185460