Sids research needs ideas and input from different types of people as well as medically trained people. Some non-medical people may have ideas or understanding overlooked by the later group. Searching for causes is not the only issue, discovering ways to reduce the probability of Sids is also very helpful.
It should not be presumed that SIDS is a constant rate of 1:500 over place and time. Rates in Australia have dropped significantly in the last few years, presumably due to recent recommendations not to put a baby to sleep facedown and to breastfeed. Lower smoking rates may have also contributed.
Active or passive smoking during pregnancy leads to a lower birthrate nad a higher incidence of SIDS. After birth, moderate smoking by the mother coincides with double the rate of SIDS while heavy smoking leads to up to 5 times the rate.
Given the above figures don't take passive smoking into account, and that babies whose father's smoke (and not their mothers) have a average lower birth rate, the differences between smoking and non-smoking (including no passive smoking) may be higher. It is suggested to have no-one smoke in the same house while a baby is asleep. (Smoke travels from room to room.)
The real surprise is that so many babies survive smoking. I dare say if all babies always slept in extremely smoke filled rooms, SIDS would increase astronomically. Passive smoking is extremely stressful for infants, reduces circulation, lowers immunity, increase respiratory infections etc.
Breast feeding is well established as reducing incidence of SIDS. In the 50s non-breast babies were so much more prone that it was believed for a while that formula milk was the sole cause. Breast feeding is well known to strengthen immunity and to reduce stress in the infant. Breast feeding on demand for young babies is suggested. This is well known to medicos, but unfortunately this information is not always passed on.
Don't have the baby under 6 months sleep in its own room. Don't leave the baby unobserved for long periods of time in the morning when Sids is most likely to happen. Don't put the baby face down.
Severe stress increases the chances of sids. Are Sids babies comforted and touched less than other babies? A small percentage of Sids babies turn out to be victims of child abuse.
To my knowledge no research has been done on the birth of SIDS and near SIDS babies. The very first breaths may establish lifelong breathing patterns. Did the child have difficulty in breathing in birth as prem babies sometimes do? Were there any interventions in birth? Was the baby given oxygen? Was the babies's breathing effected by drugs etc. Was the baby in a humicrib? An unpleasant birth experience may cause later stress. Important questions.
Vaccinations cause stress in the infant and may lower immunity for a period afterwards. Some statistics suggest that there is increased chance of Sids shortly after the triple antigen is given. A big study could be good here, but medical researchers tend to ignore medicine as a possible cause of disease. (The term for doctor caused disease is iatrogenic disease, and its more common than you realise.)
It is surprising that very young babies rarely get Sids. More likely to be breastfed? More contact from the mother? Why do the mothers tend to be younger? Why is it much more common in working class families? Is their any influence of the mother's diet or drug use? Is suffocation or overwrapping a factor in some cases? it certainly isn't in many. There is more statistical work that could be done.