On having been born, several factors of risk as the black race, the masculine sex and the low weight are associated with the syndrome of sudden infantile muete (SMIS). Often in these cases the mothers are single and poor young people; they have received little or no prenatal attention; they have been sick during the pregnancy and smoke or consume more drugs. Also it is probable that the parents are young and smoking. The adverse socioeconomic circumstances worsen the risk of syndrome of sudden infantile muete (SMIS), although the syndrome also affects the babies of privileged families.

What are the causes of the syndrome of sudden infantile muete (SMIS)? The condition is not contagious or caused by asphyxia or vomiting. A theory suggests the neurological abnormality; a cerebral chemical alteration. The studies point towards difficulties in the regulation of the respiratory control, in the transition of the sleep at wakefulness and in awakening and to be capable of turning the head in order to avoid the drowning. The affected babies can lack a protective mechanism that he allows them to wake up to turn the head when the respiration is restricted by the position. In Italy the investigators have found a clear relation between the syndrome of sudden infantile muete (SMIS) and an unusual abnormality in the cardiac rhythm, which can be identified by means of an electromiocardiograma.

It seems that the SIMS is the result of a combination of factors. An underlying biological defect can do that during a critical period of his development some babies are vulnerable to certain experiences that they contribute or unleash the syndrome as the exhibition to the cigaret or to sleep on the abdomen.

The investigation supports firmly the connection with the nicotinism in the ancestors. Almost 30 % of the sudden deaths might be avoided if the women you embarrass they will not smoke. The exhibition to the cigaret, so much earlier as after the birth, seems to be related to the pulmonary and cerebral development. The exhibition to the caffeine also can constitute a risk factor. If a mother consumes every day at least four cups of coffee (or other drinks with caffeine) while it is pregnant, his baby has a risk 65 % taller of suffering syndrome of sudden infantile muete (SMIS).

The studies endorse the relation between the syndrome of sudden infantile muete (SMIS) and to sleep on the stomach. To sleep of side is not also sure, since the babies placed in this position often are turned on the abdomen. The valuations of syndrome of sudden infantile muete (SMIS) diminished close to 70 %en some countries that continued the recommendations of the international sanitary authorities to do that the babies sleep on his backs. The babies must not place themselves in soft surfaces like pillows, comforters or skin of sheep.

To sleep on the back tends to give like turned out a temporary delay in the development of the skills motorboats that need force in the top part of the trunk, like turning on himself, sitting down, crawling and standing up. Nevertheless, these achievements still keep on being realized inside the normal ages and the moment in which the babies begin to walk does not turn out to be significantly affected.