SEASONALITY OF BIRTH IN SUDDEN-INFANT-DEATH-SYNDROME

The objective was to clarify. the optimal birth month for avoidance of SIDS and the seasonal characteristic of each birth-month cohort. The statistical method was cosinor analysis and this established seasonali ty of SIDS death and births, the extent of this seasonality (amplitude ) and the position of the peak (acrophase). There is a lowering of ris k, by one third amongst babies born in February-May compared to those born in August November The seasonal variation of death was twice as g reat for births in September as compared with those in April. Those bo rn in May-June lived on average six weeks longer than those born in No vember-April. Advice on subsequent pregnancy delivery date should be g iven to families who have already experienced SIDS. For those born in autumn there may be two Components - the first a genetic or intrauteri ne component independent of month of birth, and the second an independ ent effect of interaction with winter environment.