Season-of-Birth as a Risk Factor for the Seasonality of Suicidal Behaviour

This study investigated the interaction between season-of-birth & the seasonality of suicide. 2923 adult suicides & 33,321 deliberate self-harm hospitalizations in Western Australia were examined. A variable population at risk approach was used to determine season-of-birth. Seasonality was established by spectral analysis. Deliberate self-harm had a significant season-of-birth & seasonality occurrence, both peaking in spring. Individuals born in the 90 days centred on the peak birth period, however, showed no deliberate self-harm seasonality. In contrast, suicide had no season-of-birth. A season-of-birth effect was found among the deliberate self-harm group that eliminated any seasonality of deliberate self-harm among the high-risk by birth group. (52 refs.) JA