EDITOR—Jacobson and Bygdeman present intriguing data suggesting that the risk of suicide is influenced by birth trauma; they argue that this may explain recent increases in suicide among adolescents.1 However, deficiencies in the design and analysis of this case-control study should be addressed before the findings are accepted or possible mechanisms are considered.

The significant findings in Jacobson and Bygdeman's paper are confined to a subgroup of men who committed suicide using violent methods, were born and died in the catchment area of Stockholm's forensic medicine department, and had siblings whose birth records were available. The 175 males for whom the significant associations were found probably represent 25% of all suicides. The authors' suggestion that the association is restricted to violent suicides might be tested by presenting separate risk estimates for violent and non-violent suicides. Furthermore, there is overlap in the cases included in this analysis and those included in a previous study which reported highly significant associations …