Background: We investigated the association of early life social factors-maternal age, single motherhood, socioeconomic position, birth order and family size-with future risk of suicide in Taiwan.
Methods: Using a nested case-control design, we used linked data from Taiwan's Birth Registry (1978-93) and Taiwan's Death Registry (1993-2008) and identified 3984 suicides aged 15-30 years. For each suicide, 30 controls matched by age and sex were randomly selected, using incidence density sampling. Conditional logistic regression models were estimated to assess the association of early life risk factors with suicide.
Results: Younger maternal age (<25 years), single motherhood, lower paternal educational level and higher birth order were independently associated with increased risk of suicide. Stratified analyses suggest that lower paternal educational level was associated with male, but not female suicide risk (Pinteraction=0.02). Single motherhood was a stronger risk factor for suicide in female than in male offspring [odds ratios (95% confidence interval)=2.30 (1.47, 3.58) vs. 1.50 (1.01, 2.20), Pinteraction=0.12]. There was a suggestion that in families with large sibship size (≥4 siblings), the excess in suicide risk was greater among later born daughters compared with later born sons (Pinteraction=0.05).
Conclusions: Our findings provide support for the results of European studies, suggesting that early life social circumstances influence future risk of suicide. Factors specific to Taiwanese culture, such as a preference for male offspring, may have influenced gender-specific patterns of risk.
Keywords: Suicide; birth order; culture; family characteristics; gender.