Background Suicide is one of the leading causes of death amongst young adults in the UK. There has been no reduction in suicide deaths in the 15–24 age group since 2006. Recent evidence suggests low birthweight is associated with increased risk of suicidal behaviour in young adults. The risk of suicidal behaviour has also been shown to be higher in those with low educational attainment. We investigate whether educational attainment mediates the relationship between birthweight and attempted and completed suicide in a population of publicly-funded school leavers in Scotland during the period 2007–2012.

Methods Education data for school-leavers during the period 2007–11 were linked with birth records, mortality records and all acute and psychiatric hospital records from birth. Cox proportional hazards models were used to model the effect of birthweight on hazard of attempting or completing suicide between date of leaving school and September 2012. The mediating effect of educational attainment was observed. Educational attainment was measured using tariff points. Tariff points range from 1 to 120 per individual subject depending on the course level and award attained. A total score was calculated by summing all points accumulated during school. Models were fitted before and after adjustment for potential confounders including perinatal, early-life and maternal risk factors; other educational risk factors, such as student needs and school attendance; as well as childhood mental and physical health. Multiple-births and individuals known to have emigrated after date of leaving school were excluded.

Results In the population of 241,157 school leavers, 2827 (1.2%) attempted or completed suicide between school-leaving date and end of follow-up. Low birthweight (<2500 g) was significantly associated with increased hazard of event when compared to the baseline group (>= 2500 g), hazard ratio HR = 1.26 (95% CI = 1.08–1.46). Educational attainment was a significant mediator (p < 0.001) and accounted for 65% of the effect of birthweight on event. The significant effect of birthweight disappeared on adjustment for all covariates HR = 1.01 (95% CI = 0.86–1.19); however, educational attainment remained highly significant. Hazard of attempted or completed suicide significantly decreased for each additional tariff point achieved (HR = 0.998, 95% CI = 0.997–0.998).

Conclusion Education has the potential to lower rates of attempted and completed suicide in young adults. This is particularly important in a country with a high suicide rate such as the UK. The strong social patterning of suicide means that successful intervention at this stage would also reduce inequalities in mortality.