Background Exposure to parental self-harm has been linked to an increased risk of self-harm and suicidal thoughts in their offspring. Much of the available evidence is from population registers or clinical samples and relates to parental death by suicide; few studies have investigated associations of non-fatal suicide attempts in parents with community presenting non-fatal self-harm and suicidal thoughts in offspring. We studied the association of parental suicide attempt (SA) with offspring self-harm and suicidal thoughts using a large two-generational prospective cohort.

Methods The sample comprised 4,396 children, their mothers and 2,541 of the mothers’ partners from the Avon Longitudinal Study of Parents and Children (ALSPAC). Parents were asked to report on incident episodes of SA on 10 separate occasions from pregnancy until the children were 11 years old. Information on lifetime childhood self-harm, with and without suicidal intent, and suicidal thoughts, with and without suicidal plan, was collected through child-completed questionnaires at the age of 16–17 years.

Results Based on preliminary results, SA was reported by 1.5% of the mothers and 0.7% of the partners. Adjusting for sociodemographic factors and parental depression, maternal SA was associated with 3-fold increased risk of self-harm with suicidal intent in their children [Adjusted odds ratio (AOR) 3.0, 95% confidence interval (CI) 1.4–6.1] but not with self-harm with no suicidal intent (AOR 0.8, 95% CI 0.3–1.9). Children exposed to maternal SA were more likely than unexposed children to report both suicidal thoughts with and without suicidal plan (AOR 5.2, 95% CI 2.3–11.6; AOR 2.2, 95% CI 1.1–4.4, respectively). Partner SA was associated with 2.3-fold increased risk of self-harm with suicidal intent (95% CI 0.5–10.6) and with an increased risk of suicidal thoughts with suicidal plan (AOR 3.5, 95% CI 0.8–16.0) but these results are consistent with chance. There was no evidence of an association between partner suicide attempt with offspring self-harm with no suicidal intent (AOR 0.4, 95% CI 0.1–3.5) or with offspring suicidal thoughts without a suicidal plan (AOR 0.6, 95% CI 0.1–4.5).

Conclusion Parental SA in childhood increases the risk of self-harm with suicidal intent in offspring but is unrelated to risk of self-harm without suicide intent. Parental SA is associated with larger effect size on suicidal thoughts with a suicidal plan than without a plan. Findings provide limited evidence that maternal SA is a more potent risk factor than partner SA.