Postpartum self-harm thoughts and subsequent risk of intentional self-harm

Suicide is a leading cause of maternal mortality, with many cases considered preventable. The Edinburgh Postnatal Depression Scale (EPDS) item 10 screens for self-harm thoughts in the past 7 days. This study aimed to investigate whether a positive response ('hardly ever', 'sometimes' or 'quite often') is associated with subsequent hospital-registered intentional self-harm, non-suicidal or suicidal, among postpartum women.

We conducted a population-based cohort study of 170 218 childbirths (38% of the source population) from 142 795 unique women in Denmark by linking nationwide registers with the HOPE cohort. Self-harm thoughts were defined as any non-zero response to EPDS item 10. The primary outcome was a hospital-recorded episode of intentional self-harm within 365 days after childbirth. To account for confounding, we applied inverse propensity-score weighting, and we used Firth's penalised logistic regression to estimate ORs.

Of the 170 218 childbirths, 2935 (1.7%) reported self-harm thoughts. During a mean (SD) follow-up of 303.0 (11.2) days, eight women (0.27%) with self-harm thoughts were hospitalised due to intentional self-harm, demonstrating a 24-fold higher crude rate compared with women without self-harm thoughts (0.01%). After applying weighting, the adjusted OR remained significantly elevated at 10.91 (95% CI 7.03 to 17.99).

This is the largest study to date on this topic. We found that postpartum women reporting self-harm thoughts had a low absolute risk of intentional self-harm, but the relative risk was 11-fold higher. These results highlight the importance of further assessment and timely support for mothers identified as being at risk.