Self-harm in pregnancy and the postnatal year: prevalence and risk factors

Background Self-harm in pregnancy or the year after birth ('perinatal self-harm') is clinically important, yet prevalence rates, temporal trends and risk factors are unclear. Methods A cohort study of 679 881 mothers (1 172 191 pregnancies) was conducted using Danish population register data-linkage. Hospital treatment for self-harm during pregnancy and the postnatal period (12 months after live delivery) were primary outcomes. Prevalence rates 1997-2015, in women with and without psychiatric history, were calculated. Cox regression was used to identify risk factors. Results Prevalence rates of self-harm were, in pregnancy, 32.2 (95% CI 28.9-35.4)/100 000 deliveries and, postnatally, 63.3 (95% CI 58.8-67.9)/100 000 deliveries. Prevalence rates of perinatal self-harm in women without a psychiatric history remained stable but declined among women with a psychiatric history. Risk factors for perinatal self-harm: younger age, non-Danish birth, prior self-harm, psychiatric history and parental psychiatric history. Additional risk factors for postnatal self-harm: multiparity and preterm birth. Of psychiatric conditions, personality disorder was most strongly associated with pregnancy self-harm (aHR 3.15, 95% CI 1.68-5.89); psychosis was most strongly associated with postnatal self-harm (aHR 6.36, 95% CI 4.30-9.41). For psychiatric disorders, aHRs were higher postnatally, particularly for psychotic and mood disorders. Conclusions Perinatal self-harm is more common in women with pre-existing psychiatric history and declined between 1997 and 2015, although not among women without pre-existing history. Our results suggest it may be a consequence of adversity and psychopathology, so preventative intervention research should consider both social and psychological determinants among women with and without psychiatric history.