Background The cause of postpartum depression remains unclear, with extensive research suggesting a multi-factorial aetiology. However, epidemiological studies and meta-analyses of predictive studies have consistently demonstrated the importance of psychosocial and psychological variables. While interventions based on these variables may be effective treatment strategies, theoretically they may also be used in pregnancy and the early postpartum period to prevent postpartum depression. Objectives Primary: to assess the effect of diverse psychosocial and psychological interventions compared with usual antepartum, intrapartum, or postpartum care to reduce the risk of developing postpartum depression. Secondary: to examine (1) the effectiveness of specific types of psychosocial and psychological interventions, (2) the effectiveness of individual versus group-based interventions, (3) the effects of intervention onset and duration, and (4) whether interventions are more effective in women selected with specific risk factors.