The purpose of this study was to examine the sequential mediating effects and the effect size difference of shame-proneness and two sub-types of ambivalence over emotional expression—self-defensive and relation-involved—in the relationship between self-discrepancy and postpartum depression among first-time mothers. A total of 261 mothers within one year postpartum completed the Self-Questionnaire, Test of Self-Conscious Affect-3(TOSCA-3), Ambivalence over Emotional Expression Questionnaire–Korean version(AEQ-K), and Center for Epidemiologic Studies Depression Scale(CES-D). Results showed significant sequential mediation through both shame-proneness and each subtype of emotional ambivalence, with a statistically significant difference in the effect size of the two indirect pathways. Finally, the heterogeneous characteristics of the two types of ambivalence contributing to these differences, an integrative conceptualization of the psychological processes, and theoretical implications were discussed. Additionally, based on the study findings, implications for counseling interventions and policy recommendations were presented.
