Development and preliminary validation of the Postpartum Psychotic Experiences Scale (PPES)

Despite the emerging research interest in postpartum psychotic experiences, there is still a lack of measures for specifically measuring this construct. The contribution of this paper is to design and validate a novel self-report measure, the Postpartum Psychotic Experiences Scale (PPES), to screen for attenuated psychotic symptoms during postpartum. This cross-sectional study was conducted from September 2022 until June 2023, enrolling 438 women 4-6 weeks after delivery. Starting from an initial pool of 22 items, both Exploratory Factor Analysis and Confirmatory Factor Analysis suggested that remaining 15 items loaded on one factor (α = 0.95). The PPES showed good convergent validity with the Prodromal Questionnaire-Brief scale (correlations >0.8) and good concurrent validity with postpartum depression and anxiety scales. A PPSE score of 8.5 (sensitivity=85.2%, specificity=78.6%) was defined as the optimal cutoff point. At this cutoff, 47% of participating women were considered at possible risk for postpartum psychosis. This study provides, for the first time, a specific self-report measure to assess postpartum PEs reliably and validly. We hope that the PPES will facilitate routine screening for PEs after childbirth among women who are predisposed to developing postpartum psychosis.