Validation and factor structure of the Japanese version of the inventory to diagnose depression, lifetime version for pregnant women

Introduction: A history of major depressive disorder before pregnancy is one risk factor for peripartum depression. Therefore, the purpose of the present study was to examine the validation and factor structure of the Japanese version of the Inventory to Diagnose Depression, Lifetime version (IDDL) for pregnant women. Methods: The study participants were 556 pregnant women. Factor analysis was performed to identify the factor structure, construct validity was examined based on the results of the factor analysis, and reliability was examined using Cronbach’s α coefficient. Results: Based on the results of the factor analysis of the IDDL, a bifactor model composed of a single general dimension along with the following five factors was extracted: (1) depression, anxiety, and irritability (items 1, 2, 8–10, and 19–21); (2) retardation, decreased concentration, indecisiveness, and insomnia (items 4, 11, 12, and 17); (3) decrease in appetite/significant weight loss (items 13 and 14); (4) increase in appetite/significant weight gain (items 15 and 16); and (5) diminished interest, pleasure, and libido (items 5–7). Cronbach’s α coefficients for these five factors were as follows: 0.910, 0.815, 0.780, 0.683, and 0.803, respectively. Conclusions: The reliability, construct validity, and factor structure of the Japanese version of the IDDL were confirmed in pregnant women.