Factor structure and measurement invariance of the Edinburgh Postnatal Depression Scale during the perinatal period: a longitudinal study of Japanese women

BACKGROUND: The Edinburgh Postnatal Depression Scale1, a 10-item self-administered questionnaire, was developed as a screening instrument for postnatal depression. It is now used as a tool to identify depression after childbirth as well as during pregnancy. Our study aimed to examine the configural and measurement invariance of the factor structure of the Japanese version of the EPDS from a 4-wave prospective cohort study from pregnancy to after childbirth.METHODS: A set of questionnaires was distributed to pregnant women at 26 weeks gestation or later during pregnancy. These women were followed and distributed the same questionnaires at 1, 3, and 6 months after childbirth.RESULTS: The number of women who returned the questionnaires was 536, 450, 417, and 400 at the four measurement time points, respectively. The present study demonstrated that the 6-item 3-factor model proposed by Kubota et al. 2 fit the data better than those derived from our exploratory factor analyses. The 6-item 3-factor model was stable across the perinatal period at the level of scalar invariance.CONCLUSIONS: The present study encourages clinicians to use the 6-item EPDS rather than the full 10-item version. The 6-item version is easier to use and more stable across the perinatal period.