Cross-sectional and longitudinal validation of a 13-item fatigue scale among Japanese postpartum mothers.

This study examined the psychometric properties of a 13-item fatigue scale for postpartum mothers. Japanese mothers (n = 2026) from a cohort study completed questionnaires (e.g. fatigue scale, Japanese version of the Edinburgh Postnatal Depression Scale, demographics) during their hospital stay after childbirth (baseline) and at 1, 2, 4 and 6 months postpartum. Initial factor analysis of baseline data revealed that the fatigue scale had three factors or subscales (physical, emotional and cognitive). Within-group analysis across each measurement time revealed the same three-factor structure with acceptable fit. Between-group analysis also showed longitudinal factorial invariance across time. The fatigue subscales had acceptable divergent and convergent validities with the depression scale. The subscale scores differed significantly based on participant background. The Japanese Fatigue Scale is a concise and informative tool for assessing aspects of fatigue in clinical settings and in the community.