Objective: Mothers of premature infants are more likely to develop anxiety during the first postpartum year than mothers of term infants. However, commonly used measures of anxiety were developed for general adult populations and may produce spurious, over-inflated scores when used in a postpartum context. Although perinatal-specific tools such as the Postpartum Specific Anxiety Scale [PSAS] offer a promising alternative form of measurement, it is not clear whether the measure performs similarly in mothers of premature infants as it does in mothers of term infants. The objective of the current study was to identify whether items on the Postpartum Specific Anxiety Scale - Research Short Form (PSAS-RSF) are being interpreted in the same manner in mothers of term infants and mothers of premature infants. Mothers (N = 320) participated in an international on-line survey between February 2022 and March 2023 (n = 160 mothers of premature infants, n = 160 mothers of term infants) where they completed the PSAS-RSF. Data were analysed using a measurement invariance analysis to assess whether constructs of the PSAS-RSF are performing in a similar manner across the two groups.
Results: Whilst the PSAS-RSF achieved configural invariance and so retains its four-factor structure, metric invariance was not reached and so items are being interpreted differently in mothers of premature infants. Items concerning infant-separation, finance, and anxieties surrounding infant health are potentially problematic. Future research must now modify the PSAS-RSF for specific use in mothers of premature infants, to ensure measurement of anxiety in this population is valid.
Keywords: Gestational age; Measurement invariance; Postpartum anxiety; Preterm birth; Psychometric measurement.
© 2024. The Author(s).