Table 1 Maternal outcome measures

State-Trait Anxiety Inventory (STAI) [22]

40-item instrument that measures the presence and severity of current anxiety symptoms (State Anxiety subscale, 20 items) as well as a generalized, relatively stable tendency to be anxious (Trait Anxiety subscale, 20 items). The theoretical range of subscale scores is 20 to 80, with higher scores indicating greater anxiety. Internal consistency (0.86–0.95) and test-retest (0.73–0.86) reliabilities are high.

Edinburgh Postnatal Depression Scale (EPDS) [23]

10-item screening measure for postnatal depression. Total scores range from 0 to 30, with higher scores indicating greater depressive symptoms. Using a score of ≥13 as cut-off, the scale has acceptable sensitivity (0.86), specificity (0.78), and positive predictive value (73%). Internal consistency reliability is high (0.87), and the scale is sensitive to changes in severity of depressive symptoms over time.

Parental Stressor Scale: Neonatal Intensive Care Unit (PSS:NICU) [24]

26-item scale that captures parental perceptions of stress in the NICU on 3 subscales: sights and sounds (6 items), infant behavior and appearance (13 items), and parental role alterations (7 items). A total score is calculated by averaging the responses on all items. The theoretical range of scores is 1 to 5; higher scores indicate greater overall stress. Internal consistency reliability is 0.89 for the total score.

Perceived Maternal Parenting Self-Efficacy (PMP S-E) tool [25]

20-item measure of parenting self-efficacy in mothers of hospitalized preterm infants. Measures maternal perceptions of their abilities across 4 subscales: care taking procedures (e.g., feeding and bathing), evoking behavior(s) (e.g., soothing the infant), reading behavior(s) or signalling (e.g., knowing when the infant is tired), and situational beliefs (e.g., believing the infant responds well to them). Total scores range from 20 to 80, with higher scores indicating greater perceived parenting self-efficacy. Internal consistency (0.91) and test-retest (0.96) reliabilities are high.