Table 1 Study measures

Parental Stressor Scale: (PSS: NICU) [61]

Change in total and subscale scores between baseline and discharge

50-item scale that captures parental perceptions of stress in the NICU: (1) sights and sounds, (2) appearance and behavior of the infant, (3) impact on the parental role and relationship with the infant, and (4) parental relationship and communications with staff. Internal consistency (0.89 to 0.94 for the total scale) and test-retest (0.87) reliabilities are high

Parenting Stress Index - Short Form

(4th ed.) [62]

Total and subscale scores at 2 months CA

36-item scale that captures general parenting stress as well as the three subscales of Parental Distress, Parent-Child Dysfunctional Interaction, and Difficult Child. Internal consistency (0.91 for Total Stress, 0.80 to 0.87 for subscales) and test-retest (0.84 for Total Stress, 0.68 to 0.84 for subscales) reliabilities are acceptable

Edinburgh Postnatal Depression Scale [63]

Change in total score and proportion in the clinical range (≥13) between baseline discharge and 2 months CA

The most commonly used pre- and postnatal depression screener validated for mothers. Consists of 10 items and has a sensitivity of 0.86 and specificity of 0.78, with a positive predictive value of 73%

State-Trait Anxiety Inventory (STAI) [64]^a

Change in total score on State Anxiety between baseline, discharge and 2 months CA controlling for Trait Anxiety

40-item scale that captures dispositional/trait anxiety (20 items) and current state anxiety (20 items). Internal consistency (0.86 to 0.95) and test-retest (0.73 to 0.86) reliabilities are high. Scores on the STAI and PSS: NICU are correlated [61].

Perceived Maternal Parenting Self-Efficacy scale [65]^b

Change in total score on between baseline discharge and 2 months CA

20-item measure of parenting self-efficacy validated for mothers of preterm infants. Captures maternal perceptions of ability to (1) give basic care, (2) elicit change in infant behavior, (3) recognize infant behavior, and (4) judge interactions with her infant. Exploratory factor analysis confirms four factors; internal consistency (0.91) and test-retest (0.96) reliabilities are high

Modified Breastfeeding Self-Efficacy Scale - Short Form [66]

Change in total score and subscale scores between baseline, discharge and 2 months CA

18-item scale validated for mothers of ill and/or preterm infants. Assesses a mother’s confidence in her ability to breastfeed when her infant is ready on four subscales: (1) performance accomplishments, (2) vicarious experience, (3) verbal persuasion, and (4) physiological responses. Internal consistency (0.88) is high

Ages and Stages Questionnaires

(3rd ed.) (ASQ-3) [67]

Proportion of infants in the referral zone at 2 months CA

A widely used developmental screening instrument consisting of 21 age-appropriate questionnaires, with 30 items each, for use with infants and children 1 to 66 months of age. Assesses development in five domains: communication, gross motor, fine motor, problem-solving, and personal-social. For each domain, cut-off scores have been empirically derived for (a) appropriate development, (b) monitoring zone (≥1 and < 2 standard deviations below the mean), and (c) referral (2 standard deviations below the mean). The ASQ-3 has strong psychometric properties, including high sensitivity (0.86) and specificity (0.85) [68], and has been evaluated and recommended as an effective screener of global development in moderate and late preterm infants [23, 69, 70]