Table 1 Description of variables and measures

Ethnicity

<25 weeks

Ethnicity coded as White, Black/African, North American, First Nations (that included registered, unregistered, and Metis), Asian (including Chinese, Japanese and Korean), Other Asian (including South Asian, Filipino, Southeast Asian, and West Asian), Arab, Latin American, and Mixed/Other. Dominant culture = White/Caucasian; ethnic minority = all other ethnicities.

Edinburgh Postnatal Depression Scale (EPDS) [20, 73]

<25 and 34–36 weeks

10-item self-report scale to measure depressive symptoms in pregnant and postnatal women. Excludes somatic symptoms such as fatigue and change in appetite as these changes are likely to occur in pregnancy and could possibly confound the scores. Theoretical range 3 to 30; response categories vary by item; scores of ≥ 13 or greater are considered problematic. Sensitivity = .86; specificity = .78. EPDS discriminates between women with a diagnosis of depression and those without. A score ≥13 at either time point was defined as depressive symptoms.

MOS Short Form Health Survey-12 (SF-12) [74]

<25 and 34–36 weeks

12-item self-report scale adapted from the Medical Outcomes Study 36-Item health survey [74] to measure eight health concepts: physical functioning, physical role, bodily pain, general health; vitality, social functioning, emotional role, and mental health. Response categories vary by item., Temporal stability over 2 weeks = .89 for physical and .76 for mental components. The SF-12 discriminates between patients with minor and serious physical and mental conditions. Concurrent validity with SF-36 r = .95. SF-12 was computer-scored and coded as above or below the developers’ cut-off.

Medical Outcomes Study (MOS) Social Support Survey (SSS) [75]

<25 and 34–36 weeks

19-item self-report scale to measure perception of the availability of different forms of support: emotional support, tangible/functional support, informational support, and positive social interactions. Used extensively to explore the interaction of social support and health outcomes [76]. Theoretical range of scores is 19 to 100; higher scores indicate greater social support. Items are summed to create subscale and overall social support index. A score ≤ 69 at either time point was defined as inadequate social support.

Perceived Stress Scale (PSS) [77]

<25 and 34–36 weeks

Widely used [78], 10-item self-report scale to measure perceived stress related to unpredictability, uncontrollability, and overload over the last month. Theoretical range of scores is 10 to 50; higher score indicates higher stress. Cronbach’s α = .85; temporal stability over 2 days = .85. For this study, a PSS score in the top 20^th percentile at either time point was considered problematic.

State-Trait Anxiety Inventory (STAI) [79]

<25 and 34–36 weeks

20-item, self-report measure of anxiety in adults on two dimensions: State (temporary condition) and Trait (general and long-standing quality). Theoretical range of scores is 20 to 80; higher score indicates higher anxiety. For this study, only State Anxiety scores were used. Scores ≥ 40 at either time point indicated the presence of State Anxiety.