Primary psychological outcomes
The Pregnancy-Related Anxiety (PRA) scale is a 10-item scale used to examine the extent to which women are worried about their own and their baby’s health, labor, delivery and caring for a new baby. Items are rated on a scale ranging from 1 (
never or not at all) to 4 (
a lot of the time or very much). The scale has shown strong associations with maternal and infant health outcomes over and above other traditional measures of state and trait anxiety [
7,
88]. This scale has been found to have acceptable internal consistency (Cronbach’s alpha = 0.79).
The Edinburgh Depression Scale (EDS) will be used to assess symptoms of depression experienced during pregnancy and the postpartum period. Higher scores indicate more depressive symptoms. The EDS has been validated against interview schedules and other self-report instruments and has good internal reliability [
89].
The Generalized Anxiety Disorder Scale (GAD-7) will be used to screen for and assess the severity of generalized anxiety disorder (GAD). Higher scores indicate more symptoms of GAD. The GAD-7 has excellent reliability and good criterion and convergent validity [
90].
The Perceived Stress Scale (PSS-10) will be used to assess symptoms of perceived stress. The PSS-10 has good reliability and validity [
91]. Among pregnant and postpartum women, it has been found to have a satisfactory level of internal consistency, ranging from 0.71 to 0.83 [
92,
93].
Secondary physiological outcomes
Salivary cortisol will be collected at home on 2 weekdays using the following schedule: upon waking, 30 min after waking, and at 20:00 h. Participants will receive individualized training on collecting samples during their first study. They will be given instructions to use Salimetrics Oral Swabs (SOS) to collect saliva samples and an app (mEMA, developed by Tefsoft, Inc.) to answer questions about the timing of sample collection and their current mood. In addition, the importance of adhering to the schedule will be emphasized.
Stress reactivity. At each of the three visits (baseline, post-treatment and, follow-up), participants from both groups will complete two stress tasks: a mental arithmetic and a Stroop task [
64]. Each task will be followed by a 5-min recovery period. After the first recovery period, researchers will take 2 min to explain the second task. During the baseline period, subjects will be fitted with cardiovascular recording equipment and will sit quietly for 5 min. During the stress tasks and recovery periods, participant’s HRV and BP will be continually assessed. At the beginning of each stress task condition, participants will be instructed to respond as quickly and accurately as possible without making errors. These tasks reliably induce a stress response (REF) and have been used reliably in pregnancy.
Mental arithmetic task. During this 3-min task, participants will be presented with a series of mathematical subtraction equations with the answers included on a computer screen. They will be asked to determine whether the answer to each equation is correct or incorrect. Each correct answer is followed by a beep emitted from a speaker. Each incorrect answer is followed by a noxious blare emanating from the same speaker. The task was designed to change in difficulty according to the participant’s ability to maintain a 60 % correct answer rate [
94].
Stroop task. During the Stroop task, participants are asked to correctly identify the color of the stimulus on a computer screen [
95,
96]. During the 5-min stress period, participants will see a series of words (“red”, “green”, “blue”, “yellow”) on the screen and will be asked to correctly identify the color of the stimulus (i.e., the text) by using one of the keyboard buttons. Each correct answer is followed by a beep emitted from a speaker. Each incorrect answer is followed by a noxious blare emanating from the same speaker. Each task is followed by a 5-min recovery period. Order of the stress tasks will be fully counterbalanced across participants.
Blood pressure and heart rate variability will be assessed after a 2-min resting period at baseline by taking the mean of three seated measurements obtained during a 5-min baseline period. Systolic BP and diastolic BP (in mmHg) will be obtained at 1-min intervals during a 25-min period that includes baseline, stress tasks, and recovery periods. BP data is collected using an automatic, calibrated, oscillometric BP monitor (BpTRU Vital Signs Monitor, BpTRU Medical Devices, Coquitlam, BC, Canada). Electrocardiography (ECG) (BIOPAC MP36 system and BIOPAC MP36 Student Laboratory Program, BIOPAC Systems, Goleta, CA, USA) will be used to collect heart rate data, which in turn will be used to calculate HRV. Heart rate will be monitored on a beat-to-beat basis during baseline, stress tasks, and the two recovery periods. Three ECG leads will be placed: two leads on either side of the upper chest, equidistant from the heart, and one lead on the left side of the mid-abdomen.
Subjective and objective sleep. Subjective sleep quality and quantity will be assessed using the Pittsburgh Sleep Quality Index (PSQI). The PSQI consists of 19 self-rated items and five questions rated by the roommate or bed partner. There are seven components of the PSQI including: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medications and daytime dysfunction [
97]. The PSQI has good reliability and its validity has been confirmed by concurrent polysomnographic findings [
97] and among pregnant women [
98]. Self-reported sleep hours often do not accurately reflect objective sleep time [
99]; therefore, in this study participants’ sleep will also be assessed using wrist actigraphy (Actiwatch II, Philips, Pittsburgh, OH, USA). Participants will be asked to wear an actigraph on their nondominant arm for 48 h at each assessment point. Data will be collected on weekdays to minimize the variability caused by potential differences in weekday and weekend sleep patterns. In order to accurately assess rest and sleep intervals, participants will also complete a sleep diary and note the times when they go to bed, nap, and wake up during the day on which they wear the actigrapher. The Actiware Software (Version 6.0.1) will be used to configure and download the data from the Actiwatches. Assessment of sleep with actigraphy has demonstrated sensitivity to treatment effects [
100].
Demographic assessment
Demographic information will include marital status, ethnicity, age, family socioeconomic status (household income, education level, neighborhood characteristics of the home), working status, and number of children in the home. Health practices will be assessed via self-report and will include smoking, alcohol consumption, and level of habitual exercise. Assessment of previous mental health problems and assessment of psychotropic medication use will be assessed via interview.