Perceived Stress
The Perceived Stress Scale (PSS; 26, 27) assesses individuals’ stress appraisals and ability to successfully cope with the demands of stressors over the previous month. The 14-item PSS was administered during the 17–22 weeks’ gestation telephone interview, and the 10-item version was administered between 27–30 weeks’ gestation. Respondents were instructed to rate each item on a five-point scale ranging from 0 (never) to 4 (almost always). After reverse scoring positively worded items, a total score is calculated by summing across all items. Higher scores reflect greater distress and lower confidence in personal coping resources.
Depression
The Center for Epidemiological Studies-Depression Scale (CES-D; 28) is a 20-item measure of symptoms of depression manifest in the general population. It has been widely validated as a screening instrument for psychological distress in diverse community samples (29). This instrument requires respondents to endorse each item with respect to the last week using a Likert scale with total scores ranging from 0–60. Higher scores indicate greater reported depressive symptoms. The CES-D scale was self-administered at ≤ 20 weeks’ gestation and between 24–29 weeks’ gestation.
State and Trait Anxiety
The Spielberger State-Trait Anxiety Inventory (STAIS/T; 30) is a well-established measure of both transitory and dispositional anxiety. Each instrument includes a set of 20 items with Likert response categories. Higher scores on the state measure reflect greater current anxious affect, while higher trait scores indicate a more stable tendency to experience elevated levels of anxiety. Both the state and trait forms were self-administered before 20 weeks’ gestation. The state form was re-administered between 24–29 weeks’ gestation.
Self-esteem
The 10-item Self-esteem Scale (31) was used to evaluate participants’ general estimations of self-worth and degree of positive or negative orientation toward the self. This measure has been extensively used in research that traverses multiple health-related disciplines. Respondents indicate their level of item agreement on a 6-point scale2. Higher scores reflect more positive self-appraisals. This instrument was self-administered between 17–22 weeks’ gestation.