Table 1.

Measures of Independent Variables

Independent Variables (Coding)	Item Description, Reference, and Data Source
Personal Factors
Age (years)	Abstracted from the medical chart
Race (1 = white, 0 = non-white)	Adapted from Census 200034*
College educated (1 = yes; 0 = no)	Adapted from National Health Interview Survey35*
Marital status (1 = married; 0 = no)	Adapted from National Health Interview Survey35*
Primiparous (1 = yes; 0 = else)	Adapted from National Health Interview Survey35*
Annual household income ($)	Adapted from National Health Interview Survey35*
Prenatal smoking (1 = yes; 0 = no)	Item assessed smoking during pregnancy36*
Perceived control (1 = none/very little, 2 = some, 3 = a lot, 4 = complete)	“Before this pregnancy how much control did you have over the time and effort spent caring for family, doing home chores or paid work?”37*
Social support (5-item scale with summary score: 5 = none of the time to 25 = all of the time)	“How often are the following kinds of support available to you, if needed: someone to: (1) confide in or talk about your problems, (2) get together with for relaxation, (3) help with daily chores if you are sick, (4) turn to for suggestions about how to handle personal problems, and (5) someone to love and make you feel wanted”38*
Perinatal Factors
Chronic health problems (1 = some problems; 0 = none)	Presence/absence of hypertension, diabetes, cardiac disease, renal disease, asthma; abstracted from medical records
Preconception health (1 = poor/fair, 2 = good, 3 = very good, 4 = excellent)	“How would you rate your health in general before this pregnancy?” item adapted from SF-1233*
Prenatal mood disturbances (1 = yes; 0 = no)	“During this pregnancy did you ever have a problem with your mood, such as feeling depressed or anxious?”11*
Labor and delivery complications (1 = some problems; 0 = none)	Presence/absence of anesthetic complications, excessive bleeding, lacerations, seizures, eclampsia, abruptio placenta or infections; abstracted from medical chart
Cesarean delivery (1= yes, 0 = no)	Abstracted from medical chart
Infant girl (1= yes, 0 = no)	Abstracted from medical chart
Colicky baby (1 = yes, 0 = no)	Item developed and validated by investigators6: “Has your baby had fussy, irritable behavior that lasts for at least 2 days or had colic?” †
Postpartum Factors
Breastfeeding (1 = yes, 0 = no)	Item developed and validated by investigators,6 “Which of the following are you feeding your baby: breast milk, formula, milk (cow or soy), other? “ (Multiple response options allowed) †
Health services used ($)	Measure of price-weighted volume of health care services used after hospital discharge from childbirth through 5-wk interview. Services included emergency department visits, number of hospital days, outpatient surgeries/procedures, doctor office/urgent care visits, mental health visits; the number of encounters was multiplied by the unit price/encounter using claims data for women of reproductive years from Blue Cross Blue Shield Minnesota, 2001. All costs were summed for a price-weighted volume of services used39
Time elapsed since childbirth (days)	Computed from infant birth date and interview date
Employment characteristics
Employment status (1 = working, 0 = on leave from work)	Item adapted from Cantor et al40*
Occupational classification (blue collar/service = 1; else = 0; clerical = 1; else = 0; professional = reference)	Taken from US Census41†
Prenatal hours worked/week (hr)	Average work hours past 12 mo*
Prenatal job stress (2-item summary score of 2 = almost never to 10 almost always)	Items taken from Mardburg et al37 and validated6; “How often do you have too much to do? How often do you experience stress from your job?” *
Prenatal job satisfaction (1 = very to somewhat satisfied; 0 = very to somewhat dissatisfied)	Global job satisfaction item taken from Quinn and Staines42*
Prenatal supervisor support (1 = strongly disagree, 2 = disagree, 3 = agree, 4 = strongly agree)	Item adapted from Bond et al43 and validated6; assesses maternal perception of supervisor’s helpfulness during pregnancy†

* Data collected in person at enrollment in the hospital.

† Data collected by telephone at the 5-week interview.