Table 2.

Primary and Secondary Outcomes and Mediating Variables

Variable	Description	Assessment Method	Assessment Time*	Reference
Primary Outcome
Total gestational weight gain	Difference between the delivery weight and pre- pregnancy weight (lbs). Weight at last prenatal care visit is used if delivery weight is not available.	Delivery weight: medical record abstraction Pre-pregnancy weight: self-reported at initial screening	S, Chart	Validity of self-report measure: Oken et al [53] Phelan et al [54]
Secondary Outcomes
Meeting IOM GWG guidelines and weekly rate of GWG	Difference between delivery weight or weight at last prenatal care visit and measured baseline weight divided by number of gestational weeks; compared to 2009 IOM recommended weekly rate of weight gain (excessive, adequate, or inadequate)	Delivery weight: medical record abstraction Study starting weight: staff assessed with Seca scale	B, Chart	IOM Guidelines [3]
Postpartum weight retention	Difference between weight at 6 months and pre-pregnancy weight (lbs) Difference between weight at 12 months and pre-pregnancy weight (lbs)	6 and 12 months: staff assessed Pre-pregnancy: self- reported	S, 6M, 12M
Pregnancy and postpartum physical activity	Steps/day and minutes/week spend in moderate- to vigorous- intensity physical activity	SenseWear Armband worn continuously for at least 5- days wearing (≥1 weekend day) and having at least 21 hours/day of on- body time (main focus) Self-reported via the International Physical Activity Questionnaire (secondary focus)	B, 32W, 6M, 12M	Johannsen et al. [55] Smith et al [56] Berntsen et al [57] Craig et al [58]
Pregnancy and postpartum dietary intake	Main variable (averaged over two days): caloric intake per day. Exploratory variables (averaged over two days): fruit and vegetable cups per day; % calories from total fat, saturated fat, and transfat; servings per day of whole grains; servings per day of sugar sweetened beverages; grams/day of fiber; diet quality (HEI)	2 24-hour unannounced dietary recalls (one weekday and one weekend day) assessed via the Automated Self- Administered 24- hour Recall (ASA24)	B, 32W, 6M, 12M	ASA24: Kirkpatrick et al [65] Subar et al [66] HEI: Guenther et al [104]
Health- related quality of life	Health-related quality of life in eight areas used to create two scores: physical component summary score (PCS) and mental component summary score (MCS).	Interview- administered self- report measure: The Short Form health survey (SF-12) 12 items The raw scores of each item are coded, weighted, and summed to create the two composite scores	B, 32W, 6M, 12M	Ware et al [68]
Offspring adiposity	Measures of offspring adiposity are weight, weight-for-recumbent length (WFL), BMI, mid- upper arm circumference, triceps skinfold, and subscapular skinfold	All staff assessed Weight assessed with digital baby scale (Tanita Model 1584) Recumbent length assessed with Infantometer (SECA 417) Head circumference and mid-upper arm circumference assessed by infant head tape measure Upper arm length and mid-upper arm length measured with woven tape measure (ADC item 396) Triceps and subscapular skinfolds measured with a Lange caliper Using WHO’s Child Growth Standards, sex- and age- specific percentiles and z-scores are computed for each measure	6M, 12M	WHO Child Growth Standards [69, 71] NHANES Anthropomet ry Procedures Manual [72] Grummer- Strawn et al [70]
Mediating variables
Social support for exercise	Frequency with which friends and family are supportive of the participant’s exercise	Interview- administered self- report measure: Friend Support for Exercise Habits Scale and Family Support for Exercise Habits Scale plus 3 additional items created for pregnancy 16 items, rated for both family and friends Each item rated for frequency on 5-point Likert scale and averaged across items	B, 32W, 6M, 12M	Sallis et al [75]
Social support for healthy eating	Frequency with which friends and family are supportive of the participant’s healthy eating	Interview- administered self- report measure: Friend Support for Diet Scale and the Family Support for Diet plus 2 additional items created for pregnancy 12 items, rated for both family and friends Each item rated on a 4-point Likert scale and averaged across items	B, 32W, 6M, 12M	Sallis et al [75]
Exercise self- efficacy	Confidence for overcoming common barriers to exercise	Interview- administered self- report measure 5 items Each item rated on a 7-point Likert scale and averaged across items	B, 32W, 6M, 12M	Marcus et al [76]
Diet self- efficacy	Confidence for overcoming common barriers to eating a healthy diet	Interview- administered self- report measure: Self-Efficacy for Diet Questionnaire 10 items Each item rated on a 4-point Likert scale and averaged across items	B, 32W, 6M, 12M	Sallis et al [77]
Exercise self- regulation	The extent to which self- regulation (setting goals and planning/scheduling) skills are used for physical activity	Interview- administered self- report measures: Exercise Goal- Setting Scale and Exercise Planning and - Scheduling Scale 10 items per scale Each item rated on a 5-point Likert scale and averaged across items	B, 32W, 6M, 12M	Rovniak et al [78]
Diet self- regulation	The use of weight control strategies and frequency of weighing	Interview- administered self- report measure: Scale from the HealthStyles survey 22 items Participants report (yes/no) whether they used each of 21 strategies to control weight. Also rate frequency they weight themselves (range: never to every day)	B, 32W, 6M, 12M	Kruger et al [79]

^*B = baseline visit (≤16 wks of gestation); Chart = medical chart review after delivery; S = screening; 32W = 32-wk visit (32–34 wk of gestation); 6M = 6-month postpartum visit; and 12M = 12-month postpartum visit.