title: Who are we missing? Examining non-participants in "Fit for Delivery", a randomized, controlled trial of a lifestyle intervention in pregnancy.
abstract: BACKGROUND
  Fit for Delivery (FFD) is a randomized, controlled trial of a lifestyle intervention designed to limit weight gain and increase physical activity in pregnancy. A questionnaire for non-participants was included in the design of the study.
  
  
  METHODS
  Nulliparous women residing in southern Norway were invited to participate in FFD if they had a singleton pregnancy at ⩽20weeks gestation, age ⩾18years and body mass index (BMI) of ⩾19kg/m(2). Women who declined participation were asked to complete an anonymous questionnaire with 7 questions. They were asked reason for non-participation (8 choices), age, height, pre-pregnancy weight, smoking status, educational level and frequency of physical activity. Study participants (n=606) completed a more comprehensive questionnaire before randomization. Responses were compared using independent-samples t-test and chi-square test for continuous and categorical data, respectively.
  
  
  RESULTS
  Non-participants who completed the non-response questionnaire (n=60) most often cited satisfaction with their own nutrition and fitness plan (50%) and being too busy to exercise several days a week (43%). Compared with participants, non-participants were younger (mean difference 1.48 years, CI 0.51-2.65 (p=0.013)), more often smokers (12.5% vs. 4%, p=0.014), and fewer had ⩾4years of higher education (9.4% vs. 35.6%, p<0.001). There were no significant differences between groups in weight, height, BMI or physical activity level.
  
  
  CONCLUSIONS
  There is a statistically significant difference in age, smoking and educational status between FFD participants and non-participants. BMI and activity level do not differ between groups. These finding may help us in developing future interventions and trials.
authors.affiliation: Department of Obstetrics & Gynaecology, Sørlandet Hospital, Norway.
authors.forename: Linda Reme
authors.initials: LR
authors.lastname: Sagedal