title: You are how you recruit: a cohort and randomized controlled trial of recruitment strategies.
abstract: BACKGROUND
  Recruitment is a challenge in developing population-representative pregnancy and birth cohorts.
  
  
  METHODS
  We developed a collaborative recruitment infrastructure (CRI) to recruit pregnant women for 4 pregnancy cohorts using: faxes from obstetrical offices, in-clinic recruiters, university and funder-driven free-media events, paid-media, and attendance at relevant tradeshows. Recruitment rates and demographic differences were compared between recruitment methods.
  
  
  RESULTS
  We received 5008 referrals over 40 months. Compared to fax, free-media referrals were 13 times more likely to be recruited (OR 13.0, 95% CI 4.2, 40.4: p < 0.001) and paid-media referrals were 4 times more likely to be recruited (OR 4.6, 95% CI 2.1, 10.3: p < 0.001). Among paid-media advertisements, free-to-read print (e.g. Metro) was the most effective (OR 3.3, 95% CI 2.3, 4.5: p < 0.05). Several demographic differences were identified between recruitment methods and against a reference population. Between recruitment methods, media recruits had a similar proportion families with incomes ≥ $40,000 (paid-media: 94.4%; free-media: 93.3%) compared to fax recruits (95.7%), while in-clinic recruits were less likely to have family incomes ≥ $40,000 (88.8%, p < 0.05). Maternal recruits from fax and in-clinic were more likely to attend university (Fax: 92.6%, in-clinic 89.8%) versus the reference population (52.0%; p < 0.05 for both) and both were less likely to smoke (Fax: 6.8%, in-clinic 4.2%) versus reference (18.6%; p < 0.05 for both). However, while fax referrals were more likely to be Caucasian (85.9% versus reference 77.5%; p < 0.05), in-clinic referrals were not significantly different (78.2%; P > 0.05).
  
  
  CONCLUSIONS
  Recruitment methods result in different recruitment rates and participant demographics. A variety of methods are required to recruit a generalizable sample.
authors.forename: Amy
authors.initials: A
authors.lastname: Maghera
authors.forename: Paul
authors.initials: P
authors.lastname: Kahlke
authors.forename: Amanda
authors.initials: A
authors.lastname: Lau
authors.forename: Yiye
authors.initials: Y
authors.lastname: Zeng
authors.forename: Chris
authors.initials: C
authors.lastname: Hoskins
authors.forename: Tom
authors.initials: T
authors.lastname: Corbett
authors.forename: Donna
authors.initials: D
authors.lastname: Manca
authors.forename: Thierry
authors.initials: T
authors.lastname: Lacaze-Masmonteil
authors.forename: Denise
authors.initials: D
authors.lastname: Hemmings
authors.affiliation: Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada. mandhane@ualberta.ca.
authors.forename: Piush
authors.initials: P
authors.lastname: Mandhane
mesh_terms: D000328:Adult; D035843:Biomedical Research / Q000379:methods* / Q000706:statistics & numerical data*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D018579:Patient Selection; D011247:Pregnancy; D015983:Selection Bias