title: Methods for a Retrospective Population-based and Clinic-based Subfertility Cohort Study: the Fertility Experiences Study.
abstract: Most cohort-based research for subfertility has been conducted in clinic-based cohorts, which may differ from population-based cohorts.
  
  
  
  We retrospectively recruited parallel cohorts of subfertile women: one by sampling two specialty fertility clinics in Utah, and one by population-based sampling based on marriage and birth records. The index date (of first clinic visit or subfertility status) was between 2000 and 2009, and we linked the women recruited to subsequent birth certificate records through December 2010.
  
  
  
  We enrolled 459 women through clinic-based sampling and 501 women through population-based sampling. Clinic-based women were older, had higher annual household income and more likely to have had a most intensive treatment of intrauterine insemination (31%) or in vitro fertilisation (46%) than women from population recruitment (19% and 14% respectively). Conversely, they were less likely to have received no medical treatment (9%) compared to women from population recruitment (41%). For both types of sampling, prior to eligibility screening, non-responders were less likely to link to a live birth than responders: 51% vs. 58% for clinic-based, and 69% vs. 76% for the population-based with an index date in 2004.
  
  
  
  Population-based sampling for subfertility cohort research identifies women who were more likely to have had less intensive treatment or no treatment. However, in both clinic-based and population-based sampling, women who have had a live birth are more likely to respond to retrospective recruitment.
authors.affiliation: Office of Cooperative Reproductive Health, Division of Public Health, Department of Family and Preventive Medicine, University of Utah, Salt Lake City, UT.|Department of Obstetrics and Gynecology, University of Utah School of Medicine, Salt Lake City, UT.
authors.forename: Joseph B
authors.initials: JB
authors.lastname: Stanford
authors.affiliation: Office of Cooperative Reproductive Health, Division of Public Health, Department of Family and Preventive Medicine, University of Utah, Salt Lake City, UT.|Department of Obstetrics and Gynecology, University of Utah School of Medicine, Salt Lake City, UT.
authors.forename: Jessica N
authors.initials: JN
authors.lastname: Sanders
authors.affiliation: Office of Cooperative Reproductive Health, Division of Public Health, Department of Family and Preventive Medicine, University of Utah, Salt Lake City, UT.
authors.forename: Sara E
authors.initials: SE
authors.lastname: Simonsen
authors.affiliation: Department of Obstetrics and Gynecology, University of Utah School of Medicine, Salt Lake City, UT.|IVF Michigan Fertility Center, Bloomfield Hills, MI.|Department of Family and Consumer Studies, University of Utah, Salt Lake City, UT.
authors.forename: Ahmad
authors.initials: A
authors.lastname: Hammoud
authors.affiliation: Department of Obstetrics and Gynecology, University of Utah School of Medicine, Salt Lake City, UT.
authors.forename: Mark
authors.initials: M
authors.lastname: Gibson
authors.affiliation: Department of Family and Consumer Studies, University of Utah, Salt Lake City, UT.
authors.forename: Ken R
authors.initials: KR
authors.lastname: Smith
mesh_terms: D000328:Adult; D001723:Birth Rate; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D007246:Infertility / Q000453:epidemiology* / Q000628:therapy; D008297:Male; D018579:Patient Selection; D016742:Preconception Care / Q000379:methods*; D011247:Pregnancy; D012107:Research Design; D012189:Retrospective Studies; D011795:Surveys and Questionnaires; D014589:Utah / Q000453:epidemiology; D055815:Young Adult
keywords: clinic-based; population-based; retrospective cohort; subfertility