Pregnancy recruitment for population research: the National Children's Study vanguard experience in Wayne County, Michigan.

BACKGROUND: To obtain a probability sample of pregnancies, the National Children's Study conducted door-to-door recruitment in randomly selected neighbourhoods in randomly selected counties in 2009-10. In 2011, an experiment was conducted in 10 US counties, in which the two-stage geographic sample was maintained, but participants were recruited in prenatal care provider offices. We describe our experience recruiting pregnant women this way in Wayne County, Michigan, a county where geographically eligible women attended 147 prenatal care settings, and comprised just 2% of total county pregnancies. METHODS: After screening for address eligibility in prenatal care offices, we used a three-part recruitment process: (1) providers obtained permission for us to contact eligible patients, (2) clinical research staff described the study to women in clinical settings, and (3) survey research staff visited the home to consent and interview eligible women. RESULTS: We screened 34,065 addresses in 67 provider settings to find 215 eligible women. Providers obtained permission for research contact from 81.4% of eligible women, of whom 92.5% agreed to a home visit. All home-visited women consented, giving a net enrolment of 75%. From birth certificates, we estimate that 30% of eligible county pregnancies were enrolled, reaching 40-50% in the final recruitment months. CONCLUSIONS: We recruited a high fraction of pregnancies identified in a broad cross-section of provider offices. Nonetheless, because of time and resource constraints, we could enrol only a fraction of geographically eligible pregnancies. Our experience suggests that the probability sampling of pregnancies for research could be more efficiently achieved through sampling of providers rather than households.

The National Children's Study: Recruitment Outcomes Using the Provider-Based Recruitment Approach.

OBJECTIVE: In 2009, the National Children's Study (NCS) Vanguard Study tested the feasibility of household-based recruitment and participant enrollment using a birth-rate probability sample. In 2010, the NCS Program Office launched 3 additional recruitment approaches. We tested whether provider-based recruitment could improve recruitment outcomes compared with household-based recruitment. METHODS: The NCS aimed to recruit 18- to 49-year-old women who were pregnant or at risk for becoming pregnant who lived in designated geographic segments within primary sampling units, generally counties. Using provider-based recruitment, 10 study centers engaged providers to enroll eligible participants at their practice. Recruitment models used different levels of provider engagement (full, intermediate, information-only). RESULTS: The percentage of eligible women per county ranged from 1.5% to 57.3%. Across the centers, 3371 potential participants were approached for screening, 3459 (92%) were screened and 1479 were eligible (43%). Of those 1181 (80.0%) gave consent and 1008 (94%) were retained until delivery. Recruited participants were generally representative of the county population. CONCLUSIONS: Provider-based recruitment was successful in recruiting NCS participants. Challenges included time-intensity of engaging the clinical practices, differential willingness of providers to participate, and necessary reliance on providers for participant identification. The vast majority of practices cooperated to some degree. Recruitment from obstetric practices is an effective means of obtaining a representative sample.