Recruitment for longitudinal, randomised pregnancy trials initiated preconception: Lessons from the effects of aspirin in gestation and reproduction trial

Background Recruitment into large, preconception randomised clinical trials (RCT) is challenging. We describe clinic and community-based preconception recruitment strategies for the Effects of Aspirin in Gestation and Reproduction (EAGeR) trial and highlight approaches that were and were not successful. This longitudinal RCT was conducted at four major sites in the US. Eligible women had one to two prior pregnancy losses and were actively trying to become pregnant. Methods Provider/clinic and community-based outreach strategies were utilised, and the recruitment rate and costs of methods were assessed. Results A screening questionnaire was completed by 5485 women; 42.4% (n=2323) screened were initially eligible, of whom 50.7% (n=1228) were randomised. Provider/clinic-based recruitment yielded the highest number eligible of those screened (30.1%) and also the most randomised participants overall (40.3%). The next highest yield came from direct mail and brochures/flyers at 13.1% and 12.5% of women randomised, respectively. However, direct mailings cost $720 per participant randomised. Other than word of mouth, provider/clinic-based recruitment was the most cost effective method, costing an average of $60 per randomised participant. Web-based recruitment yielded 4.7% of participants at a cost of $278 per randomised participant. Conclusions Provider and clinic-based recruitment was the most effective and cost-efficient method of recruitment in a preconception intervention study of reproduction among women.