Online recruitment of a non-help-seeking sample for an internet intervention: Lessons learned in an alcohol-exposed pregnancy risk reduction study

Background: Recruiting a hidden population, such as the population of women at risk for alcohol-exposed pregnancy (AEP) who binge drink and are at risk of an unintended pregnancy, is challenging as this population is not typically seeking help or part of an identifiable group. We sought to identify affordable and efficient methods of recruitment for hidden populations. Methods: Several popular online social media and advertising sites were identified. Cities with high rates of binge drinking among women were targeted. We placed advertisements and study notices using Facebook, Twitter, Craigslist, University postings, and Clinical Trials gov. Results: For this study, 75 women at risk for AEP were recruited from across the U.S. within 7 months. Online advertising for study participants on Craigslist resulted in enrollment of the majority 51 (68%) of the study participants. While Craigslist advertising could be tailored to specific locations with high rates of binge drinking among women, there were challenges to using Craigslist. These included automated deletion due to repeated postings and mention of sexual behavior or drinking, requiring increased efforts and resources by the study team. Several strategies were developed to optimize advertising on Craigslist. Approximately 100 h of staff time valued at $2500 was needed over the 7-month recruitment period. Discussion: Despite challenges, the target sample of women at risk for AEP was recruited in the 7 month recruitment period using online advertising methods. We recommend that researchers consider online classified advertisements when recruiting from non-help seeking populations. By taking advantage of national data to target specific risk factors, and by tailoring advertising efforts, it is possible to efficiently and affordably recruit a non-treatment seeking sample.