Introduction: Approximately 1 in 7 pregnant women in the USA report past-month alcohol use. Strong evidence connects prenatal alcohol exposure with a range of adverse perinatal outcomes, including the spectrum of conditions known as fetal alcohol spectrum disorders. Screening and Brief Intervention (SBI) has been recommended for pregnant women but has proven difficult to implement. This study will test the efficacy of single-session technology-delivered SBI (electronic SBI) for alcohol use in pregnancy, while simultaneously evaluating the possible additional benefit of tailored text messages and/or booster sessions in a 3×2 factorial trial.

Method and analysis: This full factorial trial will use online advertising and clinic-based flyers to recruit pregnant women meeting criteria for unhealthy alcohol use, and randomly assign them to one of six conditions crossing three levels of brief intervention (none, single 120-minute session and single session plus two 5-minute boosters) with two levels of tailored text messaging (none vs twice weekly messages). The primary analysis will test for dose-response effects of the brief intervention on alcohol abstinence, defined as no self-report of alcohol use in the 90 days prior to 34 weeks' gestation, and negative results for ethyl glucuronide analysis of fingernail samples. Secondary analyses will examine main and interaction effects of tailored text messaging as well as intervention effects on birth outcomes.

Ethics and dissemination: Ethical approval was provided by the Michigan State University Biomedical and Health Institutional Review Board (STUDY00005298). Results will be presented at conferences and community forums, in addition to being published in a peer-reviewed journal. Intervention content demonstrating sufficient efficacy and safety will be made publicly available.

Trial registration number: ClinicalTrials.gov Registry (NCT04332172).