This factorial trial will include 384 participants. Participants will be pregnant women age 18-35 years who score positive on a frequently used and well-validated screening tool for alcohol use risk in pregnancy (the T-ACE). We will also add an additional requirement of either drinking weekly or more in the past month, or having 4 or more drinks at a time at least monthly in the 12 months before becoming pregnant. To be eligible for the study, participants must also report smartphone ownership, willingness to receive study-related text messages and to use their smartphone for study-related assessments and/or booster sessions, and being at 20 weeks gestation or less. Participants will be excluded if they are not planning to carry the pregnancy to term, or are unable to communicate in English. All participants must reside in Connecticut, Massachusetts, or Michigan. Completion of the baseline assessment is also necessary for inclusion.

Participants will be recruited via community flyers as well as by online posts, flyers, and other advertising via multiple digital platforms that may appear as banners, text, images, video, and/or URL links to the study website, which further links to the screening survey.. The flyers and ads will contain basic information indicating that they are for a health-related study for women 18-35 years of age who can communicate in English. Interested women meeting these criteria will be provided a website address, QR code, or link to a study website, where they will be presented with an electronic information sheet, which they may access via their own smartphone or tablet. Those who click "I agree" at the end of this information sheet, will be invited to complete the initial computer-directed screening survey via a link from the study website to a Qualtrics survey. This survey will ask a range of questions so that the study's inclusion and exclusion criteria are not readily apparent (in order to limit fraud).

The screening survey will be used to determine whether initial inclusion criteria have been met \[(age, state of residence, pregnancy status, and alcohol risk (T-ACE positive and either drinking weekly or more in the past month, or having 4 or more drinks at a time at least monthly in the 12 months before becoming pregnant)\]. Study staff will contact interested women who meet study inclusion criteria by phone in order to validate their eligibility (survey completed by a real person, who can communicate in English, has a working smartphone, is able to receive text messages, and understands study requirements). The following strategies will be implemented to reduce the possibility of fraudulent participation: 1) manual review of IP addresses to screen for duplicates and identify addresses of non-US origin, detect fraudulent completion (e.g., bots), 2) manual review of Qualtrics survey data to detect suspicious response times (e.g., completing the survey too quickly), unusual patterns in responses, respondent names, respondent email addresses, and patterned completion timestamps indicating that one person/bot is completing the survey repeatedly until eligible, 3) inclusion of a required open-ended narrative response to detect fraudulent completion, and 4) inclusion of invisible questions that only a bot could respond to, as well as visible nonsense questions directing the respondent to provide a particular answer. Only interested women who pass these screens and can be confirmed via the phone call will be enrolled.

The full trial consent will also be presented electronically and will proceed only if participants provide written informed consent via e-signature (using DocuSign, see section 10.1.3 of the protocol for additional information). Participants who meet all eligibility criteria and who provide consent will then be randomly assigned to a study condition during the baseline assessment. The staff member who enrolls the participant will not have access to the assigned condition/content at the time of consent and initial study condition assignment.

This trial includes varying levels of two separate interventions. The interactive and tailored baseline MommyCheckup single-session e-SBIRT was built on principles of Motivational Interviewing and Self-Determination Theory, and is presented to participants directly via their own electronic device (e.g., smartphone, tablet), which interacts with them through an animated talking narrator. The e-SBIRT booster sessions will be sent to participants as a text message that includes a link to the booster content. Participants will be texted these links on two occasions: 6 weeks following the baseline session, and at 30 weeks gestation. Participants assigned to the text messaging intervention will receive a test message at the conclusion of their baseline session, in order to confirm that the software has the correct cellphone number. These participants will then begin receiving text messages twice weekly until after the 34-week assessment, or until they text back "STOP" to end the messages.

Following the baseline session, participants will be asked to complete follow-up assessments at 4 weeks post-baseline, at 27 weeks gestation, 34 weeks gestation, and at 4 weeks postpartum. In addition, all participants will be mailed a nail specimen collection kit at 36 weeks gestation asking them to provide nail clippings that will be analyzed for Ethyl Glucuronide (EtG). Fingernails will be collected at 36 weeks gestation. Toenails may be collected at 38 weeks gestation as an alternative to fingernails. Nail types may not be mixed for a single specimen collection. Specimens from all available fingernails or toenails weighing 50-100 mg gathered at 36 weeks (fingernails) or 38 weeks (toenails) will allow for sufficient nail growth to capture EtG as evidence of alcohol use concentrated in the timeframe of approximately 20-34 weeks gestation, based on typical fingernail and toenail growth rates. Additionally, this timeframe will allow us to avoid detecting post-delivery alcohol use since it takes approximately two weeks for fingernails and four weeks for toenails to grow sufficiently for detectability. Participants will be reminded of the upcoming nail specimen collection at their 27-week and 34-week data collections, plus reminders will be included when the survey links are sent by text for these data collection timepoints. In the event of preterm birth, nail specimens will be requested immediately. The level of detectability for either nail type will be set at 8 pg/mg, which is the lower level of quantitation used for research (the standard level of detectability used for non-research testing is 20 pg/mg).