IntroductionPrenatal education is associated with positive health behaviours, including optimal weight gain, attendance at prenatal care, acceptance of routine screening tests, smoking cessation, decreased alcohol consumption and breast feeding. Adoption of these behaviours has been associated with reduced rates of caesarean birth, preterm birth and low birth weight. Barriers to prenatal class attendance faced by parents in Canada include geography, socioeconomic status, age, education, and, among Indigenous peoples and other equity-deserving groups, stigma. To address the need for easily accessible and reliable information, we created ‘SmartMom’, Canada’s first prenatal education programme delivered by short message service text messaging. SmartMom provides evidence-based information timed to be relevant to each week of pregnancy. The overall goal of SmartMom is to motivate the adoption of positive prenatal health behaviours with the ultimate goal of improving health outcomes among women and their newborns.Methods and analysisWe will conduct a two-arm single-blinded randomised controlled trial. Blinding of participants to trial intervention will not be possible as they will be aware of receiving the intervention, but data analysts will be blinded. Our primary research questions are to determine if women experiencing uncomplicated pregnancies randomly assigned to receive SmartMom messages versus messages addressing general topics related to pregnancy but without direction for behaviour change, have higher rates of: (1) weight gain within ranges recommended for prepregnancy body mass index and (2) adherence to Canadian guidelines regarding attendance at prenatal care appointments.Ethics and disseminationThe study has been granted a Certificate of Approval, number H22-00603, by the University of British Columbia Research Ethics Board. To disseminate our findings, we are undertaking both integrated and end-of-grant knowledge translation, which will proactively involve potential end-users and stakeholders at every phase of our project.Trial registration numberNCT05793944.