Communities may often lack the resources to deliver intensive programs to assist teen mothers, and many eligible adolescents may decline participation in lengthy interventions. Therefore, alternative approaches involving less resource and time may be needed. Behavioral economics (BE) can inform the development of such novel interventions. BE often feature low-intensity approaches designed to "nudge" people to help them reach their long-term goals. Nudges can include giving reminders, making the desired behavior more convenient, and optimizing the verbal presentation of recommended options. Three hundred thirty-one American adolescents (ages 14 to 19) who were 22 to 35 weeks pregnant were enrolled in the present trial. One hundred sixty-six participants were randomly assigned to the intervention condition featuring a three-month BE intervention delivered by a registered nurse and social worker. The remaining 165 youths were assigned usual care. Surveys were completed at baseline, 3 months, 12 months, and 18 months. Data collection occurred from 2017 to 2021. Qualitative feedback indicated that the BE intervention was well-received by adolescents. However, there were no significant differences between the intervention and control groups at any time point regarding repeat pregnancy, contraceptive usage, financial literacy, school completion, job attainment, HPV vaccinations, nicotine usage, perception of having a medical home, urgent care/ED usage, and nutritional intake (all p > 0.05). Our findings suggest that a BE-based intervention may not be sufficient to facilitate change for teen mothers. Future programs should consider lasting longer, featuring a higher dose, and/or incorporating systems-level changes. This trial was prospectively registered (NCT03194672 clinicaltrials.gov).