BackgroundYoung women worldwide face problems like unwanted pregnancy and sexually transmitted infections. Providing sexual and reproductive health education to young women in low- and middle-income countries is a priority. It is unknown if using digital health interventions to deliver health education is effective in resource-constrained settings.MethodsWe conducted an interventional trial among young women in the low–middle-income country of Lesotho to test the impact of the conversational agent system (“Nthabi”) designed to deliver sexual and reproductive health information on either a smartphone or tablet for up to 6 weeks. We measured participant’s knowledge before and after the discussion of family planning, folic acid use, and healthy eating. The main outcome measure was a change in knowledge among participants in these three topic areas. The number of correct pre- and post-test responses was compared using generalized linear models that directly estimated the proportions and percentages of correct responses.ResultsWe recruited 172 young women (mean age 22.5 years, 91% unmarried, 69% completed high school, 23% unemployed, 66% students) to use Nthabi on a mobile phone (11.6%) or loaned tablet device (88.4%). The mean number of interactions with Nthabi was 8.6. Family planning was chosen to be discussed by 82 of the 172 participants (52.2%), and of those, 49 (31.2%) completed the content on this topic, and 26 (16.6) completed the post-test. For the 11 questions about family planning, the total percent of correct responses increased from 85.5% (796 total responses) on the pre-test to 89.9% (320 responses) on the post-test (p = 0.0233). Folic acid use was chosen to be discussed by 74 (47.1%) of 172 participants, and of those, 27 (17.7%) completed the content on this topic, and all 27 (17.7%) completed the post-test. For the 5 questions about folic acid use, the total percent of correct responses was 45.3% (181 total responses) on the pre-test and 71.6% (111 responses) on the post-test (p < 0.0001).ConclusionsThe Nthabi conversational agent system increased knowledge of family planning methods and folic acid use among young women in Lesotho. Digital health interventions like Nthabi have the potential to offer new ways to deliver reproductive health information.Trial registrationClinicalTrials.gov registration April 20, 2020; ID: NCT04354168.