Introduction: In Peru, vertical transmission of the human immunodeficiency virus (HIV) persists, and unequal maternal knowledge limits prevention. Objective: To determine the factors associated with knowledge about mother-to-child transmission of HIV among Peruvian women of reproductive age. Materials and Methods: An observational, analytical, cross-sectional, and retrospective study was conducted based on secondary data from the Demographic and Family Health Survey (ENDES) 2022–2023. Sociodemographic variables included age, educational level, wealth index, place of residence, and access to health insurance. Frequencies were compared, and the Rao-Scott chi-square test and Poisson regression with robust variance were applied to estimate PRa with their 95% CIs; a p-value <0.05 was considered statistically significant. Results: Only 1.4% of women reported complete knowledge of vertical...