Background: Studies have shown that the duration of exclusive breastfeeding is shorter in adolescent mothers and preterm infants. The objective was to identify the prevalence of exclusive breastfeeding, its survival curve and associated factors, in adolescent mother-premature infant dyads and to compare two hospitals aligned or not with the Baby-Friendly Hospital Initiative up to 6 months.Methods: Follow-up and comparative study. Carried out in two reference hospitals (certified as Baby-Friendly Hospital Initiative and Non-certified). The participants were 67 adolescent mothers and 69 premature infants hospitalized in Neonatal Unit where the follow-up began in all the dyads with the informed consent. Data collection was carried out in clinical files and interview of adolescent mothers in the hospitals and by telephone in the follow-up. (February 2016 to March 2017). The variables were Exclusive breastfeeding, sociodemographic, perinatal and clinical status of the premature infants. The statistical analysis was descriptive and we applied Kaplan-Meier and Pearson's r Test (significance p ≤ .05).Results: The exclusive breastfeeding was 27.1%, 63.8%, 66.7%, 48.1% and 26.3% in internment, discharge, 15 days post-discharge, third and sixth month of life, respectively. The exclusive breastfeeding survival: at Baby-Friendly Hospital Initiative (40%, 30 days post discharge) and Non-Baby-Friendly Hospital Initiative (30%, 15 days post discharge) (p ≤ .05). Cessation of breastfeeding due to the perception of low milk production (15 days post-discharge, r = .556, p ≤ .05).Conclusions: The prevalence and the survival curve of exclusive breastfeeding are low, especially in Non-Baby-Friendly Hospital Initiative, and the perception of low milk production. The health system efforts are required to initiate and continue exclusive breastfeeding according with WHO recommendations.