Introduction and objective: Reducing the neonatal mortality rate in half is an objective proposed by WHO for the year 2025 through coverage strategies from the prenatal stage, delivery, birth, and hospitalization, one of these low-cost strategies is exclusive breastfeeding (EBF) in preterm infants, that contributes to the prevention of neonatal mortality, a population that contributes in the first place to neonatal mortality. The objective of this study was to identify the frequency and survival of exclusive breastfeeding and related factors in premature infants of two referral hospitals, one of them certified as Baby-Friendly Hospital Initiative (BFHI).Methods: Follow-up study of 111 premature infants after hospital discharge with equivalent corrected age among hospitals: BFHI 36.1 ± 1.6; non-BFHI (nBFHI) 36.4 ± 1.8 weeks (p ≥ .05). Data collection carried out from February 2016 to March 2017, through records in clinical files and surveys of mothers upon hospital discharge and by telephone during follow-up after 15 days post-discharge, 3, and 6 months of extrauterine life. Kaplan-Meier analysis to determine breastfeeding survival over time, and with Pearson’s r with significance p ≤ .05, the relation was established between EBF with sociodemographic, perinatal, and clinical status factors of the child.Results: Urban maternal origin (68.1%), maternal age (25.7 ± 7.9 years), schooling < 12 years (56.6%). EBF upon discharge on 45/111 dyads (40.5%), 15 days post-discharge 35/73 (47.9%), third month 23/61 (37.7%) and sixth month 7/44 (15.9%). EBF survival was 15 days post-discharge, at this cut-off point, among the correlated factors are: “having received guidance to use Exclusive Breastfeeding until the sixth month of extrauterine life of the premature child” positively correlated with EBF (r = 0.294, p ≤ .05), “the maternal perception that her milk dried” correlated negatively with EBF (r = -0.313, p ≤ .01), if “breastfeeding caused anxiety to the mother” it positively correlated with artificial feeding (AF) (r = 0.237, p ≤ .05).Conclusions: Exclusive breastfeeding in premature infants is below WHO standard, it is favorably related to maternal orientation, and barriers are maternal perceptions of non-milk supply and anxiety. It could be encouraged through actions carried out in hospitals certified with the Baby-Friendly Hospital Initiative and follow up with post-discharge breastfeeding at least to the sixth month of life of premature infants. Similar studies should establish better monitoring mechanisms to avoid losses during the follow-up.