OBJECTIVE: To compare the early administration of surfactant, before 12 h of life, versus late, in late preterm neonates (born between 34 DESIGN: Retrospective, observational, analytical, case-control study, with late preterm infants admitted between 2012-2021. It is divided into 2 groups: surfactant administered ≤ 12 h of life and >
12 h and evolution is compared using univariate analysis. SETTING: Neonatal Intensive Care Unit (NICU) level III of a Universitary Hospital. PATIENTS OR PARTICIPANTS: 57 patients, 30 in the early group and 27 in the late group. INCLUSION CRITERIA: neonates from 34 INTERVENTIONS: None. MAIN VARIABLES OF INTEREST: Sociodemographic, clinical and evolutionary: redosing, duration of respiratory support, oxygen and time to stop requiring it after surfactant. Also, complications and length of hospitalization. RESULTS: In the early group there was less need for redosing (3.3% vs 48.1%, P <
.001) and a decrease in duration, in days, of stay in the NICU (7 vs 10.5, P .002), invasive mechanical ventilation (2.4 vs 3.9, P .034), total respiratory support (4.6 vs 6.6, P .005) and oxygen therapy (0.4 vs 2.8, P <
.001). Also, lower incidence of pneumothorax (0% vs 33.3%, P .001). Furthermore, 12 h after administration, 83.4% maintained FiO2 0.21, compared to 44.4% in the late administration. CONCLUSIONS: In our study, early administration in late preterm infants provides benefits in terms of respiratory assistance and complications. We suggest expanding studies to establish recommendations in this group of patients.