Introduction: Preterm delivery is associated with an increased risk of newborn morbidity and mortality. Respiratory distress syndrome (RDS) is the most common comorbidity. It has been proven that this syndrome can be prevented with the administration of antenatal corticosteroids to women at risk of preterm delivery, before 35 weeks of gestational age.
Aim: To evaluate the risk factors, severity, co-morbidities, and mortality of RDS in newborns of less than 35 weeks of gestational age, with specific emphasis on the association between the elapsed time since the administration of the last dose of a full cycle of corticosteroids and the frequency and severity of RDS.
Methods: This descriptive retrospective study includes all newborns of less than 35 weeks of gestational age, who were born at our center between January 1, 2012 and December 31, 2014 and admitted to Neonatal Intensive Care Unit (NICU). Newborns with major malformations, chromosomopathies, hydrops, congenital TORCH infection or outborns were excluded. RDS was diagnosed according to the criteria of the Update on the European Consensus Guidelines on the Management of Neonatal Respiratory Distress Syndrome in Preterm Infants (2013) and classified with a grade of I to III, in accord with radiographic results.
Results: A total of 234 newborns were studied, of which 35.5% had RDS. Antenatal corticosteroids were used for 90.1% of all newborns. When adjusted to the severity of RDS, birth weight, gestational age, and vasopressor support were all predictive factors of newborn mortality. A ROC curve identified a cut-off of at most 10.5 hours between the last dose of a full cycle of corticosteroids and the delivery as higher risk of onset of RDS and another cut-off of at most 6.5 hours as higher risk of onset of moderate to severe RDS (sensitivity of 80.0% and 83.3%, respectively).
Conclusion: The last dose of a full antenatal corticosteroids cycle must be given at least 10.5 hours prior to delivery to prevent the onset of RDS and at least 6.5 hours before to prevent the onset of moderate to severe RDS.