Infant respiratory distress syndrome (RDS) occurs in 40-50% of neonates born prior to 32 weeks. RDS is caused by structural immaturity of the lungs and insufficient surfactant production. Corticosteroids can accelerate lung maturation, decreasing the severity or preventing RDS. Corticosteroids (more specifically glucocorticoids) are frequently given antenatally to women at risk of preterm delivery. This often reduces the treatment the preterm infant will require to survive at birth.
Mechanism of Action
Corticosteroids (specifically betamethasone or dexamethasone) administered to a gravid woman cross the placenta to promote accelerated fetal lung maturation and production of surfactant. Corticosteroids may be administered intramuscularly at 28-36 weeks of gestation in gravid women who show signs they may deliver preterm. In order for this treatment to be most effective, delivery should not occur for 24-48 hours after the drug is administered. Betamethasone has been used for decades and is the preferred corticosteroid for this function. Two doses of 12mg are recommended intramuscularly, 24 hours apart.
Current use in High-Resource Settings
Corticosteroids are not currently labeled for use in preterm labor in the US; however, coricosteroids are commonly used for preterm delivery. Given the relatively low cost and ease of administration, increased penetration is limited by the ability to quickly diagnose an at-risk fetus. Cost savings associated with the avoidance of surfactant and respiratory support are substantial.
Application in Low-Resource Settings
Where surfactant and ventilation are less likely to be available, corticosteroid use has the potential to save lives. In facility settings and among skilled attendants, intramuscular injection is feasible. There are ongoing efforts to pre-load betamethasone into the Uniject device in order to further reduce the skill required for administration. This could expand the base of end users, but is not yet commercially available. Corticosteroid therapy is not advised for women who have systemic infections such as tuberculosis. Caregivers in regions with high prevalence of infectious disease must be more cautious before administration of this drug.