What is the main mechanism of action of corticosteroids in late preterm birth?

Corticosteroids are primarily used in the context of late preterm birth to accelerate fetal lung maturity. This is crucial because preterm infants often suffer from respiratory distress syndrome (RDS) due to insufficient surfactant production in their underdeveloped lungs. Corticosteroids promote the synthesis and release of surfactant, a substance that coats the alveoli and reduces surface tension, facilitating more efficient breathing after birth.

In addition to enhancing lung development, corticosteroids have a range of other effects, such as modulating inflammation and improving overall fetal outcomes. However, their most significant and clinically important action in the context of preterm birth is the improvement of lung function, which directly impacts neonatal morbidity and mortality rates associated with preterm birth.

While reducing uterine contractions, decreasing maternal fever, and inhibiting cervical dilation may be relevant factors in managing preterm labor, these are not the primary mechanisms by which corticosteroids exert their beneficial effects in this specific situation. The focus on improving lung development is a well-established and critical component of antenatal corticosteroid therapy.