 Prematurity is the main cause of neonatal mortality and morbidity. Immature infants have many serious diseases such as respiratory distress syndrome RDS, intracranial hemorrhage ICH, chronic lung disease CLD, necrotizing enterocolitis NEC and retinopathy of prematurity ROP. Corticosteroids have the maturational effects on fetal cardiovascular, respiratory, nervous and gastrointestinal systems 1. Antenatal corticosteroids ANC have been widely used for prevention of RDS and other serious diseases in preterm infants since 1972s, when the controlled trial of antepartum glucocorticoid treatment was published. Administration of s of 12 mg of betamethasone given twice intramuscularly 24 hours apart has shown to be effective 2,3,4,39. Strong evidence exists for neonatal benefits from a complete course of ANC starting at 24 hours and lasting up to 7 days after treatment 2,39. Betamethasone and dexamethasone have similar biological activity and both are associated with a significant reduction in the risk of RDS, but only betamethasone with a significant decrease of the neonatal mortality. The clinical benefit had not been documented beyond 7 days after the onset of ANC therapy. 1,2 