Respiratory distress syndrome (RDS) is one of the most common respiratory complications of prematurity.In this study we explore the relationship between RDS and free thyroxin (FT4), thyroid stimulating hormone (TSH) in preterm neonates during 1st postnatal 24 hours to explore whether thyroid hormones affect lung surfactant production and hence occurance of RDS or not and after the 2nd postnatal day to explore whether hypoxia from RDS affects thyroid hormones level or not.