The object of this study is to investigate further whether glucocorticoid therapy when given to mothers at least 24 hours prior to delivery of an infant at risk will reduce incidence of morbidity and mortality from Respiratory Distress Syndrome with minimal maternal or infant toxicity -- the mechanism of action being acceleration of lung maturation. Approximately 200 women less than 34 weeks gestation inpremature labor or with premature rupture of membranes will receive 4 mg dexamethasone or placebo injections intramuscularly every eight hours for six doses. After delivery the infant will be monitored per protocol for signs and symptoms of Respiratory Distress Syndrome and infection. Blood samples from the mother and the newborn infant will be studied for dexamethasone and cortisol. All infants will be seen at one and two years in the infant follow-up clinic for complete evaluation.