In order to accelerate fetal lung maturation 46 pregnant women were given either dexamethasone or betamethasone intramuscularly during 3 consecutive days during 29–36 weeks of gestation. At birth, the infants appeared to have intact humoral immune function in that they could produce normal amounts of immunoglobulinsIn utero, and 2 fetuses responded with increased synthesis of IgA or IgM following premature rupture of the membranes. The clinical course did not show any increased incidence of puerperal or neonatal illness attributable to intrauterinc infection.