Long-term effects of betamethasone on fetal development

In previous studies, we noted that treatment of pregnant rhesus monkeys with betamethasone resulted in a marked increase in fetal lung distensibility. The purpose of the present study was to determine whether these changes persisted during subsequent in utero development. Pregnant rhesus monkeys were treated with 2 mg of betamethasone intramuscularly from day 120 to day 133 and underwent delivery by cesarean section one month later. The treated fetuses were found to have smaller lungs (-31%; p <0.005), and lower alveolar stability (-14%; p <0.025) than the control fetuses. Additional findings included smaller weights for the brain (p <0.01), liver, pancreas, and heart (p <0.05). Smaller adrenal (p <0.025) and larger pituitary weights (p <0.05) and lower plasma corticoid concentrations (p <0.001) indicated long-standing adrenal insufficiency in the treated fetuses. These persistent sequelae caution against the indiscriminate and prolonged use of these potent glucocorticoids during pregnancy.