Objective: To determine effects of maternal or fetal injections of betamethasone on postnatal growth and arterial pressure.Study design: We measured body weight, arterial pressure, and heart rate serially,in sheep born after single or repeated maternal or fetal betamethasone injections. At approximately 3.5 years, organ weights were measured.Results: Repeated maternal betamethasone injections caused intrauterine growth restriction, and low body weight and blood pressure at 3 months. From 6 months to 3 years, body, weight, blood pressure, and heart rate were not affected by treatment. At approximately 3.5 years, brain weight was reduced after single or repeated maternal betamethasone by 13% and 18%, respectively (P = .001). Fetal betamethasone reduced brain weight by 7% to 8% (P = .018). Weights of other organs were not affected by treatment. Brain weight was unrelated to body weight at approximately 3.5 years (P = .649) but was related to birth weight (P = .029).Conclusion: Prenatal betamethasone does not have long-term effects on blood pressure but causes a persistent deficit in brain weight.