The results of a randomized, double-blind, placebo-controlled trial have shown that repeat prenatal corticosteroid treatment did not increase neonatal blood pressure (BP) or myocardial wall thickness in infants who are at risk for very preterm birth 7 days after an initial course of corticosteroids. The study aimed to examine whether repeat prenatal corticosteroid treatment affects BP and myocardial wall thickness in neonates. 120 pregnant women were at a tertiary perinatal center received initial treatment with corticosteroids 7 or more days earlier and who were still considered to be at continued risk for preterm birth were randomly assigned to receive additional weekly betamethasone or placebo. The mothers participated in this study had a singleton, twin, or triplet pregnancy at gestational age less than 32 weeks. BP was measured until 4 weeks after birth or hospital discharge, and interventricular septal thickness (IVS) and left ventricular posterior wall thickness (LVPW) in diastole were measured 48 to 72 hours after birth in the 145 infants born to the 120 mothers enrolled in the study. Infants in the placebo and repeat steroid groups had no differences in mean, systolic, or diastolic BPs, and both groups had BPs similar to published normal values. Although the groups did not differ in IVS or LVPW in diastole, 24% of infants had IVS, and 32% of infants had LVPW greater than the 95th percentile for published normal ranges. Limitations of this study include insufficient power to determine the cardiovascular effects of time since corticosteroid administration and of total dose administered, and inability to distinguish between the effects of latency from the last known dose of corticosteroid and the effects of the total dose.