Effects of maternal betamethasone administration on fetal and maternal blood pressure and heart rate in the baboon at 0.7 of gestation

OBJECTIVE: We sought to determine the effects of the intramuscular maternal administration of betamethasone to the pregnant baboon at 0.7 of gestation on fetal blood pressure and heart rate. STUDY DESIGN: We treated pregnant baboons at 0.7 of gestation with intramuscular betamethasone (n 4), at a weight-adjusted dose equivalent to the daily dose administered to women in preterm labor or with saline solution (n = 5). Four injections were given at 12-hour intervals. Fetal and maternal blood pressure and heart rate were recorded continuously. Within-group differences and between-group differences were analyzed with repeated measures analysis of variance. RESULTS: Fetal blood pressure increased significantly after betamethasone treatment. Fetal heart rate, maternal blood pressure, and heart rate did not change. CONCLUSION: Exposure of the developing primate fetus to exogenous glucocorticoid at 0.7 of gestation elevates fetal blood pressure. These findings confirm and extend the observations in the fetal sheep. Further studies are needed to evaluate the mechanisms that are involved and possible long-term consequences of these cardiovascular effects of antenatal glucocorticoid exposure in the fetal primate.