Absence of significant hemodynamic changes in the fetus following maternal betamethasone administration

Maternal betamethasoneadministration causes a transient but considerable reduction in fetal body and breathing movements and in fetal heart rate variation. The aim of the present prospective study was to investigate whether there is evidence of circulatory changes in fetal, placental or uterine arteries, consistent with hypoxemia. Eighteen women at risk for preterm delivery received betamethasoneto enhance fetal lung maturation. Doppler studieswere performed before treatment, and 24 and 72 h after the second dose of betamethasone. Blood flow velocity waveforms were obtained from both uterine arteries, umbilical arteries, fetal descending aorta, fetal renal artery, and fetal cerebral arteries. No significant changes occurred in the pulsatility indexof any of these blood vessels, suggesting that the transient reduction in fetal heart rate variation and fetal body and maternal betamethasonethrough fetal bypoxemia. Copyright © 1996 International Society of Ultrasound in Obstetrics and Gynecology