Effects of maternal dexamethasone administration on fetal Doppler flow velocity waveforms

Objective To investigate the effects of maternal dexamethasone administrati on on umbilical and fetal cerebral artery flow velocity waveforms. Design Cross-sectional study. Setting Department of Obstetrics and Gynaecology, Robert Ballanger Hospital , Aulnay-sous-Bois, France. Sample Twenty-six pregnant women with singleton pregnancies considered at risk for preterm delivery. At baseline, all preg nancies had normal fetoplacental vascular resistance. Methods These women were given weekly six intravenous doses of 4 mg of dexa methasone eight hours apart. Main outcome measures Doppler studies were per formed from both umbilical artery (UA) and fetal middle cerebral artery (MC A) before (day 0), during (day 2), immediately after (day 4) and shortly af ter (day 7) every steroid course. Results No significant variation was noted in both umbilical artery pulsati lity index (PI) and fetal heart rate through dexamethasone therapy. Compare d with mean initial values, we found on day 4 a significant decrease in MCA PI of 0.28 (F = 7.17, P < 0.001)and a significant increase in UA:MCA PI ra tio of 0.08 (F = 3.85, P = 0.013); in contrast no significant change was do cumented on days 2 and 7 in both MCA pulsatility index and UA:MCA PI ratio. After multiple regression analysis, only the decrease in fetal middle cere bral artery pulsatility index on day 4 remained significant (F = 5.84, P = 0.001). Conclusions The current study finds in healthy fetuses a transient, signifi cant and unexplained decrease in fetal middle cerebral artery impedance on the fourth day following maternal dexamethasone administration. Further bas ic research and clinical studies including larger sample sizes or pregnanci es with fetoplacental dysfunction are needed.