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Fetal and umbilical flow velocity waveforms between 10-16 weeks' gestation: a preliminary study
J W Wladimiroff1, T W Huisman, P A Stewart
1Department of Obstetrics and Gynecology, Academic Hospital Rotterdam-Dijkzigt, The Netherlands.
Maximal flow velocity waveform recording was attempted in the umbilical artery, fetal descending aorta, and at the fetal intracerebral level using a cross-sectional study design in 77 normal singleton pregnancies between 10-16 weeks' gestation. At 10-12 weeks, end-diastolic flow velocities were always absent in the fetal descending aorta and umbilical artery, but were present in 58% of the intracerebral artery waveforms. The pulsatility index at all three levels decreased significantly with advancing gestational age, suggesting a reduction in fetal and umbilical placental vascular resistance during the late first and early second trimesters of normal pregnancy. Waveform changes were not related to fetal heart rate.
Maximal flow velocity waveform recording was attempted in the umbilical artery, fetal descending aorta, and at the fetal intracerebral level using a cross-sectional study design in 77 normal singleton pregnancies between 10-16 weeks' gestation. At 10-12 weeks, end-diastolic flow velocities were always absent in the fetal descending aorta and umbilical artery, but were present in 58% of the intracerebral artery waveforms. The pulsatility index at all three levels decreased significantly with advancing gestational age, suggesting a reduction in fetal and umbilical placental vascular resistance during the late first and early second trimesters of normal pregnancy. Waveform changes were not related to fetal heart rate.