Acceleration time in the aorta and pulmonary artery measured by Doppler echocardiography in the midtrimester normal human fetus.

The time to peak velocity was measured by Doppler echocardiography in the pulmonary artery in 102 normal human fetuses (gestational age 16-30 weeks). Time to peak velocity in the aorta was measured in 72. In 58 both measurements could be made in the same fetus. The time to peak velocity was shorter in the pulmonary artery than in the aorta. This difference was statistically significant. This suggests that in the midtrimester fetus mean pressure in the pulmonary artery is higher than in the aorta.