Doppler assessment of the fetoplacental circulation in normal and growth-retarded fetuses.

The Pulsatility Index (PI) of Doppler flow signals from umbilical arteries was used to study flow resistance of the placental villous circulation. A preliminary reference curve of PI values in normal pregnancy was composed from 23 healthy women examined every 2 wk from the 16th postmenstrual week until delivery. The gestational age-related decrease of PI values reflects a reduction of flow resistance in the placental villous circulation. In small-for-date fetuses significantly increased PI values were found, indicating that this simple technique may permit an early diagnosis of compromised fetoplacental circulation, even several weeks to months before fetal growth retardation is clinically presumed.