REFERENCE RESISTANCE INDEXES OF THE UMBILICAL, FETAL MIDDLE CEREBRAL AND UTERINE ARTERIES AT 24-42 WEEKS OF GESTATION

The objective of this cross-sectional study was to construct new refer ence ranges for Doppler flow velocity waveform resistance indices for the fetal umbilical artery, middle cerebral artery, placental and non- placental uterine arteries and the placentocerebral ratio in a large a nd minimally selected population attending a single clinic. Study desi gn and data analysis adhered to a number of stringent and validated me thodological recommendations derived both from the recent literature a nd from a review of earlier publications in this field. The final data base comprised initial routine Doppler velocimetry at 24-42 weeks' ges tation in 1675 pregnancies. Separate regression models were fitted to estimate the mean and standard deviation at each gestational age for e ach vessel. New charts, centile tables and regression equations are pr esented for the resistance indices of the fetal umbilical artery, midd le cerebral artery, placental and non-placental uterine arteries and t he mean of both uterine arteries and for the placentocerebral ratio.