Umbilical artery time-averaged maximum velocity: First trimester reference range

We previously showed that the umbilical artery (UA) time-averaged maximum velocity (TAMXV) measured within the first trimester seems to be a “Marker” of utero-placental development as it correlated with uterine artery pulsatility index. Aim of our study was to construct a reference range for TAMXV for first trimester. Women with Doppler of the UA blood flow velocity waveforms in the first trimester were included. To create the reference range we based on the model of Royston and Wright, assuming that at each gestational age (GA) the measurement has a Gaussian distribution with mean and standard deviation (SD) an…