Determination of fetal heart rate short‐term variation from umbilical artery Doppler waveforms

ABSTRACT Objective To evaluate the feasibility of using umbilical artery (UA) Doppler waveforms to measure fetal heart rate (FHR) short‐term variation (STV) across gestation. Methods This was a prospective longitudinal study, conducted at two study sites, of 195 pregnancies considered low risk. Pulsed‐wave Doppler of the UAs was performed at 4‐weekly intervals, between 14 and 40 weeks of gestation, using a standardized imaging protocol. Up to 12 consecutive UA Doppler waveforms were analyzed using offline processing software. FHR STV was calculated using average R–R intervals extracted from the waveforms and baseline corrected for FHR. Results Baseline‐corrected FHR STV increased significantly with gestational age (conditional R2 = 0.37; P