Estimating fetal gestational age using cardiac valve intervals

A new automated method for estimation of the gestational age is presented in this paper based on the intervals between fetal cardiac valve timings and the Q-wave of fetal electrocardiogram (fECG). The intervals were estimated automatically from one-dimensional Doppler Ultrasound and noninvasive fECG. Among the intervals, Isovolumic Contraction Time, Electromechanical Delay Time, Ventricular Filling Time and their interactions were selected in a stepwise regression process. Compared with Crown-Rump Length as gold standard, a mean absolute error of 3.8 weeks was obtained using leave-one-out cross validation. This method also outperformed a fetal heart rate based approach. Since valve intervals reflect the autonomic function, this method provides a novel measure ofthe development of fetal autonomic nervous system that may be growth curve independent.