Fetal magnetocardiography, the magnetic analog of fetal ECG, is at this time the most effective means of assessing fetal rhythms. Through the work of Zhao et al. (7), it has provided new insight into the electrophysiological characteristics of fetal AVB. Their observations suggest fetal AVB with and without structural heart disease is far more complex than previously appreciated with complex changing rhythms and variable atrioventricular conduction in second-degree AVB, and abnormal QRS waveforms, co-existence of junctional and ventricular ectopy, and atrial and ventricular rate responsivity in third-degree AVB. Fetal magnetocardiography, however, requires a magnetically shielded facility and is available in very few centers. Furthermore, Zhao et al. (7) studied patients for 50 to 100 min at a time, longer duration than is typical of fetal echocardiography. Still, these new observations should prompt a search for perhaps more practical tools to evaluate electrophysiological events in fetal AVB that will ultimately improve the care of affected pregnancies.