fMCG waveform at 30 weeks’ gestation. QT interval was extremely prolonged (normal QT interval of the same gestational week: 0.248 ± 0.316 s [6
]). P waves showed the same morphology and polarity. They were observed before the QRS complex and also in the posterior half of the T wave without following the QRS complex, which indicates a functional 2 : 1 AVB related to QT prolongation. pT: piko-Tesla.