Observations on the Configuration of the Fetal Electrocardiogram Before and During Labour

Summary The fetal electrocardiogram configuration recorded by direct fetal electrode was studied in 32 patients during labour. The PR interval, QRS interval, QT interval corrected for heart rate, R/P and R/S amplitude ratios and the fetal cardiac axis were measured and were similar in recordings made before labour, between or during uterine contractions, or during the second stage of labour. With baseline fetal tachycardia of over 160 beats per minute the mean QRS interval was significantly prolonged and the cardiac axis shifted to the right. During deceleration of the fetal heart rate the mean PR interval and corrected QT interval were significantly shortened and the cardiac axis deviated to the left. During severe deceleration the P wave might be inverted or absent. Notches in the P wave or R wave had no relation to the condition of the infant at birth. Likewise, fetal extrasystoles were not associated with hypoxia as measured by Apgar scores at one minute.