The potential impact of PR interval analysis of the fetal electrocardiogram (FECG) on intrapartum fetal monitoring.

A retrospective study was performed at the Queens Medical Centre, Nottingham, UK to evaluate the potential value of PR interval analysis of the FECG compared to conventional intrapartum assessment with fetal heart rate monitoring. Two-hundred sixty-five labours were selected for monitoring. Outcome was assessed by the number of fetal scalp blood samples (FBS) performed and the associated incidence of acidosis in the first stage of labour, the mode of delivery and whether or not this was expedited for fetal heart abnormality or an abnormal scalp pH. The condition of the fetus at delivery was assessed by arterial and venous blood acid-base status, Apgar score and the need for admission to the neonatal intensive care unit. Conventional electronic fetal heart rate monitoring (EFM) was used in all labours. The addition of PR interval assessment would potentially reduce the numbers of normal FBSs being carried out from 85.5% to 26.8% and the proportion of cases of missed acidosis at delivery from 8.5% to 4.5%. These results highlight the potential benefit of PR interval analysis in improving interpretation of the intrapartum cardiotocograph and need to be tested by prospective randomised controlled study.