Occurrence of ST-changes recorded with the STAN S21-monitor during normal and abnormal fetal heart rate patterns during labour.

OBJECTIVE

To determine the frequency of ST-changes in the fetal electrocardiogram (ECG) both during normal and abnormal fetal heart (FHR) traces and to study relations with characteristics of pregnancy and delivery.

STUDY DESIGN

Retrospective analysis of 563 FHR+ECG-recordings. ST-changes were counted for all recordings with respect to their FHR pattern. Relationships between the occurrence of ST-events and characteristics of pregnancy and delivery were determined for the recordings with a completely normal FHR tracing during the first stage.

RESULTS

ST-events were present during 51.7% of recordings in the first stage of labour and during 24.3% of the recordings in the second stage. Surprisingly, events occurred during the first stage at a similar incidence during normal and abnormal FHR-patterns. During the second stage of labour events also occurred in a similar percentage of normal, intermediary and abnormal recordings, but - if present - events were more numerous during the abnormal FHR traces. In the subgroup of cases with a normal FHR pattern more events per hour occurred in babies born at 36-37 weeks of gestation and in boys.

CONCLUSION

ST-events are a frequent finding during normal FHR tracings.