Prolonged fetal bradycardia during epidural analgesia. Incidence, timing and significance.

The mechanism of episodes of fetal bradycardia during epidural analgesia is unknown in the majority of cases. This retrospective study considers the relationship between prolonged fetal bradycardia and epidural analgesia during labour. Of 705 cardiotocographs recorded during administration of epidural analgesia for patients in labour, 207 were suitable for analysis. Prolonged fetal bradycardia occurred after 40 of 366 (11%) initial or repeat injections of local anaesthetic into the epidural space. The peak incidence of onset of bradycardia was 5-20 minutes after administration, but occurrences continued throughout the 60-minute period studied. In 1 patient a single episode of fetal bradycardia occurred before administration of the epidural block. In all cases studied the 5-minute Apgar scores were 7 or better. It is concluded that administration of epidural analgesia is significantly associated with episodes of prolonged fetal bradycardia, but that there is usually a return to pre-epidural patterns. The fetal heart rate should be monitored during epidural block administration to confirm the return to baseline rate and normal variability. Episodes of fetal bradycardia that return to a normal pattern do not necessitate early delivery.