Summary

Background: Visual interpretation of fetal heart rare monitoring is subject to intra and inter observer variability.

Objective: To examine the effect of intrapartum administration of meperidine and promethazine on fetal heart activity measured by a computerized system.

Methods: Fourteen healthy women with normal pregnancies at term were studied during the active phase of labor. Fetal heart rate was recorded with the Oxford Sonicaid system 8000. Recordings were performed for 40 minutes prior to and after maternal intravenous administration of meperidine 50 mg with promethazine 25 mg.

Results: The combination of meperidine and promethazine caused a significant decrease in the number of accelerations of 10 beats per minute (9.7 versus 2.6, P = 0.002) and 15 beats per minute (5.2 vs. l.4, P = 0.003), time spent in episodes of high variation (14.8 vs. 2.0, P = 0.005) and short-term variation (7.8 vs. 5.0, P = 0.003). On the other hand there was an increase in the time spent in episodes of low variation (5.3 vs. 19.7, P = 0.009).

Conclusions: Maternal administration of meperidine with promethazine has a significant effect on FHR[1] indices during the active phase of normal labor.