Comparison of the effects of meperidine and nalbuphine on intrapartum fetal heart rate tracings

OBJECTIVE: To examine the effects of meperidine and nalbuphine on intrapartum fetal heart rate (FHR) tracings using computer analysis. METHODS: We studied 28 women with uncomplicated pregnancies in early labor at term with reactive FHR tracings. The women were randomized to receive either meperidine 50 mg or nalbuphine 10 mg intravenously on request. One-hour FHR recordings were obtained before and immediately after administration of the medications. RESULTS: There were no significant differences in the FHR characteristics of the two groups during the pre-treatment period. Nalbuphine significantly decreased the number of accelerations of 10 beats per minute (17 versus 4, P = .003) and 15 beats per minute (10 versus 1.5, P = .001), time spent in episodes of high variation (35.5 versus 10 minutes, P = .004), long-term variation (47 versus 29.8 milliseconds, P = .002), and short-term variation (8.4 versus 6.4 milliseconds, P = .03). Meperidine had no significant effect on any FHR characteristic. CONCLUSION: In the early intrapartum period of normal term pregnancies and at commonly used dosages, nalbuphine had a significant effect on FHR tracings, whereas meperidine had no effect, as determined by computer analysis.