Influence of Meperidine on Fetal Movements and Heart Rate Beat-to-Beat Variability in the Active Phase of Labor

ABSTRACT

Eleven parturients were studied in the active phase of labor. Fetal movements, fetal heart rate, and short-term beat-to-beat variability as well as uterine contractions were evaluated for two 40-minute recording periods before and after maternal intravenous administration of 50 mg meperidine. Meperidine depressed fetal activity and increased the duration and frequency of uterine contractions. Fetal movements were significantly reduced from 156 to 60 and their relative duration from 8.6 ± 6.0% to 2.4 ± 2.6% (p < 0.01). The short-term fetal heart rate beat-to-beat variability was reduced at the baseline period 5.22 ± 1.02 versus 4.62 ± 1.47 (p < 0.05) but not during uterine contractions or fetal movements. The frequency of uterine contractions increased from 3.1 ± 0.8 to 3.7 ± 0.7 per 10 minutes (p < 0.01), and their relative duration from 35.3 ± 6.9% to 40.1 ± 5.9% (p < 0.05).