Human fetal oxygenation (tcPo2), heart rate variability and uterine activity following maternal administration of meperidine.

Abstract

Fetal tcPo2 levels were measured in 10 patients following maternal administration of 50 mg of meperidine by intravenous route. About 3 minutes following injection of meperidine, tcPo2 values started to decline to reach the lowest value of 37 +/- 25% by 7 mins of injection. tcPo2 values recovered by about 15 mins following injection. These changes in fetal tcPo2 levels preceded transient minimal increase in FHR variability. The increase in FHR variability was followed immediately by a decrease in the indices of the FHR variability. The uterine activity began to decline below the predicted positive slope values shortly following injection of meperidine. This decline was maximum 15 mins post-injection, subsequently establishing a trajectory toward the positive values expected for unmedicated labor. Two patients receiving 25 mg intravenous meperidine demonstrated no decline in tcPo2 levels; however, in the patient receiving 75 mg of intravenous meperidine, the changes noted were similar to those observed following 50 mg of meperidine.