EFFECTS OF INTRAMUSCULAR PETHIDINE ON FETAL HEART RATE VARIABILITY DURING LABOUR

Abstract

The effects of i.m. administered pethidine, an analgesic, on indices of fetal heart rate (FHR) variability were studied during labor in 20 women. The differential index, describing the short-term variability and the interval index, describing the long-term variability, were measured from direct fetal ECG by a microprocessor-based on-line system. The indices were measured from 10 min samples, once before the pethidine injection and 9 times after the injection. The interval index decreased significantly (P < 0.01) with the maximum effect 40 min after the injection. The differential index showed a decreasing trend, with a maximum at 40 min, but the change was not significant. Both indices returned to the pre-injection level after 60 min. The effect of pethidine on FHR variability during labor might cause difficulties in assessing the fetal state.