We performed a randomized controlled trial of the effect of intravenous fluid preload on maternal hypotension and fetal heart rate (FHR) changes in labour after the first epidural injection. Group 1 (49 women) received 1 litre of crystalloid preload. Group 2 (46 women) received no preload. No statistically significant difference was shown between the two groups for either of the outcomes. Hypotension was found in three women in group 1 and five in group 2 (P = 0.4). Deterioration in FHR pattern was found in four women in group 1 and 11 in group 2 (P = 0.08). This study has not shown a significant increase in the incidence of hypotension when intravenous preload is omitted before epidural analgesia using a low concentration of bupivacaine during labour. Because of the clinical importance of the difference in the rate of FHR deterioration between the two groups, we continue to administer preload for high-risk cases.
Summary
The continuous fetal heart rate pattern, condition of the baby at birth and its subsequent behaviour were compared in three groups of infants whose mothers received during labour either no drugs, intramuscular pethidine or epidural bupivacaine. The blood levels of pethidine and bupivacaine were measured at delivery in a maternal vein, and umbilical artery and vein, and in the newborn during the first 48 hours of life. The only significant changes in the fetal heart rate pattern occurred in association with maternal hypotension or uterine hyper‐stimulation. The Apgar scores at one minutes were 7 or less in more infants in the intramuscular pethidine and epidural bupivacaine groups as compared with the controls. There were no differences in the Apgar scores at five minutes. Neonatal behaviour during the first six weeks of life was not significantly affected by pethidine or epidural bupivacaine when compared with the control group. Pethidine and bupivacaine were shown to cross the placenta freely. The half‐life of these drugs in the newborn was longer than in the adult.
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