Effect of maternal position on fetal heart rate during extradural analgesia

Using continuous cardiotocography, the effect of maternal position on fetal heart rate (FHR) was studied during extradural analgesia (EA) with either 50 or 100 mg of etidocaine without adrenaline for labour and vaginal delivery. Of 70 healthy parturients, 39 were supine and 40 were in the lateral position. FHR was normal in all patients during the control period before EA, and remained normal during EA in 53. Transient abnormal patterns occurred in 26 patients, 22 (56%) in the supine group and four (10%) in the lateral group, a significant difference (P less than 0.001). The decrease in arterial pressure (AP) did not differ between the groups, but the frequency of abnormal FHR associated with a small or moderate decrease in AP (30% or less) was greater in the supine (51%) than in the lateral group (3%).