THE EFFECT OF MATERNAL POSTURE ON FETAL CEREBRAL OXYGENATION DURING LABOR

Objective To measure the effect of changes in maternal posture on feta l cerebral oxygenation during normal labour. Design A prospective stud y comparing changes in the fetal cerebral concentrations of oxyhaemogl obin, deoxyhaemoglobin and cerebral blood volume, measured by near inf rared spectroscopy, in women with effective epidural analgesia when mo ved from the left lateral to the supine position during labour. Settin g A London teaching hospital obstetric unit. Subjects Fourteen women d uring uncomplicated labour at term. Results When compared with the lef t lateral position, the supine position was associated with a signific ant decrease in the mean concentration of fetal cerebral oxyhaemoglobi n of 1.12 (SD 1.0, 95% CI 0.49 to 1.75) mu mol. 100 g(-1) (P < 0.01) w ithout any significant change in the mean concentration of deoxyhaemog lobin and cerebral blood volume. These changes were associated with a si,onificant decrease in the mean cerebral oxygen saturation of 8.3 (S D 8.8, 95% CI 1.5 to 15.1)% (P < 0.05, n = 9). Conclusion Changes in m aternal posture during labour, in women with effective epidural analge sia, are associated with a significant decrease in fetal cerebral oxyg enation.