THE EFFECT OF MATERNAL PUSHING ON FETAL CEREBRAL OXYGENATION AND BLOOD-VOLUME DURING THE 2ND STAGE OF LABOR

Objective To measure the effect of maternal pushing during the second stage of labour on fetal cerebral oxygenation and blood volume. Design A prospective study comparing changes in the fetal cerebral concentra tions of oxyhaemoglobin, deoxyhaemoglobin and cerebral blood volume, b efore and during maternal pushing in the second stage of labour. Setti ng Teaching hospital obstetric unit. Subjects Ten term fetuses during labour. Results Following the onset of maternal pushing, mean cerebral deoxyhaemoglobin concentration increased by a mean of 0.79 (SD 0.59) mu mol.100 g(-1), (P<0.01) without any consistent change in the oxyhae moglobin concentration. These changes were associated with a significa nt decrease in the calculated mean cerebral oxygen saturation from a m ean of 46.8% (SD 8.6) to 38.1% (SD 5.2) (P<0.01). Pushing was also ass ociated with a significant increase in the mean cerebral blood volume, which rose by a mean of 0.33 ml.100 g(-1) (SD 0.37) (P<0.05). Conclus ion Maternal pushing during the second stage of labour leads to a sign ificant decrease in fetal cerebral oxygenation, together with an incre ase in cerebral blood volume.