Physiological Significance of Fetal Blood Gas Changes Elicited by Different Delivery Postures

Abstract

We performed umbilical blood gas analysis for 130 pregnant women in sitting and for 50 in supine position immediately after their deliveries. To elucidate whether fetal blood gas changes were attributed to the maternal postures, we also carried out the maternal blood gas analysis during delivery (n=145) and prior to the onset of labor (n=100) in both positions. Blood gas values of the umbilical vein and artery in the sitting group were significantly higher in pH, PO2, base excess (BE) and oxygen saturation (SO2), and lower in PCO2 than those in the supine group. In contrast, maternal arternal blood gas values (pH, PaCO2, PaO2 and SaO2) did not show significant differences between these two groups in both during delivery and before the onset of labor. Thus, the sitting delivery position can elicit physiologically more beneficial blood gas aspects in fetus compared with the conventional supine delivery position. Umbilical blood gas improvements induced by sitting delivery position do not appear to be a result of the maternal blood gas alteration, but appear to be mediated by other factors. © 1988, Tohoku University Medical Press. All rights reserved.