Red cell 2.3-diphosphoglycerate in pregnancy.

In normal, primigravidae red cell 2.3-diphosphoglycerate (2.3-DPG) concentration was found to be increased significantly from the third month of pregnancy. The 2.3-DPG concentration remained elevated throughout pregnancy. Increase in the 2.3-DPG concentration leads to a decrease in the oxygen affinity of the maternal red cells. The combination of low pCO2 and low oxygen affinity of the maternal blood facilitates the transport of oxygen as well as that of carbon dioxide across the placenta. The weight of the delivered children was not significantly correlated to the 2.3-DPG changes, and no significant variation of the measured variables could be detected in 9 women with abnormal pregnancies.