THE RELATIONSHIP OF MATERNAL ERYTHROCYTE OXYGEN-TRANSPORT PARAMETERS TO INTRAUTERINE GROWTH-RETARDATION

The relation of fetal growth and maternal oxygen transport as assessed by red blood cell 2,3-diphosphoglycerate, hemoglobin oxygen affinity, hemoglobin, pH, and Pco2 was evaluated in 21 pregnant women. The study was performed in the third trimester and each subject evaluated had sonographic evidence of fetal growth retardation without other obvious abnormalities. Decreased maternal 2,3-diphosphoglycerate/hemoglobin molar ratio and hemoglobin oxygen affinity were related linearly to the birth weight normalized for the expected sea level values of gestational age expressed as a birth weight (gestational age-normalized) Z score. The correlation coefficients and p values were r = 0.71, p < 0.001 and r = 0.67, p < 0.001, reespectively. The ponderal index-normalized Z score correlated with the 2,3-diphosphoglycerate/hemoglobin molar ratio (r = 0.46, p < 0.04), but the relation was not as strong as the birth weight-normalized Z score. The crown-heel length/head circumference ratio did not correlate with the 2,3-diphosphoglycerate/hemoglobin molar ratio (r = 0.29, NS). The birth weight (gestational age)-normalized Z score did not correlate with hemoglobin, Pco2 hemoglobin oxygen affinity, calculations indicated that the 2,3-diphosphoglycerate/hemoglobin molar ratio played a highly significant role (p < 0.001), pH was minimally significant (p < 0.025), but Pco2 had little or no significant effects in this study. It appears that fetal growth is related to the maternal red blood cell oxygen transport parameters 2,3-diphosphoglycerate/hemoglobin molar ratio and hemoglobin oxygen affinity. Moreover, the 2,3-diphosphoglycerate/hemoglobin molar ratio is the principal regulator of hemoglobin oxygen affinity. © 1990.