[Behavior of glycosylated hemoglobin (HbA1) in normal and pathologic pregnancy]

Glycosylized hemoglobin (Hb-A1) was measured in 314 gravidae with normal kidneys and metabolism from the tenth to the 41st week of pregnancy. From the first to the second trimester of pregnancy a significant drop in Hb-A1 occurs, from 6.93% to 6.66%, toward the third trimester there is a significant increase to 6.86%. Post partum the Hb-A1 was also significantly lower (6.82%) than in the nonpregnant control group (7.23%). In patients with the histories and findings of risk factors influencing carbohydrate metabolism the same, though nonsignificant course was found (probably because of the lower number of cases), with a drop in Hb-A1 in the second trimester. A possible cause of this is the accelerated metabolism of glucose during pregnancy, which leads to an improvement in carbohydrate tolerance and thus lowers the Hb-A1 level, or the increased erythropoetic activity of the bone marrow during the second trimester, leading to a "thinning" and thus a reduction of the Hb-A1 concentration due to the increased volume of erythrocytes. Knowledge of the kinetics of Hb-A1 in normal pregnancy is important in order to permit correct interpretation of concentrations measured in pregnant diabetics.