Effect of oral contraceptives and pregnancy on erythrocyte deformability and surface charge.

ABSTRACT

PIP: Erythrocyte membrane deformability is a factor in blood viscosity. Progesterone and synthetic progestational steroids interact with the ery throcyte membrane and may be related to the decreased deformability. In women, reduction in net negative surface charge during pregnancy has bee n reported. This might overcome normal especially with a reduced rate of blood flow. These factors were investigated in blood taken from patients in a Family Planning Clinic and an Obstetrical Clinic. Patients taking oral contraceptives had used them for more than 2 months. Techniques employed are described. Erythrocyte deformability was unchanged in the contraceptive users. In pregnant women a difference in filtration time was observed, indicating decreased deformity of the erythrocytes. Net negative surface charge, as measured by electrophoretic mobility, was unchanged in oral contraceptive users and in pregnant women. The increased incidence of thrombosis in women taking oral contraceptives could not be explained by decreased erythrocyte deformability or surface charge. However, decreased deformability of erythrocytes in late pregnancy may relate to thrombosis during this period, and to increased hemolysis in patients with some hemoglobinopathies.