Platelet aggregation during menstrual cycle and pregnancy

Abstract Platelet aggregation induced by ADP, adrenaline and collagen was examined in 20 healthy young men, 42 healthy young women with normal menstrual cycle and 38 pregnant women (7th to 40th week of pregnancy). During menstrual cycle and pregnancy, primary aggregation did not change in intensity or speed. Also secondary aggregation did not change in intensity. However, secondary aggregation induced by ADP and adrenaline frequently observed in follicular phase and less in menstruation and luteal phase with a statistical significance. In pregnant women intensities of primary and secondary aggregation were not different with those of non-pregnant women. However the appearance rate of secondary aggregation markedly increased during pregnancy. Collagen aggregation did not show any difference among any groups. The result suggests that estrogen, which increases in the blood both in pregnancy and follicular phase, might have a role in the appearance of secondary aggregation which is related to platelet release reaction.