Maternal and fetal requirements during uncomplicated pregnancy are associated with changes in the
hematopoietic system. Platelets and erythrocytes [red blood cells (RBCs)], and especially their membranes, are
involved in coagulation, and their interactions may provide reasons for the changed hematopoietic system during
uncomplicated pregnancy.We review literature regarding RBC and platelet membrane structure and interactions
during hypercoagulability and hormonal changes. We then study interactions between RBCs and platelets in
uncomplicated pregnancy, as their interactions may be one of the reasons for increased hypercoagulability during
uncomplicated pregnancy. Scanning electronmicroscopy was used to study whole blood smears from90 pregnant
females in different phases of pregnancy. Pregnancy-specific interaction was seen between RBCs and platelets.
Typically, one or more platelets interacted through platelet spreading and pseudopodia formation with a single
RBC. However, multiple interactions with RBCs were also shown for a single platelet. Specific RBC–platelet
interaction seen during uncomplicated pregnancy may be caused by increased estrogen and/or increased
fibrinogen concentrations. This interaction may contribute to the hypercoagulable state associated with healthy
and uncomplicated pregnancy and may also play a fundamental role in gestational thrombocytopenia.