An examination has been made of the variation through the menstrual cycle of blood viscosity and some of the parameters, including the concentrations of some acute phase reactants, which affect blood flow. Effects on blood viscosity were determined by fitting values of shear stress, T, derived from a Contraves LS-2 rheometer, as a function of shear rate, D, and haematocrit, H, to the empirical constitutive function
where X1 to X4 are the adjustable parameters which characterize the intrinsic flow behaviour of the sample. Fibrinogen, albumin, α2macroglobulin, IgM and antithrobmin III levels in the plasma, whole blood clotting times and erythrocyte sedimentation rates were also measured. Based on over 70 rheological determinations on 12 women and over 200 protein concentration determinations on 43 women it was concluded that no cyclical changes occurred in either the rheological characteristics of anticoagulated blood or the other parameters measured.
