The lipoprotein measures selected are the standard lipid profile consisting of triglyceride, cholesterol, HDL cholesterol measured by precipitation and estimation of LDL by the Friedwald algorithm. The HDL2 and HDL3 sub-fractions and apoproteins AI and AII are sensitive measures of estrogen-progestin balance, as is sex-hormone binding globulin (SHBG). Lipoprotein lipids, HDL sub-fractions and SHBG will be measured at 1, 7, 21 and 28 days. The apoproteins will be measured at days 1 and 21.