On the other hand, due to the loss of inactivation of EE by 17β-HSD in the endometrium (uterus), EE is relatively more active than estradiol in the endometrium and, for this reason, is associated with a significantly lower incidence of vaginal bleeding and spotting in comparison [REF].
EE has been found to have similar effects on hepatic protein production and VTE risk regardless of whether the route of administration is oral, transdermal, or vaginal, indicating that oral versus non-oral routes do not reduce the hepatic actions of EE relative to non-hepatic actions [REF].