So all women with a uterus who are given estrogen are supposed to be given progesterone also. Most doctors do not prescribe progesterone to women who do not have a uterus because they are concerned that it may block estrogen's healthful effects on blood cholesterol levels. Recent data show that progesterone does not do this and several recent papers show that progesterone plus estrogen strengthens bones much more than estrogen alone does. We know that estrogen prevents heart attacks. This recent study from Italy shows that the second female hormone, progesterone helps to keep blocked arteries open when administered vaginally, but not when taken by mouth.
Many drugs effects depend on how they are taken.
Estrogen pills raise blood levels of the good HDL cholesterol, while estrogen patches do not. Testosterone pills cause heart attacks, while reasonable doses of injected testosterone do not. If future studies confirm this one, doctors will recommend that postmenopausal women take estrogen pills and progesterone vaginal inserts whether they have a uterus or not. I'm Dr. Gabe Mirkin on Fitness. Cardiovascular effects of the ovarian hormones.