Oral estrogens lead to high GH levels and also low IGF-1 levels, both with potential negative effects. This is a theoretical reason to take systemic estrogens over oral estrogens. On the other hand, oral estrogens may be more effective than systemic
estrogens in terms of improving some parameters related to heart disease. Oral estrogens, but not systemic estrogens, increase the good cholesterol, HDL. Oral estrogens may have other beneficial heart effects (antioxidant effects) compared to systemic estrogens.
Progesterone is usually given along with estrogen, because estrogen alone
(unopposed estrogen) is associated with endometrial hyperplasia and cancer. Progesterone compounds substantially decrease this risk and are usually given along with estrogen to women with an intact uterus. What is less appreciated is that progesterone-containing compounds have their own side effects and benefits. Some of the side effects include increased blood clots, rash, breast tenderness, weight gain, fatigue and
somnolence, edema and nausea. Some of the possible (largely unproven) benefits (besides the reduction in endometrial hyperplasia and cancer due to unopposed estrogens) include prevention of osteoporosis, improved mood and better sense of well-being. Similar to the issue of estrogens, there are both natural and synthetic progesterones. Synthetic progesterones are called Progestins and the most widely prescribed Progestin is Provera. Recently, progesterone itself has become available as a drug called Prometrium. It is postulated, but not proven, that natural progesterone is better for the patient than synthetic progesterone.
The tables below of different readily available estrogen and progesterone containing compounds may be helpful. These tables are not a complete list of all available preparations, but are a guide to commonly available hormone preparations. Again, I recommend that your decision on whether to start hormone replacement and, if so, what type of hormone replacement, be carefully considered and arrived at in conjunction with your physician.
Link to article and tables: http://www.goodhormonehealth.com/symptoms/estrogen.PDF.