The present invention provides slow release estradiol-progesterone formulations that can be used in either contraception or hormone replacement therapies. The formulations comprise shaped particles of estradiol that is in a hemicrystalline form that exhibits especially low dissolution rates. The shaped particles comprise estradiol compounded in a 1:1 molar ratio with cholesterol, and are administered in combination with progesterone. The slow release formulations of the present invention afford the dual advantages of a low dose estradiol formulation with a low frequency administration regimen. The formulations can be parenterally administered once a month or less often.