The present invention relates to an injectable formulation comprising progesterone, progestin or analogues thereof, wherein a portion of said hormone is dissolved in an organic solvent to form a free portion and a portion of said hormone is enclosed by fatty acids to form an enclosed portion and wherein both portions are included in a gel matrix. This formulation allows a controlled release profile of progesterone to promote ovulation or synchronizing the ovulation or heat/estrus of a group of female mammals more effectively than intra-vaginal devices commonly used in the art. In general, hormone formulations, dosage units including the hormone formulations, and methods of use relate to a controlled release formulation, which includes hormones, e.g., progesterone are described. Formulations and methods are for controlling the reproductive cycle and/or ovulation of a female mammal, for example, to promote ovulation in a female mammal or synchronizing the ovulation or heat/estrus of a group of female mammals. In addition, formulations are for increasing the likelihood that a female mammal becomes pregnant, for example, after insemination or embryo transference. In addition, formulations are for reducing the anestrous period in a female mammal.
