The physicochemical, immunological, and biological activities of?recombinant?hCG are comparable to those of placental and human pregnancy urine-derived hCG. Choriogonadotropin alfa stimulates late follicular maturation and resumption of?oocyte?meiosis, and initiates?rupture?of the pre-ovulatory?ovarian?follicle. Choriogonadotropin alfa, the active component of Choriogonadotropin Alpha PreFilled Syringe, is an analogue of?Luteinizing Hormone?(LH) and binds to the LH/hCG receptor of the granulosa and theca cells of the ovary to effect these changes in the absence of an?endogenous?LH surge. In pregnancy, hCG, secreted by the placenta, maintains the viability of the corpus?luteum to provide the continued secretion of?estrogen?and?progesterone?necessary to support the first trimester of pregnancy. Choriogonadotropin Alpha PreFilled Syringe is administered when monitoring of the patient indicates that sufficient follicular development has occurred in response to FSH treatment for?ovulation?induction.