Fertility medications, also known as fertility drugs, are medications which enhance reproductive fertility. For women, fertility medication is used to stimulate follicle development of the ovary. There are very few fertility medication options available for men. Agents that enhance ovarian activity can be classified as either gonadotropin releasing hormone, estrogen antagonists or gonadotropins. Treatment decision-making involves four major factors: efficacy, burden of treatment (such as frequency of injections and office visits), safety, and financial costs. Female Main techniques The main techniques involving fertility medication in females are: Ovulation induction, with the aim of producing one or two ovulatory follicles for fertilization by sexual intercourse or artificial insemination Controlled ovarian hyperstimulation, which is generally part of in vitro fertilization, and the aim is generally to develop multiple follicles (optimally between 11 and 14 antral follicles measuring 2–8 mm in diameter), followed by transvaginal oocyte retrieval, co-incubation, followed by embryo transfer of a maximum of two embryos at a time. Final maturation induction of follicles, also triggering a predictable time of ovulation. Gonadotropin-releasing hormone Either gonadotropin-releasing hormone (GnRH) or any gonadotropin-releasing hormone agonist (such as Lupron) may be used in combination with luteinizing hormone (LH) using an infusion pump to simulate endogenous hormone production. GnRH stimulates the release of gonadotropins (LH and FSH) from the anterior pituitary in the body. This set of therapy is reserved for a subset of women with infertility and have produced ovulation rates of 90% and pregnancy rates of 80% or higher. Antiestrogens Antiestrogens inhibit the effects of estrogen, which include selective estrogen receptor modulators (SERM) and aromatase inhibitors. Selective estrogen receptor modulators Clomiphene is a selective estrogen receptor modulator (SERM). It is the most widely used fertility drug. Other medications in this class include tamoxifen and raloxifene, although both are not as effective as clomiphene and are thus less widely used for fertility purposes. They are used in ovulation induction by inhibiting the negative feedback of estrogen at the hypothalamus. As the negative feedback of estrogen is inhibited, the hypothalamus secretes GnRh which in turn stimulates the anterior pituitary to secrete LH and FSH which help in ovulation. Between 60 and 85% of women, mostly with polycystic ovary syndrome (PCOS), ovulate successfully in response to clomiphene with a cumulative pregnancy rate of 30 to 40%. Aromatase inhibitors Although primarily used in breast cancer treatment, aromatase inhibitors (particularly generic letrozole) are also used in ovulation induction. Aromatase