There are several fertility drugs available to help infertile couples conceive.  Irregular or absent ovulation is a common cause of infertility.  Many fertility drugs target the ovulatory cycle to “regulate” ovulation or cause the development of many eggs (FSH).

During a normal ovulatory cycle, the hypothalamus releases GnRH (gonadotropin releasing hormone) which travels to the pituitary gland and stimulates the production of follicle stimulating hormone (FSH). This occurs during the first segment of the ovulatory cycle (recruitment).  The hypothalamus functions like a “regulator” balancing the production of several hormones based upon measurement of competing hormone levels.

As healthy follicles grow, they produce increasing amounts of estrogen. Estrogen levels are monitored by the hypothalamus, and as they increase the production of FSH declines.  Once the follicles mature, the hypothalamus signals the pituitary to release a surge of luteinizing hormone (LH) which causes egg release (i.e. ovulation) 36 hours later.

Once the follicle ruptures (after ovulation) the leftover structure known as the corpus luteum begins to produce progesterone. Progesterone causes the endometrial lining to thicken and become more vascular to support a developing embryo. After the placenta is formed, it begins to produce progesterone.

Clomid is an ovulation inducing fertility drug that works at the hypothalamus. Clomid occupies estrogen receptors blocking the normal estrogen feedback mechanism. Since the receptors are occupied, the hypothalamus “reads” lower estrogen levels and continues production of FSH. See the Clomid Page.

FSH fertility drugs, such as Follistim, Repronex, Menopur and Bravelle stimulate the ovaries directly to recruit multiple follicles.  This response is “dose dependant” meaning that the more FSH is given by injection, the higher the number of recruited and developed follicles. This is different from Clomid which does not produce a dose related response.  Once ovulation is occurring on Clomid, there is no advantage to increasing the dose. FSH fertility drugs are used in IUI cycles and in assisted reproductive technologies (IVF) where many eggs are needed. See the FSH page.

Once the follicles mature, the hypothalamus signals a release of LH (spike) which causes ovulation 36 hours later. hCG fertility drugs such as Ovidrel and Pregnyl mimic the LH spike and are effective in inducing ovulation. See the hCG page.

Lupron and Ganirelix are fertility drugs used in ART cycles to help control the timing of ovulation and prevent early egg release.  Lupron interferes with the production of FSH by the pituitary causing “down regulation” and a depletion of natural FSH and LH.  When a patient is down regulated her hypothalamus cannot cause the pituitary to release FSH or LH.  FSH must be administered by injection and ovulation must be stimulated with another injection of hCG.  Lupron is begun before the FSH fertility drug injections.  Ganirelix, on the other hand, is started after the FSH injections and blocks the action of LH and is given for just a few days before the egg retrieval.  Both Lupron and Ganirelix prevent “early ovulation” during an IVF cycle which could result in loss of the eggs before they can be retrieved.  See the Lupron, Ganirelix pages.

Progesterone is essential to proper endometrial development. The endometrium must thicken and become more vascular to facilitate embryo implantation. Initially, progesterone is produced by the leftover follicle (corpus luteum) and later by the placenta. Progesterone is used in all IVF cycles to offset the progesterone lowering effects of Lupron/Ganirelix. See the page on progesterone.