Ovarian stimulation is the development and maturation of follicles (eggs) using fertility medications. The goal of ovarian stimulation is either to treat patients with ovulation problems or stimulate multiple eggs to mature. The former is also called ovulation induction (maturation of a follicle) and the latter is called superovulation (development of multiple follicles).
Ovarian stimulation can be accomplished by using clomiphene citrate commonly known as the brand name Clomid. This oral medication acts as a false estrogen hormone at the level of the hypothalamus and occupies the estrogen receptor. When the estrogen receptor is occupied, more gonadotropin releasing hormone (GnRH) is released, which then stimulates the production of follicle stimulating hormone (FSH) and luteinizing hormone (LH) from the pituitary gland, the hormones that stimulate follicles and ovulation. The end result is more pulsatile FSH and LH release which result in ovulation or superovulation.
Clomid is taken orally for five days starting on the third or the fifth day at 50 mg daily. The dose can be increased up to 250mg daily if ovulation is not observed. Once ovulation is accomplished at a certain dose, increasing the dose does not increase pregnancy rates. Clomid can be used in women who have irregular cycles to induce ovulation or for the purpose of superovulation in those with regular cycles.
Gonadotropins include FSH and LH, which can be used together or at different times during ovarian stimulation. FSH develops eggs and LH allows the final maturation and ovulation. They can be used only as injectable medications and act directly on the ovaries. FSH and LH can be used for ovulation induction or for the purpose of superovulation. They are routinely used during in vitro fertilization (IVF) cycles to induce superovulation. Two different types of gonadotropins are available in the market, which include human menopausal gonadotropins (hMG – Repronex, Menopur and Bravelle) derived from menopausal women; and recombinant FSH (rFSH – Gonal-F or Follistim) and recombinant LH (rLH – Luveris), which are genetically engineered.