In infertility patients who are struggling with ovulation dysfunction, ovulation induction is an approach to overcome the failure of the ovaries to ovulate in a predictable fashion. Ovulation is the process of producing and releasing an egg (ovum) from the ovary. When ovaries ovulate infrequently, it becomes hard to get pregnant and results in female infertility. Induction is the use of hormone therapy to stimulate the egg development and release from the ovaries. Not only is this technique used for women with ovulation disorders but also for women undergoing in vitro fertilization (IVF) or artificial insemination for other causes of infertility. Lastly, there is evidence to suggest ovulation induction may be helpful for infertile couples with unexplained infertility.
Clomiphene Citrate (Seraphene, Clomid)
Clomiphene citrate (CC) is an oral medication that blocks estrogen receptors. Its use causes the hypothalamus (an area in the brain that controls fertility) to believe that estrogen levels are low. In response, it stimulates the pituitary gland to increase the release of follicular stimulating hormone (FSH) and stimulate the ovaries harder to ovulate. It may cause the ovaries to release more than one egg but twins and triplets occurs in about 5% of pregnancies caused by CC. Because it blocks estrogen receptors, many patients experience hot flashes, vaginal dryness and irritability.
Aromatase Inhibitors (Femara, Arimidex)
Aromatase Inhibitors (AI) are similar to CC in their affect to cause ovulation but are not approved by the FDA for this purpose. Like CC, the decrease estrogen levels cause the stimulation of the hypothalamus and pituitary to stimulate the ovaries. Studies have demonstrated its effectiveness to be similar to CC. The manufacturer of letrozole (Femara) has discouraged its use in premenopausal women.
Insulin resistance and elevated insulin levels have been demonstrated in women with polycystic ovary syndrome (PCOS). Metformin is an insulin sensitizing medication and is commonly prescribed with CC or AI in ovulation induction although the FDA has not approved it for this purpose. GI side effects are common including nausea, vomiting and diarrhea.
Human Menopausal Gonadotropin (hMG, Pergonal, Repronex)
hMG is a medication that contains FSH and luteinizing hormone (LH). It directly stimulates the ovary develop and release eggs. This injectible agent is stronger than oral medications and is very effective in ovulation induction. Because of its expense, it is used in artificial insemination or more commonly, in IVF. Overstimulation of the ovaries is common and patients are usually monitored with estrogen levels and ultrasound to detect overstimulation.
Follicle Stimulating Hormone (FSH, Follistim, Bravelle)
Instead of hMG, FSH alone may be used for ovulation induction and directly on the ovaries like hMG. Also an injectable agent, individual responses may be hard to predict and is used in combination with estrogen levels and ultrasound to monitor for ovarian overstimulation.
Human Chorionic Gonadotropin (HCG, Pregnyl, Ovidrel)
hCG is a natural hormone that occurs during pregnancy but is molecularly similar to LH. As a result, it can be used to finalize the maturation of the eggs and trigger ovulation from the ovaries. Ovulation occurs usually within 36 hours of its injection when mature eggs are available in the ovaries. hCG will cause a pregnancy test to turn positive even in the absence of pregnancy. Testing for pregnancy by urine or blood is usually delayed until after the medicine has cleared.