How Gonadotropin Fertility Drugs Work
Did you know that gonadotropins are not only a class of fertility drugs, but that there are two naturally occurring gonadotropins in a woman's body already? This article will explore the nature of gonadotropins, how gonadotropin treatment works, and some of the specific gonadotropin medications.
Naturally Occurring Gonadotropins
Two natural gonadotropins are hormones secreted each month cycle from the pituitary gland in the brain during a woman's menstrual cycle. These well-known hormones are luteinizing hormone (LH) and follicle stimulating hormone (FSH), whose purpose is to stimulate the ovaries to produce eggs. Elevated blood levels of FSH indicate that the ovary is maturing. When an egg is mature, there is a surge in LH levels, which triggers ovulation - the release of an egg into the fallopian tubes.
Fertility specialists often recommend combining fertility medications such as Gonadotropins with treatments for infertility such as IUI. Gonadotropins contain either LH or FSH, or both, and they work to mimic the action of naturally occurring gonadotropins in order to 'artificially' stimulate ovulation. In the case of IUI, this ensures that an egg or several eggs will be available to meet the sperm injected during IUI in order to facilitate fertilization.
Some of the common gonadotropins are Follistim, Gonal-F, Repronex, and Bravelle. Bravelle contains approximately 97% FSH and 3% LH. Follistim and Gonal-F contain only FSH. Repronex contains equal amounts of LH and FSH.
How Gonadotropin Treatment Works
Gonadotropins must be injected and cannot be taken orally since they are inactivated in the intestinal tract. Gonadotropin injections begin on the third day of the menstrual cycle and are continued on a daily basis until the egg or eggs have matured. This process usually lasts between six to ten days.
In order to determine how many egg follicles (fluid-filled sacs holding the eggs) have developed, how large they have grown, and how they are progressing, vaginal ultrasounds are routinely performed. Blood tests are conducted to measure the level of the hormone "Estradiol," a form of estrogen that indicates the level of egg maturity. When the necessary levels are reached, the final gonadotropin injection is administered.
Finally, one last Gonadotropin medication called hCG (human chorionic gonadotropin) is given. hCG is a special fertility drug that has been labeled the "trigger shot," as it triggers a final LH surge in order to ensure the release of eggs from the follicles prior to IUI.
The injection of hCG is timed very carefully with the insemination process. Typically, hCG shots are given 36 hours prior to IUI. However, there are new studies indicating that a double insemination, at 18 and 42 hours after hCG injection, improves pregnancy rates.
Gonadotropin Treatment Risks
Women undergoing gonadotropin treatment are monitored very carefully. If any cysts are detected in the ultrasound, treatment is cancelled due to poor prognosis. In order to suppress the cysts, some women may have to take birth control pills for a month.
The use of gonadotropins carries an increased risk for multiple pregnancies. There is an estimated 30% chance of twins, a 5% chance of triplets, and a 1% chance of higher-order pregnancies.
Gonadotropin treatment also increased the risk for ovarian hyperstimulation syndrome (OHSS), a condition in which the ovaries become over-stimulated and fill with fluid, resulting in enlarged ovaries, abdominal swelling, and dehydration. OHSS symptoms range from mild to severe.
Finally, as with any type of medicine injections, there is a small risk of infection, swelling, pain, bleeding, or allergic reaction.