HCG is short for human chorionic gonadotropin, a hormone produced by developing embryonic tissue. Normally, adults don't produce hCG, and don't have it in their bloodstream. If a woman is pregnant, she'll have hCG in her blood due to production of the hormone by her developing baby. Interestingly enough, doctors can use hCG to enhance fertility in some cases.
Your Reproductive Cycle
Many hormones normally interact to help produce your normal monthly reproductive cycle. A hormone called GnRH from the hypothalamus of the brain stimulates the production and release of two other hormones, called LH and FSH, from the brain. FSH causes your ovaries to ripen and mature one or more eggs, while LH causes the follicle containing the most mature egg to rupture, releasing the egg via the process of ovulation.
Normal Fertilization and Infertility
If you engage in intercourse shortly before or after ovulation, sperm will find and fertilize the ovulated egg. This event, called conception, results in the formation of a zygote, or developing cell ball, which travels to the uterus and embeds in the uterine lining. There are many types of female-specific infertility; an egg may not be able to travel through the Fallopian tubes to the uterus, or may not be able to implant. In some cases, you may simply not ovulate, meaning that sperm have no way to meet a mature egg.
Infertility Treatment
The treatments for infertility vary depending upon the cause of the problem. In the specific case of infertility due to not ovulating, it's possible to "trick" the ovaries into releasing an egg by using hCG. HCG isn't normally involved in the process of maturing and releasing an egg. However, explains RXList.com, there is much similarity between the shapes of the hormones LH and hCG, such that injections of hCG can fool the ovaries into thinking they're sensing LH, causing them to respond by releasing an egg.
More Complex Cases
In certain more complex cases, ovaries not only fail to release a mature egg, they fail to mature eggs at all. In this case, infertility doctors typically give a series of carefully timed hormone injections. Early injections of drugs like Follastim or Lupron contain FSH, and help induce your ovaries to mature several eggs, explains the Pacific Fertility Center. Once doctors determine by ultrasound that the eggs are mature, injections of Pregnyl or other hCG-containing drugs mimic the effects of LH, and cause ovulation.
Effects
While hCG injections can help you become pregnant if you have certain kinds of infertility, the injections make it far more likely that you'll release multiple eggs, explains Dr. Miriam Stoppard in her book "Conception, Pregnancy and Birth." Typically, each of these eggs is fully mature and can be fertilized, meaning that you are more likely to have fraternal--or non-identical--twins, triplets or higher-order multiples than if you ovulated naturally.
References
- RxList: Pregnyl
- Pacific Fertility Center: Ovulation Induction
- "Conception, Pregnancy and Birth"; Miriam Stoppard, M.D.; 2008
