Human chorionic gonadotropin, or hCG, is a hormone that is produced during pregnancy by the developing embryo and the placenta. This glycoprotein hormone stimulates production of a hormone known as progesterone, which is required for the maintenance of the pregnancy. Early pregnancy tests have a positive result if hCG is detected in the urine or blood. During ovulation, hCG levels are typically zero since conception has not yet occurred.
Function
The main function of hCG is the maintenance of the corpus luteum, the lining of the uterus, during the beginning of pregnancy. HCG hormone stimulates the corpus luteum to produce progesterone. High levels of progesterone are needed to maintain the uterine lining. If conception does not occur, hCG will not be produced. Progesterone levels will drop and menstruation will begin. Additionally, if progesterone levels drop early in a pregnancy, a miscarriage could occur. HCG may also be involved in the development of the fetal immune system.
Hormone Levels During Ovulation
As explained by the American Society for Reproductive Medicine, during the process of ovulation, levels of luteinizing hormone (LH) and follicle stimulating hormone (FSH) rise, and a mature egg is released from a follicle. At this time, hCG levels should be negligible; since hCG is produced by a fetus, there should be no hCG production during ovulation or prior to conception. If conception occurs, hCG will be produced by the embryo and placenta. This rise in hCG levels will maintain progesterone levels and support the development and maintenance of the corpus luteum.
Testing
A blood or urine test can assess hCG levels. As explained by the National Institutes of Health (NIH), hCG typically appears approximately 10 days following conception. An hCG test can also detect multiple pregnancies, ectopic pregnancies and miscarriages.
Normal hCG Levels
According to the NIH, hCG levels typically rise during the first trimester and then begin to decline slightly. Detectable levels of 5 to 50 mIU/ml occur during the first weeks following conception. These levels can rise to 100,000 mIU/ml during the first few months. Levels of hCG are often higher in instances of multiple pregnancies. A result of less than 5 mIU/ml is considered a negative pregnancy test.
Concerns
If you are not pregnant, high hCG levels can be an indication of tumor development. For example, some germ cell tumors and choriocarcinomas secrete hCG. In males, hCG levels above 5 mIU/ml can be an indication of prostate cancer.
