
Human chorionic gonadotropin (hCG), a hormone produced during pregnancy by cells of the placenta, is an indicator of the stage and development of pregnancy. Detecting its level is the principle of all freely available orientation tests that women buy in pharmacies and drugstores. However, it must be said that its level, measured precisely in the blood, has a much greater informative value for your treating gynecologist. It can also be an indicator of possible complications in pregnancy or diseases not related to pregnancy.
Immediately after fertilization, the egg travels through the fallopian tubes to the uterus. At a certain stage of cell multiplication, a group of cells is formed in the fetus, the basis for the future placenta. After the egg is implanted in the uterus, these cells begin to produce human chorionic gonadotropin. The level of this hormone can be detected in the urine a few days after conception, which serves as an indicative pregnancy test. However, the level of hCG is precisely detected in the blood.
Human chorionic gonadotropin plays an important role during pregnancy, primarily in stimulating the corpus luteum to produce progesterone, which is essential for the developing fetus (2). Both men and women who are not pregnant have low levels of hCG.
hCG levels tend to rise sharply in early pregnancy for the following reasons:
- About 10 days after conception, the fertilized egg attaches to the lining of the uterus and the body begins to produce hCG. During the following week, its level will rise again.
- Around week 4 of pregnancy, the egg – now called an embryo – implants in the uterus and the trophoblast begins to produce even more hCG, which triggers the production of other hormones, estrogen and progesterone. All these hormones work together to help build the lining of the uterus and send a signal to the ovaries to stop releasing eggs, heralding the cessation of menstruation. In the early weeks, you may not notice the first signs of pregnancy, but everything in the body is already preparing for a new life.
Human chorionic gonadotropin is not detected only by pregnancy tests. It is an important diagnostic criterion for monitoring the stage and course of pregnancy, and doctors are also guided by the exact value, who, if they want to confirm pregnancy, order to undergo one or more quantitative hCG blood tests.
hCG level and length of pregnancy
The hormone hCG starts to be released from the cells, later responsible for the formation of the placenta, 6 to 12 days after conception. "The hCG hormone level usually doubles every 29 to 53 hours," says gynecologist Brennan Lang in the article Understanding HCG Levels by Week During Pregnancy (3). This doubling trend continues until week 8 to 10 after implantation, when hCG levels peak (90,000 to 100,000 mIU/ml). Shortly thereafter, hCG begins to stagnate as the placenta begins to produce estrogen and progesterone. By this point, the hCG level would be easy to detect. However, nothing is completely clear, which also applies in this case.
A normal hCG level does not double every two days. "The level of hCG detectable in blood tests at the beginning of pregnancy rises at a rate of 35 to 200% every two days, which is a fairly wide interval that can still be considered the norm," says doctor Beata E. Seeberová (4). This is why doctors rarely pay attention to specific hCG values and prefer to focus on the rising/falling trend of the hormone.

WARNING! Although the home pregnancy test detects the presence of hCG in the urine, it does not determine its exact value. To find out the exact level of hCG, take a blood test with a gynecologist. This also applies if you have undergone artificial insemination.
Human chorionic gonadotropin (hCG) is not called the pregnancy hormone for nothing. It appears in the early stages of pregnancy and is an accurate indicator of its progress. It also has a predictive value in the case of some diseases and the pathological course of pregnancy, for example in various cancer diseases, e.g. trophoblastic disease or tumor of germ origin. The hCG test is also used in clinical practice to monitor the effectiveness of treatment in the mentioned conditions and in tertiary prevention for the early detection of possible tumor recurrence.
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Sources
- Center for Devices and Radiological Health. (2019). Pregnancy. U.S. Food And Drug Administration. Online. Dostupné z: https://www.fda.gov/medical-devices/home-use-tests/pregnancy. [cit. 2024-04-19].
- Betz, D., & Fane, K. (2023). Human chorionic gonadotropin. StatPearls - NCBI Bookshelf. Online. Dostupné z: https://www.ncbi.nlm.nih.gov/books/NBK532950/. [cit. 2024-04-19].
- Hochwald, L. (2024, March 8). Understanding HCG levels by week during pregnancy. Parents. Online. Dostupné z: https://www.parents.com/pregnancy/my-body/changing/understanding-hcg-levels/. [cit. 2024-04-19].
- Seeber, B. (2012). What serial hCG can tell you, and cannot tell you, about an early pregnancy. Fertility and Sterility, 98(5), 1074–1077. Online. Dostupné z: https://doi.org/10.1016/j.fertnstert.2012.09.014.[cit. 2024-04-19].
- American Pregnancy Association. (2023). What are HCG Levels? Online. Dostupné z: https://americanpregnancy.org/getting-pregnant/hcg-levels/. [cit. 2024-04-19].
- Hale, S. (2023). HCG levels by week: Normal pregnancy HCG levels chart. Mira Fertility. Online. Dostupné z: https://www.miracare.com/blog/hcg-levels/. [cit. 2024-04-19].
- Gnoth, C., & Johnson, S. (2014). Strips of hope: accuracy of home pregnancy tests and new developments. Geburtshilfe und Frauenheilkunde, 74(07), 661-669. Online. Dostupné z: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4119102/. [cit. 2024-04-19].
- Clearblue. (2023). hCG levels: all you need to know. Online. Dostupné z: https://uk.clearblue.com/pregnancy-tests/hcg. [cit. 2024-04-19].