What is human chorionic gonadotropin (hCG)?
Human chorionic gonadotropin is a special protein hormone that is produced by the membranes of the developing embryo during the entire period of pregnancy. HCG supports the normal development of pregnancy. Thanks to this hormone, the processes that cause menstruation are blocked in the body of a pregnant woman and the production of hormones necessary to maintain pregnancy increases.
An increase in the concentration of hCG in the blood and urine of a pregnant woman is one of the earliest signs of pregnancy.
The role of hCG in the first trimester of pregnancy is to stimulate the formation of hormones necessary for the development and maintenance of pregnancy, such as progesterone, estrogens (estradiol and free estriol). During the normal development of pregnancy, these hormones are subsequently produced by the placenta.
Human chorionic gonadotropin very important. In a male fetus, human chorionic gonadotropin stimulates the so-called Leydig cells, which synthesize testosterone. Testosterone in this case is simply necessary, as it promotes the formation of male-type genital organs, and also has an effect on the adrenal cortex of the embryo. HCG consists of two units - alpha and beta hCG. The alpha component of hCG has a similar structure to the hormone units TSH, FSH and LH, while beta hCG is unique. Therefore, laboratory analysis of b-hCG is crucial in diagnosis.
Small amounts of human chorionic gonadotropin are produced by the human pituitary gland even in the absence of pregnancy. This explains the fact that in some cases very low concentrations of this hormone are detected in the blood of non-pregnant women (including women during menopause) and even in the blood of men.
Permissible levels of hCG in the blood of non-pregnant women and men
How do human chorionic gonadotropin levels change during pregnancy?
During the normal development of pregnancy, hCG is detected in the blood of pregnant women from approximately 8-11-14 days after conception.HCG levels rise rapidly and, starting at 3 weeks of pregnancy, double approximately every 2-3 days. The increase in concentration in the blood of a pregnant woman continues until approximately 11-12 weeks of pregnancy. Between 12 and 22 weeks of pregnancy, the concentration of hCG decreases slightly. From the 22nd week until delivery, the concentration of hCG in the blood of a pregnant woman begins to increase again, but more slowly than at the beginning of pregnancy.
By the rate of increase in the concentration of hCG in the blood, doctors can determine some deviations from the normal development of pregnancy. In particular, with an ectopic pregnancy or a frozen pregnancy, the rate of increase in hCG concentration is lower than during a normal pregnancy.
An accelerated rate of increase in hCG concentrations may be a sign of a hydatidiform mole (chorionadenoma), multiple pregnancies, or chromosomal diseases of the fetus (for example, Down's disease).
There are no strict standards for the level of hCG in the blood of pregnant women. HCG levels at the same stage of pregnancy can vary significantly among different women. In this regard, single measurements of hCG levels are uninformative. To assess the process of pregnancy development, the dynamics of changes in the concentration of human chorionic gonadotropin in the blood is important.
Days since last menstruation | Gestational age | HCG levels for this period honey/ml |
Human chorionic gonadotropin normal graph
Norms of human chorionic gonadotropin in blood serum
Note!
In the last table, the weekly norms are given for pregnancy periods “from conception” (and not for the dates of the last menstruation).
Anyway!
The above figures are not a standard! Each laboratory can set its own standards, including for weeks of pregnancy. When assessing the results of the hCG norm by week of pregnancy, you need to rely only on the norms of the laboratory where you were tested.
Tests to determine hCG levels
To determine the level of hCG, various laboratory blood tests are used, which can detect pregnancy at 1-2 weeks.The test can be taken in many laboratories upon the direction of a gynecologist or independently. No special preparation is required for the blood test. However, before you get a referral for a test, be sure to tell your doctor about all the medications you are taking, as some medications may affect the test results. It is best to take the test in the morning, on an empty stomach. For higher test reliability, it is recommended to avoid physical activity on the eve of the test.
By the way, home rapid pregnancy tests are also built on the principle of determining the level of hCG, but only in the urine, and not in the blood. And it should be said that compared to a laboratory blood test, this one is much less accurate, since the level in the urine is two times lower than that in the blood.
It is recommended to carry out a laboratory test to determine pregnancy in the early stages no earlier than 3–5 days of missed menstruation. The pregnancy blood test can be repeated after 2-3 days to confirm the results.
To identify fetal pathology in pregnant women, a test for human chorionic gonadotropin is taken from 14 to 18 weeks of pregnancy. However, in order for the diagnosis of possible fetal pathologies to be reliable, it is necessary to take more than one blood test for hCG. Together with hCG, the following markers are given: AFP, hCG, E3 (alpha-fetoprotein, human chorionic gonadotropin, free estriol.)
Serum levels of AFP and hCG during physiological pregnancy
| Gestation period, weeks. | AFP, average level | AFP, min-max | HG, average level | HG, min-max |
|---|---|---|---|---|
| 14 | 23,7 | 12 - 59,3 | 66,3 | 26,5 - 228 |
| 15 | 29,5 | 15 - 73,8 | ||
| 16 | 33,2 | 17,5 - 100 | 30,1 | 9,4 - 83,0 |
| 17 | 39,8 | 20,5 - 123 | ||
| 18 | 43,7 | 21 - 138 | 24 | 5,7 - 81,4 |
| 19 | 48,3 | 23,5 - 159 | ||
| 20 | 56 | 25,5 - 177 | 18,3 | 5,2 - 65,4 |
| 21 | 65 | 27,5 - 195 | ||
| 22 | 83 | 35 - 249 | 18,3 | 4,5 - 70,8 |
| 24 | 16,1 | 3,1 - 69,6 |
Can an hCG test “make a mistake” in determining pregnancy?
HCG levels that are outside the norm for a particular week of pregnancy can be observed if the gestational age is incorrectly determined.Laboratory tests can make mistakes, but the chance of error is very small.
Decoding
Normally, during pregnancy, the level of human chorionic gonadotropin gradually increases. During the 1st trimester of pregnancy, b-hCG levels increase rapidly, doubling every 2-3 days. At 10–12 weeks of pregnancy, the highest level of hCG in the blood is reached, then its content begins to slowly decrease and remains constant during the second half of pregnancy.An increase in beta-hCG during pregnancy can occur when:
- multiple births (the rate increases in proportion to the number of fetuses)
- toxicosis, gestosis
- maternal diabetes
- fetal pathologies, Down syndrome, multiple malformations
- incorrectly determined gestational age
- taking synthetic gestagens
- production of hCG by the pituitary gland of the examined woman testicular tumors
tumor diseases of the gastrointestinal tract
neoplasms of the lungs, kidneys, uterus
hydatidiform mole, relapse of hydatidiform mole
chorionic carcinoma
taking hCG drugs
the analysis was done within 4–5 days after the abortion, etc.Usually, human chorionic gonadotropin is elevated if the test was performed 4–5 days after an abortion or due to taking hCG drugs.
Low hCG in pregnant women, it may mean incorrect timing of pregnancy or be a sign of serious disorders:
- ectopic pregnancy
- non-developing pregnancy
- delayed fetal development
- threat of spontaneous abortion (reduced by more than 50%)
- chronic placental insufficiency
- true post-term pregnancy
- fetal death (in the II-III trimester of pregnancy).
Whatever the result of the test for hormones during pregnancy, remember that only a qualified doctor can give the correct interpretation, determining which hCG norm is for you in combination with data obtained by other examination methods.
Video. Prenatal screening - hCG
The hCG calculator will help you decipher the results of a blood test for hCG in dynamics by day from the date of conception, embryo transfer (after IVF) or delay, determine the duration of pregnancy and assess the dynamics of growth in hormone levels.
HCG doubling period in singleton pregnancy
HCG begins to be produced already 6-10 days after fertilization of the egg. In the first weeks, your hCG levels should double approximately every 2 days. As the gestational age increases, the rate of its growth slows down - when the level reaches 1200 mU/ml, hCG doubles every 3-4 days (from 72 to 96 hours), and after 6000 mU/ml the doubling occurs on average every 4 days (96 hours).
PM - according to the date of the last menstruation.
DPO - days after ovulation.
The concentration of hCG reaches its maximum at 9-11 weeks of pregnancy, then the level of hCG begins to slowly decrease.
During multiple pregnancies, the hCG content increases in proportion to the number of fetuses, and on average, hCG levels in pregnant women with twins (triplets) are usually higher than in other pregnant women at the same stage.
Laboratory standards and user results
HCG standards may vary in different laboratories. This is due to the use of various research techniques, reagents and other factors. Therefore, to correctly assess the dynamics of hormone growth, it is necessary to conduct research in one laboratory and evaluate the results relative to the standards of this laboratory. The hCG calculator allows you to evaluate your results relative to the standards of different laboratories:
The results of other users on the graph may also differ (depending on laboratory standards) and contain errors (for example, data was entered incorrectly).
(HCG) is a hormone produced by a woman’s body during pregnancy. HCG appears immediately after fertilization and allows you to determine pregnancy as early as 4-5 days. HCG is produced by the chorion and continues to grow until the 12-13th week of pregnancy - the maximum rate of the hormone at this moment is 90,000 mU/ml, after which the rate begins to decrease. For example, the hCG rate at week 19 already varies between 4720-80100 mU/ml. HCG norms by day and week allow you to monitor the development of pregnancy in the first trimester, identify possible pathologies and developmental abnormalities.
Determination of hCG
HCG levels are determined in several ways. The most accurate results are provided by a blood test, which can detect pregnancy even before a missed period. By examining hCG norms by obstetric week, an experienced doctor will be able to accurately determine the duration of pregnancy and possible pathologies (the threat of miscarriage).
Less accurate data is provided by a urine test, although this is what all home pregnancy tests are based on. It is worth noting that while determining the hormone norm in a blood test for hCG makes it possible to monitor the progress of pregnancy, a urine test does not provide such accurate data.
Beta-hCG norms by week:
- 1-2 weeks – 25-156 mU/ml;
- 2-3 weeks – 101-4870 mU/ml;
- 3-4 weeks – 1110-31500 mU/ml;
- 4-5 weeks – 2560-82300 mU/ml;
- 5-6 weeks – 23100-151000 mU/ml;
- 6-7 weeks – 27300-233000 mU/ml;
- 7-11 weeks – 20900-291000 mU/ml;
- 11-16 weeks – 6140-103000 mU/ml;
- 16-21 weeks – 4720-80100 mU/ml;
- 21-39 weeks – 2700-78100 mU/ml.
All established hCG standards, whether analyzed at 4 weeks or 17-18 weeks, are relevant for the normal course of a singleton pregnancy. If there are two or more embryos, the hormone levels will be several times higher. For example, in a normal intrauterine pregnancy, the hCG rate at week 3 is on average 2000 mU/ml and continues to double every 1.5 days. Thus, by 5-6 weeks, a hCG level of about 50,000 mU/ml is considered normal.
It is worth noting that a low hCG level may indicate termination of pregnancy, that is, fetal death. Insufficient growth of the hormone also indicates an ectopic pregnancy and the threat of miscarriage. At a period of 15-16 weeks, the hCG level, the norm of which should be in the range of 10,000-35,000 mU/ml, in combination with the results of other tests, is used to identify pathologies in fetal development.
