What is beta hCG?
As is known, chorionic gonadotropin consists of beta and alpha subunits. The greatest uniqueness is beta-hCG, the level of which is determined during pregnancy.
Determination of the concentration of this hormone allows you to determine pregnancy for 2-3 days delay. However, for more accurate diagnosis it is recommended to re-conduct the analysis and undergo ultrasound.
What is the free subunit of hCG?
For early, or as they say, prenatal diagnosis of possible pathologies of the fetus, take into account the level of blood in the free beta subunit of hCG.
This analysis is carried out for a period of 10-14 weeks. The optimal is 11-13 weeks. In this case, as a rule, a so-called double test is carried out, i.e. in addition to the level of free beta-hCG, the content in the blood associated with pregnancy of plasma protein A is determined . Parallel to this, ultrasound is also performed.
In the second trimester of a normal pregnancy, the analysis is conducted from 16 to 18 weeks. A distinctive feature is that at this time, the so-called triple test is carried out. In this case, free beta-hCG, AFP (alfa-fetoprotein) and free estradiol are determined.
How are the results evaluated?
To assess and identify possible violations of intrauterine development, the blood content of the free beta subunit of hCG during pregnancy was established. At the same time the level of this hormone is not constant and directly depends on the term.
In the first trimester of pregnancy, the concentration of hCG increases almost 2-fold. It reaches its peak at the 7-8 week of bearing the fetus (up to 200 thousand mU / ml).
So, at the 11-12th week, the level of hCG can normally be 20-90 thousand mU / ml. After that, its content in the pregnant woman's blood begins to decrease gradually, which is explained by the fact that by that time all the vital organ systems have been formed, only their gradual growth occurs.
If we talk about how the level of hCG changes during the weeks of pregnancy, it usually happens as follows:
- 1-2 weeks - 25-300;
- 2-3 week - 1500-5000;
- 3-4 weeks - 10000-30000;
- 4-5 - 20000 - 100000;
- 5-6 - 50000 - 200000;
- 6-7 weeks - 50000-200000;
- 7-8 - 20000 - 200000.
After this, the concentration of gonadotropin in the blood decreases and by the end of pregnancy it is 10,000-50000 mU / ml.