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Chorionic gonadotropin in the blood
Medical expert of the article
Last reviewed: 05.07.2025
Elevated levels of human chorionic gonadotropin in the blood serum are detected as early as the 8th to 9th day after conception. During the first trimester of pregnancy, the concentration of human chorionic gonadotropin rapidly increases, doubling every 2-3 days. Subsequently, the increase in human chorionic gonadotropin levels slows down, reaching a maximum at 8-10 weeks of pregnancy, after which it begins to decrease and remains relatively constant during the second half of pregnancy.
In the second trimester of pregnancy, if the fetus has Down syndrome, the concentration of human chorionic gonadotropin in the pregnant woman's blood is increased, and AFP is decreased. Taking this into account, the study of AFP and human chorionic gonadotropin is used as a method of mass prenatal screening in the second trimester of pregnancy.
Serum Human Chorionic Gonadotropin Median Concentration Values for Screening Congenital Malformations in the Second and Third Trimesters
Gestational age, weeks |
Medians for hCG, IU/l |
14 |
63 900 |
14-15 |
58 200 |
15 |
43 600 |
15-16 |
38 090 |
16 |
37,000 |
16-17 |
35,000 |
17 |
34 600 |
17-18 |
34,000 |
18 |
33 400 |
18-19 |
29 100 |
19 |
26 800 |
19-20 |
23 600 |
20 |
20 400 |
20-21 |
20,000 |
21 |
19,500 |
In Down syndrome, the hCG level is elevated (2.0 MoM and higher), in Edwards syndrome, it is reduced (0.7 MoM). Complications in the third trimester of pregnancy most often occur with elevated levels of human chorionic gonadotropin.
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