The hormone human chorionic gonadotropin (HCG), also known as the hormone of pregnancy, occurs during gestation. It is normal for the pituitary gland to produce this hormone in small amounts. But during pregnancy, the levels increase significantly to produce the placenta.

The main function of HCG during the first weeks of pregnancy is to keep the corpus luteum (also known as the yellow body), which is a small gland that develops in the ovary and secretes estrogen and progesterone. These two hormones enrich the uterus with a thick lining of blood vessels and capillaries so that it can support the growth of the fetus.

Keeping the corpus luteum is necessary so that the mother's body does not reject the placenta, that is, it is indispensable for a successful pregnancy.

Once fertilization occurs, HCG can be detected in the bloodstream and in the urine through a home pregnancy test or a blood test.

The blood test can detect the presence of HCG at 11 days after conception. In contrast, the urine test can do so 12 to 14 days after fertilization.

HCG levels usually double every 72 hours during the first 8 to 11 weeks of pregnancy. They then go down and stabilize for the rest of the pregnancy.

HCG levels during pregnancy (in weeks since the last menstrual period)

Time of gestation Ranges

3 weeks 5 to 50 mUi / ml
4 weeks 5 to 426 mUi / ml
5 weeks 18 to 7,340 mUi / ml
6 weeks 1.080 to 56.500 mUi / ml
7 to 8 weeks 7,650 to 229,000 mUi / ml
9 to 12 weeks 25,700 to 288,000 mUi / ml
13 to 16 weeks 13,300 to 254,000 mUi / ml
17 to 24 weeks 4,060 to 165,400 mUi / ml
25 to 40 weeks 3,640 to 117,000 mUi / ml