Human chorionic gonadotropin is a glycoprotein secreted by trophoblastic cells of the placenta. Human chorionic gonadotrophin (HCG) - - is synthesized from syncytiotrophoblast cells. The glycoprotein hormones with molecular weight of 36700 are basically similar to the FSH (follicle stimulating hormone), LH (luteinizing hormone) and TSH (thyrotropin) secreted by the pituitary, so they can cross react with each other, while the structure of each subunit is different. Ak-hcg is similar in structure to ak-lh, but the last 24 amino acid extensions are not present in ak-lh.

　　Human chorionic gonadotropin information

　　In mature women, the fertilized egg moves to the uterine cavity for implantation and forms an embryo. In the process of developing into a fetus, the syncytiotrophoblast cells of the placenta produce a large amount of human chorionic gonadotropin (HCG), which can be excreted into the urine through the blood circulation of the pregnant woman. Serum and urine HCG levels rise rapidly between 1 and 2.5 weeks gestation, peak at 8 weeks of gestation, drop to moderate levels by 4 months of gestation, and remain at the end of gestation.