PLACENTAL HORMONES

HUMAN CHORIONIC

GONADOTROPIN

Human chorionic gonadotropin (hCG) is produced by the placental
syncytiotrophoblast and first appears in maternal blood 10 days after
fertilization. It peaks at 9–10 weeks and then gradually falls to a plateau level at
20–22 weeks.

By chemical structure hCG is a glycoprotein with 2 subunits. The α-subunit is
similar to luteinizing hormone (LH), follicle-stimulating hormone (FSH), and
thyrotropin (TSH). The β-subunit is specific for pregnancy.