The peak level of chorionic gonadotropin in normal pregnancy occurs

Peak maternal levels of chorionic gonadotropin in normal pregnancy occurs between 60th and 80th days after menses and is around 100,000 mIU/mL. Before 5 weeks of gestation, hCG is expressed in both cytotrophoblast and syncytiotrophoblast. Later during gestation, when maternal serum levels peak, hCG is produced almost solely in syncytiotrophoblasts. Plasma levels of hCG begin to decline at 10 to 12 weeks and a nadir is reached about 16 weeks. Plasma levels are maintained at this lower level for the remainder of pregnancy. Human Chorionic Gonadotropin is a glycoprotein with biological activity similar to luteinizing hormone. It has a molecular weight of 36,000 to 40,000 Da. It is structurally related to LH, FSH and TSH. Ref: Cunningham F.G., Leveno K.J., Bloom S.L., Hauth J.C., Rouse D.J., Spong C.Y. (2010). Chapter 3. Implantation, Embryogenesis, and Placental Development. In F.G. Cunningham, K.J. Leveno, S.L. Bloom, J.C. Hauth, D.J. Rouse, C.Y. Spong (Eds), Williams Obstetrics, 23e.