Placental Lactogen (PL)

Human placental lactogen (HPL), also called human chorionic somatomammotropin, is a polypeptide placental hormone. Its structure and function is similar to that of human growth hormone. It modifies the metabolic state of the mother during pregnancy to facilitate the energy supply of the fetus. HPL is an anti-insulin.HPL consists of 190 amino acids that are linked by two disulfite bonds and is secreted by the syncytiotrophoblast during pregnancy. Its molecular weight is 22,125. Like human growth hormone HPL is encoded by genes on chromosome 17q22-24. Its biologic half-life is 15 minutes.HPL is only present during pregnancy with maternal serum levels rising in relation to the growth of the fetus and placenta. Maximum levels are reached near term, typically to 5–7 mg/ml. Higher levels are noted in patients with multiple gestation.