Placental function 1. EXchange of Metabolites: nutrients antibody waste 2, Defense barrier 3. hormone production human chorionic gonadotropin (HCG) (绒毛膜促性腺激素) Begin: end of 2nd week Highest: 2nd month Estrogen and progesterone(雌激素和孕激素) Placental lactogen(胎盘催乳素)Placental Function 1.Exchange of Metabolites: nutrients antibody, waste 2.Defense barrier 3.hormone production - human chorionic gonadotropin (HCG) （绒毛膜促性腺激素） Begin: end of 2nd week Highest: 2nd month - Estrogen and progesterone（雌激素和孕激素） - Placental lactogen（胎盘催乳素）