During pregnancy, the placenta secretes estrogens, progesterone, human chorionic gonadotropin (hCG), and human placental lactogen (hPL). Estrogens and progesterone, which are not specific to pregnancy, are discussed in the preceding sections. In contrast, hCG and hPL are fairly specific to pregnancy, but levels may also be altered in individuals with trophoblastic tumors (e.g., hydatidiform mole, choriocarcinoma) and tumors that ectopically secrete placental hormones.