Select the correct option describing gonadotropin activity in a normal pregnant female.

Placenta secretes human chorionic gonadotropin (hCG), which has actions similar to LH. Human chorionic gonadotropin rescues the corpus luteum from degeneration and sustains its secretion of progesterone and estrogens. These hormones maintain the uterine lining in a secretory state, preventing menstruation. Peak secretion of hCG occurs about the ninth week of pregnancy, at which time the placenta is fully developed and produces the progesterone and estrogens that continue to sustain the pregnancy. hCG is secreted by trophoblast itself at the blastocyst stage. FSH and LH levels are low during pregnancy. It has no direct effect on thickening of endometrium.