During the first trimester of pregnancy, the development of new ovarian follicles remains suppressed because the corpus luteum continues to secrete high levels of progesterone. Which hormone, produced by the developing embryo and placenta, is directly responsible for rescuing and maintaining the corpus luteum during this period?

Step-by-step solution

During a normal menstrual cycle, the corpus luteum is maintained by Luteinising hormone (LH). However, if fertilisation and implantation occur, the developing embryo (specifically the trophoblast) and later the placenta secrete Human chorionic gonadotropin (hCG). hCG acts similarly to LH and rescues the corpus luteum from degeneration. The maintained corpus luteum continues to secrete large amounts of progesterone, which exerts continuous negative feedback on the pituitary. This keeps FSH and LH levels low, thereby