Complex sentence: GTD can simulate pregnancy, because the uterus may contain foetal tissue, albeit abnormal, may grow at the same rate as a normal pregnancy, and produces chorionic gonadotropin, a hormone which is measured to monitor foetal well-being.
Split into simpler sentences: GTD can simulate pregnancy, because the uterus may contain foetal tissue, albeit abnormal. This tissue may grow at the same rate as a normal pregnancy, and produces chorionic gonadotropin, a hormone which is measured to monitor foetal well-being.