The cystic structures become smaller gestational sacs at around 35 days of menopause, initially invading the endometrium when the fertilized egg is transplanted into the uterine cavity to bed down and gradually appearing as a full gestational sac growth, followed by the appearance of a primitive heart tube beat. When a woman’s menstrual cycle is irregular, such as delayed menstruation or when the fertilized egg implants in the uterine cavity and is slow to develop normally, the gestational sac may not appear until 40-50 days after menopause. If the blood level of human chorionic gonadotropin is elevated after menopause and there is no gestational sac in the uterine cavity and the woman is not experiencing lower abdominal pain or vaginal bleeding, she can be temporarily observed and rechecked after 7 or 10 days for the growth of a gestational sac in the uterine cavity, otherwise there is a possibility that ectopic pregnancy has occurred.