For women with regular menstrual cycles, menstruation occurs once every 30 days on average. 29 days pregnant, that is, 29 days after menopause, HCG values between 50-200iu/l are normal, HCG 10iu/l generally indicates a high likelihood of pregnancy, but it is not possible to prove whether it is a biochemical pregnancy, ectopic pregnancy or an intrauterine pregnancy, and it is necessary to rely on the extent of the rise in HCG at a later stage. If there is a drop in HCG on the 29th day of pregnancy and there is vaginal bleeding, it is likely that a biochemical pregnancy or a miscarriage, ectopic pregnancy, etc. If a vaginal ultrasound is performed around the 37th day of pregnancy and there is a gestational sac developing in the uterine cavity, then it can be determined that it is a normal intrauterine pregnancy, and the degree of increase in HCG is related to the quality of the fertilized egg, the location of its implantation, and the luteinization function of the ovary.