When the patient’s HCG level is 250 mIU/ml, it means that the patient is newly pregnant and the pregnancy is around 30 days old. This is a presumption based on the patient’s normal pregnancy followed by normal embryo development. If the patient has an ectopic pregnancy or intrauterine pregnancy with delayed embryonic development or preterm miscarriage, the HCG level cannot determine the number of days of pregnancy. Because the rate of HCG growth varies depending on the activity of the patient’s embryo, it is not possible to use one criterion for all patients. When this situation occurs, the time of pregnancy is generally determined by determining the time of the patient’s last menstrual period and the time of intercourse. If the patient usually has normal menstruation, the first day of the last menstrual period is used as the standard to estimate the time of pregnancy. If the patient has irregular menstruation, the time of ovulation and intercourse is used to determine the time of pregnancy, or the size of the patient’s ultrasound indicates the size of the gestational sac as the standard, so that the time of pregnancy can be roughly estimated.