Determining the time of the patient’s pregnancy mainly relies on the following means of speculation: First, if the patient’s menstruation is regular, the time of the patient’s pregnancy is determined according to the patient’s menstrual cycle. When the patient’s menstrual cycle is 30 days, the time of pregnancy is around the 16th day of menstruation. Second, according to the monitoring of ovulation and coitus time to judge belong to the time, when the patient ultrasound monitoring follicle maturity can be arranged after coitus, or the use of follicle test paper measured strong positive after coitus, if the patient was conceived, then the time of pregnancy in the patient choose to coitus time. Thirdly, the size of the gestational sac is measured by ultrasound to estimate the time of pregnancy. If you have irregular menstruation or ovulation disorders, and you don’t know when you are pregnant, you can use ultrasound to estimate the time of pregnancy according to the size of the gestational sac through the formula.