The first week of pregnancy is usually counted from the first day of the last menstrual period, and the diagnosis of pregnancy is usually made after four weeks of pregnancy. Under normal circumstances, pregnancy occurs on the fourteenth day or so before menstruation. Since it is not easy to determine the exact time of ovulation, in order to standardize the clinical practice, the time of pregnancy and the expected date of delivery are usually calculated according to the first day of the last menstrual period. The pregnancy time estimated by ultrasound is also calculated from the first day of the last menstrual period. The first week of pregnancy is counted from the first day of the last menstrual period and the first seven days of pregnancy. Forty days pregnant can check ultrasound to see if the pregnancy is intrauterine, around eight weeks pregnant ultrasound to see if the fetal heart bud yolk sac is normal, this checklist needs to be used in the third trimester to establish the reproductive profile. Forty weeks of pregnancy is the due date, and a woman’s pregnancy lasts 280 days, so when a pregnancy lasts more than thirty-seven weeks or more, the birth of a baby within forty-two weeks is usually normal. After pregnancy, please timely hospital for maternity checkups, and find abnormalities to follow up, so as not to delay the condition.