The number of days of pregnancy is usually determined by the last menstrual period and ultrasound. If you have a regular menstrual cycle, you can calculate the number of days of pregnancy according to the last menstrual period, which is calculated from the first day of the last menstrual period, not from the last day of the last menstrual period, and the date from the first day of the last menstrual period up to the present date is the number of days of pregnancy. Women who have irregular menstrual cycles or do not remember their last menstrual period can go to the hospital for an ultrasound, according to the size of the gestational sac and the length of the buds on the ultrasound, the number of days of pregnancy can be clarified. Pregnancy a whole gestation period is two hundred and eighty days, but not all pregnant women to this stage will give birth to the fetus down, advance or push back the time of fourteen days is normal. If you are pregnant, you should do a good maternity checkup, so that any abnormality can be detected and dealt with in time. If you have any symptoms of physical discomfort, you should go to the hospital in time to consult a physician for guidance.