The number of days of pregnancy is calculated according to the last menstrual period. If the menstrual period is irregular, you can go to the hospital for an ultrasound examination, and the time of pregnancy will be calculated according to the results of the examination. For women who have regular menstrual periods, the time of pregnancy should be calculated from the first day of the last menstrual period. For example, if the last menstrual period is September 1, the time of pregnancy will be 45 days on October 15, and 60 days on November 1, for example. If the period is irregular, it is not possible to determine the time of the last menstrual period. At this point, an ultrasound will be performed and the doctor will calculate the duration of pregnancy based on the size of the gestational sac and the length of the buds. After pregnancy, you should pay attention to rest, avoid exertion, and undergo regular maternity checkups, which are conducive to the healthy development of the fetus.