Generally, the week of pregnancy can be calculated based on the date of the last menstrual period, or based on the results of ultrasound examination. When calculating the week of pregnancy, the first day of the last menstrual period is generally counted as the first day of pregnancy, and in the case of regular menstruation, the number of days from the first day of the last menstrual period to the present day is divided by 7 to determine the current week of pregnancy; however, if a pregnant woman has irregular menstruation, the calculation of the week of pregnancy may deviate, in which case the week of pregnancy can be calculated according to the results of ultrasound examination. Calculation of the gestational week is of great significance in correctly determining the development of the fetus. Women should undergo prenatal checkups in a timely manner during pregnancy and seek medical attention if they experience any discomfort.