The due date should be projected according to the time of the last menstrual period, if the pregnancy is in May, then the due date is in February-March next year. For women who have regular periods, the formula for calculating the expected date of labor is, on the first day after the last menstrual period, according to the month plus 9 or minus 3, and the date plus 7, the expected date of labor can be projected. If menstruation is irregular, the due date cannot be calculated according to the time of menstruation, but according to the size of the gestational sac measured by ultrasound at the first delivery. Since the expected date of delivery is the approximate date of delivery calculated according to the last menstrual period, it is normal to deliver 1-2 weeks earlier or later than the expected date of delivery, and you need to take regular and good pregnancy tests in order to understand the development of the fetus. You should pay attention to increasing nutrition and taking calcium and vitamin supplements to ensure the nutritional needs of the fetus and to promote the development of the fetus’ bones.