Calculation of gestational age is one of the important aspects of prenatal management of pregnant women. Correct calculation of gestational age can help doctors and pregnant women better understand the growth and development of the fetus and formulate reasonable prenatal management plans. This article will introduce the methods and precautions for calculating gestational age. 1. Definition of gestational age Gestational age refers to the gestational age of the pregnant woman calculated from the first day of the last menstrual period to the current pregnant woman. It is usually expressed in weeks. For example, gestational age 10 means that the pregnant woman is 10 weeks pregnant. 2. Calculation method of gestational age: Last menstrual period method. The last menstrual period method is currently the most commonly used method of calculating gestational age. The specific operations are as follows: (1) Determine the first day of the last menstrual period. (2) Use the first day of the last menstrual period as the starting point for calculating gestational age, and extrapolate backward 280 days (40 weeks) to get the expected date of delivery. (3) Calculate the gestational age of the current pregnant woman, that is, the number of days from the current date to the first day of the last menstrual period, and then divide it by 7. The resulting quotient is the gestational age. B-ultrasound method B-ultrasound method is a method that directly measures fetal growth and development to determine gestational age. B-ultrasound can measure the fetal head circumference, abdominal circumference, femoral length and other indicators, and the gestational age can be calculated based on these indicators. The B-ultrasound method is more accurate and can be used as a supplementary method, especially when the expected date of delivery is uncertain or the gestational age calculation does not match the last menstrual period. The latest and most complete 2023 [Kindergarten, Junior High and High School] premium VIP course catalogs from famous teachers in various disciplines on the entire network, click to view now! 3. Precautions for calculating gestational age. The first day of the last menstrual period must be determined accurately. If a pregnant woman\’s menstrual cycle is irregular or not recorded, the expected date of delivery can be determined through B-ultrasound. The calculation methods of gestational age are different, and the calculation results may also be different. Therefore, pregnant women should refer to the expected date of delivery determined by the doctor. The due date is only an estimate and actual delivery may occur up to two weeks before or after the due date. Gestational weeks increase faster in the first trimester and more slowly in the third trimester, so gestational weeks should not be calculated solely by date. Gestational age calculation is a way to predict fetal growth and development, but it does not fully reflect the health of the fetus. Therefore, pregnant women also need to undergo other prenatal examinations. 4. Conclusion Calculation of gestational age is one of the important aspects of prenatal management of pregnant women. Correct calculation of gestational age can help doctors and pregnant women better understand the growth and development of the fetus. The last menstrual period method is currently the most commonly used method for calculating gestational age, and the B-ultrasound method can be used as a complementary method. When calculating gestational age, attention should be paid to issues such as determining the first day of the last menstrual period, the expected date of delivery determined by the doctor, and the uneven rate of increase in gestational age.