There are several methods to calculate pregnancy dating:
Last Menstrual Period (LMP): The most common method where the pregnancy is dated from the first day of the last menstrual period. The average pregnancy lasts about 280 days or 40 weeks from the LMP. Ultrasound: An ultrasound scan can provide a more accurate estimation, especially in the first trimester. Measurements of the fetus, such as the crown-rump length, help in determining the gestational age. Physical Examination: The size of the uterus can sometimes give an indication of the gestational age, though this method is less precise.
