A complete list of pregnancy period calculation methods. With the continuous development of modern medical technology, pregnancy period calculation methods are becoming more and more accurate. For pregnant women, the correct calculation of gestational age is crucial because it not only helps accurately predict the date of birth, but also provides doctors with diagnostic basis to protect the health of mother and baby. This article will introduce the pregnancy period calculation methods from four aspects: the last menstrual period method, B-ultrasound method, embryo development method and early pregnancy test method, to help pregnant women correctly calculate the gestational age. Last menstrual period method The last menstrual period method is the most common method of calculating pregnancy. It is based on the first day of a woman\’s last menstrual period.