If you have not had your period for forty-five days, you may be about 72 days pregnant, but not having a period does not necessarily mean you are pregnant, and you should follow your doctor’s instructions and undergo the relevant tests to make sure. Women who have a regular menstrual cycle should be highly suspicious of pregnancy when they do not have their period for more than a few days, and pregnancy can be confirmed by using a pregnancy test. Pregnancy should be calculated from the first day of the last menstrual period, and the normal menstrual cycle is 28 days, so when the period does not come for 45 days, it is about 72 days pregnant. You need to follow the doctor’s instructions for ultrasound examination to understand the development of the embryo, and according to the size of the gestational sac or the size of the fetal buds to estimate the number of days of pregnancy. However, if you have not had your period for forty-five days, you may not necessarily be pregnant. When the pregnancy test is negative, you need to follow the doctor’s instructions for ultrasound and endocrine tests to find out the reason for the delayed period. In addition, if pregnancy is confirmed, it is also necessary to pay attention to proper rest, avoid exertion and strenuous exercise, and continue to take folic acid on time as prescribed by the doctor to prevent the risk of neural tube malformation in the fetus.