1. What is the number of days of pregnancy? The number of days to pregnancy refers to the number of days from the first day of a woman\’s last menstrual period until the woman is pregnant. This period of time is usually called the pregnancy period, which is the period from the implantation of the fertilized egg until delivery. 2. How to calculate the number of days of pregnancy? Generally speaking, the number of days of pregnancy can be calculated in the following two ways: 1. Last menstrual period method: This method is the most commonly used method and the most accurate method. The specific operation method is to take the first day of the last menstrual period as the starting point and calculate backward 280 days (40 weeks). 2. Ultrasonic method: This method