The historical background and scientific nature of the ovulation chart The uterine chart, also known as the \”ovulation chart\”, is a tool that predicts the probability of pregnancy by calculating the ovulation period of women. Its origin can be traced back to ancient China, but it was named \”Qing Gong Biao\” by court officials during the Qing Dynasty and was widely spread inside and outside the palace. The principle of the uterine evacuation chart is extremely simple. Based on a woman\’s menstrual cycle and date of birth, the woman\’s ovulation period can be calculated to determine the probability of pregnancy. This method was widely used in ancient China,