I. Normally, the umbilical cord is attached to the placenta right in the middle or parietal center, about 90% (Figure 1). Figure 1 The umbilical cord sends out its vascular branches early outside the placenta, walks inside the fetal membrane, and finally connects with the marginal part of the placenta: 1. The fetal membrane is the cloth and the blood vessels are the structure, so it is called sail-like placenta or umbilical cord sail-like attachment (Figure 3). Figure 3: Sail-like placenta is essentially a disease of the umbilical cord, which should be called umbilical cord sail-like attachment or sail-like insertion, and is rare. However, its incidence is increasing year by year: it is associated with the opening of the second-child policy, the development of ovulation promotion techniques (IVF or in vitro fertilization, etc.), and the misuse of uterine operations (abortion, hysteroscopy, etc.). Due to the deepening of medical understanding of the disease and the rapid development of related examination techniques, the detection rate of the disease has been improved. Fourth, when the fetal membranes with umbilical cord vessels attached cross the internal cervical os, it is called vascular anterior, and when the fetus descends: compression of the vessels in the membranes – fetal hypoxia; tearing of the vessels in the membranes – fetal hemorrhage, leading to fetal death (Figures 4, 5). Figure 4 Figure 5