Dystocia is a common cause of stillbirth, and breeding with bulls that are prone to calf is a long-term method to prevent stillbirth. The interruption of cow delivery is also the cause of stillbirth. After the calf's hoof gives birth, it can move the cow or interrupt the delivery. Moving or interfering with the delivery cow too frequently or untimely will cause the calf to stop giving birth, which may lead to suffocation and death in the uterus.