The causes of postpartum frozen shoulder are mainly related to the following aspects. First, it is caused by cold. Many mothers need to sit and nurse for a long time after giving birth or have insufficient clothing, which can cause shoulder cold and lead to frozen shoulder. Secondly, it may be caused by excessive fatigue. Many mothers need to carry their babies for a long time after giving birth or need to lie on their sides to observe their babies, which may lead to fatigue of the muscles around the shoulder joint and inflammation of the joint capsule and ligaments of the shoulder joint, thus causing frozen shoulder. Third, it may be caused by poor posture. For example, if the posture described above is fixed for a long time, it may also lead to frozen shoulder. Fourth, it may be caused by not exercising. Many mothers are used to sitting in bed for a long time after giving birth, and the long-term braking of the shoulder joint can also lead to frozen shoulder.