Developmental dislocation of the hip (DDH) is one of the most common disorders of the musculoskeletal system in children, and if left untreated, it can lead to irreversible pathologic changes in later life, with limping, hip pain, and osteoarthritis of the hip in later life. The neonatal period is the prime time for treating DDH. Zhao Liang intervened in some neonates with hip joint α-angle <55° during 2011, and the follow-up found that the development of the acetabular apex in all of these infants improved significantly, and none of them maintained the original angle or progressed in a bad direction. The advantages of neonatal hip ultrasound screening are: 1. Early and timely grasp of the current status of neonatal postnatal hip development Because most of the neonatal acetabulum consists of cartilage components and the femoral head consists of cartilage, ordinary X-ray can not adequately show the structure of the pediatric hip joint, and the results of the Ortolani and Barlow examination in the clinic are unreliable, and there are excessive false-positive and false-negative results, the former leading to Ultrasound is able to clearly visualize the various tissues of the neonatal hip joint. Ultrasound examination of the hip joint after birth can help to grasp the current status of neonatal hip development and evaluate the development of neonatal hip joint at an early stage. 2.Help to choose the correct intervention measures Newborns in the postnatal ultrasound examination of the hip joint, can determine the type of development of the hip joint in a timely manner, according to the different types of different interventions, strengthen the nursing intervention to prevent abnormal growth of the acetabulum, and promote the development of the newborn hip joint in a good way. This not only avoids excessive treatment, but also ensures that the pediatric hip joint can develop well in the "golden time", and at the same time creates good conditions for the next step of clinical treatment, which significantly reduces the medical cost, saves medical resources, and is in line with our country's health care policy of prevention first. 3.Provide information for the evaluation of pediatric acetabular development status comparison Neonatal period is the fastest period of growth and development of human organs and tissues. Ultrasound census of hip joints of newborns after birth can enable us to grasp the first-hand information of newborns' hip joints after birth in time, and provide comparable control for review. Timely review, dynamic understanding of the development of the hip joint, truly reflecting the actual significance of "developmental", in line with the characteristics of the development of DDH. By emphasizing newborn hip ultrasound screening, there is a risk of missing those hips that do not dislocate early but develop abnormally. If hip ultrasound screening is emphasized after 6 weeks, then the prime time for neonatal treatment of true DDH patients is lost. Missing the optimal treatment period then makes it more difficult to treat DDH. If the diagnosis is missed, the consequences for the child with DDH can be catastrophic. For examination of infants older than 6 months, ultrasound can still be used. Those who emphasize the view that ultrasound is only suitable for examination of infants up to 6 months of age do not fully understand the Graf method. The Graf method should not be studied rigidly. The view that pediatric hip ultrasound should be started at 6 weeks after birth and the view that newborns are highly sensitive and advocate screening without proper examination are both irresponsible!