Newborns with three-millimeter ventricular septal defects are relatively small defects, and if they are not combined with other abnormalities, it is possible for them to grow well and close naturally. Ventricular septal defect belongs to one kind of congenital heart disease, three millimeter defect is relatively small, belongs to small ventricular septal defect, most of the babies after birth, there is no obvious symptom, as the baby slowly grows up, the defective ventricular septum will also heal. Generally, take your baby to the hospital for a heart ultrasound after three months. During this period, pay attention to keep your child warm and not to get cold. If recurrent pneumonia or slow growth occurs during growth and development, and the ventricular septal defect still hasn’t healed, surgery is always needed under the evaluation of a cardiac surgeon.