Children usually start teething at 4~6 months. Normally, babies usually start to grow their 1st incisors at 4 to 6 months of age. It may be an upper or lower incisor. However, some babies may start teething before 4 months of age or after 6 months of age, in which case you need to be careful to rule out any abnormalities. For example, if your baby has a calcium deficiency, teething may be delayed. And teething is also related to the baby’s genetic factors and nutritional health status, usually pay attention to bring the baby more sunshine, in order to promote the absorption of calcium. In addition, parents are advised to bring their babies to the hospital regularly for health checkups, so that problems can be detected and dealt with at any time, and if the child has any special discomfort, he or she should consult a doctor as soon as possible.