Due to the small stomach capacity of newborns, feeding water can affect the intake of breast milk (or formula milk), and breast milk (or formula milk) has more water content, so there is no need to feed extra water. It is usually recommended that newborns should be exclusively breastfed. For newborns whose mothers’ breastmilk is insufficient, formula milk can be added as appropriate to meet their growth and development needs. Due to the small gastric capacity of newborns, feeding extra water can affect the intake of breastmilk (or formula milk), which can seriously affect the newborn’s weight gain. And breast milk (or formula milk) in the water content is high, usually can meet the body’s demand for water, do not need to add extra. However, if the newborn has fever, diarrhea and other diseases, it is possible to add water under the guidance of the doctor.