Breast milk contains antibodies, active cells and other best nutrients that protect babies from infection and promote their growth and development. The expressed milk may lose a little bit of nutrition, because some substances will stick to the bottle, but it is far better than other foods, and the living cells still exist after breast milk is expressed, especially when it is expressed and fed or placed at room temperature without freezing When you get up, you will lose less nutrition. If it is just refrigerated, there are still living cells and they will not disappear completely. The antibacterial properties in breast milk help prolong the preservation time of breast milk. The active cells and antibodies in breast milk that inhibit the growth of bacteria in the baby's intestines can also play a bacteriostatic effect when human milk is stored in a container.