There is no need to express part of the breastmilk first for a long time between breastfeeding because the breastmilk is in the mammary glands and there is no problem of contamination, but care should be taken to clean the nipples during feeding.
The breast is a sterile environment and the milk is not contaminated by pathogenic microorganisms in the breast. Moreover, the breast is the best container for preserving milk and the temperature is constant, so there is no need to express part of the breastmilk first for a long time between breastfeeding.
The proportion of protein in breastmilk is more suitable, easy to be digested and absorbed by newborns. Breastmilk is rich in antibodies, which can help newborns resist external bacterial and viral infections to a certain extent, and cannot be replaced by any other food.
When the interval between breastfeeding is long you need to keep the local hygiene of the breast, wash it with warm water, and pay attention to a reasonable diet during breastfeeding.