When prolonged vomiting occurs during pregnancy, the body uses up its own fat when starving, causing electrolyte loss in the body, and it is necessary to go to the hospital for an electrolyte test. Some substances in our body are the basis for maintaining life, such as potassium, chloride, calcium and phosphorus are electrolytes, which are indispensable elements for the human body and they play a very important role in maintaining the normal physiological functions of the body. Pregnant women have a great need for these elements during pregnancy, and the fetus also needs electrolytes for development. Therefore, electrolyte check during pregnancy is not only for the health of the pregnant mother, but also for the normal development of the fetus.