生孩子難，養孩子更難。單就說幼兒流口水的事吧，這可是令父母們十分頭痛的問題，常常一天要換幾次衣服，用幾條手帕，那么幼兒為什么總流口水呢？快來看看下面的解釋吧。 

    Saliva is produced by the salivary glands. There are three pairs of big salivary glands and countless small salivary glands distributed on our lips, cheeks, palates and some other places. The major part of saliva is water. Saliva also contains some amylases and sticking proteins. Saliva moistens the oral cavity, helping us swallow and digest. Tests show that a normal adult secretes 1000-1500 ml of saliva in a day. Under normal circumstances, people swallow the saliva consciously and unconsciously. 

    Because newborn babies' saliva secreting functions are not perfect, they generally don't slobber. After four months, because of the increase in food intake, babies secrete a little more. In six months, they begin to teethe. The gingival nerve is stimulated and reflectively increases the secretion of the salivary glands. At this time, children have not yet formed the ability to properly swallow saliva, and so the excess saliva will 'drool' out of the corners of their mouths. This is the most obvious in one and two year olds. As children grow older, their saliva-swallowing abilities will improve, and the slobbering will stop. 

    Saliva can be acidic, so it can stimulate the skin. Parents should often wipe saliva for children; wash the skin with warm water and then use lotion to protect the skin of children's chins and necks. The handkerchiefs used to wipe the saliva should soft enough not to damage partial skin. 

    saliva: 口水 

    amylases: 淀粉酶 

    slobber: 流口水 

    gingival: 齒齦的