很多原因可以引起新生儿出血,且新生儿的凝血酶原时间一般都是延长的。传统上一直认为维生素K缺乏和肝脏酶系统发育未成熟是引起新生儿出血的主要原因,并且临床常规地以维生素K预防,必要时还进行输血治疗。有些地区因预防性地给予维生素K剂量过大,引起溶血性黄疸。现在一般认为预防应用的剂量不宜超过每天1mg。维生素K是一种脂溶性维生素。具有维生素K活性的化合物均属于2-甲基-1,4-萘醌类。在环的3位上聚异戊二烯链的存在 Many reasons can cause bleeding in newborns, and neonatal prothrombin time are generally extended. Traditionally, the lack of vitamin K and the immature liver enzyme system have been the major causes of neonatal hemorrhage and have been clinically routinely prevented with vitamin K and, if necessary, blood transfusions. In some areas due to preventive doses of vitamin K overdose, causing hemolytic jaundice. It is generally believed that the dose of prophylactic should not exceed 1mg daily. Vitamin K is a fat-soluble vitamin. The compounds having vitamin K activity all belong to 2-methyl-1,4-naphthoquinones. The presence of a polyisoprene chain at the 3 position of the ring