答:孕妇体内的维生素K胎盘通透性差,很少进入胎儿体内,胎儿的维生素K就要靠自身合成,但胎儿肝脏合成功能又不成熟,故婴儿出生时血中的维生素K水平很低,而某些凝血因子(如Ⅱ、Ⅶ、Ⅸ、Ⅹ)的凝血生物活性又直接依赖于维生素K的存在,所以缺乏维生素K,凝血因子只是无功能的蛋白质,? A: The pregnant woman’s body vitamin K placental permeability is poor, rarely enter the fetus, the fetus’s vitamin K depends on their own synthesis, but fetal liver synthesis is immature, so the baby’s blood vitamin K levels are very low, However, the coagulation activity of some clotting factors (such as Ⅱ, Ⅶ, Ⅸ, Ⅹ) is directly dependent on the existence of vitamin K, so the lack of vitamin K, clotting factor is just a non-functional protein?