Abstract
The vitamin K one-day given dose to a neonate in mother's milk is about 10 - 20 percent of artificial milk in 13% tone milk. Hind milk with many fat contents mostly contained Vitamin K. Vitamin K concentration of the neonate on 19-40 day of life after birth was the lowest value in an exclusively breastfeeding. Vitamin K concentration in the blood in which a bleeding tendency is shown was not able to be determined. The human liver epoxidase activity showed a high value in the fetus and decreased after birth. On the other hand, the activities of vitamin K-2, 3-eposidase and vitamin K reductase showed a significantly low value in the fetus and the early neonatal period. Single dose vitamin K prophylaxis at birth was inadequate for prevention of VKDB. The proper prevention method of VKDB in fetus, early neonates and infants needs to be established.