Vitamin K deficiency during the perinatal and infantile period.

Coagulation-related plasma proteins develop slowly during the gestational period and are still markedly lower than normal at birth. Great interest exists in the status of the vitamin K-dependent procoagulant factors (factors II, VII, IX and X) because a number of healthy newborns develop postpartum a bleeding tendency that is due to vitamin K deficiency. The most serious cases involve intracranial bleeding with convulsions, coma and potential death. Typically, these infants have markedly prolonged prothrombin times that shorten following the administration of vitamin K. A common feature of these infants is that they are breast-fed, although other factors, especially hepatobiliary diseases, contribute to this disorder. Vitamin K deficiency bleeding can develop as early as in the first 24 hours after birth, but most infants are diagnosed between days 2 and 7 postpartum. Late forms (> 1 week and up to 6 months) are also noted. This deficiency can be compensated for by prophylactically administering vitamin K to the newborns or by bottle-feeding. Although vitamin K2 may pass in small quantities through the placenta, it is insufficient to make up for the deficit. The first dose of vitamin K can also be given orally to the newborn after one or two regular feedings, and the second dose can be administered upon discharge from the hospital. A problem that remains to be solved is the late development of vitamin K deficiency in spite of prophylaxis at birth.