Controversies surrounding the administration of vitamin K to newborns: a review.

OBJECTIVE: To determine (1) the most effective method of administering vitamin K to infants to prevent hemorrhagic disease of the newborn (HDNB) and (2) the safest method, in light of preliminary evidence suggesting that intramuscular administration of vitamin K is associated with childhood cancer. DATA SOURCES: A MEDLINE search of articles published between Jan. 1, 1991, and Apr. 30, 1994, with the use of MeSH terms "hemorrhagic disease of the newborn", articles were limited to those involving human subjects, from birth to adolescence, and to articles from journals indexed through Index Medicus and written in English. References of all articles found through the initial search, the earliest of which was published in 1967, were also reviewed. STUDY SELECTION: Six controlled trials met the selection criteria: a minimum 4-week follow-up period, a minimum of 60 subjects and a comparison of oral and intramuscular administration or of regimens of single and multiple doses taken orally. All retrospective case reviews were evaluated. Because of its thoroughness, the authors selected a meta-analysis of almost all cases involving patients more than 7 days old published from 1967 to 1992. Only five studies that concerned safety were found, and all of these were reviewed. DATA EXTRACTION: In controlled trials, the risk of HDNB caused by vitamin K deficiency among infants receiving different regimens of vitamin K; in case studies, method of vitamin K administration and incidence of hemorrhagic disease; and in studies concerning safety, odds ratios and relative risks of childhood cancer following intramuscular administration of vitamin K. DATA SYNTHESIS: Vitamin K (1 mg, administered intramuscularly) is currently the most effective method of preventing HDNB. The previously reported relation between intramuscular administration of vitamin K and childhood cancer has not been substantiated. An oral regimen (three doses of 1 to 2 mg, the first given at the first feeding, the second at 2 to 4 weeks and the third at 8 weeks) may be an acceptable alternative but needs further testing in large clinical trials. CONCLUSION: There is no compelling evidence to alter the current practice of administering vitamin K intramuscularly to newborns.