Vitamin K regimens and incidence of childhood cancer in Denmark

This study compared infants born in 3 cohorts. Infants born in 1945-54 where defined as non-exposed (n=835,430), all infants born 1960-9 were defined as having vitamin K administered to their mothers (n=797,472), and all infants born 1975-84 were defined as those who received intramuscular vitamin K (n=586,378). The relative risk of cancer for intramuscular vitamin K compared with no vitamin K was found to be 1.29. However, as the cohorts with the different types of vitamin K have all come from different time points, it is not possible to assess whether this trend has been due to the changes in vitamin K prophylaxis, or another of the many changes that have occurred over time.