Ecological studies of relation between hospital policies on neonatal vitamin K administration and subsequent occurrence of childhood cancer.

OBJECTIVE

To investigate the possible link between neonatal administration of intramuscular vitamin K and childhood cancer.

DESIGN

Ecological studies comparing incidence of cancer in groups of children classified by the vitamin K policy in operation at their hospital of birth.

SETTING

Selected large maternity units in England, Scotland, and Wales.

SUBJECTS

Children born in these units in varying periods between 1966 and 1991.

MAIN OUTCOME MEASURES

Cancer occurring among these children before age 15 years identified by using the National Registry of Childhood Tumours. Ratios of observed to expected numbers of these conditions calculated for hospitals where the policy was to give all babies intramuscular vitamin K (non-selective) and where the policy was to use this treatment only for a selected minority of babies at increased risk of vitamin K deficiency bleeding (selective).

RESULTS

These ratios were calculated for children born in 94 hospitals with varying vitamin K policies. A raised risk was occasionally associated with vitamin K, but the overall results were not significant, and there was no evidence to support the previously suggested doubling of the risk of childhood cancer.

CONCLUSIONS

On the basis of the results reported here it is unlikely that there is a greatly increased risk of childhood cancer attributable to intramuscular vitamin K given to newborns, if indeed there is any.