Background: Studies have found only a weak or no association between birthweight and brain cancer in childhood. However, previous studies have not assessed the association between head circumference at birth and brain cancer. We aimed to assess the risk of brain cancer in childhood according to head circumference at birth.
Methods: We investigated the association between incidence of brain cancer in childhood and factors recorded at birth such as head circumference, birthweight, and gestational age based on the Norwegian medical birth registry from 1978-98, linked to the Norwegian cancer registry from 1978-2002.
Findings: We analysed 1,010,366 individuals with 12,378,172 person-years of follow-up, from which 453 individuals aged 0-15 years were diagnosed with brain cancer. The relative risk of brain cancer was 1.27 (95% CI 1.16-1.38) per 1-cm increase in head circumference after adjustment for birthweight, gestational age, and sex.
Interpretation: Head circumference is positively associated with incidence of brain cancer in childhood, suggesting that brain pathology originates during fetal life.