Neonatal vitamin D and childhood brain tumor risk.

Vitamin D deficiency among pregnant women is common. Compelling animal evidence suggests carcinogenic effects of vitamin D deficiency on the brains of offspring; however, the impact of circulating vitamin D [25(OH)D] on childhood brain tumor (CBT) risk has not been previously evaluated. Using linked birth-cancer registry data in Washington State, 247 CBT cases (<15 years at diagnosis; born 1991 or later) were identified. A total of 247 birth year-, sex- and race-matched controls were selected from the remaining birth certificates. Liquid chromatography-tandem mass spectrometry was used to measure circulating levels of vitamin D3 [25(OH)D3] in neonatal dried blood spots. Overall, no significant associations were observed. However, when stratified by median birth weight (3,458 g), there was evidence of increasing risk of CBT with increasing 25(OH)D3 among children in the higher birth weight category. Compared to the lowest quartile (2.8-7.7 ng/mL), odds ratios (ORs) and 95% confidence intervals (CIs) for the second (7.7-<11.0 ng/mL), third (11.0-<14.7 ng/mL) and fourth (14.7-37.0) quartiles of 25(OH)D3 were 1.7 (1.0-3.3), 2.4 (1.2-4.8) and 2.6 (1.2-5.6), respectively. Among children in the lower birth weight category, there was suggestive evidence of a protective effect: ORs and 95% CIs for the second, third and fourth quartiles were 0.9 (0.4-1.9), 0.7 (0.3-1.4) and 0.6 (0.3-1.3), respectively. Any associations of neonatal vitamin D with CBT may be birth weight-specific, suggesting the possible involvement of insulin-like growth factor 1, circulating levels of which have been associated with vitamin D and accelerated fetal growth.