Prenatal vitamin supplementation and risk of childhood brain tumors

An international case-control study of primary pediatric brain tumors inclu ded interviews with mothers of cases diagnosed from 1976 to 1994 and mother s of population controls. Data are available on maternal vitamin use during pregnancy for 1,051 cases and for 1,919 controls from 8 geographic areas i n North America, Europe and Israel. While risk estimates varied by study ce nter, combined results suggest that maternal supplementation for 2 trimeste rs decreased risk of brain tumor [odds ratio (OR)= 0.7; 95% confidence inte rval (CI)= 0.5, 0.9], with a trend of less risk with longer duration of use (p trend = 0.0007). The greatest risk reduction was among children diagnos ed under 5 years of age whose mothers used supplements during all 3 trimest ers (OR = 0.5; CI = 0.3, 0.8). This effect did not vary by histology and wa s seen for supplementation during pregnancy rather than during the month be fore pregnancy or while breastfeeding. Our findings are largely driven by d ata from the United States, where most mothers took vitamins. The proportio n of control mothers who took vitamins during pregnancy varied markedly fro m 3% in Israel and in France, 21% in Italy, 33% in Canada and 52% in Spain to 86-92% at the 3 U.S. centers. The composition of the various multivitami n compounds taken also varied: daily dose of vitamin C ranged from 0 to 600 mg; vitamin E from 0 to 70 mg; vitamin A from 0 to 30,000 IU; and folate f rom 0 to 2,000 mu g Mothers also took individual micronutrient supplements (e.g., vitamin C tablets), but most mothers who took these also took multiv itamins, making it impossible to determine the potential independent effect s of these micronutrients. (C) 1998 Wiley-Liss, Inc.