RESULTS FROM AN INTERNATIONAL CASE-CONTROL STUDY OF CHILDHOOD BRAIN-TUMORS - THE ROLE OF PRENATAL VITAMIN SUPPLEMENTATION

An international case-control study of primary pediatric brain tumors included interviews with mothers of cases diagnosed from 1976 to 1994 and mothers of population controls. Data are available on maternal vit amin use during pregnancy for 1051 cases and 1919 controls from eight geographic areas in North America, Europe, and Israel. Although risk e stimates varied by study center, combined results suggest that materna l supplementation for two trimesters may decrease risk of brain tumor (odds ratio [OR] 0.7, 95% confidence interval [CI] 0.5-0.9), with a tr end of less risk with longer duration of use (p trend = 0.0007). The g reatest risk reduction was among children diagnosed under 5 years of a ge whose mothers used supplements during all three trimesters (OR 0.5, CI 0.3-0.8). This effect did not vary by histology and was seen for s upplementation during pregnancy rather than during the month before pr egnancy or while breast feeding. These findings are largely driven by data from the United Stales, where most mothers took vitamins. The pro portion of control mothers who took vitamins during pregnancy varied t remendously: from 3% in Israel and France, 21% in Italy, 33% in Canada , 52% in Spain and 86 to 92% at the three U.S. centers. The compositio n of the various multivitamin compounds taken also varied: the daily d ose of vitamin C ranged from 0 to 600 mg, vitamin E ranged from 0 to 7 0 mg, vitamin A ranged from 0 to 30,000 IU, and folate ranged from 0 t o 2000 mu g. Mothers also took individual micronutrient supplements (e .g., vitamin C tablets), but most mothers who took these also took mul tivitamins, making it impossible to determine potential independent ef fects of these micronutrients.