Table 2.

Risk of childhood brain tumors associated with maternal use of folic acid supplements before or during the index pregnancy

PrepregnancyTrimester 1Trimesters 2/3
Took folic acidCases/controlsORa (95% CI)Cases/controlsORa (95% CI)Cases/ControlsORa (95% CI)
Exposure questionnaire
 Nob103/3581.00103/3581.00103/3581.00
 Yes96/4530.65 (0.43–0.96)211/9070.83 (0.61–1.15)162/7240.73 (0.53–1.03)
Food frequency questionnaire
 Nob106/2271.00106/2271.00106/2271.00
 Yes108/3570.68 (0.46–1.00)198/5790.83 (0.59–1.15)160/4440.80 (0.57–1.14)
Folic acid dose (FFQ)
 0.1–300 μg42/911.01 (0.62–1.65)66/1491.05 (0.70–1.60)74/1840.92 (0.62–1.37)
 300.1–450 μg23/1150.49 (0.28–0.85)66/1940.82 (0.55–1.23)41/1230.74 (0.46–1.19)
 >450.1 μg43/1510.60 (0.38–0.98)66/2360.67 (0.44–1.00)45/1370.68 (0.43–1.09)
P of linear trend0.010.030.08
 Per 100 μg0.93 (0.88–0.99)0.95 (0.91–1.00)0.94 (0.89–0.99)
  • aAdjusted for frequency matching variables (age, sex, state of residence), ethnicity, maternal age group, child's year of birth group, maternal education level, and data source.

  • bReference level: no folic acid prepregnancy or during pregnancy.