Table 3.

Analysis of age at first exposure to an influenza season and the intensity of that season in a study of leukemia risk among California children diagnosed between 1997 and 2007

Low-intensity influenza seasonMedium-intensity influenza seasonHigh-intensity influenza season
ControlsCasesOR (95% CI)ControlsCasesOR (95% CI)ControlsCasesOR (95% CI)
Age at first exposure to influenza season, mo
0–32,923139Ref3,689164Ref3,180152Ref
3–62,1401091.07 (0.83–1.39)3,0661501.10 (0.88–1.38)2,8121571.17 (0.93–1.47)
6–91,990991.05 (0.80–1.36)2,9041581.22 (0.98–1.53)2,6491230.97 (0.76–1.24)
9–122,0101011.06 (0.81–1.37)1,9771171.33 (1.04–1.70)837491.23 (0.88–1.71)
>1218991.00 (0.50–2.00)474190.90 (0.56–1.46)00
First births
Age at first exposure to influenza season, mo
0–31,12248Ref1,40954Ref1,28361Ref
3–6859381.03 (0.67–1.60)1,195531.16 (0.79–1.70)1,097621.19 (0.83–1.71)
6–9743351.10 (0.71–1.72)1,118531.24 (0.84–1.82)1,035420.85 (0.57–1.28)
9–12766371.13 (0.73–1.75)762521.78 (1.21–2.63)313241.61 (0.99–2.63)
>1288219091.24 (0.60–2.54)00
Second or subsequent births
Age at first exposure to influenza season, mo
0–31,79991Ref2,280110Ref1,89491Ref
3–61,280711.10 (0.80–1.51)1,871971.08 (0.81–1.42)1,713951.15 (0.86–1.55)
6–91,247641.02 (0.73–1.41)1,7861051.22 (0.93–1.60)1,612811.05 (0.77–1.42)
9–121,243641.02 (0.73–1.41)1,215651.11 (0.81–1.52)524250.99 (0.63–1.56)
>1210171.37 (0.62–3.03)284100.73 (0.38–1.41)00