Table 2 Principal characteristics of childhood acute leukemia cases and controls age between 2 and 20 years
ALL | AML | |||
|---|---|---|---|---|
Variablea | Case (n = 112) | Control (n = 279) | Case (n = 33) | Control (n = 91) |
Age (years) (median (SD)) | 6.9 (5.6) | 7.8 (5.5) | 14.6 (4.9) | 14.8 (4.9) |
Sex | ||||
   Male (%) | 76 (67.9) | 185 (66.3) | 18 (54.5) | 53 (58.2) |
   Female (%) | 36 (32.1) | 94 (33.7) | 15 (45.5) | 38 (41.8) |
Maternal age (years) | ||||
   < 25 (%) | 27 (24.5) | 73 (26.3) | 6 (18.2) | 21 (23.1) |
   25–34 (%) | 74 (67.3) | 185 (66.5) | 27 (81.8) | 68 (74.7) |
   ≧ 35 (%) | 9 (8.2) | 20 (7.2) | 0 (0.0) | 2 (2.2) |
Birth weight (g) | ||||
   < 3000 (%) | 27 (24.1) | 72 (25.8) | 11 (33.3) | 25 (27.5) |
   3000–3499 (%) | 48 (42.9) | 134 (48.0) | 10 (30.3) | 42 (46.2) |
   ≧ 3500 (%) | 37 (33.0) | 73 (26.2) | 12 (36.4) | 24 (26.4) |
Breastfeeding | ||||
   Never (%) | 70 (62.5) | 157 (56.3) | 25 (75.8) | 59 (64.8) |
   Ever (%) | 41 (36.6) | 121 (43.3) | 8 (24.2) | 32 (35.2) |
   Unknown (%) | 1 (0.9) | 1 (0.4) | 0 (0.00) | 0 (0.0) |
Maternal smoking during pregnancy | ||||
   Yes (%) | 1 (0.9) | 4 (1.4) | 1 (3.0) | 0 (0.0) |
   No (%) | 111 (99.1) | 275 (98.6) | 32 (97.0) | 91 (100.0) |
Paternal smoking during pregnancy | ||||
   Yes (%) | 59 (53.6) | 152 (54.5) | 20 (60.6) | 55 (50.4) |
   No (%) | 51 (46.4) | 127 (45.5) | 13 (39.4) | 36 (39.6) |
Subjects smoking before diagnosis | ||||
   Yes (%) | 1 (0.9) | 6 (2.2) | 0 (0) | 1 (1.1) |
   No (%) | 111 (99.1) | 273 (97.8) | 33 (100) | 90 (98.9) |
Parental education levels b | ||||
   Not junior high school graduated (%) | 5 (4.5) | 15 (5.4) | 0 (0.00) | 10 (11.0) |
   Junior high school graduated (%) | 9 (8.0) | 35 (12.5) | 7 (21.2) | 13 (14.3) |
   High school graduated (%) | 55 (49.1) | 114 (40.9) | 13 (39.4) | 41 (45.1) |
   Four-year college/university and above (%) | 43 (38.4) | 115 (41.2) | 13 (39.4) | 27 (29.7) |