Table 1. Association between selected early life factors and birth characteristics and risk of brain tumour, univariable analyses.
| Variable | Cases N (%) | Non-case N (%) | Odds ratio (95% CI) | P-value/trend |
|---|---|---|---|---|
| Sex | ||||
| Male | 99 (63.9) | 216 535 (51.5) | 1.67 (1.20, 2.31) | |
| Female | 56 (36.1) | 203 901 (48.5) | 1.0 (ref) | 0.002 |
| Year of birth | ||||
| 1971–1972 | 16 (10.3) | 57 562 (13.7) | 1.0 (ref) | |
| 1973–1974 | 12 (7.7) | 51 299 (12.2) | 0.84 (0.40, 1.78) | |
| 1975–1976 | 24 (15.5) | 49 685 (11.8) | 1.74 (0.93, 3.27) | |
| 1977–1978 | 33 (21.3) | 49 920 (11.9) | 2.38 (1.31, 4.32) | 0.001 |
| 1979–1980 | 20 (12.9) | 53 793 (12.8) | 1.34 (0.69, 2.58) | |
| 1981–1982 | 17 (11.0) | 52 212 (12.4) | 1.17 (0.59, 2.32) | |
| 1983–1984 | 13 (8.4) | 52 680 (12.5) | 0.89 (0.43, 1.85) | |
| 1985–1986 | 20 (12.9) | 53 283 (12.7) | 1.35 (0.70, 2.61) | 0.007/0.95 |
| Maternal age (years) | ||||
| <25 | 48 (31.0) | 155 625 (37.1) | 0.76 (0.53, 1.08) | |
| 25–34 | 88 (56.8) | 217 232 (51.8) | 1.0 (ref) | |
| ⩾35 | 19 (12.3) | 47 447 (11.1) | 1.01 (0.62, 1.67) | 0.29/0.16 |
| Paternal age (years) | ||||
| <25 | 33 (23.2) | 85 939 (22.8) | 1.14 (0.75, 1.72) | |
| 25–34 | 73 (51.4) | 216 059 (57.4) | 1.0 (ref) | |
| ⩾35 | 36 (25.4) | 74 160 (19.7) | 1.44 (0.96, 2.14) | 0.20/0.34 |
| Social class | ||||
| Non-manual | 39 (25.2) | 89 469 (21.3) | 1.24 (0.87–1.79) | 0.24 |
| Manual/other | 116 (74.8) | 330 967 (78.7) | 1.0 (ref) | |
| Miscarriage history | ||||
| None | 99 (71.2) | 308 778 (80.6) | 1.0 (ref) | |
| ⩾1 | 40 (28.8) | 74 486 (19.4) | 1.68 (1.16, 2.42) | 0.005 |
| Gestation age (weeks) | ||||
| <38 | 9 (5.8) | 34 522 (8.2) | 0.68 (0.34, 1.39) | |
| 38–39 | 52 (33.6) | 136 390 (32.4) | 1.0 (ref) | |
| ⩾40 | 94 (60.7) | 249 524 (59.4) | 0.99 (0.70, 1.39) | 0.55/0.47 |
| Presumptive birth order | ||||
| First born | 41 (28.5) | 115 578 (29.7) | 1.0 (ref) | |
| Not first born | 103 (71.5) | 274 095 (70.3) | 1.06 (0.74, 1.52 | 0.75 |
| Breast fed | ||||
| Yes | 29 (18.7) | 77 969 (18.5) | 1.0 (ref) | 0.76 |
| No | 120 (77.4) | 320 573 (76.3) | 1.01 (0.67–1.51) | |
| Birth weight (g) | ||||
| <2500 | 5 (3.2) | 19 218 (4.6) | 0.73 (0.30, 1.79) | 0.18/0.07 |
| 2500–4000 | 127 (81.9) | 356 887 (84.9) | 1.0 (ref) | |
| >4000 | 23 (14.8) | 44 331 (10.5) | 1.46 (0.91, 2.27) | |
| Number of children in household <15 yearsa | ||||
| <3 | 44 (71.0) | 143 217 (82.1) | 1.0 (ref) | |
| ⩾3 | 18 (29.0) | 31 160 (17.9) | 1.88 (1.09, 3.25) | 0.02 |
| Number of adults in household | ||||
| <3 | 73 (87.0) | 214 582 (92.4) | 1.0 (ref) | |
| ⩾3 | 11 (13.1) | 17 576 (7.6) | 1.84 (0.98, 3.47) | 0.06 |
| Household density | ||||
| <1 person/room | 11 (7.1) | 37 272 (8.9) | 1.0 (ref) | 0.74 |
| ⩾1 person/room | 51 (32.9) | 136 580 (32.5) | 1.27 (0.66–2.43) | |
a
Includes the newborn.