Table 2. Adjusted incidence rate ratios for associations between perinatal or familial characteristics and acute lymphoblastic leukemia (ALL) in 1973-2010.
| Total population N (%) | ALL cases n (%) | Adjusted Model 1a | Adjusted Model 2b | |||||
|---|---|---|---|---|---|---|---|---|
|
|
||||||||
| IRR | 95% CI | P | IRR | 95% CI | P | |||
| Age at diagnosis (years) | ||||||||
| <5 | 1,041 (53.1) | |||||||
| 5-9 | 469 (23.9) | |||||||
| 10-14 | 240 (12.2) | |||||||
| ≥15 | 210 (10.7) | |||||||
| Sex | ||||||||
| Female | 1,734,966 (48.6) | 863 (44.0) | 1.00 | 1.00 | ||||
| Male | 1,834,367 (51.4) | 1,097 (56.0) | 1.20 | 1.10, 1.31 | <0.001 | 1.20 | 1.10, 1.31 | <0.001 |
| Fetal growth (SD) | ||||||||
| <-1 | 647,584 (18.1) | 357 (18.2) | 0.99 | 0.88, 1.12 | 0.92 | 1.00 | 0.89, 1.13 | 0.97 |
| -1 to <1 | 2,384,285 (66.8) | 1,275 (65.1) | 1.00 | 1.00 | ||||
| ≥1 | 537,464 (15.1) | 328 (16.7) | 1.35 | 1.12, 1.63 | 0.01 | 1.15 | 1.02, 1.30 | 0.02 |
| Per SD (trend test) | 1.07 | 1.03, 1.12 | 0.001 | 1.07 | 1.02, 1.11 | 0.002 | ||
| Gestational age at birth (weeks) | ||||||||
| <37 | 206,387 (5.8) | 111 (5.7) | 1.00 | 0.83, 1.21 | 0.99 | 1.00 | 0.83, 1.22 | 0.97 |
| 37-41 | 3,064,550 (85.9) | 1,657 (84.5) | 1.00 | 1.00 | ||||
| ≥42 | 298,396 (8.4) | 192 (9.8) | 1.14 | 0.98, 1.33 | 0.09 | 1.14 | 0.98, 1.33 | 0.08 |
| Per week (trend test) | 1.01 | 0.98, 1.03 | 0.60 | 1.01 | 0.98, 1.03 | 0.60 | ||
| Birth weight (g) | ||||||||
| <2500 | 149,020 (4.2) | 83 (4.2) | 1.06 | 0.85, 1.32 | 0.62 | 1.06 | 0.85, 1.32 | 0.61 |
| 2500-3999 | 2,777,911 (77.8) | 1,470 (75.0) | 1.00 | 1.00 | ||||
| ≥4000 | 642,402 (18.0) | 407 (20.8) | 1.22 | 1.09, 1.36 | <0.001 | 1.19 | 1.06, 1.32 | 0.003 |
| Per 1000 g (trend test) | 1.15 | 1.06, 1.24 | 0.001 | 1.12 | 1.04, 1.21 | 0.005 | ||
| Birth length (cm) | ||||||||
| <48 | 359,182 (10.1) | 185 (9.4) | 0.97 | 0.83, 1.13 | 0.72 | 0.98 | 0.84, 1.15 | 0.81 |
| 48-52 | 2,600,085 (72.9) | 1,402 (71.5) | 1.00 | 1.00 | ||||
| ≥53 | 576,918 (16.2) | 363 (18.5) | 1.14 | 1.02, 1.28 | 0.03 | 1.09 | 0.96, 1.24 | 0.16 |
| Unknown | 33,148 (0.9) | 10 (0.5) | ||||||
| Per cm (trend test) | 1.02 | 1.01, 1.04 | 0.009 | 1.01 | 0.99, 1.03 | 0.24 | ||
| Size for gestational age | ||||||||
| Small (<10th percentile) | 356,521 (10.0) | 202 (10.3) | 1.01 | 0.87, 1.17 | 0.88 | 1.02 | 0.88, 1.18 | 0.80 |
| Appropriate (10th-90th percentile) | 2,854,197 (80.0) | 1,528 (78.0) | 1.00 | 1.00 | ||||
| Large (>90th percentile) | 356,655 (10.0) | 230 (11.7) | 1.23 | 1.07, 1.41 | 0.003 | 1.22 | 1.06, 1.40 | 0.005 |
| Season of birth | ||||||||
| Spring (Mar-May) | 990,165 (27.7) | 558 (28.5) | 1.05 | 0.93, 1.19 | 0.40 | 1.05 | 0.93, 1.19 | 0.42 |
| Summer (Jun-Aug) | 915,319 (25.6) | 484 (24.7) | 1.00 | 1.00 | ||||
| Fall (Sep-Nov) | 821,829 (23.0) | 464 (23.7) | 1.07 | 0.94, 1.21 | 0.32 | 1.07 | 0.94, 1.21 | 0.31 |
| Winter (Dec-Feb) | 842,020 (23.6) | 454 (23.2) | 1.01 | 0.89, 1.15 | 0.86 | 1.01 | 0.89, 1.15 | 0.86 |
| Birth order | ||||||||
| 1 | 1,827,129 (51.2) | 1,060 (54.1) | 1.00 | 1.00 | ||||
| 2 | 1,200,398 (33.6) | 620 (31.6) | 0.93 | 0.84, 1.03 | 0.15 | 0.91 | 0.82, 1.01 | 0.07 |
| ≥3 | 541,806 (15.2) | 280 (14.3) | 0.96 | 0.83, 1.10 | 0.52 | 0.93 | 0.81, 1.06 | 0.29 |
| Per higher category (trend test) | 0.98 | 0.93, 1.04 | 0.58 | 0.97 | 0.92, 1.03 | 0.32 | ||
| Multiple birth | ||||||||
| Singleton | 3,484,910 (97.6) | 1,907 (97.3) | 1.00 | 1.00 | ||||
| Twin or higher order | 84,423 (2.4) | 53 (2.7) | 1.21 | 0.92, 1.59 | 0.17 | 1.23 | 0.94, 1.62 | 0.14 |
| Maternal age at birth (years) | ||||||||
| <20 | 83,987 (2.4) | 51 (2.6) | 1.04 | 0.78, 1.39 | 0.77 | 1.06 | 0.80, 1.41 | 0.70 |
| 20-24 | 678,027 (19.0) | 396 (20.2) | 1.03 | 0.91, 1.17 | 0.65 | 1.04 | 0.91, 1.17 | 0.58 |
| 25-29 | 1,251,348 (35.1) | 677 (34.5) | 1.00 | 1.00 | ||||
| 30-34 | 1,033,763 (29.0) | 562 (28.7) | 1.09 | 0.97, 1.22 | 0.15 | 1.08 | 0.97, 1.21 | 0.16 |
| ≥35 | 518,097 (14.5) | 272 (13.9) | 1.10 | 0.95, 1.27 | 0.19 | 1.10 | 0.95, 1.27 | 0.19 |
| Unknown | 4,111 (0.1) | <5 (0.1) | ||||||
| Per higher category (trend test) | 1.03 | 0.98, 1.08 | 0.23 | 1.02 | 0.98, 1.07 | 0.29 | ||
| Paternal age at birth (years) | ||||||||
| <20 | 16,943 (0.5) | 10 (0.5) | 1.05 | 0.56, 1.96 | 0.89 | 1.06 | 0.57, 1.98 | 0.86 |
| 20-24 | 326,974 (9.2) | 202 (10.3) | 1.09 | 0.92, 1.27 | 0.32 | 1.09 | 0.93, 1.28 | 0.29 |
| 25-29 | 1,021,644 (28.6) | 564 (28.8) | 1.00 | 1.00 | ||||
| 30-34 | 1,161,177 (32.5) | 625 (31.9) | 1.05 | 0.93, 1.17 | 0.43 | 1.05 | 0.93, 1.17 | 0.44 |
| ≥35 | 1,014,007 (28.4) | 541 (27.6) | 1.10 | 0.97, 1.24 | 0.14 | 1.10 | 0.98, 1.24 | 0.12 |
| Unknown | 28,588 (0.8) | 18 (0.9) | ||||||
| Per higher category (trend test) | 1.02 | 0.97, 1.07 | 0.40 | 1.02 | 0.97, 1.07 | 0.40 | ||
| Both parents born in Sweden | ||||||||
| Yes | 2,852,520 (79.9) | 1,622 (82.8) | 1.13 | 1.01, 1.28 | 0.04 | 1.13 | 1.00, 1.27 | 0.045 |
| No | 716,813 (20.1) | 338 (17.2) | 1.00 | 1.00 | ||||
| Maternal education (years) | ||||||||
| ≤9 | 674,884 (18.9) | 390 (19.9) | 1.00 | 1.00 | ||||
| 10-11 | 1,149,737 (32.2) | 694 (35.4) | 1.04 | 0.92, 1.19 | 0.52 | 1.03 | 0.91, 1.17 | 0.64 |
| 12-14 | 1,044,760 (29.3) | 520 (26.5) | 1.01 | 0.88, 1.16 | 0.88 | 1.00 | 0.87, 1.15 | 0.99 |
| ≥15 | 554,418 (15.5) | 288 (14.7) | 1.13 | 0.96, 1.32 | 0.15 | 1.11 | 0.95, 1.31 | 0.19 |
| Unknown | 145,534 (4.1) | 68 (3.5) | ||||||
| Per higher category (trend test) | 1.03 | 0.98, 1.08 | 0.29 | 1.02 | 0.97, 1.08 | 0.35 | ||
| Paternal education (years) | ||||||||
| ≤9 | 767,366 (21.5) | 454 (23.2) | 1.00 | 1.00 | ||||
| 10-11 | 1,128,568 (31.6) | 610 (31.1) | 0.98 | 0.86, 1.11 | 0.73 | 0.97 | 0.85, 1.11 | 0.67 |
| 12-14 | 959,668 (26.9) | 518 (26.4) | 1.06 | 0.93, 1.21 | 0.38 | 1.06 | 0.93, 1.20 | 0.41 |
| ≥15 | 537,725 (15.1) | 294 (15.0) | 1.07 | 0.92, 1.24 | 0.39 | 1.06 | 0.92, 1.23 | 0.42 |
| Unknown | 176,006 (4.9) | 84 (4.3) | ||||||
| Per higher category (trend test) | 1.03 | 0.98, 1.08 | 0.21 | 1.03 | 0.99, 1.08 | 0.18 | ||
| ALL in a parent or sibling | ||||||||
| No | 3,565,267 (99.9) | 1,943 (99.1) | 1.00 | 1.00 | ||||
| Yes | 4,066 (0.1) | 17 (0.9) | 7.61 | 4.64, 12.09 | <0.001 | 7.41 | 4.60, 11.95 | <0.001 |
a
Adjusted for birth year (modeled simultaneously as continuous and categorical variables).
b
Adjusted for birth year (as noted above), sex, fetal growth, parental country of birth, and family history of ALL in a parent or sibling. Birth weight, birth length, and size for gestational age were each examined in separate models as alternatives to the standardized fetal growth variable. The reference category for all variables is indicated by an IRR of 1.00. Multiple imputation was used for missing data.
ALL = acute lymphoblastic leukemia, CI = confidence interval, IRR = incidence rate ratio, SD = standard deviation.