Table 1. Baseline Characteristics of the Study Population and Duration of Exclusive Breastfeeding in Infancy According to Childhood Cancer Overall and ALL.
| Characteristic | Children, No. (%) | ||
|---|---|---|---|
| All (N = 309 473) | With any cancer (n = 332) | With ALL (n = 81) | |
| Sex | |||
| Boys | 158 613 (51.3) | 194 (58.4) | 50 (61.7) |
| Girls | 150 860 (48.7) | 138 (41.6) | 31 (38.3) |
| Birth order | |||
| 1 | 150 452 (48.6) | 141 (42.5) | 34 (42.0) |
| 2 | 111 651 (36.1) | 129 (38.8) | 30 (37.0) |
| ≥3 | 47 370 (15.3) | 62 (18.7) | 17 (21.0) |
| Birth weight, g | |||
| <2500 | 13 349 (4.3) | 13 (3.9) | <5a |
| 2500 to <3000 | 36 143 (11.7) | 37 (11.2) | <10a |
| 3000 to <3500 | 101 762 (32.9) | 102 (30.7) | 29 (35.8) |
| 3500 to <4000 | 107 187 (34.6) | 105 (31.6) | 21 (26.0) |
| ≥4000 | 51 032 (16.5) | 75 (22.6) | 22 (27.2) |
| Gestational age, wk | |||
| <36 | 10 053 (3.2) | 9 (2.7) | <5a |
| 36-37 | 21 929 (7.1) | 35 (10.6) | <15a |
| 38-39 | 108 327 (35.0) | 100 (30.1) | 32 (39.5) |
| 40-41 | 160 929 (52.0) | 178 (53.6) | 35 (43.2) |
| ≥42 | 8235 (2.7) | 10 (3.0) | <5a |
| Mode of birth | |||
| Vaginal | 246 497 (79.7) | 269 (81.0) | 66 (81.5) |
| Cesarean delivery | 62 976 (20.3) | 63 (19.0) | 15 (18.5) |
| Mother’s age at delivery, y | |||
| <25 | 30 888 (9.9) | 26 (7.8) | 5 (6.3) |
| 25-29 | 94 672 (30.6) | 98 (29.5) | 25 (30.8) |
| 30-34 | 111 913 (36.2) | 130 (39.2) | 25 (30.8) |
| ≥35 | 72 000 (23.3) | 78 (23.5) | 26 (32.1) |
| Mother’s highest educational level, y | |||
| <9 | 44 528 (14.4) | 53 (16.0) | 12 (14.8) |
| 10-12 | 99 503 (32.1) | 102 (30.7) | 28 (34.6) |
| ≥13 | 165 442 (53.5) | 177 (53.3) | 41 (50.6) |
| Exclusive breastfeeding duration | |||
| Never or <14 d | 37 014 (11.9) | 45 (13.6) | 9 (11.1) |
| ≤2 mo | 67 118 (21.7) | 82 (24.7) | 25 (30.9) |
| 3-5 mo | 144 702 (46.8) | 143 (43.0) | 34 (42.0) |
| ≥6 mo | 60 639 (19.6) | 62 (18.7) | 13 (16.0) |
Abbreviation: ALL, acute lymphoblastic leukemia.
a
Exact numbers are not presented to blind numbers less than 5 (directly or by calculation through group totals) in accordance with the interpretation of the General Data Protection Regulation by Statistics Denmark.