Duration of any breastfeeding (N = 6796) | ||||
---|---|---|---|---|
≥ 6 months (n = 5695) | < 6 months (n = 1101) | |||
Characteristics | na | na | ||
Maternal age at birth, years, mean (SD) | 5670 | 30.2 (4.4) range: 16.8–44.5 | 1095 | 28.7 (5.1) range: 17.0–44.2 |
Maternal education, n (%) | 2625 | 392 | ||
< 12 years (less than high school) | 116 (4.4) | 62 (15.8) | ||
12–16 years (up to 4 years university) | 1298 (49.5) | 237 (60.5) | ||
> 16 years (more than 4 years university) | 1211 (46.1) | 93 (23.7) | ||
Mean incomeb, NOK, mean (SD) | 5465 | 255,414 (29175) | 1053 | 250,191 (30405) |
Family history of allergyc, n (%) | 5675 | 4200 (74.0) | 1092 | 784 (71.8) |
Older sibling, n (%) | 3943 | 2245 (56.9) | 731 | 401 (54.9) |
Maternal smoking, n (%) | ||||
During pregnancy | 2020 | 92 (4.6) | 316 | 55 (17.4) |
During child’s first 2 years | 5638 | 887 (15.7) | 1078 | 391 (36.3) |
Paternal smoking, n (%) | 5397 | 1072 (19.9) | 994 | 330 (33.2) |
Child exposed to smoke during first 2 yearsd, n (%) | 5675 | 1462 (25.8) | 1095 | 502 (45.8) |
Petse, n (%) | 5695 | 1143 (20.1) | 1101 | 264 (24.0) |
Birthweight, gram, mean (SD) | 5625 | 3608 (552) range: 640–5560 | 1072 | 3463 (705) range: 585–5960 |
Birthweight < 2500 g, n (%) | 5625 | 156 (2.8) | 1072 | 88 (8.2) |
Sex, male, n (%) | 5693 | 2798 (49.2) | 1101 | 581 (52.8) |
Lower respiratory tract infection within first yearf, n (%) | 3217 | 333 (10.4) | 606 | 78 (12.9) |
Antibiotic treatment within first year, n (%) | 3746 | 756 (20.2) | 695 | 163 (23.5) |
Introduced to formula < 6 months of age, n (%) | 5625 | 966 (17.2) | 1093 | 972 (88.9)g |
Start of day-care < 12 months of age, n (%) | 5051 | 394 (7.8) | 930 | 65 (7.0) |