Affluent countries+ | Nonaffluent countries§ | |||||||
Crude | Adjustedƒ | Crude | Adjustedƒ | |||||
OR | 95% CI | OR | 95% CI | OR | 95% CI | OR | 95% CI | |
Atopic wheeze | ||||||||
Breastfeeding## | ||||||||
No | 1 | Reference | 1 | Reference | 1 | Reference | 1 | Reference |
Yes | 0.87 | 0.68–1.11 | 0.85 | 0.67–1.08 | 0.84 | 0.57–1.25 | 0.85 | 0.54–1.34 |
Duration of breastfeeding¶¶ | ||||||||
Not breastfed | 1 | Reference | 1 | Reference | 1 | Reference | 1 | Reference |
<6 months | 0.90 | 0.70–1.16 | 0.89 | 0.70–1.13 | 1.02 | 0.81–1.30 | 1.01 | 0.64–1.57 |
≥6 months | 0.88 | 0.68–1.13 | 0.87 | 0.68–1.11 | 0.78 | 0.50–1.23 | 0.78 | 0.46–1.33 |
Exclusive breastfeeding++ | ||||||||
Not breastfed | 1 | Reference | 1 | Reference | 1 | Reference | 1 | Reference |
2 months | 0.93 | 0.66–1.31 | 0.92 | 0.65–1.29 | 1.01 | 0.94–1.09 | 1.08 | 0.74–1.58 |
2–4 months | 0.88 | 0.71–1.08 | 0.85 | 0.69–1.05 | 1.00 | 0.94–1.06 | 0.92 | 0.68–1.24 |
≥4 months | 0.90 | 0.68–1.21 | 0.92 | 0.69–1.24 | 0.66 | 0.44–0.98 | 0.68 | 0.44–1.05 |
Nonatopic wheeze | ||||||||
Breastfeeding§§ | ||||||||
No | 1 | Reference | 1 | Reference | 1 | Reference | 1 | Reference |
Yes | 0.88 | 0.73–1.05 | 0.87 | 0.72–1.06 | 0.71 | 0.55–0.92 | 0.69 | 0.53–0.90 |
Duration of breastfeedingƒƒ | ||||||||
Not breastfed | 1 | Reference | 1 | Reference | 1 | Reference | 1 | Reference |
<6 months | 0.87 | 0.71–1.07 | 0.88 | 0.69–1.11 | 0.32 | 0.03–3.23 | 0.82 | 0.61–1.11 |
≥6 months | 0.98 | 0.78–1.22 | 1.00 | 0.79–1.26 | 0.68 | 0.52–0.89 | 0.64 | 0.49–0.85 |
Exclusive breastfeeding### | ||||||||
Not breastfed | 1 | Reference | 1 | Reference | 1 | Reference | 1 | Reference |
2 months | 0.92 | 0.72–1.17 | 0.93 | 0.71–1.21 | 0.77 | 0.56–1.06 | 0.72 | 0.51–1.02 |
2–4 months | 0.91 | 0.74–1.13 | 0.90 | 0.72–1.13 | 0.71 | 0.53–0.95 | 0.68 | 0.50–0.90 |
≥4 months | 0.96 | 0.72–1.27 | 0.98 | 0.73–1.31 | 0.73 | 0.55–0.98 | 0.75 | 0.55–1.00 |
OR: odds ratio; CI: confidence interval. #: defined as wheeze with (atopic) and without (nonatopic) skin prick test positivity; ¶: random effect models for meta-analysis; +: gross national income (GNI) ≥US$9,200 per capita in 16 centres with 29,222 children; §: GNI <US$9,200 per capita in 11 centres with 21,851 children; ƒ: adjusted for sex, age, maternal atopic disease, environmental tobacco smoke and present bedroom sharing; ##: without Pichincha (Ecuador), for affluent countries 1,676 out of 15,610 and nonaffluent countries 907 out of 8,503; ¶¶: without Utrecht (the Netherlands), Pichincha (Ecuador), Kintampo (Ghana) and Ramallah (West Bank), for affluent countries 1,514 out of 13,646 and nonaffluent countries 805 out of 6,882; ++: without Utrecht (The Netherlands) and Pichincha (Ecuador), for affluent countries 1,532 out of 13,894 and nonaffluent countries 906 out of 7,952; §§: without Reykjavik (Iceland) and Pichincha (Ecuador), for affluent countries 1,676 out of 15,610 and for nonaffluent countries 1,004 out of 9,741; ƒƒ: for affluent countries 1,606 out of 14,580 and nonaffluent countries 1,027 out of 10,723; ###: without Reykjavik (Iceland), Utrecht (the Netherlands), Pichincha (Ecuador) and Kintampo (Ghana), for affluent countries 1,429 out of 12,776 and nonaffluent countries 818 out of 7,173.