Associations between breastfeeding practice and lifetime prevalence of asthma# by affluence¶
| Affluent countries+ | Nonaffluent countries§ | |||||||
| Crude | Adjustedƒ | Crude | Adjustedƒ | |||||
| OR | 95% CI | OR | 95% CI | OR | 95% CI | OR | 95% CI | |
| Breastfeeding## | ||||||||
| No | 1 | Reference | Reference | 1 | Reference | 1 | Reference | |
| Yes | 0.87 | 0.78–0.96 | 0.87 | 0.78–0.97 | 0.93 | 0.79–1.10 | 0.89 | 0.71–1.11 |
| Duration of breastfeeding¶¶ | ||||||||
| Not breastfed | 1 | Reference | 1 | Reference | 1 | Reference | 1 | Reference |
| <6 months | 0.89 | 0.77–1.03 | 0.90 | 0.77–1.04 | 1.12 | 0.90–1,39 | 1.09 | 0.86–1.39 |
| ≥6 months | 0.84 | 0.72–0.97 | 0.87 | 0.75–1.00 | 0.85 | 0,71–1.03 | 0.83 | 0.67–1.03 |
| Exclusive breastfeeding++ | ||||||||
| Not breastfed | 1 | Reference | 1 | Reference | 1 | Reference | 1 | Reference |
| 2 months | 0.91 | 0.79–1.05 | 0.92 | 0.79–1.06 | 1.20 | 0.96–1.50 | 1.14 | 0.91–1.44 |
| 2–4 months | 0.87 | 0.76–0.99 | 0.88 | 0.77–1.01 | 0.92 | 0.68–1.23 | 0.86 | 0.63–1.17 |
| ≥4 months | 0.87 | 0.75–1.02 | 0.91 | 0.78–1.07 | 0.74 | 0.59–0.92 | 0.75 | 0.60–0.94 |
OR: odds ratio; CI: confidence interval. #: defined by parental report on asthma diagnosis; ¶: 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 2,723 out of 27,550 and nonaffluent countries 1,192 out of 15,593; ¶¶: without Utrecht (the Netherlands), Pichincha (Ecuador), Ankara (Turkey) and Kintampo (Ghana), for affluent countries 2,369 out of 23,250 and nonaffluent countries 1,100 out of 14,047; ++: without Utrecht (the Netherlands), Pichincha (Ecuador) and Ankara (Turkey), for affluent countries 2,279 out of 22,091 and nonaffluent countries 1,154 out of 14,514.