摘要：Objectives. We investigated the relationship between breastfeeding, asthma and atopy, and child body mass index (BMI). Methods. From a prospective birth cohort (n = 2860) in Perth, Western Australia, 2195 children were followed up to age 6 years. Asthma was defined as doctor-diagnosed asthma and wheeze in the last year, and atopy was determined by skin prick test of 1596 children. Breastfeeding, BMI, asthma, and atopy were regressed allowing for confounders and the propensity score for overweight. Results. Using fractional polynomials, we found no association between breastfeeding and overweight. Less exclusive breastfeeding was associated with increased asthma and atopy, and BMI increased with asthma. Conclusions. Less exclusive breastfeeding leads to increases in child asthma and atopy and a higher BMI is a risk factor for asthma. Asthma is the leading cause of hospitalization among Australian children, and its prevalence is increasing worldwide. 1, 2 In developed nations, the increase in prevalence of childhood asthma has been paralleled by an increase in childhood obesity. 3, 4 Overweight and obesity are leading causes of morbidity and a major public health problem, 5 as they are associated with numerous risk factors for cardiovascular disease and chronic diseases later in life, including hyperlipidemia, hyperinsulinemia, hypertension, and early atherosclerosis. 5– 7 There has been considerable debate as to whether formula feeding is a risk factor for childhood obesity. Dewey et al. studied growth patterns for weight, length, head circumference, and indexes of body composition 8 and found that infants breastfed for 12 months or longer are leaner than formula-fed infants. 9 The impact of breastfeeding on obesity has been investigated in small studies, but no effect was observed. 10– 12 On the other hand, a protective effect has been reported in a Canadian cross-sectional study of 1320 adolescents born in the late 1960s. 13 Another cross-sectional study in Bavaria 14 concluded that breastfeeding may help decrease the prevalence of obesity in childhood. Investigators have speculated that obesity may be a causal factor in the inception of childhood asthma, and a number of studies have shown positive associations between body mass index (BMI; weight in kilograms divided by height in meters squared) or obesity and asthma. 15– 19 Little is known about the effects of BMI on atopy, but 1 study found positive effects before but not after adjustment for BMI. 15 Breastfeeding has been shown to protect against overweight and obesity 14, 20– 22 as well as asthma in childhood, 23, 24 although the relationship between breastfeeding and childhood asthma remains speculative. 25 The aim of this study was to investigate whether the relationship of breastfeeding to asthma was influenced by BMI. The objectives of the report were to determine the interrelationships of (a) breastfeeding with BMI, (b) BMI with asthma and atopy, and (c) breastfeeding with asthma and atopy after adjustment for BMI.
