Asthma and wheezing disorders are common chronic health problems in childhood. Breastfeeding provides health benefits, but it is not known whether or how breastfeeding decreases the risk of developing asthma. We performed a systematic review and meta-analysis of studies published between 1983 and 2012 on breastfeeding and asthma in children from the general population. We searched the PubMed and Embase databases for cohort, cross-sectional, and case-control studies. We grouped the outcomes into asthma ever, recent asthma, or recent wheezing illness (recent asthma or recent wheeze). Using random-effects meta-analyses, we estimated pooled odds ratios of the association of breastfeeding with the risk for each of these outcomes. We performed meta-regression and stratified meta-analyses. We included 117 of 1,464 titles identified by our search. The pooled odds ratios were 0.78 (95% confidence interval: 0.74, 0.84) for 75 studies analyzing "asthma ever," 0.76 (95% confidence interval: 0.67, 0.86) for 46 studies analyzing "recent asthma," and 0.81 (95% confidence interval: 0.76, 0.87) for 94 studies analyzing recent wheezing illness. After stratification by age, the strong protective association found at ages 0-2 years diminished over time. We found no evidence for differences by study design or study quality or between studies in Western and non-Western countries. A positive association of breastfeeding with reduced asthma/wheezing is supported by the combined evidence of existing studies.

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Breastfeeding and Childhood Asthma: Systematic Review and Meta-Analysis

Incidence of childhood allergic disease including asthma (AD-A) has risen since the mid-20th century with much of the increase linked to changes in environment affecting the immune system. Childhood allergy is an early life disease where predisposing environmental exposures, sensitization, and onset of symptoms all occur before adulthood. Predisposition toward allergic disease (AD) is among the constellation of adverse outcomes following developmental immunotoxicity (DIT; problematic exposure of the developing immune system to xenobiotics and physical environmental factors). Because novel immune maturation events occur in early life, and the pregnancy state itself imposes certain restrictions on immune functional development, the period from mid-gestation until 2 years after birth is one of particular concern relative to DIT and AD-A. Several prenatal-perinatal risk factors have been identified as contributing to a DIT-mediated immune dysfunction and increased risk of AD. These include maternal smoking, environmental tobacco smoke, diesel exhaust and traffic-related particles, heavy metals, antibiotics, environmental estrogens and other endocrine disruptors, and alcohol. Diet and microbial exposure also significantly influence immune maturation and risk of allergy. This review considers (1) the critical developmental windows of vulnerability for the immune system that appear to be targets for risk of AD, (2) a model in which the immune system of the DIT-affected infant exhibits immune dysfunction skewed toward AD, and (3) the lack of allergy-relevant safety testing of drugs and chemicals that could identify DIT hazards and minimize problematic exposure of pregnant women and children.

Early-life environment, developmental immunotoxicology, and the risk of pediatric allergic disease including asthma.

There is conflicting evidence concerning the relationship between breast feeding and wheezing illness. The objective of this study was to investigate whether there is any association between breast feeding and wheezing in children aged over 5 years and to discover possible sources of heterogeneity. An electronic search of MEDLINE and EMBASE databases was conducted from January 2000 to June 2010. In addition, reference lists from relevant publications were searched. Birth cohort, cross-sectional and case-control studies were included if they measured any breast feeding or exclusive breast feeding for 3 or 4 months. Wheezing illness, including asthma, was identified based on symptoms, reported diagnosis or objective criteria. Thirty-one publications were identified for meta-analysis. There was no association found between any or exclusive breast feeding and wheezing illness, although there was a high level of heterogeneity between the studies. Subgroup analysis revealed that any breast feeding slightly lowers the odds of wheeze (pooled odds ratio 0.92 [0.86, 0.98]) but slightly increases the odds of asthma defined by specific criteria (pooled odds ratio 1.10 [1.00, 1.22]). This meta-analysis does not provide evidence that breast feeding is protective against wheezing illness in children aged 5 years and over. The difference in the effects of breast feeding according to the nature of the wheezing illness highlights the importance of the heterogeneity of illness phenotypes.

Systematic review and meta‐analysis investigating breast feeding and childhood wheezing illness

Examination of intergenerational asthma beyond maternal asthma has been limited. The association between childhood asthma and intergenerational asthma status among a national cohort of children was examined. The genealogical sample (2552 children) participating in the Child Development Supplement of the Panel Study of Income Dynamics was studied. Multivariate regression was used to determine intergenerational asthma. Children with a parent with asthma were almost twice as likely (odds ratio [OR] = 1.96) to have asthma compared with those without a parent with asthma. Children with a parent and grandparent with asthma were more than 4 times more likely to have asthma compared with those without a parent and grandparent with asthma (OR = 4.27). Children with a grandparent with asthma were more likely to have asthma (OR = 1.52). A family history of asthma was a significant predictor of physician diagnosed asthma in children regardless of race/ethnicity and socioeconomic status. Findings support the collectio...

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Examining the Association Between Childhood Asthma and Parent and Grandparent Asthma Status: Implications for Practice

A reliable screening test in newborns for the subsequent development of bronchial asthma (BA) has not been found yet. This is mainly due to the complexity of BA, being made up by different types and underlying mechanisms. In different studies, a number of risk factors for BA have been identified. These include a positive family history of BA, passive smoking (also during pregnancy), prematurity (including pulmonary infections, RDS and BPD), early viral respiratory infections (such as RSV-bronchiolitis), male gender, early lung function abnormalities and atopic constitution. The major risk factor for persistent BA is an underlying allergic constitution. Therefore, early symptoms and markers of allergy (i.e. The Allergic March) and a positive family history for allergy should be considered as important risk factors for the development of BA.

/pdf/determinants-in-early-life-for-asthma-development-3x4a2uo0x7.pdf

Determinants in early life for asthma development

We identified main asthma risk factors for children living in the South Bronx, where asthma rates are eight times higher than the national average. This case-control study enrolled 261 children at Lincoln Medical and Mental Health Center from 2002 to 2003. We questioned the mothers on medical history and home environment. The most important risk factors for asthma in the South Bronx pediatric population are Hispanic ethnicity, family history of asthma, and exposure to tobacco smoke. South Bronx children limited to breast-feeding during the first 3 months of age are less likely to develop asthma.

Jonathan Wong

Papers

Risk factors for pediatric asthma in the South Bronx.