The effects of birthweight and breastfeeding on asthma among children aged 1-5 years

Investigating the influence of breastfeeding on asthma in children under 12 years old in the UK Biobank

Background

Childhood-onset asthma (COA) has become a major and growing problem worldwide and imposes a heavy socioeconomic burden on individuals and families; therefore, understanding the influence of early-life experiences such as breastfeeding on COA is of great importance for early prevention.

Objectives

To investigate the impact of breastfeeding on asthma in children under 12 years of age and explore its role at two different stages of age in the UK Biobank cohort.

Methods

A total of 7,157 COA cases and 158,253 controls were obtained, with information regarding breastfeeding, COA, and other important variables available through questionnaires. The relationship between breastfeeding and COA were examined with the logistic regression while adjusting for available covariates. In addition, a sibling analysis was performed on 398 pairs of siblings to explain unmeasured family factors, and a genetic risk score analysis was performed to control for genetic confounding impact. Finally, a power evaluation was conducted in the sibling data.

Results

In the full cohort, it was identified that breastfeeding had a protective effect on COA (the adjusted odds ratio (OR)=0.875, 95% confidence intervals (CIs): 0.831~0.922; P=5.75×10^-7). The impact was slightly pronounced in children aged 6-12 years (OR=0.852, 95%CIs: 0.794~0.914, P=7.41×10^-6) compared to those aged under six years (OR=0.904, 95%CIs: 0.837~0.975, P=9.39×10^-3), although such difference was not substantial (P=0.266). However, in the sibling cohort these protective effects were no longer significant largely due to inadequate samples as it was demonstrated that the power was only 23.8% for all children in the sibling cohort under our current setting. The protective effect of breastfeeding on COA was nearly unchanged after incorporating the genetic risk score into both the full and sibling cohorts.

Conclusions

Our study offered supportive evidence for the protective effect of breastfeeding against asthma in children less than 12 years of age; however, sibling studies with larger samples were warranted to further validate the robustness our results against unmeasured family confounders. Our findings had the potential to encourage mothers to initiate and prolong breastfeeding.

Complementary Feeding: Recommendations for the Introduction of Allergenic Foods and Gluten in the Preterm Infant

BACKGROUND

The aim of this systematic review is to analyze the available literature on the introduction of allergenic foods and gluten among preterm infants.

METHODS

A systematic review of published studies concerning the introduction of gluten and allergenic foods in preterm infants was performed on PubMed and on the Cochrane Library.

RESULTS

Of the 174 PubMed results, 15 papers were considered suitable for the review. A total of 83 records were identified through the Cochrane Library search; eight papers were included in the review. Additional papers were identified from the reference lists of included studies. A secondary search was conducted on the same databases to find recommendations and advice regarding healthy full-term infants that could be translated to preterm infants. Therefore, 59 additional papers were included in the review.

CONCLUSIONS

Current guidelines for the introduction of solid food cannot be directly transposed to preterm infants. Further research is needed to provide evidence-based guidelines regarding weaning in preterm infants. To date, we can suggest that in preterm infants allergenic foods and gluten may be introduced when complementary feeding is started, any time after 4 months of corrected age, avoiding delayed introduction and irrespective of infants' relative risk of developing allergy. Avoiding large amounts of gluten during the first few weeks after gluten introduction and during infancy is advised, despite limited evidence to support this recommendation.

Household Food Insecurity is Associated with Childhood Asthma

BACKGROUND

In 2013, 20% of U.S. households with children experienced food insecurity. Asthma afflicts over 7 million children; prevalence has steadily increased while incidence peaks in young children. Asthma and food insecurity share the determinants of poverty and race that are associated with weight, yet limited research on the relation between food insecurity and asthma exists.

OBJECTIVE

The objective of this study was to determine the association between food insecurity and asthma in a diverse sample of children.

METHODS

Cross-sectional data from grade 3 of the Early Childhood Longitudinal Study-Kindergarten Cohort were analyzed (n = 11,099). Food security based on the USDA module and asthma diagnosis were reported by parents; anthropometric factors were measured. Multivariate logistic regression models of food security and asthma were analyzed overall and by race/ethnicity.

RESULTS

Children in food-insecure households had a 4% higher adjusted odds of asthma (95% CI: 1.02, 1.06). Adjusted odds of asthma were also higher by 70% for males (95% CI: 1.69, 1.71), 53% for non-Hispanic black (NHB) children (95% CI: 1.51, 1.54), 20% for Hispanic children (95% CI: 1.19, 1.21), 38% for overweight children (95% CI: 1.36, 1.39), 67% for obese children (95% CI: 1.65, 1.68), 23% for low-birth weight children (95% CI: 1.21, 1.24), 24% if mothers had a high school diploma (95% CI: 1.23, 1.26), and 33% if mothers had some college education (95% CI: 1.32, 1.35). High-birth weight children (OR: 0.84; 95% CI: 0.83, 0.85) and those with foreign-born mothers (OR: 0.52; 95% CI: 0.51, 0.53) had lower odds of asthma. Being food-insecure remained positively associated with asthma in non-Hispanic whites and Hispanics but was inversely associated with odds among NHBs. Odds of asthma doubled (OR: 2.00; 95% CI: 1.97, 2.03) for all children in households that were both food-insecure and poor; this relation remained positive in race/ethnicity-specific models.

CONCLUSIONS

Food insecurity is positively associated with asthma in U.S. third graders, and household poverty strengthens the association.

Birth weight and risk factors for cardiovascular disease and type 2 diabetes in US children and adolescents: 10 year results from NHANES

Previous studies have shown that birth weight and other birth characteristics may be associated with risk for type 2 diabetes and cardiovascular disease (CVD) later in life; however, results using large US national survey data are limited. Our goal was to determine the aforementioned associations using nationally representative data. We studied children and adolescents 6-15 years using data from the National Health and Nutrition Examination Survey cycles 2001-2010. Survey and examination data included demographic and early childhood characteristics, current health status, physical activity information, anthropometric measurements, dietary data (total energy, saturated fat, sodium, and sugar intakes), biomarkers related to selected risk factors of CVD [systolic blood pressure (SBP), plasma C-reactive protein (CRP) and lipid profiles], and type 2 diabetes [fasting glucose, insulin, and homeostasis model assessment (HOMA)]. Birth weight (proxy-reported) was inversely associated with SBP among girls; SBP levels increased 1.4 mmHg for each 1,000 g decrease in birth weight (p = 0.003) after controlling for potential confounders. Birth weight was not associated with levels of CRP or lipid profiles across the three racial groups. In addition, birth weight was inversely related to levels of fasting insulin and HOMA among non-Hispanic Whites; for each 1,000 g decrease in birth weight, fasting insulin levels increased 9.1% (p = 0.007) and HOMA scores increased 9.8% (p = 0.007). Birth weight was inversely associated with the levels of SBP, fasting insulin, and HOMA. These results support a role for birth weight, independent of the strong effects of current body weight status, in increasing risk for CVD and type 2 diabetes.

Birth weight and childhood wheezing disorders: a systematic review and meta-analysis

BACKGROUND

Previous observational studies have claimed that birth weight and childhood wheezing disorders are associated although the results remained inconsistent. One systematic review and two systematic reviews that included meta-analyses reported inconsistent results. We aimed to conduct a systematic review and meta-analysis to investigate this.

METHODS

An online search of published papers linking childhood asthma and wheezing disorders with birth weight up to February 2014 was carried out using EMBASE and Medline medical research databases. Summary ORs were estimated using random-effects models. Subgroup meta-analyses were performed to assess the robustness of risk associations and between-study heterogeneity.

RESULTS

A total of 37 studies comprising 1,71, 737 participants were included in our meta-analysis. The unadjusted summary ORs for risk of childhood wheezing disorders associated with low birth weight (<2.5 kg) were 1.60 (95% CI 1.39 to 1.85, p<0.001) and 1.37 (95% CI 1.05 to 1.79, p=0.02) when compared with ≥2.5 and 2.5-4.0 kg birthweight groups, respectively. The overall summary OR for high birth weight (>4 kg) as compared to the 2.5-4.0 kg birthweight group was 1.02 (95% CI 0.99 to 1.04, p=0.13). There was substantial heterogeneity in the unadjusted low birth weight risk estimates which was not accounted for by predefined study characteristics. There was no significant heterogeneity in the high birth weight risk estimates. There was some evidence of funnel plot asymmetry and small study effects in the low birth weight (2.5 vs ≥2.5 kg and <2.5 vs 2.5-4 kg) OR estimates.

CONCLUSIONS

Our results suggest that low birth (<2.5 kg) is an independent risk factor for wheezing disorders during childhood and adolescence although there was substantial heterogeneity among the risk estimates. However, we found no significant association of high birth weight with wheezing disorders.

Exploring the origins of asthma: Lessons from twin studies

This thesis explores the contribution of twin studies, particularly those studies originating from the Danish Twin Registry, to the understanding of the aetiology of asthma. First, it is explored how twin studies have established the contribution of genetic and environmental factors to the variation in the susceptibility to asthma, and to the variation in several aspects of the clinical expression of the disease such as its age at onset, its symptomatology, its intermediate phenotypes, and its relationship with other atopic diseases. Next, it is explored how twin studies have corroborated theories explaining asthma's recent increase in prevalence, and last, how these fit with the explanations of the epidemiological trends in other common chronic diseases of modernity.

Aleitamento materno em crianças de 0 a 59 meses no Estado de Pernambuco, Brasil, segundo o peso ao nascer

Objetivou-se descrever e analisar a prática do aleitamento materno em crianças menores de cinco anos no estado de Pernambuco, em 2006, segundo o peso ao nascer. Estudo transversal, com amostra de 1.595 crianças. Utilizou-se o teste chi-quadrado de Pearson para analisar associações bivariadas e a regressão de Poisson para o ajustamento de modelo multivariado dos fatores condicionantes ao aleitamento exclusivo > 4 meses, segundo o peso ao nascer. Verificou-se que a realização do pré-natal e o número de consultas beneficiaram as crianças que nasceram com peso > 2.500g, quando comparadas aos casos com peso < 2.500g (baixo peso ao nascer - BPN). Não houve diferença estatística nas classificações do aleitamento materno, segundo o peso ao nascer. As variáveis anos de estudo formal e tipo de parto apresentaram-se associadas ao grupo de BPN, enquanto que para as crianças com peso > 2.500g foram detectadas associações com as variáveis renda per capita, espaço geográfico, orientação sobre aleitamento materno no pré-natal e sexo das crianças. O grupo de crianças BPN não foi favorecido quanto às recomendações referentes ao aleitamento materno, bem como foram diferentes os resultados das relações das variáveis que permaneceram nos dois grupos representando os modelos finais de análises multivariadas.

Breastfeeding and childhood asthma: systematic review and meta-analysis

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.

Engaging Community With Promotores de Salud to Support Infant Nutrition and Breastfeeding Among Latinas Residing in Los Angeles County: Salud con Hyland's

The Salud con Hyland's Project: Comienzo Saludable, Familia Sana [Health With Hyland's Project: Healthy Start, Healthy Family],was developed to provide education and support to Latina mothers regarding healthy infant feeding practices and maternal health. The promotora-delivered intervention was comprised of two charlas (educational sessions) and a supplemental, culturally and linguistically relevant infant feeding and care rolling calendar. Results indicate that the intervention increased intention to breastfeed exclusively, as well as to delay infant initiation of solids by 5 to 6 months. Qualitative feedback identified barriers to maternal and child health education as well as highlighted several benefits of the intervention.

Birth weight and subsequent risk of asthma: a systematic review and meta-analysis

BACKGROUND

Previous studies suggest that birth weight is related to later risk of asthma. However, few meta-analyses have investigated these associations. Therefore, we performed a meta-analysis with different classifications to further validate the relationship between birth weight and asthma.

METHODS

PubMed (1990-2013), ScienceDirect (1990-2013), EMBASE(1990-2013),EBSCO (1990-2013) and Springer (1990-2013) were searched for articles. The following MeSH terms were used: "birth weight", "fetal growth retardation", "intrauterine growth restriction", "asthma", "wheezing".

RESULTS

We included 18 studies with data from a total of over 90,000 children and adults. (1) Low birth weight (<2,500g) as compared with BW>2,500g and BW=2500-4000g was associated with increased risk of asthma (Children: OR, 1.28; 95% CI, 1.09-1.50, P<0.05; OR, 1.34; 95% CI, 1.13-1.60, P<0.05, Adults: OR, 1.25; 95% CI, 1.12-1.39, P<0.05; OR, 1.25; 95% CI, 1.12-1.40, P<0.05). (2) High birth weight (>4,000g) was not associated with the risk of asthma when BW<4,000g and BW=2500-4000g were used as the reference.

CONCLUSIONS

These results suggest that low birth weight (<2,500g) is associated with increased risk of asthma both in children and adults and may serve as a mediator between prenatal influences and later disease risk; but high birth weight (>4,000g) was not associated with increased risk of asthma.

Early lung development: lifelong effect on respiratory health and disease

Interest in the contribution of changes in lung development during early life to subsequent respiratory morbidity is increasing. Most evidence of an association between adverse intrauterine factors and structural effects on the developing lung is from animal studies. Such evidence has been augmented by epidemiological studies showing associations between insults to the developing lung during prenatal and early postnatal life and adult respiratory morbidity or reduced lung function, and by physiological studies that have elucidated mechanisms underlying these associations. The true effect of early insults on subsequent respiratory morbidity can be understood only if the many prenatal and postnatal factors that can affect lung development are taken into account. Adverse factors affecting lung development during fetal life and early childhood reduce the attainment of maximum lung function and accelerate lung function decline in adulthood, initiating or worsening morbidity in susceptible individuals. In this Review, we focus on factors that adversely affect lung development in utero and during the first 5 years after birth, thereby predisposing individuals to reduced lung function and increased respiratory morbidity throughout life. We focus particularly on asthma and COPD.

What is new in the prevention of atopy and asthma?

PURPOSE OF REVIEW

Increasing understanding of mechanisms and influencing factors in the development of uncontrolled inflammatory responses in atopy and asthma should serve for the introduction of new preventive measures. This review tries to present the current state of the art and resumes that until now, no really effective concept can be offered to families at risk.

RECENT FINDINGS

In addition to modified feeding regimes (hydrolysed formula feeding in infancy), timing of the introduction of solids (avoidance of allergens versus early induction of tolerance), immune modulation using prebiotics or probiotics, a new target of potential intervention could be the human microbiome as a key player in the development of inflammatory diseases such as allergy and asthma. However, during the last 5 years, this concept could not yet be verified in interventional trials. There are new trials ongoing, studying the effect of microbial compounds in early infancy, vitamin D and polyunsaturated fatty acid supplementation during late pregnancy and the effect of azithromycin in children with recurrent wheeze. Results are to be expected within the next couple of years.

SUMMARY

New data on multifaceted intervention and the analysis of the human microbiome are to be expected. The recommendation for atopy and asthma prevention still focuses on avoidance of tobacco smoke exposure and food allergens during the first 4 months of life and feeding of hydrolysed formula if breast-feeding is not possible in high-risk infants, potentially early feeding of prebiotic sugars and/or certain strains of probiotic bacteria or bacterial compounds in certain subpopulations.

Perinatal factors and respiratory health in children

BACKGROUND

There is conflicting evidence regarding the associations between anthropometric birth measures and asthma and lung function in children, particularly for apparently healthy infants born at term.

OBJECTIVE

Our objective was to elucidate these relationships paying particular attention to features of study design and analysis that may threaten the validity of previous studies in this field.

METHODS

We analysed data from a cohort of children with a family history of asthma who were recruited antenatally. Anthropometric birth measures and potential confounders were recorded at birth and within the first year of life. Lung function and asthma outcomes were measured at 8 years of age. Airway hyperresponsiveness (AHR) was measured by methacholine challenge. The potential for a reversal paradox, due to inclusion of covariates on the causal pathway, was investigated.

RESULTS

Four hundred and fifty (73% of the initial cohort) children were tested at age 8 years. Birth weight in the lowest tertile was associated with current asthma (OR 1.95, 95% CI 1.08, 3.54) and recent wheeze (OR 1.87, 95%CI 1.08, 3.24), but not with AHR (OR 1.37, 95% CI 0.68, 2.78). Birth weight was positively associated with lung function. Current height modified the relationship between birth length and lung function suggesting that post-natal growth has an effect on this relationship.

CONCLUSIONS

Low birth weight is associated with a greater risk of current asthma and lower lung function at 8 years in children with a family history of asthma. Current height should be treated as an effect modifier when investigating the fetal origins hypothesis.

Perinatal programming of childhood asthma: early fetal size, growth trajectory during infancy, and childhood asthma outcomes

The “fetal origins hypothesis” or concept of “developmental programming” suggests that faltering fetal growth and subsequent catch-up growth are implicated in the aetiology of cardiovascular disease. Associations between reduced birth weight, rapid postnatal weight gain, and asthma suggest that there are fetal origins to respiratory disease. The present paper first summarises the literature relating birth weight and post natal growth trajectories to asthma outcomes. Second, issues regarding the interpretation of antenatal fetal ultrasound measurements are discussed. Finally, recent reports linking antenatal measurement and growth trajectory to early childhood asthma outcomes are discussed. Understanding the nature and timing of factors which influence antenatal growth may give important insight into the antecedents of early-onset asthma with implications for interventions.

High-dose docosahexaenoic acid supplementation of preterm infants: respiratory and allergy outcomes

BACKGROUND

Docosahexaenoic acid (DHA) has been associated with downregulation of inflammatory responses.

OBJECTIVE

To report the effect of DHA supplementation on long-term atopic and respiratory outcomes in preterm infants.

METHODS

This study is a multicenter, randomized controlled trial comparing the outcomes for preterm infants <33 weeks' gestation who consumed expressed breast milk from mothers taking either tuna oil (high-DHA diet) or soy oil (standard-DHA) capsules. Data collected included incidence of bronchopulmonary dysplasia (BPD) and parental reporting of atopic conditions over the first 18 months of life.

RESULTS

Six hundred fifty-seven infants were enrolled (322 to high-DHA diet, 335 to standard), and 93.5% completed the 18-month follow-up. There was a reduction in BPD in boys (relative risk [RR]: 0.67 [95% confidence interval (CI): 0.47-0.96]; P=.03) and in all infants with a birth weight of <1250 g (RR: 0.75 [95% CI: 0.57-0.98]; P=.04). There was no effect on duration of respiratory support, admission length, or home oxygen requirement. There was a reduction in reported hay fever in all infants in the high-DHA group at either 12 or 18 months (RR: 0.41 [95% CI: 0.18-0.91]; P=.03) and at either 12 or 18 months in boys (RR: 0.15 [0.03-0.64]; P=.01). There was no effect on asthma, eczema, or food allergy.

CONCLUSIONS

DHA supplementation for infants of <33 weeks' gestation reduced the incidence of BPD in boys and in all infants with a birth weight of <1250 g and reduced the incidence of reported hay fever in boys at either 12 or 18 months.

Maternal and childhood asthma: risk factors, interactions, and ramifications

Asthma is emerging as a premier example of a health risk that can largely be molded by the status of the mother and the environmental conditions encountered during sensitive windows of prenatal and early childhood development. While genetic background, allergic status of parents, and predisposition for atopy and inflammation play a role, early-life environmental conditions can completely alter the course of immune and respiratory system development. Environmentally induced alterations that (1) maintain the Th2 bias seen during gestation, (2) block the maturation of innate immune cells and (3) create inflammatory dysfunction in the infant provide the foundation for childhood asthma. No single risk factor can fully explain the increased prevalence of asthma in recent decades but it is assumed that the rapid increase is due to environmental and/or epigenetic changes. Well-established and suspected environmental risk factors cover all categories of early life interactions from diet, exposure to environmental contaminants and drugs, maternal and neonatal infections, hygiene, timing of vaccinations and even the mode of birth delivery. Because asthma is connected to the risk of several comorbid chronic conditions, the benefit of asthma risk reduction and prevention is greater than initially may be apparent. This review discusses strategies to optimize preventative and therapeutic options across life stages.