Population-based study on association between birth weight and risk of asthma: a propensity score approach

An Association Between Pediatric Bronchiolitis and Atopic Dermatitis: A Multi-Institutional Electronic Medical Records Database Study From Taiwan

Atopic dermatitis (AD) is triggered by many environmental factors. We sought to determine the relationship between birth weight, infectious diseases, and AD. This retrospective cohort study analyzed data from the CGR Database for the period 2004 through 2015 in Taiwan. All diseases were classified using the International Classification of Disease codes. Logistic regression adjusted for birth weights and comorbidities were analyzed by SAS (version 9.4). P < .05 were considered statistically significant. In children with AD, bronchiolitis was significantly associated with the development of AD, whether the patients were aged < 2 years (odds ratio [OR] = 1.497; P = .014) or ≥ 2 years (OR = 1.882; P = .022). There was also no difference in the association between AD and different birth weights. We conclude that AD is associated with a previous history of bronchiolitis in children, regardless of age (less than or greater than 2 years).

Non-linear association of birth weight with lung function and risk of asthma: A population-based study

Background

The impact of birth weight on lung function and risk of asthma remains contentious. Our aim was to investigate the specific association of birth weight with lung function and the risk of asthma in children.

Methods

We performed cross-sectional analyses of 3,295 children aged 6-15 years who participated in the 2007-2012 National Health and Nutrition Examination Survey (NHANES). After controlling for potential covariates other than gestational diabetes, maternal asthma and obesity, the linear and non-linear associations of birth weight with lung function metrics and the risk of asthma were evaluated by a generalized linear model and generalized additive model, respectively.

Results

We observed a non-linear association of birth weight with FEV₁ %predicted, FEV₁/FVC %predicted and FEF_{25 - 75} %predicted (P for non-linearity was 0.0069, 0.0057, and 0.0027, respectively). Further threshold effect analysis of birth weight on lung function detected the turning point for birth weight was 3.6 kg. When the birth weight was < 3.6 kg, birth weight was significantly positively associated with all pulmonary function metrics. However, negative associations were found in FEV₁ %predicted, FEV₁/FVC %predicted and FEF_{25 - 75} %predicted when the birth weight was ≥3.6 kg. These results were consistent in the stratified and sensitivity analyses. Additionally, a possible non-linear relationship was also detected between birth weight and the risk of asthma.

Conclusion

Although not all maternal factors were accounted for, our findings provided new insight into the association of birth weight with lung function. Future studies are warranted to confirm the present findings and understand the clinical significance.

The role of Caesarean section in childhood asthma

OBJECTIVE

As indicated by previous studies, children born via Caesarean section may have an increased risk of developing asthma compared with those born via vaginal delivery. The aim of this study is to assess the association between a Caesarean section and the risk of childhood asthma. Methods: This was a case-control study carried out in Basrah, Iraq including 952 children aged 3-12 years. Four hundred and seven asthmatic cases and a control group of 545 age-matched non-asthmatic children were enrolled. Binary logistic regression was used to assess the relationship between asthma and birth via Caesarean section.

RESULTS

The mean age of the children was 6.7±2.5 years. Two-hundred eighty-three children (29.7%) were delivered via Caesarean section. The binary logistic regression analysis showed that delivery via Caesarean section was found to be an independent significant risk factor for asthma (OR=3.37; 95% CI=1.76-6.46; p<0.001). In addition, many other risk factors were found to be significant predictors of asthma, including bottlefeeding (OR=27.29; 95% CI=13.54-54.99; p<0.001) and low birth weight (OR=16.7; 95% CI=6.97-37.49; p<0.001).

CONCLUSION

Caesarean section is significantly associated with an increased risk of childhood asthma.

Birth weight is not causally associated with adult asthma: results from instrumental variable analyses

The association between lower birth weight and childhood asthma is well established. However, it remains unclear whether the influence of lower birth weight on asthma can persist into adulthood. We conducted a Mendelian randomization analysis to assess the causal relationship of birth weight (~140,000 individuals) on the risk of adult asthma (~62,000 individuals). We estimated the causal effect of birth weight to be 1.00 (95% CI 0.98~1.03, p = 0.737) using the genetic risk score method. We did not observe nonlinear relationship or gender difference for the estimated causal effect. With the inverse-variance weighted method, the causal effect of birth weight on adult asthma was estimated to be 1.02 (95% CI 0.84~1.24, p = 0.813). Additionally, the iMAP method provides no additional genome-wide evidence supporting the causal effects of birth weight on adult asthma. Our results were robust against various sensitivity analyses, and MR-PRESSO and MR-Egger regression showed that no instrument outliers and no horizontal pleiotropy were likely to bias the results. Overall, our study provides no evidence for the fetal origins of diseases hypothesis for adult asthma, implying that the impact of birth weight on asthma in years of children and adolescents does not persist into adult and previous findings may be biased by confounders.

Asthma, Rhinoconjunctivitis, Eczema, and the Association with Perinatal Anthropometric Factors in Vietnamese Children

Few studies have investigated possible causative and protective factors associated with allergic diseases in resource-limited countries, Southeast Asia. We estimated the current prevalence of asthma, rhinoconjunctivitis, and eczema among 6-year-old children, and identified anthropometric factors associated with asthma, rhinoconjunctivitis and eczema, in South-Central Vietnam. A birth cohort study recruited 1,999 children born at a provincial hospital in Nha Trang, Vietnam between May 2009 and May 2010. A 6-year follow-up survey was conducted where clinical, familial, and environmental information was collected by interviewing caregivers using a standardized form based on the International Study of Asthma and Allergies in Childhood, Phase Three Core and Environmental Questionnaire for 6–7-year-old children. The odds ratios of asthma, rhinoconjunctivitis, and eczema for anthropometric factors were estimated using logistic regression analysis. In total, 1202 children participated in the follow-up survey. The proportions of children who had current asthma, rhinoconjunctivitis, and eczema were 5.1% (95% confidence interval [CI] 3.9–6.5%), 11.5% (9.7–13.4%), and 6.7% (5.3–8.2%), respectively. Low birthweight (adjusted odds ratio 5.12, 95% CI 1.92–13.64) was independently associated with increased risk of eczema. Further studies are necessary to understand the involved mechanism.

Factors associated with asthma expression in adolescents

Objective:

To evaluate risk factors associated with asthma symptoms in adolescents in the 13- to 14-year age bracket.

Methods:

This was a cross-sectional study involving adolescents enrolled in randomly selected public schools in the city of Belo Horizonte, Brazil, and conducted with the use of the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire and its supplementary module for risk factor assessment. The ISAAC questionnaire was completed by the students themselves, whereas the supplementary questionnaire was completed by their parents or legal guardians. Variables showing p ≤ 0.25 in the univariate analysis were included in the multivariate analysis. Stepwise regression with backward elimination was used for variable selection.

Results:

We evaluated 375 adolescents, 124 (33.1%) of whom had asthma symptoms. The final multivariate analysis model revealed that asthma symptoms were associated with birth weight < 2,500 g (p < 0.001), day care center or nursery attendance (p < 0.002), maternal history of asthma (p < 0.001), contact with animals during the first year of life (p < 0.027), current contact with animals outside the home (dogs, cats, or farm animals; p < 0.005), and more than 20 cigarettes per day smoked by parents or other household members (p < 0.02).

Conclusions:

Exposure to animals in and outside the home is associated with asthma symptoms, as is environmental tobacco smoke exposure. Families, health professionals, and administrators of health care facilities should take that into account in order to prevent asthma and reduce asthma morbidity.

Impact of perinatal environmental tobacco smoke on the development of childhood allergic diseases

Allergic diseases such as asthma, allergic rhinitis, atopic dermatitis, and food allergy, are most common chronic, noncommunicable diseases in childhood. In the past few decades, the prevalence has increased abruptly worldwide. There are 2 possible explanations for the rising prevalence of allergic diseases worldwide, that an increased disease-awareness of physician, patient, or caregivers, and an abrupt exposure to unknown hazards. Unfortunately, the underlying mechanisms remain largely unknown. Despite the continuing efforts worldwide, the etiologies and rising prevalence remain unclear. Thus, it is important to identify and control risk factors in the susceptible individual for the best prevention and management. Genetic susceptibility or environments may be a potential background for the development of allergic disease, however they alone cannot explain the rising prevalence worldwide. There is growing evidence that epigenetic change depends on the gene, environment, and their interactions, may induce a long-lasting altered gene expression and the consequent development of allergic diseases. In epigenetic mechanisms, environmental tobacco smoke (ETS) exposure during critical period (i.e., during pregnancy and early life) are considered as a potential cause of the development of childhood allergic diseases. However, the causal relationship is still unclear. This review aimed to highlight the impact of ETS exposure during the perinatal period on the development of childhood allergic diseases and to propose a future research direction.

The Association between Birth Weight and Gestational Age and Asthma in 6-7- and 13-14-Year-Old Children

Background. Previous studies that assessed the role of birth weight and gestational age in the risk of asthma have been conflicting. Objectives. To examine the association between birth weight and gestational age and symptoms of asthma. Patients and Methods. Subjects were 6656 school children of ages 6-7 and 13-14 years from urban districts of Mazandaran, Iran. ISAAC questionnaires were used. Results. There was an increased risk of "wheeze ever" in both age groups with birth weight under 2.5 kg and in all subgroups of low birth weight (LBW). Birth weight more than 3.5 kg was associated with lower risk of "severe asthma" in age group 6-7 years. With respect to gestational age, higher risks of "wheeze ever," "asthma ever," and "night cough in the past 12 months" were found in age group 13-14 years born before 37 weeks and the risk of "severe asthma" was higher in younger group (6-7 years). A lower risk of "asthma ever" was also found in 6-7-year-old children and 13-14-year-old girls who were born after 40 weeks. Conclusions. This study showed that there is a direct relation between "wheeze ever" and LBW and an inverse relation between risk of "severe asthma" and birth weight more than 3.5 kg.

Prevalence and risk factors of asthma in First Nations children living on reserves in Canada

OBJECTIVES

To explore the prevalence and determine the risk factors of asthma in First Nations children aged 0 to 11 years living on reserves in Canada.

METHODS

In this cross-sectional study, we considered the data collected as part of the First Nations Regional Health Survey involving 6,657 children living in 238 First Nations communities in the 10 Canadian provinces, the Northwest Territories and the Yukon.

RESULTS

The overall prevalence of asthma that has lasted or is expected to last at least six months (ever-asthma) among children living on reserves was 14.6%: a prevalence of 12.9% among 0 to 4 year olds and 15.6% among 5 to 11 year olds. The prevalence of ever-asthma was greater among boys (16.1%) than girls (13.2%). Children from homes with two or more children aged less than 11 years and those who were engaged in daily physical activities were less likely to have a report of ever-asthma. Children from high-income families and smoke-free homes were more likely to have a report of ever-asthma. The association between allergy and ever-asthma was stronger in children with low birth weight. The association between chronic ear infections and ever-asthma was stronger in girls than boys.

CONCLUSIONS

The overall prevalence of ever-asthma and factors associated with ever-asthma in First Nations children living on reserves were similar to those reported for off-reserve Aboriginal children and non-Aboriginal Canadian children.

Birth weight and asthma incidence by asthma phenotype pattern in a racially diverse cohort followed through adolescence

OBJECTIVE

Low birth weight (LBW) has been shown to be an independent risk factor for asthma. We hypothesized that LBW would have its greatest impact on early onset disease.

METHODS

A racially diverse cohort of children born from 1983 to 1985 at two hospitals, one urban and one suburban in the same metropolitan area, and oversampled for babies weighing ≤2500 g, was identified retrospectively when the children were 6 years of age and followed periodically. At the age 17 years study visit, cohort members and their parent/guardians were separately interviewed face-to-face regarding the subject's history of asthma using the standardized ISAAC questionnaire. We measured the cumulative incidence of asthma from birth through adolescence defined by age of diagnosis and persistence/remittance.

RESULTS

Six-hundred and eighty teens (82.6% of the original cohort) were included in the analyses, 387 with LBW and 293 of normal birth weight. The prevalence of physician-diagnosed "Current Asthma" was associated with LBW (p = 0.003 for trend), with patterns stronger in males and whites. LBW was associated most strongly with Late Onset Persistent asthma (current asthma that was diagnosed after 8 years); p for trend 0.032. This trend was again most evident in males and whites. None of the asthma categories classified as "remittent" were statistically associated with LBW.

CONCLUSIONS

LBW was not associated with diagnosed asthma that remitted before age 17 years. LBW was associated with asthma diagnosis in mid-childhood that persisted through adolescence, suggesting that the asthmagenic effects of LBW can become evident post the early years of childhood and persist into adulthood.

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.

Effect of low birth weight on childhood asthma: a meta-analysis

Background

Low birth weight is strongly correlated with an increased risk of adult diseases. Additionally, low birth weight might be a risk factor for asthma later in life.

Methods

A systematic literature search of the PubMed database from 1966 to November 2013 was conducted. The criteria for inclusion of papers were as follows: case–control or cohort studies; the odds ratio (OR) or risk ratio (RR) estimates with the corresponding 95% confidence intervals (CIs) were presented, or there were sufficient data for calculation; and studies were published in English up to October 2013. Random-effect and fixed-effect meta-analyses, meta-regression, and cumulative meta-analysis were conducted.

Results

Thirteen cohort studies and 1,105,703 subjects were included. The overall pooled RRs (95% CIs) of asthma risk for low birth weight were 1.162 (fixed-effects model, 95% CI, 1.128–1.197) and 1.152 (random-effects model, 95% CI, 1.082–1.222). In stratified analyses, the effect of low birth weight on childhood asthma was strong, particularly in studies conducted in Europe, those with a small sample size, and those published recently. A meta-regression analysis did not find significant determinants.

Conclusions

This meta-analysis shows that low birth weight significantly increases the risk of childhood asthma.