Relationship between mode of delivery in childbirth and prevalence of allergic diseases in Korean children

Perinatal Risk Factors for Asthma and Allergic Rhinitis in Children and Adolescents

OBJECTIVES

In this study, we evaluated the associations between birth-related exposures, postnatal factors, and the risk of allergic rhinitis and asthma in children and adolescents.

METHODS

We performed a comprehensive search of five literature databases up to May 2023. To quantify the associations of birth-related exposures (birth weight, delivery mode, prematurity, sex, maternal age, and parental allergy history) and postnatal factors (birth order, number of siblings, breastfeeding exclusivity, and breastfeeding duration) with allergic disease, we calculated pooled odds ratios and 95% confidence intervals. We conducted subgroup analyses for allergic disease type, birth order, number of siblings, and parental allergy history. The methodological quality of the identified studies was evaluated using the Newcastle-Ottawa Scale.

RESULTS

This meta-analysis included 31 studies, encompassing 218,899 patients in total. The birth-related exposures of low birth weight, maternal age, and prematurity (less than 37 weeks gestation) were not significantly associated with the risk of asthma or allergic rhinitis during childhood or adolescence. Male sex, family history of allergy, and cesarean delivery were linked to an elevated risk of asthma or allergic rhinitis. Among postnatal factors, exclusive breastfeeding, breastfeeding for longer than 6 months, second or later birth order, and having siblings exhibited protective effects against allergic diseases in offspring.

CONCLUSION

The risks of allergic rhinitis and asthma were elevated in male patients, those delivered by cesarean section, and those with a family history of allergy. Conversely, exclusive breastfeeding, breastfeeding for longer than 6 months, and having siblings corresponded to a reduced risk of respiratory allergic diseases.

Correlation of Blomia tropicalis-specific immunoglobulin epsilon profiles with family history of atopy in a Filipino population

Background

House dust mites are the major source of indoor allergens in the tropical and subtropical regions with Blomia tropicalis (Bt) allergens as one of the leading causative agents of sensitization among patients from the tropics. Despite the clinical importance of Bt in various populations, its allergenicity remains unclear among Filipino allergic patients.

Objective

This study determined the sensitization profiles of allergic Filipinos against Bt allergens and its correlation with atopy.

Methods

Total immunoglobulin epsilon (IgE) (n = 960), Bt-specific IgE (n = 247), and Blomia tropicalis 5 (Blo t 5)-specific IgE (n = 87) profiles of allergic and nonallergic subjects were measured through enzyme-linked immunosorbent assay (ELISA). Point-biserial correlation coefficient was used to determine the association between Bt-specific IgE levels and selected demographics. Inhibition ELISA was performed to measure the inhibition capacity of recombinant Blo t 5 (rBlo t 5) against Bt allergen extracts.

Results

Mean total IgE levels of allergic cases (n = 171) were significantly higher (P < 0.001) compared to the mean IgE levels of nonallergic controls (n = 76). Among allergic subjects, 58% were sensitized to Blo t extract and 80% of which were sensitized to rBlo t 5 allergen. A positive correlation was observed between Bt-specific IgE and family history of atopic disease (P = 0.031). Inhibition assay revealed that 54% mean reactivity of 7 plasma samples was caused by rBlo t 5, validating that rBlo t 5 is a major allergen in Bt.

Conclusions

This study has shown the importance of Bt as an allergen source that sensitizes atopic Filipino subjects. Hence, inclusion of Bt allergen extract and rBlo t 5 in the panel for allergy diagnosis and immunotherapy in Filipino populations is strongly recommended.

Association of cesarean section with asthma in children/adolescents: a systematic review and meta-analysis based on cohort studies

BACKGROUND

Whether cesarean section (CS) is a risk factor for asthma in offspring is controversial. The purpose of this study was to investigate the association between CS and asthma in children/adolescents.

METHODS

Pubmed, Embase, Web of Science, and Cochrane Library electronic databases were searched for cohort studies on the relationship between mode of delivery and asthma in children/adolescents up to February 2023. Birth via CS was considered an exposure factor. Asthma incidence was taken as a result.

RESULTS

Thirty-five cohort studies (thirteen prospective and twenty-two retrospective cohort studies) were included. The results showed that the incidence of asthma was higher in CS offspring (odds ratio (OR) = 1.18, P < 0.001) than in the vaginal delivery (VD) group. Partial subgroup analyses showed a higher incidence of asthma in female offspring born via CS (OR = 1.26, P < 0.001) compared with the VD group, while there was no difference in males (OR = 1.07, P = 0.325). Asthma incidence was higher in CS offspring than in the VD group in Europe (OR = 1.20, P < 0.001), North America (OR = 1.15, P < 0.001), and Oceania (OR = 1.06, P = 0.008). This trend was not found in the Asian population (OR = 1.17, P = 0.102). The incidence of atopic asthma was higher in offspring born via CS (OR = 1.14, P < 0.001) compared to the VD group. The CS group had a higher incidence of persistent asthma, but the difference did not reach statistical significance (OR = 1.15, P = 0.063).

CONCLUSION

In this meta-analysis, CS may be a risk factor for asthma in offspring children/adolescents compared with VD. The relationship between CS and asthma was influenced by sex and region.

Cesarean section and the risk of allergic rhinitis in children: a systematic review and meta-analysis

Multiple evidence indicates that perinatal factors make impact on immune development and affect offspring allergic rhinitis (AR) risk. In this systematic review and meta-analysis, we examined available published studies to clarify the relationship between cesarean section (C-section) and offspring AR in children. To explore the relationship between C-section, especially the special attention was paid to different cesarean delivery mode, and the risk of AR in children. Articles were searched using PubMed, Web of Science, EMBASE, Cochrane Library, China knowledge Network, Wanfang, and China Science and Technology Journal databases. A meta-analysis of 22 studies published before August 1, 2022, which included 1,464,868 participants, was conducted for statistical analysis with RevMan5.4. The correlation strength between C-section and offspring AR was determined by combining odds ratio (OR) and 95% confidence interval (95% CI). Meta-regression and subgroup analyses were used to explore potential sources of heterogeneity. Publication bias was detected using the funnel chart and Egger tests. Meta-analysis revealed that there was a significant correlation between C-section and children AR (OR = 1.19, 95% CI: 1.12-1.27, P < 0.001), especially C-section with a family history of allergy (OR = 1.82, 95% CI: 1.36-2.43, P < 0.001). Moreover, elective C-section (without genital tract microbe exposure) had the higher risk of offspring AR (OR = 1.24, 95% CI: 1.05-1.46, P = 0.010) compared with the whole study. Meta-regression demonstrated that sample size explained 38.0% of the variability between studies, and year of publication explained 18.8%. Delivery by C-section, particularly elective C-section and C-section with a family history of allergy can increase the risk of AR in children.

The global/local (limited to some regions) effect of cesarean delivery on the risk of pediatric allergic rhinitis: a systematic review and meta-analysis

Background

Allergic rhinitis is a chronic and refractory disease that can be affected by a variety of factors. Studies have shown an association between cesarean section and the risk of pediatric allergic rhinitis.

Methods

The PubMed, Springer, Embase, Cochrane Library, and Web of Science databases were searched to retrieve all studies published from January 2000 to November 2022, focusing on the relationship between cesarean section and the risk of pediatric allergic rhinitis. A meta-analysis was conducted to find a correlation between cesarean section and the risk of pediatric allergic rhinitis. A subgroup analysis was performed, considering the region and family history of allergy, after adjusting for confounding factors. Pooled odds ratios (ORs) were calculated, publication bias was assessed using a funnel plot, and heterogeneity between study-specific relative risks was taken into account.

Results

The results showed that cesarean section was significantly associated with an increased risk of pediatric allergic rhinitis (OR: 1.27, 95% CI: 1.20-1.35). Subgroup analysis stratified by region indicated that cesarean section increased the risk of pediatric allergic rhinitis, with the highest increase in South America (OR: 1.67, 95% CI: 1.10-2.52) and the lowest in Europe (OR: 1.13, 95% CI: 1.02-1.25). The results of the subgroup analysis stratified by family history of allergy indicate that family history of allergy was not associated with the risk of pediatric allergic rhinitis.

Conclusion

An association exists between cesarean section as the mode of delivery and the increased risk of pediatric allergic rhinitis, and cesarean section is a risk factor for allergic rhinitis.

Associations of childhood allergies with parental reproductive and allergy history

PURPOSE

There has been a noted parallel rise in both the use of Assisted Reproductive Technology (ART) to conceive and childhood allergies in the last few decades. The purpose of this study was to investigate the possible association between reproductive and allergy history in parents and allergies in their children.

METHODS

This exploratory study used a cross-sectional study design and web-based survey to collect anonymous data on demographics, allergy, and health history from parents and about each of their children under 18 years of age. Children were stratified into two groups by allergy status (yes/no), and associations between each variable and the odds of allergies were tested using univariable and multivariable mixed logistic regression models.

RESULTS

Of the 563 children in the study, 237 were reported to have allergies whereas 326 did not. Age, residential community, household income, mode of conception, paternal age at conception, biological parental allergy status, and history of asthma and eczema were significantly associated with allergies in univariable analysis. Multivariable analysis revealed household income ($50 k to $99 k vs ≥ $200 k adj OR = 2.72, 95% CI 1.11, 6.65), biological parental allergies (mother-adj OR 2.74, 95% CI 1.59, 4.72, father-adj OR 2.06, 95% CI 1.24, 3.41) and each additional year of age of children (adj OR 1.17, CI 1.10, 1.24) were significantly associated with odds of allergies in children.

CONCLUSION

Although the exploratory nature of this convenience, snowballing sample limited the generalizability of the findings, initial observations warrant further investigation and validation in a larger more diverse population.

Short-term and long-term effects of cesarean section on asthma and wheezing: A cohort study and meta-analysis

OBJECTIVE

To describe the short-term and long-term effects of cesarean section on childhood asthma and wheezing.

METHOD

Firstly, in the cohort study, 6640 infants were included in the cohort baseline from January 2018 to December 2019, in which 6501 children completed the follow-up study for respiratory diseases at age 2 years. The effect of cesarean section on asthma and wheezing was estimated by the logistic regression model. Secondly, we conducted a meta-analysis of studies with outcomes of childhood asthma and wheezing under 2 years of age and over 2 years of age, respectively, to investigate the short-term and long-term effects of cesarean section on asthma and wheezing.

RESULTS

In our cohort study, the cumulative incidence of asthma and wheezing was 1.3% (84/6501). 45.5% of children (2961/6501) were born by cesarean section. The adjusted odds ratio for the effect of cesarean section on asthma and wheezing in children under 2 years of age was 1.14 (95%CI 0.73-1.78). Combining previous studies (outcomes of asthma and wheezing under 2 years of age) with our results for a meta-analysis, the odds ratio was 1.15 (95%CI 1.05-1.25, I² = 46.82%). Meanwhile, cesarean section had a long-term effect on asthma and wheezing in the child population over 2 years of age (OR = 1.17, 95%CI 1.11-1.24, P < 0.001, I² = 79.38%).

CONCLUSION

Cesarean section had a short-term effect on asthma and wheezing before the age of 2, in addition, the long-term effect of cesarean section on asthma and wheezing persisted in the child population (under 18).

Perinatal Characteristics and the Sensitization to Cow Milk, Egg Whites and Wheat in Children up to 3 Years of Age

Food sensitization in early life identifies children at risk of developing allergic diseases. We investigated the sensitization to cow milk (CM), egg whites, and wheat. Newborns and infants under 3 years of age with available specific immunoglobulin E (sIgE) data were identified. A retrospective survey was conducted using data from the Chang Gung Research Database. Perinatal characteristics, such as singleton or multiples in a single pregnancy, parity, meconium staining, maternal age, spontaneous delivery or cesarean section, meconium passage, weeks of gestation, birth length, body weight, head and chest circumferences, and season, were obtained. The data on sIgE were collected, and a logistic regression model was used to determine the odds of sensitization. Positive sIgE for CM and egg whites was more likely to occur in boys than in girls. Early-life egg white and wheat sensitization was associated with increased birth body length and weight. A multivariate analysis indicated an association between egg white sIgE positivity and logarithmic total IgE. Higher total IgE levels and younger age were associated with egg white sensitization, and elevated weight and length at birth were linked to food sensitization, particularly to egg whites and wheat.

Alternatives to Cow’s Milk-Based Infant Formulas in the Prevention and Management of Cow’s Milk Allergy

Cow’s milk-based infant formulas are the most common substitute to mother’s milk in infancy when breastfeeding is impossible or insufficient, as cow’s milk is a globally available source of mammalian proteins with high nutritional value. However, cow’s milk allergy (CMA) is the most prevalent type of food allergy among infants, affecting up to 3.8% of small children. Hypoallergenic infant formulas based on hydrolysed cow’s milk proteins are commercially available for the management of CMA. Yet, there is a growing demand for more options for infant feeding, both in general but especially for the prevention and management of CMA. Milk from other mammalian sources than the cow, such as goat, sheep, camel, donkey, and horse, has received some attention in the last decade due to the different protein composition profile and protein amino acid sequences, resulting in a potentially low cross-reactivity with cow’s milk proteins. Recently, proteins from plant sources, such as potato, lentil, chickpeas, quinoa, in addition to soy and rice, have gained increased interest due to their climate friendly and vegan status as well as potential lower allergenicity. In this review, we provide an overview of current and potential future infant formulas and their relevance in CMA prevention and management.

Are children born by cesarean delivery at higher risk for respiratory sequelae?

BACKGROUND

Globally, the number of children born by cesarean delivery is constantly increasing. However, hormonal and physiological changes associated with labor and vaginal delivery are considered necessary for lung maturation.

OBJECTIVE

We aimed to assess whether the mode of delivery is associated with changes in respiratory and atopic outcomes during infancy and at school age.

STUDY DESIGN

We included 578 children, born at ≥37 weeks of gestation, from a prospective birth cohort study. We compared weekly respiratory symptoms throughout the first year of life and infant lung function (tidal breathing and multiple-breath washout) at 5 weeks of age between children born by cesarean delivery (N=114) and those born by vaginal delivery (N=464) after term pregnancy in healthy women. At a follow-up visit conducted at 6 years of age (N=371, of which 65 were delivered by cesarean delivery), we assessed respiratory, atopic, and lung function outcomes (spirometry, body plethysmography, and multiple-breath washout). We performed adjusted regression analyses to examine the association between cesarean delivery and respiratory and atopic outcomes. To account for multiple testing, we used the Bonferroni correction, which led to an adapted significance level of P<.002.

RESULTS

During infancy, children born by cesarean delivery did not have more respiratory symptoms than those born by vaginal delivery (median, 4 weeks; interquartile range, 7 weeks vs median, 5 weeks; interquartile range, 7 weeks; adjusted incidence rate ratio, 0.8; 95% confidence interval, 0.6-1.0; P=.02). Infant lung function was similar between the groups. Children born by cesarean delivery did not have a higher incidence of "ever wheezing" (adjusted odds ratio, 0.9; 95% confidence interval, 0.5-1.8; P=.78) or current asthma (adjusted odds ratio, 0.4; 95% confidence interval, 0.0-3.5; P=.42) at school age than those born by vaginal delivery. There was no difference in the lung function parameters between the groups.

CONCLUSION

Cesarean delivery was not associated with respiratory symptoms in the first year of life, nor with different respiratory or atopic outcomes at school age, when compared with vaginal delivery. Our results indicate that there are no long-term consequences on the respiratory health of the child associated with cesarean delivery.

Preventing Atopic Diseases During Childhood - Early Exposure Matters

Atopic diseases in childhood are a major burden worldwide and there is still a lack of knowledge about treatable causes. In industrialized countries such as Germany, almost every second child is sensitized to at least one common allergen. Recent studies show that although the predisposition to allergies is inherited, the adaptive immune system of neonates and infants follows a developmental trajectory and whether an allergy actually occurs depends also on timing of allergen exposure including diet as well as environmental factors. New recommendations are far from being rigid of allergen avoidance; it is rather moving toward conditions that stand for more biodiversity. The observation that introduction of peanuts or eggs early in life significantly reduced the development of a later allergy will change our recommendations for the introduction of complementary foods. This is consistent with the hygiene hypothesis that early provocation shapes the developing immune system so that it reacts appropriately. Therefore, promoting the development of tolerance is at the heart of sensible allergy prevention - and this begins with the last trimester of pregnancy. In light of this concept, actual recommendations are discussed.

How does parental history of atopic disease predict the risk of atopic dermatitis in a child? A systematic review and meta-analysis

BACKGROUND

Parental history of atopic disease is a well-established risk factor for the development of atopic dermatitis (AD), but several aspects of this association remain unclear.

OBJECTIVE

We sought to determine the association of parental history of atopic disease with AD in offspring.

METHODS

We searched PubMed and EMBASE through June 2018 for relevant records and adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Pooled odds ratios (ORs) with 95% CI were calculated using random-effects models.

RESULTS

A total of 163 records covering 149 unique studies were included. Of these, 119 studies were included in the meta-analysis. Individuals with parental history of atopic disease had increased odds of AD (OR, 1.81; 95% CI, 1.65-1.99). Parental asthma (OR, 1.56; 95% CI, 1.18-2.05) and allergic rhinitis (OR, 1.68; 95% CI, 1.34-2.11) had a smaller effect than AD (OR, 3.30; 95% CI, 2.46-4.42). The effect of maternal and paternal history was comparable for all atopic diseases. An increase in odds was observed when comparing the effect of having 1 (OR, 1.30; 95% CI, 1.15-1.47) or 2 atopic parents (OR, 2.08; 95% CI, 1.83-2.36), as well as having a parent with 1 (OR, 1.49; 95% CI, 1.28-1.74) or more atopic diseases (OR, 2.32; 95% CI, 1.92-2.81).

CONCLUSIONS

This study provides evidence-based risk estimates that may guide physicians who counsel parents with a history of atopic disease about their children's risk of AD. This information is of particular importance for future efforts toward establishing prophylactic interventions for AD on a general population level.

Bacterial Baptism: Scientific, Medical, and Regulatory Issues Raised by Vaginal Seeding of C-Section-Born Babies

Several lines of evidence suggest that children born via Cesarean section (C-section) are at greater risk for adverse health outcomes including allergies, asthma and obesity. Vaginal seeding is a medical procedure in which infants born by C-section are swabbed immediately after birth with vaginal secretions from the mother. This procedure has been proposed as a way to transfer the mother's vaginal microbiome to the child, thereby restoring the natural exposure that occurs during vaginal birth that is interrupted in the case of babies born via C-section. Preliminary evidence indicates partial restoration of microbes. However, there is insufficient evidence to determine the health benefits of the procedure. Several studies, including trial, are currently underway. At the same time, in the clinic setting, doctors are increasingly being asked to by expectant mothers to have their babies seeded. This article reports on the current research on this procedure and the issues it raises for regulators, researchers, physicians, and patients.

The association between caesarean section and childhood asthma: an updated systematic review and meta-analysis

Background

Investigating the association between caesarean section (SC) and childhood asthma has shown contradictory results in different studies. The present study was conducted to determine the association between SC and childhood asthma.

Material and method

The present study was conducted based on the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. All the steps of the study were conducted independently by two reviewers from the inception until February 1, 2019. In case of disagreement, the third reviewer resolved it. We searched international online databases, including Scopus, Cochrane Library, PubMed/Medline, Embase, Web of Science (ISI), Science Direct, and Google scholar. The results of studies were combined using random effects model, and heterogeneity was measured through I² index and Cochran’s Q test. Comprehensive Meta-Analysis Software was used for meta-analysis. The significance level of all tests was considered to be P < 0.05.

Results

The heterogeneity rate was high (I² = 67.31%, P < 0.001) in 37 studies. The results showed that SC increased the risk of childhood asthma (RR (relative risk) = 1.20 [95% CI 1.15–1.25, P < 0.001]). The association between emergency and elective SC and childhood asthma was significant with RR of 1.18 (95% CI 1.07–1.29, P < 0.001) in 13 studies and 1.23 (95% CI 1.20–1.26, P < 0.001) in 13 studies, respectively. The subgroup analysis for RR of childhood asthma in SC indicated that study design (P = 0.306), prospective/retrospective studies (P = 0.470), quality of studies (P = 0.514), continent (P = 0.757), age of diagnosis (P = 0.283) and year of publication (P = 0.185) were not effective in the heterogeneity of studies. Sensitivity analysis by removing one study at a time indicated that the overall estimate is robust.

Conclusion

According to the meta-analysis, SC (overall, elective, and emergency) increased the risk of childhood asthma. Therefore, it is hoped that developing clinical guidelines and implementing appropriate management plans would diminish the risk of asthma.

Wheeze and Food Allergies in Children Born via Cesarean Delivery: The Upstate KIDS Study

We examined whether cesarean delivery (CD) increased the risk of wheeze or food allergy in early childhood compared with vaginal delivery and whether these associations were mediated by breastfeeding. The study population was the Upstate KIDS cohort (2008-2010) of mothers and infants from the State of New York (excluding New York City). Infant's wheeze was reported by questionnaire every 4-6 months until 3 years of age, as were food allergies beginning at 8 months. Modified Poisson regression was used to compare risks of the outcomes according to mode of delivery (MOD). Potential confounders were identified a priori using directed acyclic graphs. Emergency CD (n = 1,356) was associated with elevated risk of wheeze, adjusting for pregnancy complications, maternal atopy, gestational age, birth weight, and smoking during pregnancy (risk ratio = 2.47, 95% confidence interval: 1.31, 4.66), and an increased risk of food allergy, adjusting for maternal atopy, prepregnancy body mass index, smoking during pregnancy, and parity (risk ratio = 3.02, 95% confidence interval: 1.26, 7.25). Neither outcome was significantly associated with planned CD (n = 1,565 infants). Breastfeeding mediated the association between MOD and wheeze but not food allergy. Other factors not associated with early-life microbial transfer, but relating to the development of the outcomes, might contribute to the association between MOD and wheeze/food allergy.

Milk Other Than Breast Milk and the Development of Asthma in Children 3 Years of Age. A Birth Cohort Study (2006⁻2011)

Prevalence of asthma in Australian children is amongst the highest in the world. Although breastfeeding positively influences infant immunity, early introduction of Milk Other than Breast Milk (MOTBM) may also play an important role in the development of Asthma. The aim of this study was to investigate the association between the introduction of MOTBM in the first six months after birth and the development of reported persistent asthma in 3-year olds. A sample of 1121 children was extracted from the Environments for Healthy Living longitudinal birth cohort study. Introduction of MOTBM during the first six months after birth increased almost two-fold the risk of development of persistent asthma after adjusting for other covariates (Adjusted Relative Risk (ARR): 1.71, 95% CI: 1.03⁻2.83, p = 0.038). This study indicates that the introduction of MOTBM in the first six months of life is a risk factor for asthma incidence among 3-year old children. This result is important in explaining the benefits of breastfeeding as part of public health interventions to encourage mothers to increase breastfeeding initiation and duration, and avoid the introduction of MOTBM in the first six months after childbirth.

The effect of selected risk factors, including the mode of delivery, on the development of allergic rhinitis and bronchial asthma

Introduction

Cesarean section affects the process of colonization by bacteria transferred from the mother’s skin and hospital bacteria, which in turn contributes to development of allergic conditions.

Aim

To assess selected risk factors, including the mode of delivery, parity, and the role of genetic factors for the development of allergic rhinitis and bronchial asthma.

Material and methods

The study was conducted in 18,617 respondents aged 6–7, 13–14, and 20–44 years who completed the ECRHS II and ISSAC questionnaires. Thirty percent of the study population underwent complementary assessments in the form of skin-prick tests, serum IgE levels, lung function tests, and peak nasal inspiratory flow (PNIF). The study is a part of the Epidemiology of Allergic Disorders in Poland (ECAP) study conducted in 8 areas in Poland (Warsaw, Lublin, Bialystok, Gdansk, Poznan, Wroclaw, Katowice, Krakow, and two rural areas – Zamosc and Krasnystaw counties).

Results

Respondents diagnosed with allergic rhinitis were at a significantly higher risk of inheriting the allergic condition if their mother (OR = 2.17; 95% CI: 1.98–2.39, p = 2.00 × 10^–16) or father (OR = 2.20; 95% CI: 1.96–2.47; p = 2.00 × 10^–16) suffers from this allergy. Conversely, in the group diagnosed with bronchial asthma, the highest risk of an inherited allergy was observed in situations where maternal (OR = 2.00; 95% CI: 1.57–2.55; p = 1.69 × 10^–5) or paternal (OR = 1.94; 95% CI: 1.42–2.66; p = 3.61 × 10^–5) grandparent was affected. Moreover, the risk of developing allergic rhinitis depended on the mode of delivery: i.e. it was higher for a Cesarean section (OR = 1.20; 95% CI: 1.01–1.43; p = 0.04) than vaginal delivery (OR = 0.88; 95% CI: 0.78–0.99; p = 0.03). The higher the number of siblings, the lower the risk of allergic rhinitis.

Conclusions

Allergy risk factors, especially those predisposing to allergic rhinitis, include not only genetic factors but also the mode of delivery: vaginal delivery or Cesarean section.

A rural environment does not protect against asthma or other allergic diseases amongst Mexican children

INTRODUCTION

The commonly held notion that a rural environment decreases the frequency of allergic diseases has proven to be inconsistent amongst children.

OBJECTIVE

Our objective was to contrast the prevalence of bronchial asthma (BA), allergic rhinitis (AR), and atopic dermatitis (AD) between children that live in a rural environment and those that live in urban areas.

METHODS

We carried out a cross-sectional study amongst children aged six to seven; they were selected through probabilistic, stratified and conglomerated sampling. The prevalence of BA, AR, and AD was identified with the use of the questionnaire provided by The International Study of Asthma and Allergies in Childhood, additionally, we inquired about each child's family history of atopy, their exposure to farm animals, the intake of unpasteurised cow's milk, and the number of siblings related to every child. We used logistic regression and multivariate analysis to determine the correlation between asthma, allergic diseases, and rural environment.

RESULTS

We included 189/1003 (18.8%) children from a rural environment, and 814/1003 (81.2%) from an urban area. BA and AR were associated to a family history of atopy (OR=2.15, p=0.001; OR=2.58, p=0.002, respectively). BA was more prevalent in males (OR=1.92, p=0.007). Notably, a higher number of siblings seems to protect against AR (OR=0.45, p=0.008). A paternal history of allergies was associated to AD.

CONCLUSIONS

In our study, we were unable to find protective factors in a rural environment that might decrease the prevalence of asthma or allergic diseases.

Environmental determinants of allergy and asthma in early life

Allergic disease prevalence has increased significantly in recent decades. Primary prevention efforts are being guided by study of the exposome (or collective environmental exposures beginning during the prenatal period) to identify modifiable factors that affect allergic disease risk. In this review we explore the evidence supporting a relationship between key components of the external exposome in the prenatal and early-life periods and their effect on atopy development focused on microbial, allergen, and air pollution exposures. The abundance and diversity of microbial exposures during the first months and years of life have been linked with risk of allergic sensitization and disease. Indoor environmental allergen exposure during early life can also affect disease development, depending on the allergen type, dose, and timing of exposure. Recent evidence supports the role of ambient air pollution in allergic disease inception. The lack of clarity in the literature surrounding the relationship between environment and atopy reflects the complex interplay between cumulative environmental factors and genetic susceptibility, such that no one factor dictates disease development in all subjects. Understanding the effect of the summation of environmental exposures throughout a child's development is needed to identify cost-effective interventions that reduce atopy risk in children.

Skin Colonization by Staphylococcus aureus Precedes the Clinical Diagnosis of Atopic Dermatitis in Infancy

Atopic dermatitis (AD) has a well-established association with skin colonization or infection by Staphylococcus aureus, which can exacerbate the disease. However, a causal relationship between specific changes in skin colonization during the first years of life and AD development still remains unclear. In this prospective birth cohort study, we aimed to characterize the association between skin colonization and AD development in 149 white infants with or without a family history of atopy. We assessed infants clinically and collected axillary and antecubital fossa skin swabs for culture-based analysis at birth and at seven time points over the first 2 years of life. We found that at age 3 months, S. aureus was more prevalent on the skin of infants who developed AD later on. S. aureus prevalence was increased on infants' skin at the time of AD onset and also 2 months before it, when compared with age-matched, unaffected infants. Furthermore, at AD onset, infants testing positive for S. aureus were younger than uncolonized subjects. In conclusion, our results suggest that specific changes in early-life skin colonization may actively contribute to clinical AD onset in infancy.

Increased risk of allergic rhinitis among children delivered by cesarean section: a cross-sectional study nested in a birth cohort

BACKGROUND

Few studies have evaluated the association between delivery by cesarean section (CS) and asthma, allergic rhinitis and chronic rhinitis and whether this association is different in children with and without a family history of asthma. This study aims to investigate whether children born by CS have a higher chance to develop asthma, allergic rhinitis and chronic rhinitis and to evaluate the influence of parental history of asthma on these associations.

METHODS

This is a cross-sectional study of 672 children nested in a birth cohort evaluated at 6-years of age. Asthma and chronic/allergic rhinitis were identified by means of the mother's responses to the ISAAC questionnaire. The association between CS, asthma, chronic rhinitis and allergic rhinitis was evaluated by multivariable logistic regression. The evidence of effect modification of parental history of asthma on the association CS and outcomes was examined by introducing interactions terms in the logistic regression models adjusting for confounders.

RESULTS

Asthma was not associated with birth by CS irrespective of parental history of asthma (odds ratio (OR) 1.03; 95 % CI 0.61-1.74). Chronic rhinitis and allergic rhinitis were both significantly associated with birth by CS but only in the subgroup of children with by parental history of asthma (OR 1.56; 95 % CI 1.04-2.34) and (OR 1.60; 95 % CI 1.01-2.55) respectively, after adjustment for confounders. The parental history of asthma was a effect modifier in the association between CS, chronic rhinitis and allergic rhinitis (p for effect modification = 0.10 and 0.02, respectively).

CONCLUSION

CS increases the risk of chronic rhinitis and allergic rhinitis in children at 6 years of age with parental history of asthma. Health professionals must be alerted with regard to the increased risk of allergic rhinitis and made aware this is another reason to avoid unnecessary CS.

Mode of delivery and childhood hospitalizations for asthma and other wheezing disorders

BACKGROUND

Observationally, delivery by Caesarean section is associated with higher risk of childhood asthma and wheeze in developed Western settings, but associations are less consistent in other settings.

OBJECTIVE

To examine the association of mode of delivery with hospitalizations for asthma and other wheezing disorders in a developed non-Western setting with high rates of Caesarean section.

METHODS

Using Cox regression, we examined the adjusted association of mode of delivery with public hospital admissions for asthma, bronchitis, and bronchiolitis (International Classification of Diseases, Ninth Version Clinical Modification 466, 490 and 493) from 9 days to 12 years of age in a population-representative prospective birth cohort of 8327 Chinese children in Hong Kong. Confounders included sex, birth and parental characteristics, and socio-economic position (SEP).

RESULTS

Delivery by Caesarean section accounted for 27% of all births and was not clearly associated with hospitalizations for asthma and other wheezing disorders to 12 years [hazard ratio (HR) 1.11, 95% confidence interval (CI) 0.91 to 1.36] compared to vaginal delivery. Similarly, there were no clear associations to 2 years (HR 1.07, 95% CI 0.83 to 1.38) or 6 years (HR 1.12, 95% CI 0.91 to 1.37), although we cannot rule out residual confounding by SEP.

CONCLUSIONS AND CLINICAL RELEVANCE

We cannot rule out an association, but our findings suggest that the observed associations of delivery by Caesarean section with childhood wheezing disorders may vary with setting and may not be biologically mediated. Further studies with different designs are needed to clarify the role of the microbiome and mode of delivery in the aetiology of asthma and other childhood wheezing disorders.

Atopic dermatitis is associated with Caesarean sections in Korean adolescents, but asthma is not

AIM

Studies on the associations between mode of delivery and allergic diseases have produced different results, and research has rarely been conducted in Asian countries such as South Korea. This study assessed the relationship between mode of delivery and atopic dermatitis and asthma in Korean adolescents.

METHODS

Data collected from the Korea National Health and Nutrition Examination Survey between 2010 and 2011 were used. We included 1302 adolescents aged from 12 to 18 years, and multivariable logistic regression analysis was performed.

RESULTS

The odds ratio (OR) of having atopic dermatitis in adolescents born by Caesarean section compared with vaginal delivery was 1.50, with a 95% confidence interval (95% CI) of 1.01-2.22, after adjusting for age and sex. The association remained significant after further adjustments for body mass index, breastfeeding and serum 25-hydroxyvitamin D level (OR = 1.61, 95% CI = 1.05-2.47) and when fat intake was added to those variables (OR = 1.80, 95% CI = 1.14-2.85). However, asthma was not associated with mode of delivery in any of the models.

CONCLUSIONS

Atopic dermatitis in adolescents was associated with Caesarean delivery, which is common in South Korea. The findings suggest that the frequency of this practice should be reconsidered and that further research with longitudinal evaluation of relevant mechanisms is needed.

Is elective cesarean section associated with a higher risk of asthma? A meta-analysis

Abstract Background: Recent meta-analyses indicate that children delivered by cesarean section have increased risk for asthma. However, the studies included in these previous meta-analyses showed significant heterogeneity. Furthermore, no previous meta-analysis has distinguished the association of elective and emergency CS, spontaneous and instrumental vaginal deliveries (VD) with the odds of asthma.

OBJECTIVE

To examine the association between specific mode of delivery and the prevalence of asthma.

METHODS

PUBMED, Google Scholar, EMBASE, and MEDLINE were searched to identify relevant studies. Odds ratio (OR) and 95% confidence interval (CI) were calculated from the prevalence of asthma in children born by elective CS, emergent CS, instrumental VD and spontaneous VD. Meta-analysis was then used to derive a combined OR. Heterogeneity between studies was also tested in the findings.

RESULTS

A total of 26 studies were identified. The overall meta-analysis revealed an increase in the risk of asthma in children delivered by CS (OR=1.16, 95% CI 1.14, 1.29), and no evidence of heterogeneity was found (I(2)=24.6%). Elective and emergency CS moderately increased the risk of asthma (OR=1.21, 95% CI 1.17, 1.25; I(2)=39.9%; OR=1.23, 95% CI 1.19-1.26). The risk of asthma was also higher in the children born by instrumental VD (OR=1.07, 95% CI, 1.04-1.11) but with evidence of heterogeneity (I(2)=54.9%).

CONCLUSION

About 20% increase in the subsequent risk of asthma was both found in children delivered by elective and emergency CS. The increasing rates of CS worldwide might partly explain the concomitant rise in asthma during the same time period.

The natural course of allergic rhinitis: a 32-year follow-up study

CONCLUSION

Early intervention may change the natural course of allergic rhinitis, preventing the progression to asthma. In particular, immunotherapy guarantees remission of local symptoms and valid protection against local and bronchial complications. Symptomatic treatment represents a valid alternative; it is always to be preferred to abstention from any treatment.

OBJECTIVES

Data emerging from various studies on the increase of the prevalence of allergic rhinitis in recent decades appear to be widely dishomogeneous. Another point that needs clarification is the relationship between allergic rhinitis and lower airways pathologies such as asthma or bronchitis.

METHODS

We followed the evolution of allergic rhinitis in a group of patients for the last 30 years to highlight the efficacy of different treatments in the prevention of complications, specifically asthma. After 32 years (1980-2012), 46/73 (63%) patients completed the follow-up.

RESULTS

Symptomatic drugs exhibited maximum efficacy from the third to the eighth year, with 13 of 15 patients reporting an improvement of symptoms; immunotherapy achieved the best efficacy starting from the sixth to the tenth year (8 of 10 patients recovered). Subsequently, improvements decreased in the two groups, to a steady level of 11 of 15 and 6 of 10 recovered patients. Asthma developed in 3 of 46 patients and only among patients that were not treated.

Cord blood cellular proliferative response as a predictive factor for atopic dermatitis at 12 months

Since the risk of developing allergic disease increases in individuals exposed to allergens previously, even during the neonatal period, the immunologic status of a fetus may be important in the subsequent development of allergy. We evaluated the fetal factors to predict atopic dermatitis (AD) at 12 months in 412 infants of a COhort for Childhood Origin of Asthma and Allergic Diseases (COCOA) in the general Korean population. Cord blood mononuclear cells (CBMCs) were stimulated with ovalbumin and phytohemagglutinin and cellular proliferative response and concentrations of interleukin-13 and interferon-γ, were measured. The risk of developing AD was greater in boys than girls (OR 1.97, 95% CI 1.26-3.09), infants delivered by cesarean section than vaginally (OR 1.93, 95% CI 1.14-3.26) and infants with than without parental history of AD (OR 2.34, 95% CI 1.29-4.24). The CBMC proliferative response to phytohemagglutinin stimulation was higher in infants with than without AD (P = 0.048), but no difference was observed in ovalbumin-stimulated cells (P = 0.771). Risk factors for the development of AD at 12 months include male gender, delivery by cesarean section and parental history of AD. Increased CBMC proliferative response to phytohemagglutinin stimulation may predict the development of AD at 12 months.

Association of CFTR gene mutation with bronchial asthma and its severity in Indian children: a case-control study

BACKGROUND

Asthma is a complex genetic disorder. Several genes have been found associated with asthma. The cystic fibrosis transmembrane conductance regulator (CFTR) gene is one of them.

AIM

To assess the association of CFTR gene mutation with asthma and its severity as per GINA guidelines.

SUBJECTS AND METHODS

This was a hospital-based case-control study. Excluded from cases and controls were those with clinically suspected cystic fibrosis or sweat chloride level>60 mmol/L or suffering from other respiratory diseases. Included were 200 cases and 180 controls, aged 5 months to 15 years. Screening was done for CFTR gene mutations; ΔF508, G542X, G551D, R117H and W1282X using the ARMS-PCR method.

RESULTS

ΔF508 was found in three (1.5%) cases and two (1.1%) controls (p = 0.739), G542X in nine (4.5%) cases and five (2.8%) controls (p = 0.374), R117H in one (0.5%) case and one (0.6%) control (p = 0.940) and G551D in twelve (6.0%) cases and two (1.1%) controls (p = 0.012). Individuals carrier for G551D mutation had increased risk for persistent asthma (p = 0.006). Percent predicted FEV1 (p = 0.014) and FVC (p = 0.028) were significantly lower among carriers as compared to non-carriers.

CONCLUSION

Significantly higher frequency of G551D mutation among asthma patients compared with controls suggests that this mutation may increase risk for the disease and also its severity.

Delivery by Cesarean section and early childhood respiratory symptoms and disorders: the Norwegian mother and child cohort study

Studies have indicated that children delivered by cesarean section are at an increased risk of developing wheezing and asthma. This could be the result of an altered immune system development due to delayed gut colonization or of increased neonatal respiratory morbidity. The authors examined the associations between delivery by cesarean section and the development of wheezing, asthma, and recurrent lower respiratory tract infections in children up to 36 months of age among 37,171 children in the Norwegian Mother and Child Cohort Study. Generalized linear models were used in the multivariable analysis. Children delivered by cesarean section had an increased likelihood of current asthma at 36 months of age (relative risk = 1.17, 95% confidence interval: 1.03, 1.32), and the association was stronger among children of nonatopic mothers (relative risk = 1.33, 95% confidence interval: 1.12, 1.58). No increased risk of wheezing or recurrent lower respiratory tract infections was seen among children delivered by cesarean section. Findings were similar among children delivered by acute and elective cesarean section. In conclusion, children delivered by cesarean section may have an increased risk of current asthma at 36 months, but residual confounding cannot be excluded. In future prospective studies, investigators should reexamine this association in different age groups.