Caesarean sections and risk of wheezing in childhood and adolescence: data from two birth cohort studies in Brazil

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).

Characteristics of inpatients with atopic asthma in a tertiary center: Do age and gender have an influence?

Background: Several studies have demonstrated gender influence on asthma prevalence, being higher among males during early childhood. Little is known about the impact of gender and age on asthma exacerbation characteristics in pediatrics. This study aimed to determine the differences in acute asthma between males and females in three different age groups regarding perinatal characteristics of asthmatic patients, comorbidities, medication adherence, level of blood eosinophils, and pattern of hospitalization.Methods: The medical records of 130 pediatric patients with asthma, who presented to the emergency department at Jordan University hospital with asthma exacerbations, were retrospectively reviewed. Demographic information and clinical characteristics were collected.Results: The mean age of patients was 10.7±4.7 years. The age at diagnosis and gestational age were significantly higher in older children. Furthermore, younger children were significantly more likely to experience winter exacerbations and more emergency presentations. Male patients were considerably younger than their female counterparts and were diagnosed younger. In addition, male patients were more likely to have eosinophil levels higher than 3% than female patients.Conclusion: Gender plays a role in the development and outcome of asthma exacerbations at different ages of pediatrics. A better understanding of gender-based and age-based differences in asthma dictates a personalized approach to treatment.

Pediatrics Consequences of Caesarean Section-A Systematic Review and Meta-Analysis

BACKGROUND

Cesarean section is a surgical procedure, which is the most frequently performed in gynecology and obstetrics. It is commonly believed that an operative delivery is a less painful and safer mode of delivery, which translates into an increasing number of the procedures performed without medical indications. The maternal sequelae of cesarean sections are well elucidated and widely discussed in the literature, while long-term neonatal consequences still remain the issue of research and scientific dispute. The aim of the present paper was to perform a systematic review of current literature regarding pediatrics consequences of cesarean section.

METHODS

We reviewed available data from PubMed, Science Direct as well as Google Scholar bases concerning early and long-term neonatal sequelae of operative deliveries. The following key words were used: "cesarean section", "caesarean section", "neonatal outcomes", "respiratory disorders", "asthma", "obesity", "overweight", and "neurological disorders". A total of 1636 papers were retrieved out of which 27 were selected for the final systematic review whereas 16 articles provided data for meta-analysis. Statistical analyses were performed using RevMan 5.4. To determine the strength of association between the caesarean section and respiratory tract infections, asthma, diabetes type 1 as well as obesity the pooled odds ratios (OR) with the 95% confidence intervals (CI) were calculated.

RESULTS

Conducted meta-analyses revealed that caesarean section is a risk factor for respiratory tract infections (pooled OR = 1.30 95%CI 1.06-1.60, p = 0.001), asthma (pooled OR = 1.23 95%CI 1.14-1.33, p < 0.00001) as well as obesity (pooled OR = 1.35 95%CI 1.29-1.41, p < 0.00001) in offspring.

CONCLUSIONS

The results of the studies included indicated that children delivered by cesarean section more commonly developed respiratory tract infections, obesity and the manifestations of asthma than children delivered vaginally. The risk of developing diabetes mellitus type 1 or neurological disorders in offspring after caesarean section is still under discussion.

Health Implications of Increased Cesarean Section Rates

Introduction:

The health implications of Caesarean section are a significant factor in evaluating the use of Caesarean section as a method of completing childbirth. The increased rate of Cesarean section augmenting in a statistical way the health implications of the use of Cesarean section as a way of operative technique of childbirth finalization.

Aim:

To investigate the incidence of health implications on mother and child after Cesarian section in comparison to vaginal delivery.

Methods:

In our study, which was conducted as a retrospective-prospective and targeted study, the observed research period is from 2007 to 2019. The data sources are: medical histories, birth protocols and neonatal medical histories. Group A: represents the number of surveyed patients with a Cesarean section in a one-year period (2018) in General Hospital „Prim.dr A. Nakaš“. Group B: represents a control group of the same number of patients born by Caesarean section in 2007 in General Hospital „Prim.dr A.Nakaš“ with all parameters and variables detected in the research group. Evaluation of the examinee’s findings includes: anamnestic data, sonographic data, gynecological finding, colposcopic finding. PAPA test, HPV typing and laboratory findings due to the extensiveness of the study.

Results:

A comparison of the number of Caesarean sections in BiH before and now shows a statistically significant increase from about 6 caesareans per year to almost 21 Cesarean section per year (p<0.05). This increase led to a statistically significant decrease in perinatal mortality from 30 per thousand per year to only 6 per thousand per year (p<0.05). Complications after Cesarean section during both observed periods are dominated by subjective problems, followed by early complications after Cesarean section. According to the types of complications after Caesarean section, hemorrhages were the most numerous during both examined years, with 1 case of other complications and without a statistically significant difference between the observed years. There were no statistically significant differences in the duration of hospitalization, although in 2007 somewhat longer stay in the hospital after Caesarean section was recorded.

Conclusion:

Our study has shown that one of the most visible trends in modern perinatology is a significant increase in number of Cesarean sections. This is the basis of long-term side effects of Caesarean section, the frequency of which correlates with the increase in this surgical procedure.

Infant wheezing and prenatal antibiotic exposure and mode of delivery: a prospective birth cohort study

Introduction: Assessments on whether prenatal antibiotic exposure and mode of delivery increase the risk of wheezing in infants and toddlers are inconsistent. Our goal is to evaluate the association between prenatal antibiotic use and Cesarean section with three subtypes of wheezing in infancy.Methods: An ongoing prospective three generations cohort study provides data on prenatal antibiotic use and mode of delivery. Respective questionnaire data was used to distinguish three subtypes of wheezing: any wheezing, infectious wheezing, and noninfectious wheezing. Repeated measurements of wheezing at 3, 6, and 12 months were analyzed using generalized estimation equations. Latent transition analysis assessed patterns of infant wheezing development in the first year of life.Results: The prevalence of any wheezing was highest at 12 months (40.1%). The prevalence of infectious wheezing was higher (3 months 23.8%, 6 months 33.5%, 12 months 38.5%) than of noninfectious wheezing (3 months 13.0%, 6 months 14.0%, 12 months 11.1%). About 11-13% of children had both infectious and noninfectious wheezing at 3, 6, and 12 months (3 months 10.7%, 6 months 13.9%, 12 months 13.1%). Children born via Cesarean section have approximately a 70-80% increase in the risk of any wheezing (RR = 1.83, 95% CI 1.29-2.60) and of infectious wheezing (RR = 1.72, 95% CI 1.18-2.50).Conclusions: Analyses of infectious and noninfectious wheezing subtypes suggests that children born by Cesarean sections may be more susceptible to infectious wheezing, warranting investigations into microbial factors of infectious wheezing. No significant associations were found between prenatal antibiotic exposure and wheezing types.

Cesarean Section and Development of Childhood Bronchial Asthma: Is There A Risk?

BACKGROUND:

Asthma is a chronic inflammatory disease of the airways that results from complex interactions between multiple environmental and genetic influences. In recent years, studies have observed an increase in caesarean section rates, and have suggested a strong association with the rapid increase in the incidence of childhood asthma that cannot be explained by genetic factors alone. In this case-control study, we investigate the association between the developments of childhood asthma with the mode of delivery. We also explored the relationship between mode of delivery and control of asthma.

METHODS:

Two groups (509 pediatric patients in total) were assessed between January 1, 2017, and January 1, 2018. Part of these patients, 257 (50.4%) were asthmatic children visiting specialised clinics, and 252 (49.6%) controlled cases selected from a primary health care clinic from the same institution (control group).

RESULTS:

The Chi-square test revealed a significant association between cesarean sections and bronchial asthma (OR, 1.483 [95% CI, 1.013–21.71]; P =0.042). However, the adjusted OR from our binary logistic regression model revealed this association to be insignificant (adjusted OR, 1.417 [95% CI, 0.885–2.269]; P =0.804). The value of the chi-square of the model shows that the overall model is statistically significant at 1%. The Nagelkerke R square indicates that 34.9% of the variation in having asthma is explained by the risk factors included in the model.

CONCLUSION:

We do not believe that the rise in cesarean sections explains the increase in childhood bronchial asthma – at least not in our population. We also found no association between the mode of delivery and asthma control. We encourage further research into this topic, namely to recruit a larger number of patients, and to adjust for the significant risk factors found in our study.

Elective cesarean delivery at term and the long-term risk for respiratory morbidity of the offspring

Maternal morbidity is associated with cesarean deliveries. However, new evidence suggests that short- and long-term neonatal morbidity is also associated. This includes respiratory morbidity with conflicting results. To determine whether mode of delivery has an impact on the long-term risk for respiratory morbidity in the offspring, a population-based cohort analysis was conducted including all singleton term deliveries occurring between 1991 and 2014 at a single tertiary medical center. A comparison was performed between children delivered via elective cesarean delivery (CD) and those delivered vaginally. Multiple gestations and fetuses with congenital malformations were excluded from the analysis as were all cases of urgent CDs. Pediatric hospitalizations involving respiratory morbidity of offspring up to the age of 18 years were evaluated. A Kaplan-Meier survival curve was used to compare cumulative respiratory morbidity incidence and a Cox regression model to control for confounders. During the study period, 132,054 term deliveries met the inclusion criteria; 8.9% were via elective CDs (n = 11,746) and 91.1% (n = 120,308) were vaginal deliveries. Hospitalizations of the offspring involving respiratory morbidity were significantly more common in offspring delivered by CDs (5.2 vs. 4.3% in vaginal deliveries, p < 0.001). The Kaplan-Meier survival curve demonstrated a significantly higher cumulative incidence of respiratory morbidity in the elective CD group (log rank p < 0.001). In a Cox proportional hazards model, while controlling for maternal age, gestational age, and birthweight, CD exhibited a significant and independent association with long-term respiratory morbidity of the offspring (adjusted hazard ratio = 1.22 (CI, 1.12-1.33), p < 0.001).Conclusion: Elective cesarean delivery at term is a significant risk factor for long-term pediatric respiratory morbidity of the offspring. What is Known: • Cesarean delivery is a major surgery with known possible complications. • Cesarean delivery has possible immediate complications for the newborn including respiratory complications. What is New: • Our study shows more long term respiratory morbidity in the CD group including asthma and obstructive sleep apnea. • Different possible explanations have been proposed including exposure to maternal flora during vaginal delivery and the stress hormones secreted during contractions and delivery.

Caesarean delivery, childhood asthma, and effect modification by sex: An observational study and meta-analysis

BACKGROUND

Numerous studies indicate caesarean delivery is associated with childhood asthma. Sex-specific associations were reported in four of these studies, and in all four studies, the estimated association between caesarean delivery and asthma was of greater magnitude among girls, although most report a lack of evidence of multiplicative interaction.

METHODS

We assessed potential effect modification by sex, on the additive and multiplicative scales, of the association between caesarean delivery and asthma by ages 2 through 6 in up to 17 075 racially diverse children from a retrospective birth cohort, the Kaiser Air Pollution and Pediatric Asthma (KAPPA) Study. We also conducted a random-effects meta-analysis, combining our sex-stratified results (using the odds ratio for compatibility with previous studies) with previously published results.

RESULTS

Adjusted risk differences for caesarean delivery and asthma in the KAPPA cohort were higher among girls than boys at every follow-up age. By age 5, caesarean delivery was associated with an absolute 3.8% (95% confidence interval [CI] 0.4%, 7.3%) higher asthma risk among girls and a 1.9% (95% CI -1.7, 5.4) higher risk among boys. The summary odds ratio from the meta-analysis for caesarean delivery and asthma among girls was 1.26 (95% CI 1.14, 1.39) and 1.08 (95% CI 0.98, 1.20) among boys (P = 0.036).

CONCLUSIONS

Higher, but imprecise, estimates for females across five studies should motivate investigators to estimate sex-specific associations for caesarean delivery and asthma and to explore biological mechanisms or sex-dependent biases that could explain this possible heterogeneity.

Causes of an Increased Rate of Caesarean Section

Introduction:

The increase in the percentage of the Cesarean sections has got an important place in determination of modern obstetrics. The evaluation of that needs actual, modern opinion for obstetrics and transformation actual obstetric science than investigating the best situation for the mother and child in the actual moment. All medical, organizational, economic and ethical capacities with support of modern diagnostic and therapeutic procedures present a reason for the access in modern obstetrics. It takes the descriptive and analytic method at work. In our country the percentage of the Caesarean section is 15% (according to WHO data), with large variations in frequency depending on the writer and the investigated time.

Aim:

To investigate the prevalence of Cesarean section in Bosnia and Herzegovina until 2017.

Patients and Methods:

In our investigation made prospective and target analysis is investigated at 2017 as a target year. Sources are: patient charts, notes and charts of new born. Group A presents number investigated patients with made Cesarean section in time at one year (2017) in General hospital „Prim.dr A.Nakaš“. Group B presents control group with identical number of deliveries with Cesarean section in 2007 in General hospital „Prim.dr A. Nakaš“ with all variables who detected in investigation group.

Results:

Analysis the number of deliveries finished Cesarean section in time from 2007 to 2017 in General hospital „Prim.dr Abdulah Nakaš “Sarajevo presents augmentation frequency from 15,5 % in 2007 year to 21,7 % in 2011; smaller number in 2012 to 20,3% and finally 22.9% in 2017 for all deliveries.

Conclusion:

Our investigation shows an important number of Cesarean section and is still working because of clearer obstetric indication but they make a vital indication for the mother and baby. It worries percent of poorly described indications, that are something important for the comfort of doctor and any patients that wants natural delivery. It worries the public because the more important short term and long-term unwanted effects; Cesarean delivery in correlation with augmentation of this operation.

Long-term risks and benefits associated with cesarean delivery for mother, baby, and subsequent pregnancies: Systematic review and meta-analysis

BACKGROUND

Cesarean birth rates continue to rise worldwide with recent (2016) reported rates of 24.5% in Western Europe, 32% in North America, and 41% in South America. The objective of this systematic review is to describe the long-term risks and benefits of cesarean delivery for mother, baby, and subsequent pregnancies. The primary maternal outcome was pelvic floor dysfunction, the primary baby outcome was asthma, and the primary subsequent pregnancy outcome was perinatal death.

METHODS AND FINDINGS

Medline, Embase, Cochrane, and Cumulative Index to Nursing and Allied Health Literature (CINAHL) databases were systematically searched for published studies in human subjects (last search 25 May 2017), supplemented by manual searches. Included studies were randomized controlled trials (RCTs) and large (more than 1,000 participants) prospective cohort studies with greater than or equal to one-year follow-up comparing outcomes of women delivering by cesarean delivery and by vaginal delivery. Two assessors screened 30,327 abstracts. Studies were graded for risk of bias by two assessors using the Scottish Intercollegiate Guideline Network (SIGN) Methodology Checklist and the Risk of Bias Assessment tool for Non-Randomized Studies. Results were pooled in fixed effects meta-analyses or in random effects models when significant heterogeneity was present (I2 ≥ 40%). One RCT and 79 cohort studies (all from high income countries) were included, involving 29,928,274 participants. Compared to vaginal delivery, cesarean delivery was associated with decreased risk of urinary incontinence, odds ratio (OR) 0.56 (95% CI 0.47 to 0.66; n = 58,900; 8 studies) and pelvic organ prolapse (OR 0.29, 0.17 to 0.51; n = 39,208; 2 studies). Children delivered by cesarean delivery had increased risk of asthma up to the age of 12 years (OR 1.21, 1.11 to 1.32; n = 887,960; 13 studies) and obesity up to the age of 5 years (OR 1.59, 1.33 to 1.90; n = 64,113; 6 studies). Pregnancy after cesarean delivery was associated with increased risk of miscarriage (OR 1.17, 1.03 to 1.32; n = 151,412; 4 studies) and stillbirth (OR 1.27, 1.15 to 1.40; n = 703,562; 8 studies), but not perinatal mortality (OR 1.11, 0.89 to 1.39; n = 91,429; 2 studies). Pregnancy following cesarean delivery was associated with increased risk of placenta previa (OR 1.74, 1.62 to 1.87; n = 7,101,692; 10 studies), placenta accreta (OR 2.95, 1.32 to 6.60; n = 705,108; 3 studies), and placental abruption (OR 1.38, 1.27 to 1.49; n = 5,667,160; 6 studies). This is a comprehensive review adhering to a registered protocol, and guidelines for the Meta-analysis of Observational Studies in Epidemiology were followed, but it is based on predominantly observational data, and in some meta-analyses, between-study heterogeneity is high; therefore, causation cannot be inferred and the results should be interpreted with caution.

CONCLUSIONS

When compared with vaginal delivery, cesarean delivery is associated with a reduced rate of urinary incontinence and pelvic organ prolapse, but this should be weighed against the association with increased risks for fertility, future pregnancy, and long-term childhood outcomes. This information could be valuable in counselling women on mode of delivery.

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.

Caesarean Section is associated with reduced perinatal cytokine response, increased risk of bacterial colonization in the airway, and infantile wheezing

The relationship between cesarean section (CS) and allergic disorders such as asthma and wheezing has been inconsistent, and the mechanisms for their connection remained largely unknown. We aimed to investigate whether CS is associated with infantile wheeze and to explore the connection between CS and several risk factors known to correlate with allergy development. Mononuclear cells were isolated from cord blood and assessed for cytokine responses by ELISA. Bacteria from nasopharyngeal specimens were identified with traditional culture methods. Infant lung function tests were performed at 6 and 12 months of age. IgE levels and clinical outcomes were assessed at 12 months. The result showed that children delivered by CS were associated with increased risk of wheezing (aHR 1.63; 95% CI: 1.01–2.62) and decreased compliance of the respiratory system at 12 months (p = 0.045). In addition, CS was associated with reduced TLR1–2- triggered TNF-α and IL-6 responses at birth. By12 months of age, children delivered by CS had significantly less airway bacterial clearance. Our findings suggested that CS was associated with decreased pro-inflammatory cytokine response to TLR1–2 stimulation, followed by higher abundance of bacterial colonization in the airway during late infancy, thus increasing the risk of infantile wheezing.

Mode of Delivery and Asthma at School Age in 9 European Birth Cohorts

Evidence on the association between mode of delivery and asthma at school age is inconclusive. We assessed the associations between specific modes of delivery and asthma in children from 9 European birth cohorts that enrolled participants between 1996 and 2006. Cohort-specific crude and adjusted risk ratios for asthma at ages 5-9 years were calculated using Poisson regression models and pooled. A sensitivity analysis was carried out in children born at term to reduce confounding due to perinatal factors. The study included 67,613 participants. Cohort-specific rates of cesarean delivery varied from 9.4% to 37.5%. Cesarean delivery, as opposed to vaginal delivery, was associated with an increased risk of asthma (adjusted risk ratio (aRR) = 1.22, 95% confidence interval (CI): 1.02, 1.46). Compared with spontaneous vaginal delivery, the adjusted risk ratio was 1.33 (95% CI: 1.02, 1.75) for elective cesarean delivery, 1.07 (95% CI: 0.94, 1.22) for emergency cesarean delivery, and 0.97 (95% CI: 0.84, 1.12) for operative vaginal delivery. In children born at term, the associations were strengthened only for elective cesarean delivery (aRR = 1.49, 95% CI: 1.13, 1.97). The large sample size allowed analysis of the associations between specific modes of delivery and asthma at school age. The increased risk of asthma associated with elective cesarean delivery, especially among children born at term, is relevant in counteracting the increasing use of this procedure, which is often performed without a clear medical indication.

The respiratory consequences of early-term birth and delivery by caesarean sections

In England and Wales, 19% of live births in 2012 were at 37-38 weeks' gestation, equating to nearly 140 000 early-term births each year. Since caesarean sections (CS) are often performed at early-term gestations, this accounts for some of the increased proportion of the early-term births. Infants born early-term are at an increased risk of neonatal respiratory morbidity particularly if they are delivered by caesarean section. The long term lung function data are limited but available data suggest that early-term delivery is associated with respiratory morbidity in childhood. CS also appears to be associated with increased neonatal morbidity and future development of respiratory symptoms. However, future studies need to confirm the independent effects of caesarean sections and early-term deliveries particularly for long term outcomes as both are likely to affect the respiratory system differently.

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.

In utero Programming of Allergic Susceptibility

BACKGROUND

Around 30-40% of the world's population will experience allergy, the most common and earliest-onset noncommunicable disease. With a steady rise in the incidence of allergic disease over recent decades, up to 18% of children will suffer a respiratory, food or skin allergy before their 18th birthday. There is compelling evidence that the risk of developing allergy is influenced by early life events and particularly in utero exposures.

METHODS

A comprehensive literature review was undertaken which outlines prenatal risk factors and potential mechanisms underlying the development of allergy in childhood.

RESULTS

Exposures including maternal cigarette smoking, preterm birth and Caesarean delivery are implicated in predisposing infants to the later development of allergy. In contrast, restricted growth in utero, a healthy maternal diet and a larger family size are protective, but the mechanisms here are unclear and require further investigation.

CONCLUSION

To ameliorate the allergy pandemic in young children, we must define prenatal mechanisms that alter the programming of the fetal immune system and also identify specific targets for antenatal interventions.

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.

Early-term birth is a risk factor for wheezing in childhood: A cross-sectional population study

BACKGROUND

Early term-born (37-38 weeks' gestation) infants have increased respiratory morbidity during the neonatal period compared with full term-born (39-42 weeks' gestation) infants, but longer-term respiratory morbidity remains unclear.

OBJECTIVE

We assessed whether early term-born children have greater respiratory symptoms and health care use in childhood compared with full term-born children.

METHODS

We surveyed 1- to 10-year-old term-born children (n = 13,361). Questionnaires assessed respiratory outcomes with additional data gathered from national health databases.

RESULTS

Of 2,845 eligible participants, 545 were early term-born and 2,300 were full term-born. Early term-born children had higher rates of admission to the neonatal unit (odds ratio [OR], 1.7; 95% CI, 1.2-2.5) and admission to the hospital during their first year of life (OR, 1.6; 95% CI, 1.2-2.1). Forty-eight percent of early term-born children less than 5 years old reported wheeze ever compared with 39% of full term-born children (OR, 1.5; 95% CI, 1.1-1.9), and 26% versus 17% reported recent wheezing (OR, 1.7; 95% CI, 1.3-2.4). Early term-born children older than 5 years reported higher rates of wheeze ever (OR, 1.4; 95% CI, 1.05-1.8) and recent wheezing over the last 12 months than full-term control subjects (OR, 1.4; 95% CI, 1.02-2.0). Increased rates of respiratory symptoms in early term-born children persisted when family history of atopy and delivery by means of cesarean sections were included in logistic regression models.

CONCLUSION

Early term-born children had significantly increased respiratory morbidity and use of health care services when compared with full term-born children, even when stratified by mode of delivery and family history of atopy.

Allergic airway diseases in childhood: an update

Complex multifactorial diseases such as allergic rhinitis and asthma are not only becoming an increasing burden to healthcare systems, but especially affect the life quality of children and families suffering from their allergic symptoms. Also physicians are challenged by the multifaceted diseases as their work involves not only the often difficult decisions on case-adapted diagnostics, treatment, and monitoring, but also possible preventive measures. This review gives an outline of the latest scientific developments related to the etiology, diagnosis, and management of allergic airway diseases in childhood, as well as prenatal and early life risk factors and strategies for prevention.

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.

Cohort profile update: 2004 Pelotas (Brazil) Birth Cohort Study. Body composition, mental health and genetic assessment at the 6 years follow-up

This is an update of the 2004 Pelotas Birth Cohort profile, originally published in 2011. In view of the high prevalence of overweight and mental health problems among Brazilian children, together with the availability of state-of-the-art equipment to assess body composition and diagnostic tests for mental health in childhood, the main outcomes measured in the fifth follow-up (mean age 6.8 years) included child body composition, mental health and cognitive ability. A total of 3722 (90.2%) of the original mothers/carers were interviewed and their children examined in a clinic where they underwent whole-body dual X-ray absorptiometry (DXA), air displacement plethysmography and a 3D photonic scan. Saliva samples for DNA were obtained. Clinical psychologists applied the Development and Well-Being Assessment questionnaire and the Wechsler Intelligence Scale for Children to all children. Results are being compared with those of the two earlier cohorts to assess the health effects of economic growth and full implementation of public policies aimed at reducing social inequalities in the past 30 years. For further information visit the programme website at [http://www.epidemio-ufpel.org.br/site/content/coorte_2004/questionarios.php]. Applications to use the data should be made by contacting 2004 cohort researchers and filling in the application form available at [http://www.epidemio-ufpel.org.br/site/content/estudos/formularios.php].

Conception via in vitro fertilization and delivery by Caesarean section are associated with paediatric asthma incidence

BACKGROUND

The association between perinatal factors and asthma inception is under rigorous investigation. Nevertheless, evidence of a correlation between asthma, conception via in vitro fertilization (IVF) and delivery through Caesarean section (C-section) is inconclusive.

OBJECTIVE

We aimed to assess the relation of asthma incidence with IVF and C-section, after controlling for several potential confounding factors.

METHODS

Parent-reported wheeze in the last 12 months (current), wheeze ever, physician-diagnosed asthma, method of conception, and type of delivery were recorded from questionnaires filled in by the parents of 2016 Greek children aged 9-13, (the Healthy Growth Study population). Some perinatal data were recorded from children's medical records and others were reported by parents; anthropometric measurements were also conducted in children.

RESULTS

IVF was correlated with physician-diagnosed asthma (OR = 2.25; 95% CI = 1.11-4.56), but not with current/ever wheeze after adjustment for potential confounding factors. After adjustment, C-section was also associated with asthma (OR = 1.39; 95% CI = 1.04-1.87), but not with current/ever wheeze. When the association of both IVF and C-section with asthma was examined in the same multivariate logistic regression model, it was weakened to borderline significance (OR = 2.04; 95% CI = 1-4.15 and OR = 1.34; 95% CI = 1-1.81 respectively).

CONCLUSIONS AND CLINICAL RELEVANCE

Conception via IVF and delivery by C-section may predispose children to future asthma development. Either variable could also exert a confounding effect on the link of the other to asthma; this may partially be accountable for inconsistencies in the findings of pertinent studies.

Cohort profile update: The 1993 Pelotas (Brazil) birth cohort follow-up visits in adolescence

In this paper we update the profile of the 1993 Pelotas (Brazil) Birth Cohort Study, with emphasis on a shift of priority from maternal and child health research topics to four main categories of outcome variables, collected throughout adolescence: (i) mental health; (ii) body composition; (iii) risk factors for non-communicable diseases (NCDs); (iv) human capital. We were able to trace 81.3% (n = 4106) of the original cohort at 18 years of age. For the first time, the 18-years visit took place entirely on the university premises, in a clinic equipped with state-of-the-art equipment for the assessment of body composition. We welcome requests for data analyses from outside scientists. For more information, refer to our website (http://www.epidemio-ufpel.org.projetos_de_pesquisas/estudos/coorte_1993) or e-mail the corresponding author.

New Views on Cesarean Section, its Possible Complications and Long-Term Consequences for Children's Health

Historical developments and advancements in cesarean section techniques and logistics have reduced the maternal and neonatal risks associated with the procedure, while increasing the number of operatively completed pregnancies for medically unjustifiable reasons. The uncritical attitude towards cesarean section and the fast emergence of ‘modern’ diseases such as obesity at a young age, asthma, type 1 diabetes mellitus and various forms of dermatitis have stimulated researches associating cesarean section with these diseases. Intestinal flora of the children born by cesarean section contains less bifidobacteria, i.e. their intestinal flora is similar to the intestinal flora in diabetic individuals. In children born by cesarean section, the ‘good’ maternal bacterial that are normally found in the maternal birth canal and rectum are lacking, while the ‘bad’ bacteria that may endanger the child’s immune system are frequently present. In children born by vaginal delivery, the ‘good’ maternal bacteria stimulate the newborn’s white blood cells and other components of the immune system, which has been taken as a basis for the hypotheses explaining the evident association of the above morbidities and delivery by cesarean section.

Caesarean section and allergic manifestations: insufficient evidence of association found in population-based study of children aged 1 to 4 years

AIM

To provide evidence on the association between caesarean section and allergic manifestations in an unselected child population.

METHODS

Research focused on all children aged from one to 4 years (N = 4779), born between April 2001 and March 2005 and living in the province of South Karelia, Finland. They were identified from the nationwide population register. Questionnaire data on 3181 participants were individually merged with allergy test results (skin prick tests, IgE antibodies and open food challenges) from all patient records.

RESULTS

Compared with vaginal delivery, the adjusted relative incidence of positive allergy tests (with 95% confidence intervals, CI) in children born by caesarean section was 1.14 (0.79, 1.65) for food, 1.16 (0.66, 2.05) for animals, 0.94 (0.46, 1.92) for pollen and 1.19 (0.87, 1.63) for any allergens. The corresponding adjusted prevalence odds ratios (with 95% CI) of physician-diagnosed allergic manifestations were 1.15 (0.80, 1.63) for food allergy, 0.90 (0.47, 1.59) for pollen allergy or hay fever, 1.00 (0.75, 1.31) for atopic eczema, 0.96 (0.53, 1.65) for asthma and 1.08 (0.85, 1.38) for any allergic manifestation.

CONCLUSION

Insufficient evidence was found in our population for any association between birth by caesarean section and allergic manifestations. Further evidence from unselected populations, with longer follow-up periods, is needed.

Effect of barrier microbes on organ-based inflammation

The prevalence and incidence of chronic inflammatory disorders, including allergies and asthma, as well as inflammatory bowel disease, remain on the increase. Microbes are among the environmental factors that play an important role in shaping normal and pathologic immune responses. Several concepts have been put forward to explain the effect of microbes on the development of these conditions, including the hygiene hypothesis and the microbiota hypothesis. Recently, the dynamics of the development of (intestinal) microbial colonization, its effect on innate and adaptive immune responses (homeostasis), and the role of environmental factors, such as nutrition and others, have been extensively investigated. Furthermore, there is now increasing evidence that a qualitative and quantitative disturbance in colonization (dysbiosis) is associated with dysfunction of immune responses and development of various chronic inflammatory disorders. In this article the recent epidemiologic, clinical, and experimental evidence for this interaction is discussed.

Developments in the field of allergy in 2011 through the eyes of Clinical and Experimental Allergy

As in previous years, we felt it would be of value to our readership to summarize the new information provided by the authors who have published in Clinical and Experimental Allergy in 2011 and set this in the context of recent advances in our understanding of the pathogenesis and management of allergic disease in all its many manifestations. In 2011, about 210 articles were published in Clinical and Experimental Allergy including editorials, reviews, opinion articles, guidelines, letters, book reviews and of course at the heart of the journal, papers containing original data. As before, this review is divided into sections based on the way the journal is structured, although this year we have grouped together all the papers dealing with mechanisms of allergic disease, whether they involve patients (clinical mechanisms), pure in vitro studies (basic mechanisms) or animal models (experimental models), as we felt this was a more coherent way to deal with the subject. In the field of asthma and rhinitis, the relationship between airway inflammation and airway dysfunction was of perennial interest to investigators, as were phenotypes and biomarkers. Aspirin hypersensitivity appeared in studies in several papers and there was new interest in asthma in the elderly. The mechanisms involved in allergic disease describe advances in our understanding of T cell responses, the relationship between inflammation and disease, mast cell and basophil activation, steroid resistance and novel therapies. In the section dealing with epidemiology, studies seeking to identify risk factors for allergic disease including vitamin D are prominent, as once again are studies investigating gene-environment interactions. The clinical allergy section focuses on drug allergy, food allergy and immunotherapy. The area of oral immunotherapy for food allergy is well covered and we were grateful to Stephen Durham for guest editing an outstanding special issue on immunotherapy in the centenary year of Leonard Noon's pioneering work. Lastly, in the field of allergens, the interest in component-resolved diagnosis continues to grow and there are also articles describing important novel cultivars and the effect of food processing on the allergenic properties of foods. Another terrific year, full of important and high-quality work,which the journal has been proud to bring to the allergy community.

Cesarean section and offspring's risk of multiple sclerosis: a Danish nationwide cohort study

BACKGROUND

Apart from a recent study reporting a 2- to 3-fold increased risk of multiple sclerosis (MS) among women and men who were delivered by Cesarean section (C-section), little attention has been given to the possible association between mode of delivery and the risk of MS.

OBJECTIVES

We studied the association between C-section and risk of MS, in a cohort of 1.7 million Danes born from 1973 to 2005.

METHODS

Information on C-section and MS was obtained from the Danish Medical Birth Register and the Danish MS Register, respectively. The association between C-section and MS was evaluated by means of MS incidence rate ratios (RR) with 95% confidence intervals (CI) obtained in log-linear Poisson regression analyses.

RESULTS

There were 930 cases of MS in the study cohort, of whom 80 (9%) were delivered by C-section. Overall, we found there was no significant association between C-section and risk of MS (RR = 1.17; 0.92-1.46). Analyses stratified by sex revealed no unusual risk of MS for women (RR = 1.08: 0.80-1.42) nor men (RR = 1.37: 0.91-1.98). A supplementary sibling-matched Cox regression analysis likewise suggested there was no excess risk of MS in persons delivered by C-section (HR = 1.03; 0.63-1.69).

CONCLUSIONS

Mode of delivery appears to be unimportant in relation to MS development in the offspring.

The impact of birth mode of delivery on childhood asthma and allergic diseases--a sibling study

BACKGROUND

Caesarean section (CS) has been reported to increase the risk of asthma in offspring. This may be due to that infants delivered by CS are unexposed to vaginal flora, according to the 'hygiene hypothesis'.

OBJECTIVE

Our aim was to investigate if CS increases risk of childhood asthma, and if the risk increase remains after adjustment for familial confounding using sibling design.

METHODS

A register-based cohort study with 87 500 Swedish sibling pairs was undertaken. Asthma outcome variables were collected from national health registers as diagnosis or asthma medication (ICD-10 J45-J46; ATC code R03) during the 10th or 13th year of life (year of follow-up). Mode of delivery and confounders were retrieved from the Medical Birth Register. The data were analysed both as a cohort and with sibling control analysis which adjusts for unmeasured familial confounding.

RESULTS

In the cohort analyses, there was an increased risk of asthma medication and asthma diagnosis during year of follow-up in children born with CS (adjusted ORs, 95% CI 1.13, 1.04-1.24 and 1.10, 1.03-1.18 respectively). When separating between emergency and elective CS the effect on asthma medication remained for emergency CS, but not for elective CS, while both groups had significant effects on asthma diagnosis compared with vaginal delivery. In sibling control analyses, the effect of elective CS on asthma disappeared, while similar but non-significant ORs of medication were obtained for emergency CS.

CONCLUSIONS AND CLINICAL RELEVANCE

An increased risk of asthma medication in the group born by emergency CS, but not elective, suggests that there is no causal effect due to vaginal microflora. A more probable explanation should be sought in the indications for emergency CS.

Asthma and atopy in children born by caesarean section: effect modification by family history of allergies - a population based cross-sectional study

Background

Studies on the association of birth by caesarean section (C/S) and allergies have produced conflicting findings. Furthermore, evidence on whether this association may differ in those at risk of atopy is limited. This study aims to investigate the association of mode of delivery with asthma and atopic sensitization and the extent to which any effect is modified by family history of allergies.

Methods

Asthma outcomes were assessed cross-sectionally in 2216 children at age 8 on the basis of parents’ responses to the ISAAC questionnaire whilst skin prick tests to eleven aeroallergens were also performed in a subgroup of 746 children. Adjusted odds ratios of asthma and atopy by mode of delivery were estimated in multivariable logistic models while evidence of effect modification was examined by introducing interaction terms in the models.

Results

After adjusting for potential confounders, children born by C/S appeared significantly more likely than those born vaginally to report ever wheezing (OR 1.36, 95% CI 1.07-1.71), asthma diagnosis (OR 1.41, 95% CI 1.09-1.83) and be atopic (OR 1.67, 95% CI 1.08-2.60). There was modest evidence that family history of allergies may modify the effect of C/S delivery on atopy (p for effect modification=0.06) but this was not the case for the asthma outcomes. Specifically, while more than a two-fold increase in the odds of being a topic was observed in children with a family history of allergies if born by C/S (OR 2.62, 95% CI 1.38-5.00), no association was observed in children without a family history of allergies (OR 1.16, 95% CI 0.64-2.11).

Conclusions

Birth by C/S is associated with asthma and atopic sensitization in childhood. The association of C/S and atopy appears more pronounced in children with family history of allergies.

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.