Caesarean section delivery and the risk of allergic disorders in childhood

BACKGROUND: The composition of the intestinal flora in young children, if unfavourable, may increase the susceptibility to allergic disorders. Beneficial intestinal microbes originate from the maternal vaginal tract and thus are more likely to be transferred during vaginal births than during Caesarean sections (C-sections). OBJECTIVE: To determine whether children born by C-section have a different risk of allergic disorders compared with those delivered vaginally. We also tested the hypothesis that the risk of allergic disorders is highest for children born after 'repeat C-sections'. METHODS: A retrospective cohort study of 8,953 children aged 3-10 years. Children diagnosed with allergic rhinoconjunctivitis (AR), asthma, atopic dermatitis (AD), or food allergies were identified from the Kaiser Permanente Northwest Region electronic records. The children's sex, birth weight, birth order, postnatal exposure to antibiotics as well as the mothers' age, ethnicity, education, marital status, smoking status during pregnancy, and use of asthma or hayfever medications were identified through the mothers' medical records or through the Oregon Birth Registry. RESULTS: The risk of being diagnosed with AR was significantly higher in the children born by C-section than in those delivered vaginally: adjusted odds ratio (OR)=1.37%, 95% confidence interval (CI)=1.14-1.63. Delivery by C-section was also associated with the subsequent diagnosis of asthma (OR=1.24%, 95% CI=1.01-1.53); this association was gender specific, with a positive association restricted to girls (OR for asthma in girls: OR=1.53%, 95% CI=1.11-2.10; in boys: OR=1.08%, 95% CI=0.81-1.43). There was no significant association between mode of delivery and AD. If children born in a 'repeat C-section' were considered separately the risk of being diagnosed with AR increased further (OR=1.78%, 95% CI=1.34-2.37). The same increase was noted for asthma in girls (OR=1.83%, 95% CI=1.13-2.97) but not in boys. CONCLUSION: Caesarean sections may be associated with an increased risk of developing AR in childhood.     

Mode of delivery is not associated with asthma or atopy in childhood

BACKGROUND: Caesarean-section delivery has been associated with the subsequent development of atopy and wheezing in childhood. OBJECTIVE: To examine the association between mode of delivery (vaginal vs. caesarean section) and development of atopy, asthma and wheezing disorders in a population-based cohort of children. METHODS: The Avon Longitudinal Study of Parents and Children is a longitudinal birth cohort of children born 1 April 1991 to 31 December 1992. Mode of delivery was categorized as vaginal (including forceps and ventouse extractions) or caesarean section (elective and emergency). Primary outcomes were parental report of asthma or wheezing between 69 and 81 months of age, physician-diagnosed asthma (PDA) at 91 months of age and atopy at 7 years by skin prick testing. Possible confounding factors were considered in a multivariable logistic regression model. RESULTS: Total livebirths were 14,062, from which were selected 12 367 born to mothers resident in a defined area and delivered in one of two major obstetric hospitals. Of these infants, 10,980 (88.8%) were delivered vaginally and 1387 (11.2%) by caesarean section. Outcome data were available for 7495 (61%) subjects (asthma 69-81 months); 7389 (60%) (wheeze 69-81 months); 7196 (58%) (PDA 91 months) and 5916 (48%) (atopy 7 years). Adjusted odds ratios [95%confidence interval] for caesarean section compared with vaginal delivery were not statistically significant for any outcome we considered: asthma 69-81 months 1.16 [0.9, 1.5]; wheeze 69-81 months 0.95 [0.7, 1.3]; PDA 1.14 [0.9, 1.4]; atopy 1.04 [0.8, 1.3]. CONCLUSION: Delivery by caesarean section was not associated with the subsequent development of asthma, wheezing or atopy in later childhood in this population.     

Thymus size and head circumference at birth and the development of allergic diseases

BACKGROUND: The positive association between a large head circumference at birth and total serum IgE levels has been suggested to be due to negative associations between head circumference at birth and thymus development and between thymus development and total serum IgE levels. OBJECTIVES: To examine the associations between head circumference and thymus size at birth and the development of allergic disease. METHODS: The size of the thymus was assessed by sonography during the first week of life in 149 healthy term infants. Information on birth characteristics and mode of delivery was collected at delivery. The presence of allergic disease was assessed 5 years later by mailed questionnaires, which were returned by 85% of the eligible families. RESULTS: At birth, head circumference was positively associated with thymus size (P < 0.001). In all, 27 (23%) of the children had developed at least one allergic disease. Multivariate analysis revealed that both parental allergy (Prevalence Ratio and 95% CI) = 3.18 (1.49-6.78)) and caesarean delivery (2.62 (1.48-4.64)) were independently correlated with allergic disease, whereas thymus size was not. CONCLUSIONS: Our study does not support that a large head circumference is associated with a small thymus size, nor that a small thymus size is associated with allergic disease. Whether thymus size at birth is related to total serum IgE levels still remains to be elucidated.     

Incidence and remission of self-reported allergic rhinitis symptoms in adults

BACKGROUND: A few studies have examined the incidence and remission of allergic rhinitis (AR) in the same general population. METHODS: A questionnaire focused on respiratory symptoms and airway diseases was mailed out in 1992 and in 2000 to the same subjects. Of 4933 subjects, in 1992 aged 20-59 years, 4280 (86.8%) answered at both occasions. AR was defined on self-reported AR and a simultaneous report of nasal symptoms provoked by exposure either to tree-, grass-pollen, furred animals or house dust. Multiple logistic regression adjusted for age and gender was used to analyze potential predictors, reported in 1992, for incidence and remission of AR. RESULTS: The prevalence of AR increased from 12.4% in 1992 to 15.0% in 2000. The incidence of AR from 1992 to 2000 was 4.8%, while 23.1% of the cases with AR in 1992 stated no AR symptoms in 2000 indicating remission. The highest incidence was seen in the youngest age group (20-29 years), whereas remission was highest in the oldest age group (50-59 years). Asthma symptoms during the last year (as reported in 1992) predicted increased incidence of AR and less chance for remission, 1.89 (95%CI 1.08-3.31) and 0.52 (0.31-0.87), respectively. Family histories of AR or asthma predicted increased incidence of AR 1.99 (1.42-2.80) and 1.62 (1.10-2.37), respectively, but were not associated with chance for remission, OR = 1.23 (0.81-1.87) and 0.94 (0.60-1.48). CONCLUSION: This study showed that AR became more common between 1992 and 2000, but also indicated remission in about 20% of the cases within the 8-year period, particularly in older ages. Asthma seems to be associated with higher risk for AR as well as less chance for remission, while heredity of asthma (or AR) may only be associated with the risk for the development and not remission of AR.     

Caesarean section increases the risk of hospital care in childhood for asthma and gastroenteritis

OBJECTIVE: To investigate if caesarean section (CS) increases the risk for childhood asthma and gastroenteritis with reference made to children born with vaginal delivery (VD). METHODS: Retrospective study of data from linked Swedish medical service registers--Medical Birth Registry (MBR) and Hospital Discharge Registry (HDR). Data were obtained from women without any background/perinatal morbidity noted, and from children without any neonatal complications. Children that had reached at least 1 year of age and were found in the HDR were considered as cases, whereas children not found in the HDR or hospitalized for other causes than asthma or gastroenteritis were defined as controls. Odds ratios (OR) stratified for year of birth, maternal age, parity and smoking in early pregnancy were calculated. Investigations were made comparing the risk for in hospital treatment for asthma or gastroenteritis in CS children and in VD siblings of CS children. The overall inpatient morbidity in CS and VD children were also investigated. RESULTS: The OR for asthma in CS children was 1.31 [95% confidence interval (CI) 1.23-1.40]. The same OR, 1.31, was found for gastroenteritis (95% CI 1.24-1.38). The OR for CS children having experienced both asthma and gastroenteritis was further increased (1.74, 95% CI 1.36-2.23). The risk for asthma in VD siblings of CS children was not significantly increased, whereas VD siblings experienced a slightly increased risk for gastroenteritis. CS children had an increased overall in hospital morbidity when compared to VD children. CONCLUSION: There is a significant increase of the risk for developing symptoms of asthma and/or gastroenteritis that motivates admission for hospital care in CS children older than 1 year. It is speculated that a disturbed intestinal colonization pattern in CS children may be a common pathogenic factor.     

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

Cite this as: A. M. B. Menezes,P. C. Hallal, A. M. Matijasevich,A. J. D. Barros, B. L. Horta, C. L. P. Araujo,D. P. Gigante, I. S. Santos, G. Minten,M. R. Domingues, S. C. Dumith and F. C. Barros, Clinical & Experimental Allergy, 2011 (41) 218–223.

Summary

Background There is evidence from two meta‐analyses that children born through caesarean section (C‐section) may have an increased risk of developing asthma compared with those born through vaginal delivery. Objective To evaluate the association between mode of delivery and wheezing (current and persistent) in childhood and adolescence, in two birth cohort studies in Brazil. Methods The outcome variable was based on the International Study of Allergy and Asthma questionnaire, which collects information about wheezing within the 12 months before the interview. Persistent wheezing was defined when it was present in more than one follow‐up at different ages, in the 1993 cohort. The questions were asked to mothers when children were aged 4 years (1993 and 2004 cohorts) and directly to cohort participants at 11 and 15 years (1993 cohort). Mode of delivery was collected by the research team of each cohort when children were born. Results Response rates in the last follow‐up visit of the 1993 and 2004 cohorts were 85% and 92%, respectively. The prevalence of current wheezing increased from 20% to 28% at 4 years from 1993 to 2004; at 11 and 15 years, the prevalence was around 14% and 12%, in the 1993 cohort. The proportion of C‐sections increased from 30.5% to 45% between 1993 and 2004. In each cohort, the prevalence of current wheezing was similar among children born through vaginal and C‐section. The risk for persistent wheezing in the 1993 cohort was higher among girls born through C‐section than boys. Conclusion Despite the increase in the proportion of C‐section in two cohorts in Southern Brazil, we found no evidence of an association between mode of delivery and the subsequent risk of wheezing. Among girls, although there was no statistical significance, the risk was higher for those born by C‐section, especially regarding persistent wheezing.     

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.     

The impact of caesarean delivery and type of feeding on cow’s milk allergy in infants and subsequent development of allergic march in childhood

Background: The incidence of IgE‐mediated cow’s milk allergy (CMA) has increased over the last few years. There are several genetic and environmental risk factors that may be related to this allergy and the subsequent allergic march (AM). Methods: A prospective, cohort study was conducted in patients recruited into the study between 1998 and 2002. Information on clinical variables and complementary tests, perinatal and obstetric factors and the type of hydrolysed formula used was recorded. A cross sectional study on the prevalence of allergic diseases in this cohort was performed in 2004. Results: We compared IgE‐mediated CMA patients with non‐IgE‐mediated CMA patients and found that IgE‐mediated CMA is associated with caesarean delivery (OR = 2.14 95% CI: 1.02–4.49), duration of breast feeding (>2 months, OR = 4.14; 95% CI: 2.17–7.89) and the use of supplementary artificial formula whilst breast feeding (OR = 2.86; 95% CI: 1.33–6.13). The factors associated with AM in IgE‐mediated CMA patients were caesarean delivery (OR = 0.42; 95% CI: 0.19–0.92) and the use of more extensively hydrolysed high grade hydrolysates (+EH/HGH) (OR = 0.44; 95% CI: 0.20–0.98), both as protective factors. Conclusions: Caesarean delivery is demonstrated as being a risk factor for IgE‐mediated CMA, but it does not increase the risk of AM in these infants. The use of +EH/HGH appears to protect IgE‐mediated CMA patients from eventually developing AM.     

Rhinitis in pre-school children: prevalence, association with allergic diseases and risk factors

BACKGROUND: The aim of our study was to assess the prevalence of rhinitis, sneezing, runny or blocked nose apart from colds in a pre-school children population and to evaluate the risk factors and relationship with allergic diseases and sensitization. METHODS: Eighteen nursery schools were randomly selected. The International Study of Asthma and Allergies in Childhood (ISAAC) written questionnaire (WQ) was distributed and filled by parents of pre-school children (3-5 years). The allergic sensitization to common aeroallergens and foods was evaluated by skin prick test (SPT). chi2 tests were used to compare proportions between rhinitic and non-rhinitic children. RESULTS: One thousand four hundred and two (92%) valuable questionnaires were returned. Prevalence of rhinitis in the last 12 months was 16.8%. Rhinitic children compared to non-rhinitic children presented a significant increase of diagnosed asthma (20.8% vs. 6.2%, P<0.001), lifetime wheezing (43.2% vs. 21.6%, P<0.001), wheezing in the last 12 months (25.0% vs. 9.4%, P<0.001), atopic dermatitis (22.9% vs. 13.9%, P<0.001) and allergic sensitization (29.9% vs. 13.7%, P<0.001). Sensitization to grass pollen and house dust mites were significant risk factors for rhinitis (P<0.01). A family history of atopy, having pets at home, male gender and greater age were significant risk factors for rhinitis, but not smoking exposure, sharing a bedroom or breastfeeding. CONCLUSIONS: In pre-school children rhinitis has a strong association with wheezing symptoms, asthma and atopic dermatitis. Allergic sensitization is a risk factor for rhinitis and should be evaluated even in pre-school children.     

Bronchial hyperresponsiveness in young children with allergic rhinitis and its risk factors

BACKGROUND: Subjects with allergic rhinitis but no clinical evidence of asthma have greater bronchial hyperresponsiveness (BHR), and several factors have been implicated as its determinants. However, studies in young children are lacking. The aims of this study were to evaluate the prevalence of BHR in young children with allergic rhinitis and to investigate its risk factors. METHODS: Methacholine bronchial challenges were performed in 4- to 6-year-old nonasthmatic children with allergic rhinitis (n = 83) and in healthy nonatopic controls (n = 32), using a modified auscultation method. The end-point was defined as the appearance of wheezing and/or oxygen desaturation. Subjects were considered to have BHR when they had end-point concentrations of methacholine 相似文献   

Prevalence of childhood asthma and allergic diseases in Ankara, Turkey

Kalyoncu AF, Selçuk ZT, Karakoca Y, Emri AS, Çöplü L, Şahin AA, Bariş YI. Prevalence of childhood asthma and allergic diseases in Ankara, Turkey.
The first epidemiologic survey of the prevalence of childhood asthma and other allergic disease in Ankara, Turkey, was done in May 1992. A questionnaire on factors influencing the atopic status and allergic symptoms was distributed to parents of 1226 children aged 6-12 years. In this questionnaire, parents were asked to give information about physician-diagnosed asthma and atopic dermatitis (AD), and self-reported wheezing and rhinoconjunctivitis (perennial or seasonal). The overall response rate was 85 % and included 502 boys (48.5%) and 534 girls (51.5%). The lifetime prevalences of asthma, wheezing, rhinoconjunctivitis, and AD were 17.4%, 23.3%, 28%, and 6.1%, respectively, and the reported prevalences for the last 12 months were 8.3%, 11.9%, 15.4%, and 4%, respectively. Asthma and other allergic disease had been recognized in 23.2% of the children during the last year; in half of these, more than one disease was present. Eight percent of the families kept pet animals; 95.4% of children had been breast-fed, of whom 61% for more than 6 months; and at least one person smoked at home in the case of 73.9% of children. Some health insurance was available to 72.8% of the families. Cumulative prevalences of wheezing, rhinoconjunctivitis, and AD were significantly associated with the presence of pets, passive smoking at home, and absence of health insurance. The prevalence of asthma was not affected by any of these factors except atopic family history. In conclusion, asthma and other allergic diseases constitute a major health problem for schoolchildren in Ankara.     

Evaluating the allergic risk of genetically modified soybean

Genetically modified (GM) soybean (carrying the EPSPS transgene) is the most common GM food in Korea. In order to assess whether genetic modification increases the allergenic risk of soybeans, the allergenicity and IgE-reactive components of wild-type and GM soybean extracts were compared in allergic adults who had been sensitized to soybeans. We enrolled 1,716 adult allergy patients and 40 healthy, non-atopic controls. Skin prick tests and IgE enzyme linked immunosorbent assays (ELISAs) were performed using wild-type and GM soybean extracts, along with other common inhaled allergens. The specificities of serum IgE antibodies from allergic patients and the identities of the IgE-reactive components of the soybean extracts were compared using ELISA inhibition testing, 2-dimensional gel electrophoresis, and IgE immunoblotting. To evaluate the effects of digestive enzymes and heat treatment, the soybean extracts were heated or pre- incubated with or without simulated gastric and intestinal fluids. The IgE sensitization rates to wild-type and GM soybeans were identical (3.8% of allergic adults), and circulating IgE antibodies specific for the two extracts were comparable. The results of the ELISA inhibition test, SDS-PAGE, and IgE immunoblotting showed a similar composition of IgE-binding components within the wild-type and GM extracts, which was confirmed using two-dimensional gel electrophoresis, IgE immunoblotting, and amino acid sequencing. None of the subjects had a positive response to purified EPSPS protein in the skin prick test, ELISA, or IgE immunoblot analysis. These findings suggest that the IgE sensitization rate to GM soybean extracts is identical to that of wild-type soybean extracts in adult allergy patients. In addition, based on both in vivo and in vitro methods, the allergenicity of wild type and GM soybean extracts was identical.     

Pregnancy: Coffee and alcohol intake, smoking and risk of multiple pregnancy

We analysed the relationship between coffee and alcohol intake,smoking and risk of multiple pregnancies using data from a case-controlstudy on risk factors for multiple births conducted in Italy.Cases were 133 women who delivered multiple births not relatedto treatment for infertility (33 monozygotic and 100 dizygotictwins). Controls were 395 women admitted for normal deliveryat the same clinic where cases had been identified. The oddsratios (OR) of multiple pregnancy were 1.5 [95% confidence interval(CI) 0.8–2.8] and 2.0 (95% CI 1.0–3.7) for womendrinking respectively one to two or three or more cups of coffeeper day in comparison with non-coffee drinkers. Consideringseparately dizygotic and monozygotic pregnancies, the estimatedOR were respectively for women drinking three or more cups ofcoffee, 1.7 and 3.1 for dizygotic and monozygotic pregnancies.The risk of multiple pregnancy tended to be higher in womendrinking 15 alcohol drinks per week: in comparison with tea-totallersthe estimated OR for drink 15 glasses per week were 23 and 2.6respectively for dizygotic and monozygotic pregnancies. Heavysmokers (10 cigarettes per day) were at increased risk of multiplepregnancy: in comparison with never smokers, the estimated ORfor multiple pregnancy was 1.6 (95% CI 0.9–2.7). Consideringseparately the two groups of multiple pregnancy, the OR of dizygoticand monozygotic pregnancy were 1.4 (95% CI 0.8–2.5) and2.4 (95% CI 0.9–6.1) for women smoking 10 cigarettes/day, but the trend in risk with number of cigarettes smokedper day and duration of the habit was not significant.