Cesarean delivery and cow milk allergy/intolerance

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.

Mode of Birth Is Not Associated With Food Allergy Risk in Infants

BACKGROUND

The association between mode of delivery and the risk of food allergy remains unclear due to the absence of studies with both challenge-proven food allergy outcomes and detailed information on the type of caesarean delivery.

OBJECTIVE

We assessed whether emergency or elective caesarean, or caesarean delivery in the presence or absence of labor initiation, is associated with the risk of food allergy.

METHODS

The HealthNuts study recruited 5276 12-month-old infants who underwent skin prick testing and oral food challenge to ascertain food allergy status, and linked the child's study data to additional birth data from the Victorian Perinatal Data Collection.

RESULTS

Parents of 3006 children consented to data linkage, and birth data were obtained on 2045. In this subgroup, 30% were born by caesarean and 13% had food allergy. Caesarean delivery, compared with vaginal birth, was not associated with the risk of food allergy (adjusted odds ratio [aOR]: 0.95, 95% confidence interval [CI]: 0.70, 1.30). Neither caesarean delivery before the onset of labor, nor after the onset of labor, was associated with the risk of food allergy (aOR: 0.83, 95% CI: 0.55-1.23 and aOR: 1.13, 95% CI: 0.75-1.72, respectively). Delivery by elective or emergency caesarean, compared with vaginal delivery, was not associated with risk of food allergy (aOR: 1.05, 95% CI: 0.71-1.55 and aOR: 0.86, 95% CI: 0.56-1.31). There was no evidence of effect modification by breastfeeding, older siblings, pet dog ownership, or maternal allergy.

CONCLUSION

Caesarean delivery, either with or without labor, or elective or emergency, was not associated with the risk of food allergy in a population-based cohort of 12-month-old infants.

INDUCED PROCTOCOLITIS - ORAL FOOD CHALLENGE SHOULD BE DONE TO CONFIRM THE DIAGNOSIS OF COW'S MILK ALLERGY IN NEONATES?

BACKGROUND

Suspicion of food protein-induced proctocolitis based on empirical understanding of rectal bleeding can lead to misdiagnosis.

OBJECTIVE

to verify clinical and evaluative characteristics of patients who presented neonatal rectal bleeding and were on a restricted cow's milk diet.

METHODS

A cross-sectional retrospective study included patients followed up in a tertiary care center, who presented rectal bleeding in the neonatal period. The analyzed data included gender, gestational age, type of delivery, use of antibiotics during the last trimester of pregnancy, use of parenteral nutrition before the first manifestation, use of mechanical ventilation, initial clinical manifestations associated with rectal bleeding, diet before the first manifestation, period of elimination diet, oral food challenge (OFC) results and symptoms presented in cases of positive OFC. Fisher's exact test and Mann-Whitney test were used to analyze the data. The level of significance was set to 5%.

RESULTS

Forty-two patients were selected: 30 preterm infants, 34 cesarean deliveries, 10 exclusively breastfed patients before rectal bleeding. Median age at OFC was 6.3 months old. Median of length of the elimination period before OFC was 5.9 months. OFC was negative in 33/42 (79%) patients and positive in 9/42 (21%). There was no association between OFC results and the evaluated data. The main symptom observed in patients with positive OFC was blood in stools.

CONCLUSION

OFC was negative in most cases of suspected cow's milk allergy due to rectal bleeding in neonates, most of them with a history of prematurity.

The prevalence of food allergy in cesarean-born children aged 0-3 years: A systematic review and meta-analysis of cohort studies

PURPOSE

Previous studies reported a higher risk of food allergy for cesarean-born children than vaginal-born children. This study aims to systematically compare the prevalence of food allergy among cesarean-born and vaginal-born children aged 0-3 years.

METHODS

Three English and two Chinese databases were searched using terms related to food allergies and cesarean sections. Cohort studies that reported the prevalence of food allergy in cesarean-born and vaginal-born children aged 0-3 years were included. Two reviewers performed study selection, quality assessment, and data extraction. The pooled prevalence of food allergy in cesarean-born and vaginal-born children was compared by meta-analysis.

RESULTS

Nine eligible studies, with 9,650 cesarean-born children and 20,418 vaginal-born children aged 0-3 years, were included. Of them, 645 cesarean-born children and 991 vaginal-born children were identified as having food allergies. The pooled prevalence of food allergy was higher in cesarean-born children (7.8%) than in vaginal-born children (5.9%). Cesarean section was associated with an increased risk of food allergy [odds ratio (OR): 1.45; 95% confidence interval (CI): 1.03-2.05] and cow's milk allergy (OR: 3.31; 95% CI: 1.98-5.53). Additionally, cesarean-born children with a parental history of allergy had an increased risk of food allergy (OR: 2.60; 95% CI: 1.28-5.27).

CONCLUSION

This study suggests that cesarean sections was associated with an increased risk of food and cow's milk allergies in children aged 0-3 years. Cesarean-born children with a parental history of allergy demonstrated a higher risk for food allergy than did vaginal-born children. These results indicate that caregivers should be aware of the risks of food allergies in cesarean-born children, reducing the risk of potentially fatal allergic events. Further research is needed to identify the specific factors affecting food allergies in young children.

SYSTEMATIC REVIEW REGISTRATION

http://www.crd.york.ac.uk/prospero, identifier: International Prospective Register of Systematic Reviews (NO. CRD42019140748).

Cesarean Delivery and Healthcare Utilization and Costs in the Offspring: A Retrospective Cohort Study

OBJECTIVE

To examine the association between cesarean delivery and healthcare utilization and costs in offspring from birth until age 7 years.

STUDY DESIGN

A retrospective cohort study of singleton term births in the Canadian province of Nova Scotia between 2003 and 2007 followed until age 7 years was conducted using data from the Nova Scotia Atlee Perinatal Database and administrative health data. The main exposure was mode of delivery (cesarean delivery vs vaginal birth); the outcome was healthcare utilization and costs during the first 7 years of life. Associations were modeled using multiple regression adjusting for maternal prepregnancy weight and sociodemographic factors.

RESULTS

In total, 32 464 births were included in the analysis. Compared with children born by vaginal birth, children born by cesarean delivery had more physician visits (incidence rate ratio 1.06, 95% CI 1.05-1.08) and longer hospital stays (incidence rate ratio 1.12, 95% CI 1.03-1.21) and were more likely to be high utilizers of physician visits (OR 1.23, 95% CI 1.10-1.37). Physician and hospital costs were $775 higher for children born by cesarean delivery compared with vaginal birth.

CONCLUSIONS

Cesarean delivery compared with vaginal birth is associated with small but statistically significant increases in healthcare utilization and costs during the first 7 years of life.

Microbial Colonization at Early Life Promotes the Development of Diet-Induced CD8αβ Intraepithelial T Cells

Intraepithelial lymphocytes (IELs) develop through the continuous interaction with intestinal antigens such as commensal microbiome and diet. However, their respective roles and mutual interactions in the development of IELs are largely unknown. Here, we showed that dietary antigens regulate the development of the majority of CD8αβ IELs in the small intestine and the absence of commensal microbiota particularly during the weaning period, delay the development of IELs. When we tested specific dietary components, such as wheat or combined corn, soybean and yeast, they were dependent on commensal bacteria for the timely development of diet-induced CD8αβ IELs. In addition, supplementation of intestinal antigens later in life was inefficient for the full induction of CD8αβ IELs. Overall, our findings suggest that early exposure to commensal bacteria is important for the proper development of dietary antigen-dependent immune repertoire in the gut.

Solid Food Introduction and the Development of Food Allergies

The rise of food allergy in childhood, particularly among developed countries, has a significant weight on public health and involves serious implications for patients' quality of life. Even if the mechanisms of food tolerance and the complex interactions between the immune system and environmental factors are still mainly unknown, pediatricians have worldwide implemented preventive measures against allergic diseases. In the last few decades, the prevention of food allergy has tracked various strategies of complementary feeding with a modification of international guidelines from delayed introduction to early weaning. Current evidence shows that complementary foods, including allergenic ones, should be introduced into diet after four months, or even better, following World Health Organization advice, around six months irrespective of risk for allergy of the individual. The introduction of peanut is recommended before 12 months of age among infants affected by severe eczema and/or egg allergy to diminish the occurrence of peanut allergy in countries with high peanut consumption. The introduction of heated egg at 6⁻8 months of age may reduce egg allergy. Infants at high risk of allergy similarly to healthy children should introduce complementary foods taking into account family and cultural preferences.

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.

Association between Caesarean Delivery and Isolated Doses of Formula Feeding in Cow Milk Allergy

BACKGROUND

Cow milk allergy (CMA) is the most common food allergy in breastfed infants. The aim of this study is to verify whether certain perinatal factors may influence the development of CMA immunoglobulin E (IgE)+.

METHODS

A retrospective, observational study of case and control groups was carried out. Information was collected of patients with CMA IgE+ from our department during the years 1990-2013. Patients of the same age and sex were recruited for the control group. Information on the following variables was collected: sex, age, pregnancy tolerance, duration of pregnancy, type of delivery, isolated doses of formula feeding in hospital (FFH), duration of breastfeeding, and family history of allergy (defined as ≥1 first-degree family member with allergic disease). Statistical analysis was performed using multivariate logistic regression techniques.

RESULTS

A total of 211 cases were included in this study. Multivariate analysis showed an influence of duration of breastfeeding, FFH to be a risk factor (OR 4.94; 95% CI 2.68-9.08), especially in caesarean delivery (OR 11.82; 95% CI 2.64-47.50), and prematurity (OR 0.29; 95% CI 0.09-0.92) to be a protective factor.

CONCLUSIONS

Perinatal factors play a key role in the development of CMA IgE+, with an influence of breastfeeding duration, FFH and caesarean delivery as risk factors and prematurity as a protective factor. While family history had no important role, environmental factors were more decisive.

Childhood body mass is positively associated with cesarean birth in Yucatec Maya subsistence farmers

OBJECTIVE

The epidemiologic link between cesarean birth and childhood obesity is unresolved, partly because most studies come from industrialized settings where many post-birth factors affect the risk for obesity. We take advantage of an unusual ethnographic situation where hospital and cesarean birth modes have recently been introduced among Yucatec Maya subsistence farmers, but young children have had minimal exposure to the nutritional transition. While we expect to find very low rates of childhood obesity, we predict that cesarean-born children will be larger and heavier than vaginally born children.

METHODS

Weight and height were collected monthly on 108 children aged 0-5 (3576 observations total). Birth mode and birthweight were collected by maternal interview. Data were analyzed using linear mixed models that compare child growth [Maya population-specific Z-scores for weight-for-age and body mass index-for-age (WAZ and BMIZ)] in cesarean and vaginally born children aged 0-5 years.

RESULTS

The cesarean rate was 20%, no children were obese, and 5% were overweight. Cesarean birth was a significant predictor of child WAZ and BMIZ after accounting for maternal effects, child birthweight, and sex. Children who were born by cesarean to mothers with high BMI had the highest WAZ of all children by 5 years of age, and the highest BMIZ of all children at all ages.

CONCLUSION

Cesarean-born Maya children had higher BMI than vaginally born children, even in the absence of many known confounding factors that contribute to childhood obesity. Child growth was most sensitive to birth mode when mothers had high BMI.

Cesarean section delivery and development of food allergy and atopic dermatitis in early childhood

BACKGROUND

Delivery by Cesarean section (CS) may predispose to allergic disorders, presumably due to alterations in the establishment of normal gut microbiota in early infancy. In this study, we sought to investigate the association between CS and physician-diagnosed food allergy and atopic dermatitis during the first 3 years of life, using data from a homogeneous, population-based, birth cohort.

METHODS

A total of 459 children born and cared for in the same tertiary maternity unit were examined at birth and followed up at 1, 6, 12, 18, 24, 30 and 36 months of age. Participants with symptoms suggestive of food allergy or atopic dermatitis were evaluated by a pediatric allergy specialist to confirm the diagnosis based on well-defined criteria.

RESULTS

The rate of CS was 50.8% (n = 233). Food allergy was diagnosed in 24 participants (5.2%) while atopic dermatitis was diagnosed in 62 children (13.5%). Cesarean section (OR 3.15; 95% CI 1.14-8.70), atopic dermatitis of the child (OR 3.01; 95% CI 1.18-7.80), parental atopy (OR 4.33; 95% CI 1.73-12.1), and gestational age (OR 1.57; 95% CI 1.07-2.37) were significant and independent predictors of food allergy. Children with at least one allergic parent delivered by CS had higher probability of developing food allergy compared with vaginally delivered children of non-allergic parents (OR 10.0; 95% CI 3.06-32.7). Conversely, the effect of CS on atopic dermatitis was not significant (OR 1.35; 95% CI 0.74-2.47).

CONCLUSIONS

Delivery by CS predisposes to the development of food allergy but not atopic dermatitis in early childhood. Cesarean section delivery seems to upregulate the immune response to food allergens, especially in children with allergic predisposition.

Bugs for atopy: the Lactobacillus rhamnosus GG strategy for food allergy prevention and treatment in children

Food allergy (FA) is a major health issue for children living in Western countries. At this time the only proven treatment for FA is elimination of offender antigen from the diet. It is becoming clear that the development of gut microbiota exerts a profound influence on immune system maturation and tolerance acquisition. Increasing evidence suggests that perturbations in gut microbiota composition of infants are implicated in the pathogenesis of FA. These findings have unveiled new strategies to prevent and treat FA using probiotics bacteria or bacterial substance to limit T-helper (Th)/Th2 bias, which changes during the disease course. Selected probiotics administered during infancy may have a role in the prevention and treatment of FA. Lactobacillus rhamnosus GG (LGG) is the most studied probiotic in this field. Administration of LGG in early life have a role in FA prevention. Preliminary evidence shows that LGG accelerates oral tolerance acquisition in cow's milk allergic infants. We are understanding the mechanisms elicited by LGG and metabolites in influencing food allergen sensitization. A deeper definition of these mechanisms is opening the way to new immunotherapeutics for children affected by FA that can efficiently limit the disease burden.

Gut Microbiome and the Development of Food Allergy and Allergic Disease

The impact of gut microbiome on human development, nutritional needs, and disease has become evident with advances in the ability to study these complex communities of microorganisms, and there is growing appreciation for the role of the microbiome in immune regulation. Several studies have examined associations between changes in the commensal microbiota and the development of asthma, allergic rhinitis, and asthma, but far less have evaluated the impact of the microbiome on the development of food allergy. This article reviews the human gastrointestinal microbiome, focusing on the theory and evidence for its role in the development of IgE-mediated food allergy and other allergic diseases.

Perinatal factors associated with the development of cow's milk protein allergy

The prevalence of cow's milk protein allergy (CMPA) has increased in recent years, and is associated with antimicrobial use during the perinatal period, prematurity, the type of childbirth, and the decrease in breastfeeding. The aim of this study was to analyze whether there is any association between these factors and the development of CMPA.

MATERIAL AND METHODS

A retrospective, comparative, cross-sectional, observational study was conducted by reviewing the case records of 101 children diagnosed with CMPA and seen at the Department of Gastroenterology and Nutrition of the Instituto Nacional de Pediatría within the time frame of January 2012 and August 2013. The following variables were included: age, sex, weeks of gestation, history of maternal infection and antimicrobial use during the pregnancy, type of delivery, and feeding with human milk, and its duration. Likewise, the case records of 90 children were reviewed as a control group on not having CMPA or any other allergy. The chi-square test was used for proportions, and the Mann-Whitney U test was used for comparing means in the statistical analysis.

RESULTS

The factors associated with CMPA were the use of antimicrobials during gestation and breastfeeding duration in months. Both factors were statistically significant (P<.001). No association was found between CMPA and gestational age or type of delivery.

CONCLUSIONS

The statistically significant associated factors were breastfeeding duration and the use of antimicrobials during the gestational stage. These results underline the necessity for prospective studies.

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.

Is there an association between microbial exposure and food allergy? A systematic review

The environmental factors driving the recent increase in the prevalence of food allergy (FA) are unclear. Since associations have been demonstrated between microbial exposure and the likelihood of eczema and respiratory allergies, we reviewed the evidence for FA. Medline was systematically searched from inception to the end of July 2012 for studies investigating links between FA and environmental exposures, likely to influence microbial exposure, such as Caesarean delivery, family size, day-care attendance, childhood infections, immunizations and antibiotic use. We selected studies reporting food challenge data, reported doctor-diagnosed (RDD) FA and food sensitization. Methodological differences and study heterogeneity precluded meta-analysis. A total of 46 studies were identified, of which 28 (60.9%) were prospective and 13 (28.3%) used food challenges to diagnose FA. Caesarean delivery was investigated in 13 studies, of which three infant cohorts demonstrated an increase in challenge-proven FA (one cohort) and food sensitization (two cohorts), and one cross-sectional study reported increased RDDFA. Four studies investigated the effect of having siblings, with one infant cohort demonstrating less challenge-proven FA and a cross-sectional study showing a decrease in RDDFA. Attending childcare before 6 months was associated with less challenge-proven FA in one cohort. A cross-sectional survey identified an inverse relationship between hepatitis A serology and peanut sensitization. One of eleven trials investigating probiotics demonstrated a quicker acquisition of milk tolerance amongst allergic infants. Factors influencing microbial exposure may be partly responsible for rising FA burden, but further prospective studies using double-blind placebo controlled food challenges as an outcome are required.

Food allergy: temporal trends and determinants

This review summarizes studies discussing temporal trends in the prevalence of food allergy as well as potential factors associated with the development of food allergy. In addition, we will address the potential hypotheses accounting for the apparent increase in food allergy prevalence. Studies suggest increased prevalence of food allergy. However, relatively little is known about its pathogenesis. This review aims to assess temporal trends in the prevalence of food allergy and discuss potential genetic, environmental, and demographic determinants. The search strategy examined the medical literature database MEDLINE (using PubMed) for the time period of January 1, 2002 to January 31, 2012. In recent decades, the prevalence of food allergy in general has increased by 0.60 % [95 % confidence interval (CI), 0.59 %-0.61 %] and the prevalence of peanut allergy by 0.027 % (95 % CI, 0.026 %-0.028 %), but it has now likely stabilized in developed countries. Genes, the environment, and demographic characteristics play a role in the pathogenesis of food allergy. Numerous environmental and demographic factors as well as gene-environment interactions may account for this increase in prevalence, but further studies are required to tease out their relative contribution.

Cesarean section and development of the immune system in the offspring

This review examines the relation between the mode of delivery and development of the immune system in the offspring. Recent epidemiological studies provide evidence that elective cesarean section (CS) is associated with aberrant short-term immune responses in the newborn infant, and a greater risk of developing immune diseases such as asthma, allergies, type 1 diabetes, and celiac disease. However, it is still unknown whether CS causes a long-term effect on the immune system of the offspring that contributes to compromised immune health. With the dramatic increase in the rate of CS today, a greater emphasis should be placed on the discussion among both professionals and childbearing women on potential consequences of CS on the health of the offspring.

Rhinoconjunctivitis prevalence and associated factors in school children aged 6-7 and 13-14 years old in Bogota, Colombia

OBJECTIVE

Allergic rhinitis is one of the most frequent chronic diseases among children. The objective of the study was to assess the prevalence of rhinoconjunctivitis and determine clinical, social and environmental associated factors, among school children aged 6-7 years and adolescents aged 13-14 years in Bogotá, Colombia.

METHODS

We used ISAAC (International Study of Asthma and Allergies in Childhood) phase III study methodology and questionnaire for design and data collection, and we did a secondary analysis of these data. The sample consisted of 3830 registers from adolescents between 13 and 14 years old and 3256 registers from children between 6 and 7 years.

RESULTS

The prevalence of rhinoconjunctivitis symptoms in the last year was 17.2% (95% CI, 15.9-18.5) in children vs. 24.9% (95% CI, 23.6-26.3) in adolescents. In both groups there was a female predominance in children (17.8% vs. 16.5%), and in the teenagers group (28.0% vs. 21.4%), though the differences were not statistically significant. The factors associated with rhinoconjunctivitis in the group of 6-7 years where: asthma [OR 3.9; (95% CI, 2.8-5.4)], atopic dermatitis [OR 2.3; (95% CI, 1.7-3.1)], use of acetaminophen in the last year [OR 2.6; (95% CI, 1.4-4.9)], use of antibiotics in the first year of live [OR 1.7; (95% CI, 1.3-2.3)], higher maternal education [OR 1.5; (95% CI, 1.0-2.3)] and cesarean delivery [OR 1.6; (95% CI, 1.2-2.1)]. Among the 13-14 year age-group, factors associated with rhinoconjunctivitis included: asthma [OR 2.6; (95% CI, 2.0-3.4)], atopic dermatitis [OR 1.8; (95% CI, 1.4-2.3)], use of acetaminophen in the last year [OR 1.8; (95% CI, 1.4-2.4)], consumption of fast-food three times or more per week [OR 1.5; (95% CI, 1.2-2.0), ever smoked [OR 1.4; (95% CI, 1.2-1.7)] and meat consumption was protective factor [OR 0.7; (95% CI, 0.5-0.9)].

CONCLUSION

In both studied groups, the estimated prevalence of rhinoconjunctivitis symptoms was relatively high. Future in-depth research is needed to assess the complex interactions between allergic rhinoconjunctivitis symptoms and social and environmental factors.

The health implications of birth by Caesarean section

Since the first mention of fetal programming of adult health and disease, a plethora of programming events in early life has been suggested. These have included intrauterine and postnatal events, but limited attention has been given to the potential contribution of the birth process to normal physiology and long-term health. Over the last 30 years a growing number of studies have demonstrated that babies born at term by vaginal delivery (VD) have significantly different physiology at birth to those born by Caesarean section (CS), particularly when there has been no exposure to labour, i.e. pre-labour CS (PLCS). This literature is reviewed here and the processes involved in VD that might programme post-natal development are discussed. Some of the effects of CS are short term, but longer term problems are also apparent. We suggest that VD initiates important physiological trajectories and the absence of this stimulus in CS has implications for adult health. There are a number of factors that might plausibly contribute to this programming, one of which is the hormonal surge or "stress response" of VD. Given the increasing incidence of elective PLCS, an understanding of the effects of VD on normal development is crucial.

Development of gut microbiota in infants not exposed to medical interventions

Knowledge of the composition of a normal healthy gut microbiota during infancy is important for understanding the role of gut microbiota in disease. A limitation of previous studies is that they are based on infants who have been subject to factors, which can have a profound disruptive effect on the natural colonization process. We describe the colonization process, during the first 4 months after birth, in 85 infants who have experienced no major medical or dietary interventions. They were all vaginally delivered, healthy, term infants, who were not exposed to antibiotics, exclusively breastfed during their first month of life and at least partially breastfed up to 4 months. Selected microbial groups were identified by targeting small subunit microbial ribosomal RNA genes. In contrast to more recent studies, but in agreement with older studies, almost all our infants harbored γ-Proteobacteria and Bifidobacterium. Yet undefined non-cultivable species belonging to Bacteroides, as well as microbes identified as Lachnospiraceae 2, were common. Strong associations were observed between some specific constituents of microbiota at day 4 and the concentration of specific microbial groups at day 120, indicating that early gut microbiota may influence later microbiota. Novel information of the undisturbed composition of early gut microbiota in babies is presented.

Food allergy: separating the science from the mythology

Numerous genes are involved in innate and adaptive immunity and these have been modified over millions of years. During this evolution, the mucosal immune system has developed two anti-inflammatory strategies: immune exclusion by the use of secretory antibodies to control epithelial colonization of microorganisms and to inhibit the penetration of potentially harmful agents; and immunosuppression to counteract local and peripheral hypersensitivity against innocuous antigens, such as food proteins. The latter strategy is called oral tolerance when induced via the gut. Homeostatic mechanisms also dampen immune responses to commensal bacteria. The mucosal epithelial barrier and immunoregulatory network are poorly developed in newborns. The perinatal period is, therefore, critical with regard to the induction of food allergy. The development of immune homeostasis depends on windows of opportunity during which innate and adaptive immunity are coordinated by antigen-presenting cells. The function of these cells is not only orchestrated by microbial products but also by dietary constituents, including vitamin A and lipids, such as polyunsaturated omega-3 fatty acids. These factors may in various ways exert beneficial effects on the immunophenotype of the infant. The same is true for breast milk, which provides immune-inducing factors and secretory immunoglobulin A, which reinforces the gut epithelial barrier. It is not easy to dissect the immunoregulatory network and identify variables that lead to food allergy. This Review discusses efforts to this end and outlines the scientific basis for future food allergy prevention.

Maternal and perinatal characteristics and the risk of cow's milk allergy in infants up to 2 years of age: a case-control study nested in the Finnish population

This study examined whether maternal background and perinatal factors were associated with the risk of cow's milk allergy (CMA) in infants up to 2 years of age in a nested case-control study. All children born in 1996-2004 in Finland and diagnosed with CMA by 2006 were identified (n = 16,237). For each case, one matched control was selected. Information on maternal and perinatal factors was derived from the Medical Birth Register. The associations were analyzed by conditional logistic regression. Cesarean section (adjusted odds ratio (OR) = 1.18, 95% confidence interval (CI): 1.10, 1.27) and high maternal age (> or =35 years; adjusted OR = 1.23, 95% CI: 1.11, 1.36) were associated with increased risk, whereas low maternal socioeconomic status (adjusted OR = 0.65, 95% CI: 0.59, 0.71), smoking (adjusted OR = 0.72, 95% CI: 0.67, 0.79), high number of previous deliveries (> or =5; adjusted OR = 0.71, 95% CI: 0.59, 0.86), and multiple pregnancy (adjusted OR = 0.70, 95% CI: 0.60, 0.82) were associated with decreased risk of CMA. In conclusion, maternal background and perinatal factors may play a role in the development of CMA, but further research is needed to clarify these associations and the underpinning biologic mechanisms.

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.

Birth by cesarean section, allergic rhinitis, and allergic sensitization among children with a parental history of atopy

BACKGROUND

Cesarean delivery can alter neonatal immune responses and increase the risk of atopy. Studies of the relation between cesarean delivery and allergic diseases in children not selected on the basis of a family history of atopy have yielded inconsistent findings.

OBJECTIVE

We sought to examine the relation between birth by cesarean delivery and atopy and allergic diseases in children at risk for atopy.

METHODS

We examined the relation between mode of delivery and the development of atopy and allergic diseases among 432 children with a parental history of atopy followed from birth to age 9 years. Asthma was defined as physician-diagnosed asthma and wheeze in the previous year, and allergic rhinitis was defined as physician-diagnosed allergic rhinitis and naso-ocular symptoms apart from colds in the previous year. Atopy was considered present at school age if there was 1 or more positive skin test response or specific IgE to common allergens. Stepwise logistic regression was used to study the relation between cesarean delivery and the outcomes of interest.

RESULTS

After adjustment for other covariates, children born by cesarean section had 2-fold higher odds of atopy than those born by vaginal delivery (odds ratio, 2.1; 95% CI, 1.1-3.9). In multivariate analyses birth by cesarean section was significantly associated with increased odds of allergic rhinitis (odds ratio, 1.8; 95% CI, 1.0-3.1) but not with asthma.

CONCLUSIONS

Our findings suggest that cesarean delivery is associated with allergic rhinitis and atopy among children with a parental history of asthma or allergies. This could be explained by lack of contact with the maternal vaginal/fecal flora or reduced/absent labor during cesarean delivery.