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

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

Pig Farmers' Homes Harbor More Diverse Airborne Bacterial Communities Than Pig Stables or Suburban Homes

Airborne bacterial communities are subject to conditions ill-suited to microbial activity and growth. In spite of this, air is an important transfer medium for bacteria, with the bacteria in indoor air having potentially major consequences for the health of a building’s occupants. A major example is the decreased diversity and altered composition of indoor airborne microbial communities as a proposed explanation for the increasing prevalence of asthma and allergies worldwide. Previous research has shown that living on a farm confers protection against development of asthma and allergies, with airborne bacteria suggested as playing a role in this protective effect. However, the composition of this beneficial microbial community has still not been identified. We sampled settled airborne dust using a passive dust sampler from Danish pig stables, associated farmers’ homes, and from suburban homes (267 samples in total) and carried out quantitative PCR measurements of bacterial abundance and MiSeq sequencing of the V3–V4 region of bacterial 16S rRNA genes found in these samples. Airborne bacteria had a greater diversity and were significantly more abundant in pig stables and farmers’ homes than suburban homes (Wilcoxon rank sum test P < 0.05). Moreover, bacterial taxa previously suggested to contribute to a protective effect had significantly higher relative and absolute abundance in pig stables and farmers’ homes than in suburban homes (ALDEx2 with P < 0.05), including Firmicutes, Peptostreptococcaceae, Prevotellaceae, Lachnospiraceae, Ruminococcaceae, Ruminiclostridium, and Lactobacillus. Pig stables had significantly lower airborne bacterial diversity than farmers’ homes, and there was no discernable direct transfer of airborne bacteria from stable to home. This study identifies differences in indoor airborne bacterial communities that may be an important component of this putative protective effect, while showing that pig stables themselves do not appear to directly contribute to the airborne bacterial communities in the homes of farmers. These findings improve our understanding of the role of airborne bacteria in the increasing prevalence of asthma and allergy.

Relationship between maternal nutrient intakes in early and late pregnancy and infants weight and proportions at birth: prospective cohort study

Experimental studies indicate that fetal undernutrition programmes life-long physiology and disease risk. The objective of this study was to investigate relationships between maternal nutrient intakes in early and late pregnancy with birth weights, placental weights, and infant proportions at birth. A prospective cohort study set in a district general hospital in the east midlands of England considered the diets of 300 pregnant women recruited from an antenatal ultrasound dating scan clinic. Estimation of nutrient intakes utilised five-day food diaries in the first and third trimesters of pregnancy. Two hundred and four diaries were returned and analysed for trimester one and 176 for trimester three. Birth weight and infant head circumference at birth were unrelated to nutrient intakes in the first or third trimester of pregnancy. Placental weight was not related to any maternal nutrient intakes. Thinness at birth was associated with low contributions of carbohydrate to dietary energy (p=0.036). The present study shows that maternal nutrition in well-nourished populations does not exert a strong influence upon fetal growth. These data suggest that reported associations between low weight, thinness or greater head circumference at birth and disease in later life are not attributable to the effects of maternal undernutrition.

Prevalence of asthma-like symptoms and assessment of lung function in schoolchildren born with low birth weight

INTRODUCTION

This study aimed to determine the prevalence of asthma-like symptoms among schoolchildren with low birth weight (LBW), and to compare the lung function of these children with that of children with normal birth weight.

METHODS

This was a comparative cross-sectional study. We recruited children aged 8-11 years from eight primary schools in Kota Bharu, Kelantan, Malaysia. The children were divided into two groups: those with LBW (< 2,500 g) and those with normal birth weight (≥ 2,500 g). Parents of the enrolled children were asked to complete a translated version of the International Study of Asthma and Allergies in Childhood questionnaire. Lung function tests, done using a MicroLoop Spirometer, were performed for the children in both groups by a single investigator who was blinded to the children's birth weight.

RESULTS

The prevalence of 'ever wheezed' among the children with LBW was 12.9%. This value was significantly higher than that of the children with normal birth weight (7.8%). Forced vital capacity (FVC), forced expiratory volume in one second, and forced expiratory flow when 50% and 75% of the FVC had been exhaled were significantly lower among the children with LBW as compared to the children with normal birth weight.

CONCLUSION

LBW is associated with an increased prevalence of asthma-like symptoms and impaired lung function indices later in life. Children born with LBW may need additional follow-up so that future respiratory problems can be detected early.

In utero Head Circumference is Associated with Childhood Allergy

BACKGROUND

Altered fetal growth is known to be associated with allergic disease. Specifically, increased head circumference at birth has been linked to asthma and elevated IgE. However, few studies have examined a link between early fetal anthropometry and allergic disease. The aim of this study was to examine head circumference at mid-gestation in children diagnosed with allergy.

METHODS

This was a retrospective cohort study, comprising pregnancies delivered between 10/2006 and 9/2010 at Nepean Hospital, Australia. Exclusion criteria were illegal drug use, alcohol consumption, gestation <35 weeks, and gestational hypertension. Pregnancy data were sourced from the Nepean Obstetric Database. Atopic diseases (asthma, atopic dermatitis, and IgE-mediated food allergy) were assessed by questionnaire at age 1-5 years. Infants from pregnancies with completed questionnaires, who also had a mid-gestation ultrasound scan, were included (N = 121). Multiple logistic regression techniques were used to model head circumference against the development of allergies.

RESULTS

Smaller head circumference at mid-gestation was associated with increased odds of allergic disease in children aged 1-5 years. A 1 mm smaller head circumference was associated with a 7% increased chance of allergies being later diagnosed, adjusted for gestation (95% CI: 1-14%, p = 0.036). Head circumference at mid-gestation was also inversely correlated with the presence of multiple atopic disease.

CONCLUSION

Smaller mid-gestational head circumference is associated with early childhood allergic disease, which suggests that fetal programing of allergic disease occurs before mid-gestation. This suggests that mediators such as brain-derived neurotrophic factor may be dysregulated early in utero in a milieu, which also predisposes to atopic disease.

Birth weight and childhood wheezing disorders: a systematic review and meta-analysis

BACKGROUND

Previous observational studies have claimed that birth weight and childhood wheezing disorders are associated although the results remained inconsistent. One systematic review and two systematic reviews that included meta-analyses reported inconsistent results. We aimed to conduct a systematic review and meta-analysis to investigate this.

METHODS

An online search of published papers linking childhood asthma and wheezing disorders with birth weight up to February 2014 was carried out using EMBASE and Medline medical research databases. Summary ORs were estimated using random-effects models. Subgroup meta-analyses were performed to assess the robustness of risk associations and between-study heterogeneity.

RESULTS

A total of 37 studies comprising 1,71, 737 participants were included in our meta-analysis. The unadjusted summary ORs for risk of childhood wheezing disorders associated with low birth weight (<2.5 kg) were 1.60 (95% CI 1.39 to 1.85, p<0.001) and 1.37 (95% CI 1.05 to 1.79, p=0.02) when compared with ≥2.5 and 2.5-4.0 kg birthweight groups, respectively. The overall summary OR for high birth weight (>4 kg) as compared to the 2.5-4.0 kg birthweight group was 1.02 (95% CI 0.99 to 1.04, p=0.13). There was substantial heterogeneity in the unadjusted low birth weight risk estimates which was not accounted for by predefined study characteristics. There was no significant heterogeneity in the high birth weight risk estimates. There was some evidence of funnel plot asymmetry and small study effects in the low birth weight (2.5 vs ≥2.5 kg and <2.5 vs 2.5-4 kg) OR estimates.

CONCLUSIONS

Our results suggest that low birth (<2.5 kg) is an independent risk factor for wheezing disorders during childhood and adolescence although there was substantial heterogeneity among the risk estimates. However, we found no significant association of high birth weight with wheezing disorders.

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

Background

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

Methods

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

Results

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

Conclusions

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

Birthweight and the risk of atopic diseases: the ISAAC Phase III study

BACKGROUND

The association between birthweight and asthma, eczema and rhinoconjunctivitisis conflicting.

AIMS

To examine the association between birthweight and symptoms of asthma, eczema and rhinoconjunctivitis.

METHODS

Parents or guardians of children aged 6–7 yr completed written questionnaires about symptoms of asthma, rhinoconjunctivitis and eczema, and several risk factors, including birthweight.

RESULTS

There were 162,324 children from 60 centres in 26 countries. Low birthweight(<2.5 kg) was associated with an increased risk of symptoms of asthma (current wheeze odds ratio = 1.20; 95% confidence interval = 1.12–1.30). Low birthweight was associated with a lower risk of eczema ever. Low birthweight was not associated with rhinoconjunctivitis. Large babies (birthweight ≥4.5 kg) were not associated with any of these outcomes.

CONCLUSIONS

This study has confirmed that low birthweight is a risk factor for symptoms of asthma, but not for rhinoconjunctivitis. The findings for eczema are equivocal.

Asthma in children in relation to pre-term birth and fetal growth restriction

To assess the impact of parental asthma on risk of pre-term birth (PTB) and intrauterine growth restriction, and their subsequent association with childhood asthma. Three sequential cross-sectional surveys were conducted in 1993 (3,746), 1998 (1,964) and 2006 (1,074) in the same 15 schools among 5-11 year old children in Merseyside using the same respiratory health questionnaire completed by parents (sample size in brackets). Between 1993 and 2006, prevalence of PTB varied between 12.4 and 15.2 %, and of small for gestational age (SGA or growth restricted) babies between 2.1 and 4.6 %, and maternal asthma prevalence between 8.1 and 13.4 %. For the combined surveys mothers with asthma were more likely to have a PTB than non-asthmatic mothers (OR 1.39, 95 % CI 1.10-1.95, p < 0.001), and in the 2006 survey were more likely to have an SGA baby. 40.9 % of PTBs of asthmatic mothers developed doctor diagnosed asthma compared to 34.3 % for term babies (adjusted OR 1.65, 1.34-2.04, p < 0.001). The corresponding estimates for the symptom triad of cough, wheeze and breathlessness were 19.4 and 17.6 % (adjusted OR 1.78, 0.79-3.98). Conversely SGA babies were less likely to develop doctor diagnosed asthma (adjusted OR 0.49, 0.27-0.90, p < 0.021), or the symptom triad of cough, wheeze and breathlessness (adjusted OR 0.22, 0.05-0.97, p < 0.043), whether or not the mother was asthmatic. Maternal asthma is an independent risk factor for PTB which predisposes to childhood asthma. Intrauterine growth restriction was protective against childhood asthma.

Forceps birth delivery, allergic sensitisation and asthma: a population-based cohort study

BACKGROUND

Studies indicate an increased risk of allergies among children born by caesarean section, possibly because immune development is altered by avoiding exposure to maternal vaginal flora. It is unknown if other obstetric interventions are associated with allergies.

OBJECTIVE

To assess associations between delivery with forceps assistance and development of atopy and asthma.

METHODS

In a population-based cohort of 1037 individuals born in 1972/73, atopy was assessed by skin-prick tests for common allergens at ages 13 and 32 years. A history of asthma was obtained at the same ages. Associations between birth with forceps assistance, atopy and asthma were assessed with adjustments for sex, head circumference at birth, parental atopy disease, birth order and socio-economic status.

RESULTS

Children born using forceps were more likely to have atopy at ages 13 (53% vs. 44%) and 32 (68% vs 59%). They were also more likely to have asthma (21% vs. 11% and 23% vs. 16% at ages 13 and 32 respectively). Except for asthma at age 13, these associations were not statistically significant after adjustment for multiple confounding factors.

CONCLUSIONS & CLINICAL RELEVANCE

Delivery with forceps assistance is associated with an increased risk of atopy and asthma, but the associations were weaker after adjustment for confounding factors. The previously reported association between caesarean birth and atopic disease may be due to confounding rather than altered exposure to maternal flora, although other factors associated with a difficult labour cannot be ruled out.

Neonatal size in term children is associated with asthma at age 7, but not with atopic dermatitis or allergic sensitization

BACKGROUND

We hypothesized that anthropometrics in the newborn is associated with development of asthma later in life.

METHODS

The study included a prospective, longitudinal clinical study of a birth cohort of 411 Danish neonates born at term of mothers with a history of asthma. The primary endpoint was physician-diagnosed asthma at age 7 years. Allergic sensitization and atopic dermatitis (AD) were also investigated. Infant size was measured at the research clinic on four occasions during the first year of life. Risk for asthma, AD, and allergic sensitization at age 6-7 were estimated from logistic regression. Time to first asthma and AD were investigated by Cox regression. Multivariate models were adjusted for gender, gestational age, and mothers smoking during pregnancy.

RESULTS

Neonatal weight, length, body mass index and head circumference (z-score) were all significantly associated with asthma at age 7. Adjusted odds ratio for asthma by estimated birth weight z-score: 1.87 [1.23-2.84]; P = 0.004. Adjusted HR for onset of asthma by neonatal weight z-score: 1.46 [1.08-1.96]; P = 0.013. Neonatal size did not associate with AD or allergic sensitization.

CONCLUSIONS

Increased neonatal size was significantly associated with asthma at age 7 but not AD or allergic sensitization in at-risk children born at term. The findings suggest some common prenatal mechanisms linking body size and asthma.

Long term respiratory consequences of intrauterine growth restriction

Epidemiological studies demonstrate that in-utero growth restriction and low birth weight are associated with impaired lung function and increased respiratory morbidity from infancy, throughout childhood and into adulthood. Chronic restriction of nutrients and/or oxygen during late pregnancy causes abnormalities in the airways and lungs of offspring, including smaller numbers of enlarged alveoli with thicker septal walls and basement membranes. The structural abnormalities and impaired lung function seen soon after birth persist or even progress with age. These changes are likely to cause lung symptomology through life and hasten lung aging.

Perinatal Risk Factors for Hay Fever — A Study Among 2550 Finnish Twin Families

Previous studies have suggested that perinatal factors influence the risk for asthma but population studies on perinatal factors and risk for hay fever are few. We studied the effect of perinatal factors on the risk for hay fever among adolescent twins by a questionnaire study involving five consecutive nation-wide birth cohorts of 16-year-old twins and their parents. The risk for parent-reported, doctor-diagnosed hay fever in the adolescents associated with several perinatal characteristics was assessed with logistic regression analysis among individuals and by a discordant pair analysis. In the univariate analysis of the birth factors, the risk for hay fever increased with increasing birth weight (p for trend = 0.048, OR for those ≥ 3000g 1.35, 95% CI 0.91–2.02 compared to those < 2000g) and gestational age (p for trend = 0.04, OR for those born after 40 weeks of gestation 2.24, 95% CI 1.03–4.86, compared to those born before 33 weeks of gestation) and was lower in those subjects hospitalised in the neonatal period (OR 0.74, 95% CI 0.58–0.93). Because of significant interactions between parental hay fever status and birth factors (ponderal index, p = 0.03 and maternal age p = 0.04), stratified analysis were performed. The positive association between birth weight and hay fever was most obvious among adolescents with no parental history of hay fever (p for trend = 0.03). Similar, though not significant, trends were found with other birth factors among these families, whereas no such trend was found among adolescents with parental hay fever, suggesting that gestational maturity increases the risk for hay fever in the absence of genetic predisposition. However, of the perinatal factors only neonatal hospitalisation (OR 0.75, 95% CI 0.59–0.96) remained a significant risk factor for the development of hay fever, when adjusted for non-perinatal factors.

Mode and place of delivery, gastrointestinal microbiota, and their influence on asthma and atopy

BACKGROUND

Both gastrointestinal microbiota composition and cesarean section have been linked to atopic manifestations. However, results are inconsistent, and the hypothesized intermediate role of the microbiota in the association between birth mode and atopic manifestations has not been studied yet.

OBJECTIVES

We sought to investigate the relationship between microbiota composition, mode and place of delivery, and atopic manifestations.

METHODS

The Child, Parent and Health: Lifestyle and Genetic Constitution Birth Cohort Study included data on birth characteristics, lifestyle factors, and atopic manifestations collected through repeated questionnaires from birth until age 7 years. Fecal samples were collected at age 1 month (n = 1176) to determine microbiota composition, and blood samples were collected at ages 1 (n = 921), 2 (n = 822), and 6 to 7 (n = 384) years to determine specific IgE levels.

RESULTS

Colonization by Clostridium difficile at age 1 month was associated with wheeze and eczema throughout the first 6 to 7 years of life and with asthma at age 6 to 7 years. Vaginal home delivery compared with vaginal hospital delivery was associated with a decreased risk of eczema, sensitization to food allergens, and asthma. After stratification for parental history of atopy, the decreased risk of sensitization to food allergens (adjusted odds ratio, 0.52; 95% CI, 0.35-0.77) and asthma (adjusted odds ratio, 0.47; 95% CI, 0.29-0.77) among vaginally home-born infants was only found for children with atopic parents. Mediation analysis showed that the effects of mode and place of delivery on atopic outcomes were mediated by C difficile colonization.

CONCLUSION

Mode and place of delivery affect the gastrointestinal microbiota composition, which subsequently influences the risk of atopic manifestations.

Risk of asthma in young adults who were born preterm: a Swedish national cohort study

OBJECTIVE

Preterm birth is associated with asthma-like symptoms in childhood and possibly in adolescence, but the longer-term risk of asthma is unknown and increasingly relevant as larger numbers of these individuals enter adulthood. Our objective was to evaluate whether those who were born preterm are more likely to be prescribed asthma medications in young adulthood than those who were born term.

PATIENTS AND METHODS

We conducted a national cohort study of all singleton infants born in Sweden from 1973 through 1979 (n = 622 616), followed to ages 25.5 to 35.0 years to determine whether asthma medications were prescribed in 2005-2007. Asthma medication data were obtained from all outpatient and inpatient pharmacies throughout Sweden. To improve the positive predictive value for asthma, the outcome was defined as prescription of (1) both a β-2 agonist inhalant and a glucocorticoid inhalant or (2) a combination inhalant containing a β-2 agonist and other drugs for obstructive airway diseases.

RESULTS

Young adults who were born extremely preterm (23-27 weeks' gestation) were 2.4 times more likely (adjusted 95% CI: 1.41-4.06) to be prescribed asthma medications than those who were born term. No association was found between later preterm birth (28-32 or 33-36 weeks' gestation) and asthma medications in young adulthood.

CONCLUSIONS

This is the first study with sufficient statistical power to evaluate the risk of asthma beyond adolescence in individuals who were born extremely preterm. The results suggest that extreme preterm birth (23-27 weeks' gestation), but not later preterm birth, is associated with an increased risk of asthma at least into young adulthood.

Gestational age at birth and risk of allergic rhinitis in young adulthood

BACKGROUND

Previous studies of the association between gestational age or birth weight and allergic rhinitis in later life have had various limitations, including the inability to estimate risk among subjects born extremely preterm or to examine specific contributions of gestational age and fetal growth.

OBJECTIVE

We sought to determine whether gestational age at birth independent of fetal growth is associated with allergic rhinitis medication prescription in a national cohort of young adults.

METHODS

We conducted a national cohort study of 630,090 infants born in Sweden from 1973 through 1979 including 27,953 born preterm (<37 weeks) and followed for prescription of nasal corticosteroids and oral antihistamines in 2005-2009 (age, 25.5-37.0 years). Medication data were obtained from all outpatient and inpatient pharmacies throughout Sweden.

RESULTS

The overall prevalence of nasal corticosteroid and oral antihistamine prescription was 16.3% and 16.8%, respectively, which is similar to the reported prevalence of allergic rhinitis in this population. Low gestational age at birth was associated with a decreased risk of nasal corticosteroid and oral antihistamine prescription in young adulthood after adjusting for fetal growth and other potential confounders. For subjects born extremely preterm (23-28 weeks), adjusted odds ratios were 0.70 (95% CI, 0.51-0.96) for nasal corticosteroid prescription and 0.45 (95% CI, 0.27-0.76) for both nasal corticosteroid and oral antihistamine prescription relative to those born at full term.

CONCLUSION

These findings suggest that low gestational age at birth independent of fetal growth is associated with a decreased risk of allergic rhinitis in young adulthood, possibly because of a protective effect of earlier exposure to pathogens.

Preterm birth reduces the incidence of atopy in adulthood

BACKGROUND

Immunologic pathways are primed in early life. Preterm birth can influence this process and thereby affect whether a person will have atopy later in life. Previous studies on the effects of preterm birth on atopy in adulthood have been inconclusive and limited to children or subjects born moderately preterm.

OBJECTIVE

Our aim was to compare the incidence of atopy among young adults who were born preterm and at very low birth weight (≤ 1500 g) with that of term-born young adults (control subjects).

METHODS

The study comprised 166 adults who were born preterm and at very low birth weight and 172 control subjects, all of whom were from the Helsinki Study of Very Low Birth Weight Adults. We assessed atopic predisposition at ages 18 to 27 years using skin prick tests for 6 common aeroallergens and measurements of serum concentrations of total IgE and 3 types of allergen-specific (cat, birch, and timothy) IgE. We asked the subjects whether they had been given a diagnosis of asthma or allergic rhinitis or had atopic eczema and analyzed data by using logistic or linear regression, adjusting for potential confounding factors.

RESULTS

The risk for having at least 1 positive reaction on a skin prick test was reduced (adjusted odds ratio, 0.43; 95% CI, 0.23-0.79, P = .007), and the concentration of cat-specific IgE was less (25% less; 95% CI, 43% to 2.3% less; P = .033) in sera from very-low-birth-weight subjects compared with that seen in sera from control subjects. Within the very-low-birth-weight group, those born at an earlier gestational age were less likely to have positive skin prick test reactions (adjusted odds ratio for 1 week, 0.82; 95% CI, 0.68-0.98, P = .029) and less likely to have high levels of allergen-specific IgE. Cumulative incidences of atopic disease were similar between adults of very low birth weight and control subjects.

CONCLUSIONS

Young adults born prematurely and at very low birth weight have a lower incidence of atopy than adults who were born full term. This finding supports the hypothesis that the risk for atopy is determined during early stages of development.

Can childhood asthma be predicted at birth?

BACKGROUND

Early life appears optimal for prevention of asthma, but interventions require a relevant target population, to date not clearly identified at birth.

OBJECTIVE

We therefore aimed to identify the predicting capacity of factors known around birth for asthma and rhinitis at 10 years.

METHODS

The included 614 healthy term babies with lung function measured at birth in the 1992/1993 Environment and Childhood Asthma study in Oslo attended a 10-year follow-up visit including a structured interview and skin prick test (SPT) for allergies. The logistic regression analyses included 37 general variables from an extensive birth questionnaire; lung function; cord blood total immunoglobulin E and soluble CD14. A history of asthma, current asthma, history of rhinitis and 'healthy' (no history of asthma, rhinitis and negative SPT) was predicted on a group level and individual predicted probabilities were calculated.

RESULTS

The predictability of the models [area under the curve (95% confidence intervals)] was 0.74 (0.69, 0.79), 0.72 (0.64, 0.78), 0.69 (0.54, 0.72) and 0.67 (0.62, 0.71) for a history of asthma, current asthma, rhinitis and 'healthy', respectively. The best model predicted a history of asthma correctly in 93/124 (75%), and incorrectly in 176/490 (36%) children without asthma. The positive predictive values for all outcomes were low (19-61), the highest predicting healthy.

CONCLUSION

Although at best 75% of children with a history of asthma could be predicted at birth, an intervention applied to our predicted high-risk children would be started more often in children without than with future disease. Parental allergic disease alone appears insufficient to identify high-risk populations in future studies of asthma and allergic disease.

Impaired fetal growth decreases the risk of childhood atopic eczema: a Swedish twin study

BACKGROUND

Studies have found associations between birth weight and risk of atopic eczema or allergic rhinitis (AR), although this could be due to confounding.

OBJECTIVE

We sought to evaluate associations between fetal growth and the risk of atopic eczema or AR in childhood, controlling for gestational age (GA), shared (familial) environmental and genetic factors.

METHODS

Data on atopic eczema, AR, birth characteristics and confounders were collected from registers and telephone interviews with the parents of 9- and 12-year-old twins. Firstly, cohort analyses on all twins (eczema n=10 132 and AR n=10 896) were performed. Secondly, to control for genetic and shared environment, co-twin-control analyses were performed in twin pairs discordant for atopic eczema (n=480) and AR (n=332).

RESULTS

The rate of atopic eczema increased with birth weight, from 12.6% in twin children <2000 g to 17.3% in children >or=3500 g. The rate of AR varied between 7.8% and 8.8%. In the cohort analyses, the odds ratio (OR) for atopic eczema was 1.62 (95% CI: 1.27-2.06) for 500 g increase in birth weight and 1.00 (95% CI: 0.75-1.33) for AR. In co-twin-control analyses on atopic eczema, OR was 3.93 (95% CI: 1.55-9.98) for 500 g increase in birth weight, with no significant difference between monozygotic and dizygotic twins (P=0.84).

CONCLUSIONS

We found a positive association between fetal growth and childhood atopic eczema, but not AR, independent of GA, shared environmental and genetic factors. This indicates fetal growth affects the immune system, and supports further studies on early mechanisms.

Association among size of thymus, anthropometric dimensions and number of lymphocytes in peripheral blood in newborns from Slovakia

AIMS

Thymus is the central lymphatic organ in humans with important endocrine function that is involved in maturation of immunocompetent T-lymphocytes. In our study we investigated the relationship among thymus size and the anthropometric dimensions as well as between thymus size and the number of lymphocytes in peripheral blood in full-term newborns.

METHODS

The examined group consisted of 212 full-term newborns from the region of Southern Slovakia. We examined birth weight, birth body length, head circumference and chest circumference. Thymus size was estimated by ultrasonography and it was expressed as Thymic Index. The number of lymphocytes in peripheral blood was determined from the number of total leukocytes and from the leukogram.

RESULTS

We have found a statistically significant positive correlation among thymus size and the body dimensions of newborns. The highest correlation with thymus size was found for birth weight (r = 0.409; P < 0.001) followed by birth body length (r = 0.368; P < 0.001), head circumference (r = 0.365; P < 0.001) and chest circumference (r = 0.340; P < 0.001). We have proven also a statistically significant positive correlation between the number of lymphocytes in peripheral blood and thymus size (r = 0.208; P = 0.039).

CONCLUSION

Our results confirmed the findings of other authors about a close relationship of Thymic Index and basic body parameters in newborns.

The effects of birthweight and breastfeeding on asthma among children aged 1-5 years

AIM

Asthma is a major cause of morbidity and mortality among children and has steadily increased in prevalence. The combined effect of birthweight and breastfeeding on childhood asthma remains unclear.

METHODS

In this study, we analysed a nationally representative sample of children aged 1-5 years from the National Health and Nutrition Examination Survey 1999-2002. Logistic regression was performed to examine the hypothesis whether birthweight and breastfeeding are independently associated with the prevalence of asthma after accounting for the complex sampling design. In addition, we sought to describe the relationship between birthweight and childhood asthma and to assess the potentially combined effect between birthweight and breastfeeding on asthma among children aged 1-5 years after considering the possible effects of social and environmental factors.

RESULTS

We found that birthweight (measured continuously) was inversely and linearly associated with the prevalence of childhood asthma (odds ratio (OR) = 0.80 per 1 kg increase in birthweight, 95% confidence interval (CI): 0.65-0.98). Using a categorical variable, low birthweight (LBW) was positively associated with childhood asthma (OR = 1.28, 95% CI: 0.81-2.68). Furthermore, we detected an interaction between birthweight and breastfeeding on childhood asthma. Breastfeeding had a strong protective effect on asthma among children with high birthweight (OR = 0.14, 95% CI: 0.04-0.43) while it had no significant effect on asthma among children with normal birthweight or LBW.

CONCLUSIONS

The mechanisms underlying these relationships remain uncertain and warrant further explanation.

Is the association between low birth weight and asthma independent of genetic and shared environmental factors?

Epidemiologic evidence linking birth weight and asthma is inconsistent. The authors examined the association between birth weight and asthma during childhood and adult life in twins. Using prospectively collected data on 21,588 like-sexed Swedish twins of known zygosity born in 1928-1952, they first conducted a cohort study to examine the risk of asthma in relation to birth weight. Next, they conducted nested co-twin control analyses among 643 dizygotic and 365 monozygotic twin pairs discordant for asthma to ascertain whether the association between birth weight and asthma could be confounded by genetic and shared environmental exposures. In the cohort analysis, birth weight of <2,500 g was associated with significantly greater risk of asthma independent of perinatal characteristics and within-twin-pair correlations. In the co-twin control analyses, birth weight of <2,500 g was significantly related to increased risk of asthma among monozygotic twins (relative risk for 2,000 g vs. 2,500 g = 1.58, 95% confidence interval: 1.06, 2.38). A negative association between birth weight and asthma, albeit not statistically significant, was also found among dizygotic twins. In conclusion, there is a negative association between birth weight and asthma in twins that is unlikely to be confounded by genetic or shared environmental factors.

Influence of prenatal psychosocial stress on cytokine production in adult women

The aim of the present study was to determine the association between prenatal stress and immune function in human adults. Peripheral blood mononuclear cells (PBMCs) from 34 healthy young women whose mothers experienced major negative life events during their pregnancy (Prenatal Stress, PS group, mean age 25, SD +/- 4.34 years), and from a female comparison group (n = 28, CG, mean age 24 +/- 3.40 years), were stimulated with phytohemagglutinin (PHA), and subsequent cytokine production was measured. A bias for T-helper 2 (Th2) cytokine production due to an overproduction of IL-4 relative to IFN-gamma after PHA stimulation was observed in PS subjects. In addition, IL-6 and IL-10 were also significantly elevated. To the best of our knowledge, this study is the first to suggest a direct association between prenatal stress exposure and alterations in immune parameters in adult women.

Birth size effect on pulmonary functions and atopic sensitization in preadolescence

BACKGROUND

The purpose of the present paper was to examine whether low birth size is associated with reduced pulmonary function and increased atopic sensitization in preadolescence.

METHODS

A cohort of 25 small-for-gestational-age (SGA) infants and an age- and sex-matched comparison group of 29 appropriate-for-gestational-age (AGA) infants born in 1993/94 were studied in preadolescence. Forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and forced expiratory flow when 25-75% of FVC is expired (FEF(25-75%)) were measured using a spirometer. Atopic sensitization was assessed on serum total IgE levels and skin prick tests (SPT) to common allergens.

RESULTS

There were positive correlations among FEV1 (r = 0.30, P = 0.001), FVC (r = 0.20, P = 0.03), and FEF(25-75%) (r = 0.5, P = 0.001) and ponderal index (PI), although the FEV1/FVC ratio was not correlated with birth size. Mean value of serum total IgE was higher in SGA (106.0 +/- 73.4 IU/mL) than AGA children (71.4 +/- 67.1 IU/mL; P = 0.02). PI under 10th centile was associated with high IgE levels (P = 0.04, odds ratio, 3.2; 95%CI: 1.0-9.8). The overall prevalence of atopy was 14.8% and there was no significant difference between the groups (P > 0.05).

CONCLUSION

Preadolescents who were born SGA with low birth size compared to controls had reduced pulmonary function. In preadolescence the prevalence of atopy is not higher in SGA than AGA children, although low PI at birth is associated with high IgE levels. Further follow up of this cohort is required to establish the pattern of pulmonary functions and atopic sensitizations in relation to birth size.

Life history theory and the immune system: steps toward a human ecological immunology

Within anthropology and human biology, there is growing interest in immune function and its importance to the ecology of human health and development. Biomedical research currently dominates our understanding of immunology, and this paper seeks to highlight the potential contribution of a population-based, ecological approach to the study of human immune function. Concepts from life-history theory are applied to highlight the major challenges and demands that are likely to shape immune function in a range of ecological contexts. Immune function is a major component of maintenance effort, and since resources are limited, trade-offs are expected between investment in maintenance and other critical life-history functions involving growth and reproduction. An adaptationist, life-history perspective helps make sense of the unusual developmental trajectory of immune tissues, and emphasizes that this complex system is designed to incorporate information from the surrounding ecology to guide its development. As a result, there is substantial population variation in immune development and function that is not considered by current biomedical approaches. In an attempt to construct a framework for understanding this variation, immune development is considered in relation to the competing life-history demands that define gestation, infancy, childhood, adolescence, and adulthood. Each life stage poses a unique set of adaptive challenges, and a series of hypotheses is proposed regarding their implications for immune development and function. Research in human ecological immunology is in its earliest stages, but this is a promising area of exploration, and one in which anthropology is well-positioned to make important contributions.

Antenatal steroid therapy and childhood asthma: Is there a possible link?

This paper presents a hypothesis that fetal exposure to corticosteroids is an independent risk factor for the development of asthma in childhood. The prevalence of childhood asthma saw a dramatic rise from the 1980s up until the early 2000s. Among the explanations for the increase in asthma prevalence included interest in exposures arising in the gestational period. Overlapping the time period of the increasing prevalence of childhood asthma is the increased use of antenatal corticosteroid therapy for fetal lung maturation. Through an examination of the published literature, a time dependent association between year of birth (and hence exposure to the antenatal corticosteroids) and the relationship between preterm birth and childhood asthma is noted. A brief review of the trends in the prevalence of asthma, the use of antenatal corticosteroids including their established latent effects and the time dependant association between preterm birth and the risk of childhood asthma are provided.

Diet and the developing immune system

Undernutrition during fetal life is known to have programming effects upon tissue morphology and function. This generally promotes poor health in adult life, with increased risk of metabolic syndrome and cardiovascular mortality noted among individuals whose growth was constrained in utero. Undernutrition in early life impacts upon the development of the immune organs and appears to diminish cellular immunity and increase the risk of atopic disorders during childhood. A limited body of evidence implicates fetal programming in the development of autoimmune disorders. This area represents an interesting target for further research and preventive medicine.

Childhood asthma and indoor allergens in Native Americans in New York

BACKGROUND

The objective of this study was to assess the correlation between childhood asthma and potential risk factors, especially exposure to indoor allergens, in a Native American population.

METHODS

A case-control study of St. Regis Mohawk tribe children ages 2-14 years, 25 diagnosed with asthma and 25 controls was conducted. Exposure was assessed based on a personal interview and measurement of mite and cat allergens (Der p 1, Fel d 1) in indoor dust.

RESULTS

A non-significant increased risk of childhood asthma was associated with self-reported family history of asthma, childhood environmental tobacco smoke exposure, and air pollution. There was a significant protective effect of breastfeeding against current asthma in children less than 14 years (5.2 fold lower risk). About 80% of dust mite and 15% of cat allergen samples were above the threshold values for sensitization of 2 and 1 mug/g, respectively. The association between current asthma and exposure to dust mite and cat allergens was positive but not statistically significant.

CONCLUSION

This research identified several potential indoor and outdoor risk factors for asthma in Mohawks homes, of which avoidance may reduce or delay the development of asthma in susceptible individuals.

Early life circumstances and atopic disorders in childhood

The prevalence of childhood atopic disorders has risen dramatically in the last decades of the past century. Risk factors for the development of these disorders have been studied extensively. This review focuses on the role of early life risk factors such as pre-natal development, perinatal circumstances, birth order and childhood vaccinations.

Intervention during pregnancy and allergic disease in the offspring

The etiology of allergy is multifactorial, with many variables contributing to the final expression of atopic disease. Three breeding grounds are needed to develop allergic disease: the appropriate genetic background, contact with the allergen(s) and environmental factors. Timing and dosing of allergen(s) are of major importance. Contact with (dietary) allergens and various agents such as tobacco smoke and infections occur not only during post-natal life, but also perinatally and even pre-natally. A critical review of published evidence regarding the impact of maternal exposure to antigens during pregnancy on later development of allergy in the offspring can only conclude that more research is urgently needed. Contact with multiple dietary allergens should be in general of benefit to the fetus to develop tolerance. Current knowledge suggests that pregnant women should have a normal diversified diet, avoiding toxic agents such as tobacco and alcohol. The role of maternal intake of poly-unsaturated fatty acids on the development of atopy in the infants needs to be further evaluated. If parental history would be insufficient to determine the fetal risk, preventive measurements would be advisable for all fetuses.

Are influences during pregnancy associated with wheezing phenotypes during the first decade of life?

AIM

Recently, attention has focused on possible early life origins for asthma. We sought to identify whether factors present during pregnancy were associated with development of childhood wheezing phenotypes.

METHODS

A whole population birth cohort (n=1456) on the Isle of Wight, UK, was followed through to age 10 y. Where possible, information regarding environmental exposures and events during pregnancy was obtained from the maternity records (n=1238). Children were seen at ages 1, 2, 4 and 10 y, and wheezing symptoms were used to define wheezing phenotypes in the first decade (n=1034).

RESULTS

Risk of early-onsetpersistent wheeze (onset in the first 4 y, still present at age 10) was increased by environmental tobacco smoke exposure in pregnancy (OR=2.44; 95% CI: 1.37-4.34) plus maternal asthma (3.57; 1.84-6.94), but reduced by cat ownership (0.30; 0.13-0.62). Early transient wheeze (onset in the first 4 y, but not present at age 10) was increased by environmental tobacco smoke exposure (1.58; 1.02-2.45), male gender (1.68; 1.09-2.60) and low birthweight (3.65; 1.27-10.52). No environmental factors in pregnancy were associated with late-onset persistent wheeze (onset after age 4 y, still present at 10 y).

CONCLUSION

In addition to genetics, maternal exposures during pregnancy show association with childhood and especially early-life wheezing phenotypes.

Allergic manifestations in very low-birthweight infants: a 6-year follow-up

The incidence of allergic manifestations was evaluated from birth until 6 y of age in 83 very low-birthweight infants (VLBWIs). In the same period 98 full-term babies were followed from birth to 24 mo of life. All the subjects were examined by paediatricians to establish the presence of atopic dermatitis (AD), gastrointestinal disturbances (GD) and asthma (AS). The incidence of total allergic manifestations (31.3%) in VLBWIs was significantly lower than that (52%) in 24-mo-old infants, born at full term. The incidence of allergies in VLBWIs did not differ at all at the subsequent checks, up to 6 y of age. AD (33.7%) was the most common symptom, statistically higher in full-term infants than in VLBWIs (7.2%). GD had a similar distribution (8.2% in full-term infants vs 7.2% in VLBWIs). AS (16.8%) was significantly higher in VLBWIs than in those born full term (10.2%). In the various VLBWI subgroups analysed, AD was more prevalent in babies weighing >1000 g and in babies >30 wk of age; the incidence of GD was higher in infants weighing <1000 g and in SGA infants, and AS was more prevalent in infants weighing <1000 g, in infants <30 wk of age and in babies appropriate for gestational age. A family history of allergy was related to a major incidence of allergies.

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.

Asthma and allergic rhinitis at 4 years of age in relation to fish consumption in infancy

It has been suggested that consumption of fish and polyunsaturated fatty acids could have a protective effect against inflammation in the airways and the development of asthma and other allergic diseases. Our objective was to test the hypothesis that fish consumption during the first year of life decreases the risk of childhood asthma and allergic rhinitis. We assessed the relation between introduction of fish in the diet during the first year of life and risk of asthma and allergic rhinitis in a prospective 4-year cohort study of 2531 Norwegian children. We estimated odds ratios (OR) in logistic regression analysis adjusting for potential confounders. A total of 47.6% children had fish during the first year of life. The adjusted OR for allergic rhinitis was 0.45 (95% confidence interval [CI]=0.28, 0.74) and for asthma 0.84 (95% CI=0.57, 1.22). Fish consumption in the first year of life may reduce the risk of developing asthma and allergic rhinitis in childhood.

Neonatal head circumference, neonatal weight, and risk of hayfever, asthma and eczema in a large cohort of adolescents from Sheffield, England

BACKGROUND

Neonatal physical characteristics, including head circumference and birth weight, have been hypothesized to be markers of in utero thymic development. Greater head circumference and lower birth weight have been linked in previous studies to subsequent development of asthma, and greater birth weight has been associated with subsequent development of eczema.

OBJECTIVE

To investigate potential associations between neonatal head circumference and weight and hayfever, asthma and eczema in a cohort of adolescents from Sheffield, England.

METHODS

Responses to a questionnaire inquiring about physician-diagnosed hayfever, asthma and eczema among adolescents in Sheffield, England, were linked to previously recorded measurements of weight at birth and at 1 month and head circumference at 1 month. Logistic regression methods were used to relate diagnoses to neonatal measurements and potential confounders.

RESULTS

The cohort consisted of 10,809 adolescents, of whom 16.5% reported hayfever, 18.0% asthma, and 16.2% eczema. After adjusting for sex, age at the time of the questionnaire, maternal age and gestational age at birth, number of older and younger siblings, time since birth of next older sibling, neonatal sickness, type of neonatal feeding, and maternal and paternal educational backgrounds, hayfever was the only disease associated with neonatal measurements. Comparing the highest with the lowest fifths of distributions, lifetime prevalence of hayfever was positively associated with neonatal head circumference (adjusted odds ratio 1.23, 95% CI 1.03 to 1.47) and with birth weight (1.17, 0.99 to 1.39). Hayfever was inversely related to the ratio of head circumference to birth weight (0.89, 0.75 to 1.05) and to gestational age. The associations with head circumference and birth weight were not substantially altered by further adjustment for gestational age.

CONCLUSION

Greater neonatal head circumference may be associated with an increased risk of hayfever, but the inverse relationship between hayfever prevalence and the ratio of head circumference to birth weight challenges the prior hypothesis that greater head circumference relative to body mass reflects abnormal thymic development in utero, increasing the likelihood of allergic sensitization.

Fetal growth and hospitalization with asthma during early childhood: a follow-up study in Denmark

BACKGROUND

Childhood asthma may have a fetal origin. In order to examine this hypothesis we examined the association between fetal growth indicators and hospitalization with asthma during early childhood.

METHODS

We performed a cohort study with 10 440 children whose mothers attended the midwife centres in Odense and Aalborg, Denmark, from April 1984 to April 1987 at approximately the 36th week of gestation. Information on hospitalization with asthma was extracted from the National Hospital Discharge Registry, which allowed a complete follow-up of all members of the cohort who remained alive and residents in the county.

RESULTS

The cumulative incidence rates of hospitalization with 'definite' and 'any' asthma were 3.5% and 5.0%, respectively, at 12 years of age. After adjusting for potential confounders, there were increased trends in the risk of asthma hospitalization with birthweight and ponderal index. More pronounced trends, particularly in the risk of definite asthma, were found among children of over the average birthweight (IRR = 1.62, 95% CI: 1.02-2.59 per 1000 g increase) or ponderal index (IRR = 1.06, 95% CI: 1.02-1.10 per 0.1 g/cm(3) increase). However, the increased risk in large babies was seen only in children with a ponderal index of > or =2.5 g/cm3.

CONCLUSION

Birthweight and ponderal index were associated with childhood asthma indicated by hospitalization. Fetal growth itself, determinants of fetal growth, or any unadjusted factors that correlate with fetal growth, could cause the association.

Early life factors related to clinical manifestations of atopic disease but not to skin-prick test positivity in young children

The relative influence of early life events in the development of IgE-mediated allergy is still undetermined. We investigated early life factors in relation to skin-prick test positivity (SPT) and clinical manifestations of atopic disease in a population-based sample of 201 Italian children (3 months-5 years), after considering their interactions with known determinants of allergy. Among them, 143 children had SPT performed to common allergens. Threatened abortions, general anesthesia at delivery, prematurity, birthweight < 2500 g, maternal smoking, dampness and gas heating exposure were all significantly related to an increased risk of frequent rhinitis in the absence of cold (18%). In utero smoking, threatened abortions, fetal health complications, infantile colic, maternal smoking in childhood (satisfactorily correlated with maternal expired CO during the survey) and respiratory infections were all independent determinants of frequent wheezing (23%). Doctor's diagnosis of asthma (3%) was related to in utero smoking, being born in spring, infantile colic and respiratory infections. A simultaneous exposure to in utero smoking and infantile colic put the infants to a fourfold higher risk of frequent wheezing and to a ninefold risk of asthma, respectively. Having a pet and washing blankets at < 60 degrees C were inversely related to frequent wheezing. Data confirmed also that maternal phenotype influences the inheritance of atopic disease. No event, except a low intake of fruit (< 3/week), was significantly associated with positive SPT (20%) or eczema. Besides allergic sensitization, other events, which occur early in life, seem critical to the development of IgE-mediated allergy.

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.

Risk of childhood asthma and allergic rhinitis in relation to pregnancy complications

BACKGROUND

Events occurring during fetal life may affect the development of the immune and respiratory systems and increase the risk of asthma and allergic diseases.

OBJECTIVES

We sought to elaborate the relations between the occurrence of pregnancy complications and other pregnancy-related conditions and the risk of bronchial obstruction during the first 2 years of life and the occurrence of asthma and allergic rhinitis by the age of 4 years. Pregnancy complications were considered both as predictors of the health outcomes and as possible effects caused by other prenatal factors.

METHODS

A population-based, 4-year, cohort study was carried out involving 2531 children born in Oslo, Norway. We collected information on maternally related (hyperemesis, hypertension, and preeclampsia) and uterus-related complications in pregnancy (antepartum hemorrhage, preterm contractions, insufficient placenta, and restricted growth of the uterus) and the child's health and environmental exposures at birth and at 6, 12, 18, and 24 months and 4 years of age. The outcomes of interest were bronchial obstruction during the first 2 years and asthma and allergic rhinitis at the age of 4 years.

RESULTS

In a logistic regression analysis adjusting for potential confounders, uterus-related, but not other pregnancy-related, complications increased the risk of bronchial obstruction (odds ratio [OR], 2.1; 95% confidence interval [CI], 1.3-3.4), asthma (OR, 3.0; 95% CI, 1.8-5.4), and allergic rhinitis (OR, 2.9; 95% CI, 1.6-5.2). These relations were similar in children of atopic and nonatopic parents.

CONCLUSIONS

Uterus-related complications in pregnancy increase the risk of having asthma and allergic rhinitis in childhood.

Very low birthweight and asthma by age seven years in a national cohort

Several studies have suggested that very low birthweight (VLBW < 1500 g) is associated with increased rates of respiratory problems in childhood and that the presence of chronic lung disease further increases the risk. We aimed to assess rates of asthma at 7-8 years of age in a national cohort of VLBW infants born in 1986 and for whom perinatal data were available. Two hundred ninety-nine former VLBW children (96% of surviving children living in New Zealand) were assessed at a home visit. Parents were asked a comprehensive questionnaire, including three questions aimed at assessing morbidity from asthma: 1) was the child diagnosed as having asthma before age 7 years; 2) was the child still experiencing asthma at the age of 7 years; and 3) was the child prescribed daily medication for asthma at the age of 7 years. Overall, 50% of the cohort had been diagnosed with asthma before age 7, compared with 27% of a sample of New Zealand children assessed contemporaneously in an international study; 32% had asthma at age 7, and 11% were taking daily medication. All three categories of asthma were associated with a family history of asthma, but there was no association with any perinatal factors. A diagnosis of asthma before age 7 was more likely when the mother smoked in pregnancy (P < 0.005) and currently smoked (P < 0.01), and trended so when parents lacked high school qualifications and in Maori or Pacific Island families (P < 0.10). In contrast, daily medication was more frequent when parents had educational qualifications and in non-Maori or Pacific Island families (P < 0.05). On multiple logistic regression, a family history of asthma was a significant predictor for any and current asthma (P < 0.001) and daily medication (P < 0.05); maternal smoking in pregnancy was a significant predictor for any asthma (P < 0.05); and non-Maori or Pacific Island ethnicity was a significant predictor for asthma treatment (P < 0.05). We conclude that rates of childhood asthma are high in this VLBW cohort, but the high prevalence appears to be unrelated to perinatal factors, including respiratory morbidity. There are suggestions that social factors contribute to both asthma risk and treatment.