Pulmonary function in children with initial low birth weight

Associations between cord blood acetaminophen biomarkers and childhood asthma with and without allergic comorbidities

BACKGROUND

Previous studies have linked prenatal acetaminophen use to increased asthma risk in children. However, none have explored this association while differentiating between asthma cases with and without other allergic conditions or by employing objective biomarkers to assess acetaminophen exposure.

OBJECTIVE

To evaluate whether the detection of acetaminophen biomarkers in cord blood is associated with the subgroups of asthma both with and without allergic comorbidities in children.

METHODS

Acetaminophen biomarkers, including unchanged acetaminophen and acetaminophen glucuronide, were measured in neonatal cord blood samples from the Boston Birth Cohort. Asthma subgroups were defined on the basis of physician diagnoses of asthma and other allergic conditions (atopic dermatitis and allergic rhinitis). Multinomial regressions were used to evaluate the associations between acetaminophen biomarkers and asthma subgroups, adjusting for multiple confounders, including potential indications for maternal acetaminophen use such as maternal fever.

RESULTS

The study included 142 children with asthma and at least 1 other allergic condition, 55 children with asthma but no other allergic condition, and 613 children free of asthma. Detection of acetaminophen in cord blood, reflecting maternal exposure to acetaminophen shortly before delivery, was associated with 3.73 times the odds of developing asthma without allergic comorbidities (95% CI: 1.79-7.80, P = .0004). In contrast, the detection of acetaminophen in cord blood was not associated with an elevated risk of asthma with allergic comorbidities. Analysis of acetaminophen glucuronide yielded consistent results.

CONCLUSION

In a prospective birth cohort, cord blood acetaminophen biomarkers were associated with an increased risk of childhood asthma without allergic comorbidities, but were not associated with childhood asthma with allergic comorbidities.

Maternal risk factors associated with term low birth weight in India: A review

Low birth weight is one of the leading factors for infant morbidity and mortality. To a large extent affect, various maternal risk factors are associated with pregnancy outcomes by increasing odds of delivering an infant with low birth weight. Despite this association, understanding the maternal risk factors affecting term low birth weight has been a challenging task. To date, limited studies have been conducted in India that exert independent magnitude of these effects on term low birth weight. The aim of this review is to examine the current knowledge of maternal risk factors that contribute to term low birth weight in the Indian population. In order to identify the potentially relevant articles, an extensive literature search was conducted using PubMed, Goggle Scholar and IndMed databases (1993 – Dec 2020). Our results indi­cate that maternal age, educational status, socio-economic status, ethnicity, parity, pre-pregnancy weight, maternal stature, maternal body mass index, obstetric history, maternal anaemia, gestational weight gain, short pregnancy outcome, hypertension during pregnancy, infection, antepartum haemorrhage, tobacco consumption, maternal occupation, maternal psychological stress, alcohol consumption, antenatal care and mid-upper arm circumference have all independent effects on term low birth weight in the Indian pop­ulation. Further, we argue that exploration for various other dimensions of maternal factors and underlying pathways can be useful for a better understanding of how it exerts independent association on term low birth weight in the Indian sub-continent.

Determinants of Lung Function at Age 8.5 Years in a Birth Cohort of Thai Children

BACKGROUND AND AIMS

Early life factors have reported the associations with impaired lung function in later life. In the present study, the birth cohort was followed up longitudinally to investigate the determinants of lung function in Thai children.

METHODS

Cohort subjects were recruited from children born in Songkhla Province in southern Thailand. Data collections were obtained starting from antenatal, at birth, and at 1, 5 and 8.5 years of age. Spirometry was assessed at age 8.5 years. The variables investigated included birth weight, smoke exposure, respiratory diseases during the newborn period and during the first year of life, and asthma diagnosed at age 5 or 8.5 years.

RESULTS

Of 1056 subjects, 892 (84.5%) subjects completed the spirometric measurements. The presence of asthma was the only factor that was significantly associated with a lower forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) ratio, forced expiratory flow at 25-75% vital capacity (FEF25-75%VC) and peak expiratory flow rate (PEFR). The regression analysis found that asthma was significantly associated with a lower FEV1/FVC ratio, FEF25-75%VC, and PEFR value with estimated coefficients ± standard error of -1.27 ± 0.55%, p = 0.02; -131.8 ± 48.2 ml/s, p = 0.006; and -166.2 ± 65.0 ml/s, p = 0.01, respectively. Asthma diagnosed at age 5 or 8.5 years was more likely among children who had lower respiratory tract illness during the first year of life. The odds ratio for the association was 4.81 (95% confidence interval 2.14-10.83, p < 0.001).

CONCLUSION

The main factor associated with lower lung function in Thai cohort subjects was the present of asthma by age 5 or 8.5 years and early respiratory illness was the risk factor for asthma in childhood period.

Perinatal Undernutrition, Metabolic Hormones, and Lung Development

Maternal and perinatal undernutrition affects the lung development of litters and it may produce long-lasting alterations in respiratory health. This can be demonstrated using animal models and epidemiological studies. During pregnancy, maternal diet controls lung development by direct and indirect mechanisms. For sure, food intake and caloric restriction directly influence the whole body maturation and the lung. In addition, the maternal food intake during pregnancy controls mother, placenta, and fetal endocrine systems that regulate nutrient uptake and distribution to the fetus and pulmonary tissue development. There are several hormones involved in metabolic regulations, which may play an essential role in lung development during pregnancy. This review focuses on the effect of metabolic hormones in lung development and in how undernutrition alters the hormonal environment during pregnancy to disrupt normal lung maturation. We explore the role of GLP-1, ghrelin, and leptin, and also retinoids and cholecalciferol as hormones synthetized from diet precursors. Finally, we also address how metabolic hormones altered during pregnancy may affect lung pathophysiology in the adulthood.

Distinctive lung function trajectories from age 10 to 26 years in men and women and associated early life risk factors - a birth cohort study

Pre-bronchodilator lung function including forced vital capacity (FVC), forced expiratory flow in 1 second (FEV1), their ratio (FEV1/FVC), and forced expiratory flow 25-75% (FEF25-75) measured at age 10, 18, and 26 years in the Isle of Wight birth cohort was analyzed for developmental patterns (trajectories). Early life risk factors before the age of 10 years were assessed for the trajectories.

METHOD

Members of the birth cohort (1989/90) were followed at age 1, 2, 4, 10, 18, and 26 years. Allergic sensitization and questionnaire data were collected. Spirometry tests were performed and evaluated according to the American Thoracic Society (ATS) criteria at 10, 18, and 26 years. To identify developmental trajectories for FVC, FEV1, FEV1/FVC, and FEF25-75 from 10 to 26 years, a finite mixture model was applied to the longitudinal lung function data, separately for males and females. Associations of early life factors with the respective lung function trajectories were assessed using log-linear and logistic regression analyses.

RESULTS

Both high and low lung function trajectories were observed in men and women. FVC continued to grow beyond 18 years in men and women, whereas FEV1 peaked at age 18 years in female trajectories and in one male trajectory. For the FEV1/FVC ratios and FEF25-75 most trajectories appeared highest at age 18 and declined thereafter. However, the low FEV1/FVC trajectory in both sexes showed an early decline at 10 years. Lower birth weight was linked with lower lung function trajectories in males and females. Eczema in the first year of life was a risk factor for later lung function deficits in females, whereas the occurrence of asthma at 4 years of age was a risk factor for later lung function deficits in males. A positive skin prick test at age four was a risk for the low FEV1 trajectory in females and for the low FEV1/FVC trajectory in males.

CONCLUSION

Men and women showed distinctive lung function trajectories and associated risk factors. Lower lung function trajectories can be explained by not achieving maximally attainable function at age 18 years and by a function decline from 18 to 26 years.

Relationship between birth weight, maternal smoking during pregnancy and childhood and adolescent lung function: A path analysis

BACKGROUND

Low birth weight and gestational maternal smoking have been linked with reduced lung function in children in many cross sectional studies. However, these associations have not yet been assessed with repeated measurements of lung function. Our aim was to investigate the effects of birth weight, gestational age, and gestational maternal smoking on lung function in children at age 10 and 18 years.

METHODS

In the Isle of Wight birth cohort spirometry was performed at age 10 and 18 years. Information on birth weight and gestational age were obtained from hospital records. Mothers were asked about smoking during pregnancy. We employed linear mixed models to estimate the effect of these risk factors on repeated measurements of lung function. We considered maternal asthma, sex, neonatal intensive care unit admission, height, socio-economic status, personal smoking in participants at age 18, body mass index and environmental tobacco smoke exposure as potential confounders. Finally, we used path analysis to determine links between birth weight, gestational age and gestational maternal smoking on lung function at age 10 and 18 years.

RESULTS

Linear mixed models showed that with every 1 kg increase in birth weight, Forced expiratory volume in one second (FEV₁) increased by 42.6 ± 17.2 mL and Forced expiratory flow between 25% and 75% (FEF_25-75) of Forced vital capacity (FVC) increased by 95.5 ± 41.2 mL at age 18 years after adjusting for potential confounders. Path analysis suggested that birth weight had positive direct effects on FEV₁ and FEF_25-75 and positive indirect effect on FVC at 10 years which were carried forward to 18 years. Additionally, results also suggested a positive association between gestational age and FEV₁, FVC and FEF_25-75 at ages 10 and 18 years and an inverse association between gestational smoke exposure and FEV₁/FVC ratio and FEF_25-75 at age 18 years.

CONCLUSIONS

Higher birth weight and gestational age were associated with higher FEV₁, FVC and FEF_25-75 and maternal smoking during pregnancy was associated with reduced FEV₁/FVC ratio and FEF_25-75. The use of path analysis can improve our understanding of underlying "causal" pathways among different prenatal and childhood factors that affect lung function in both pre-adolescent and adolescent periods.

FGR in the setting of preterm sterile intra-uterine milieu is associated with a decrease in RDS

OBJECTIVE

To determine if fetal growth restriction (FGR) in the setting of sterile intra-uterine milieu would be associated with a decrease in respiratory distress syndrome (RDS) of preterm-neonates.

METHODS

The relationship between FGR and neonatal RDS was examined in 92 singleton preterm-neonates (gestational age [GA]: 24.5-33.4 weeks) born to mothers with sterile intra-uterine milieu, which consisted of both sterile amniotic fluid (AF), and inflammation-free placenta. Sterile AF was defined in the absence of both infection and inflammation in AF. AF inflammation was defined in the presence of AF MMP-8 ≥23 ng/ml. FGR was defined in the presence of birth-weight (BW) below the 5th percentile for GA.

RESULTS

FGR was present in 32% and RDS was found in 46% of patients. RDS was less common (24% vs. 56%; P < 0.01) and umbilical arterial pH at birth ≤7.15 was more common (33% vs. 13%; P < 0.05) in preterm-neonates with FGR than in those without FGR. There is a stepwise increase in RDS with increasing BW (i.e., below the 5th percentile, the 5th ∼10th percentile, and above the 10th percentile for GA) (P < 0.01, linear by linear association). Logistic regression analysis demonstrated that FGR was a better independent predictor of a decrease in RDS (OR = 0.049, 95%CI 0.009-0.259, P < 0.0005) than advanced GA at delivery (OR = 0.584, 95%CI 0.423-0.806, P < 0.005) after adjusting for other confounding variables.

CONCLUSION

FGR in the setting of sterile intra-uterine milieu is associated with a decrease in RDS of preterm-neonates. This observation suggests that chronic intra-uterine hypoxic stress related to FGR may be beneficial to fetal lung maturation. Pediatr Pulmonol. 2016;51:812-819. © 2015 Wiley Periodicals, Inc.

In utero Programming of Allergic Susceptibility

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

The effect of birth weight on lung spirometry in white, school-aged children and adolescents born at term: a longitudinal population based observational cohort study

OBJECTIVE

To evaluate how birth weight affects lung function measurements in childhood and adolescence in term-born children.

STUDY DESIGN

We used data for white, term-born, singletons, from the Avon Longitudinal Study of Parents and Children to determine the association between birth weight and lung function at age 8-9 (n=4086) and 14-17 (n=2582) years. z-scores for lung function measures, adjusted for sex, height, and age, were modeled in terms of birth weight z-score adjusted for sex. In addition, gestation and head circumference then confounders (maternal smoking during pregnancy and social class) were added to the model.

RESULTS

At age 8-9 years, birth weight z-scores were significantly associated with lung function z-scores (forced expiratory volume in 1 second, forced vital capacity [FVC], and forced mid-expiratory flow between 25% and 75% of FVC). These relationships essentially were unchanged when birth weight z-scores were further adjusted for gestation, head circumference, and confounders, except for forced mid-expiratory flow between 25% and 75% of FVC, which was no longer significant after we adjusted for head circumference and confounders. At age 14-17 years, the associations between adjusted birth-weight z-scores and spirometry z-scores were in general not significant. Estimated differences for forced expiratory volume in 1 second were 30 mL at ages 8-9 years and 33 mL at 14-17 years for 1 kg change in birth-weight standardized for gestation and sex.

CONCLUSIONS

Birth weight is associated with lung function in term-born children at 8-9 years, but less so at 14-17 years, suggesting that birth weight influences lung function in early childhood but has lesser effect later in life.

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.

Targeted health department expenditures benefit birth outcomes at the county level

BACKGROUND

Public health leaders lack evidence for making decisions about the optimal allocation of resources across local health department (LHD) services, even as limited funding has forced cuts to public health services while local needs grow. A lack of data has also limited examination of the outcomes of targeted LHD investments in specific service areas.

PURPOSE

This study used unique, detailed LHD expenditure data gathered from state health departments to examine the influence of maternal and child health (MCH) service investments by LHDs on health outcomes.

METHODS

A multivariate panel time-series design was used in 2013 to estimate ecologic relationships between 2000-2010 LHD expenditures on MCH and county-level rates of low birth weight and infant mortality. The unit of analysis was 102 LHD jurisdictions in Washington and Florida.

RESULTS

Results indicate that LHD expenditures on MCH services have a beneficial relationship with county-level low birth weight rates, particularly in counties with high concentrations of poverty. This relationship is stronger for more targeted expenditure categories, with expenditures in each of the three specific examined MCH service areas demonstrating the strongest effects.

CONCLUSIONS

Findings indicate that specific LHD investments in MCH have an important effect on related health outcomes for populations in poverty and likely help reduce the costly burden of poor birth outcomes for families and communities. These findings underscore the importance of monitoring the impact of these evolving investments and ensuring that targeted, beneficial investments are not lost but expanded upon across care delivery systems.

Small for gestational age birth weight: impact on lung structure and function

Accumulating data suggest that prenatal compromises leading to intrauterine growth restriction (IUGR) increase the risk for respiratory deficiencies after birth. In this respect, a growing body of epidemiological evidence in infants, children and adults indicates that small for gestational (SGA) birth weight can adversely affect lung function, thus questioning the widely accepted concept that IUGR accelerates lung maturation and improves outcome. Although the mechanisms responsible for the relationship between SGA and later lung dysfunction remain poorly documented, animal data indicate that intrauterine lung development can be adversely affected by factors associated with IUGR, namely reduced substrate supply, fetal hypoxemia and hypercortisolemia. Thus, it is suggested that fetal adaptations to intrauterine undernutrition result in permanent changes in lung structure, which in turn lead to chronic airflow obstruction. The purpose of this review is to describe and discuss the effects of IUGR on lung structure and function.

GSTM1 and GSTP1 gene variants and the effect of air pollutants on lung function measures in South African children

BACKGROUND

Several genes are associated with an increased susceptibility to asthma, which may be exacerbated by ambient air pollution. These genes include GSTM1 (glutathione-S-transferase M1 gene) and GSTP1 (glutathione-S-transferase P1 gene), which may modulate the response to epithelial oxidative changes caused by air pollutant exposure. This study evaluated fluctuations in the forced expiratory volume in one second (FEV(1)) in relation to lagged daily averages of ambient air pollutants (SO(2), NO(2), NO, and PM(10)) while considering genotype as an effect modifier.

METHODS

A longitudinal cohort of 129 schoolchildren of African descent from Durban, South Africa was assessed. GSTM1 (null vs. present genotype) and GSTP1 (Ile105Val; AA → AG/GG) genotypes were determined using standard techniques. SO(2), NO(2), NO, and PM(10) were measured continuously over a year using validated methods. The outcome was intraday variability in FEV(1) . Data were collected daily over a 3-week period in each of four seasons (2004-2005).

RESULTS

Among the children tested, 27% had the GSTM1 null genotype and 81% carried the GSTP1 G allele. Approximately 26 out 104 children (25%) showed evidence of bronchial hyperreactivity, 13% reported having symptoms in keeping with persistent asthma, and a further 25% reported symptoms of mild intermittent asthma. PM(10) and SO(2) levels were moderately high relative to international guidelines. Neither GSTM1 nor GSTP1 genotypes alone were significantly associated with FEV(1) intraday variability. In models not including genotype, FEV(1) variability was statistically significantly associated only with NO(2) for 5-day lags (% change in intraday variability in FEV1 per interquartile range = 1.59, CI 0.58, 2.61). The GSTP1 genotype modified the effect of 3 days prior 24-hr average PM(10) and increased FEV(1) variability. A similar pattern was observed for lagged 3 day SO(2) exposure (P interaction < 0.05). Adverse effects of these pollutants were limited to individuals carrying the G allele for this polymorphism.

CONCLUSION

Among this indigenous South African children cohort, the GSTP1 genotype modified the effects of ambient exposures to PM(10) and SO(2) and lung function. A plausible mechanism for these observed effects is decreased capacity to mount an effective response to oxidative stress associated with the GSTP1 AG + GG genotype.

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.

Relationship between infant weight gain and later asthma

Like obesity, the prevalence of asthma has increased over the past several decades. Accelerated patterns of infant growth have been associated with obesity and its co-morbidities. We aimed to determine if infant weight gain pattern is associated with asthma development later in childhood. Birth weight, growth, pulmonary function, and symptom data were collected in a trial of 2- to 3-yr-old children at-risk for asthma randomized to a 2-yr treatment with inhaled corticosteroids or placebo followed by a 1-yr observation period of study medication. Patterns of infant weight gain between birth and study enrollment were categorized as accelerated, average, or decelerated. Regression analyses were used to test the effects of infant weight gain pattern prior to study enrollment on outcomes during the observation year and at study conclusion while adjusting for demographics, baseline symptom severity, study treatment, and atopic indicators. Among the 197 study participants, early life weight gain pattern was not associated with daily asthma symptoms or lung function at the study's conclusion. However, both prednisone courses (p = 0.01) and urgent physician visits (p < 0.001) were significantly associated with weight gain pattern with fewer exacerbations occurring amongst those with a decelerated weight gain pattern. We conclude that early life patterns of weight change were associated with subsequent asthma exacerbations, but were not associated with asthma symptoms or pulmonary function during the pre-school years for these children at-risk for asthma.

Spirometric lung function in school-age children: effect of intrauterine growth retardation and catch-up growth

RATIONALE

Few studies have investigated childhood respiratory outcomes of intrauterine growth retardation (IUGR), and it is unclear if catch-up growth in these children influences lung function.

OBJECTIVES

We determined if lung function differed in 8- to 9-year-old children born at term with or without growth retardation, and, in the growth-retarded group, if lung function differed between those who did and those who did not show weight catch up.

METHODS

Caucasian singleton births of 37 weeks or longer gestation from the Avon Longitudinal Study of Parents and Children (n = 14,062) who had lung spirometry at 8-9 years of age were included (n = 5,770).

MEASUREMENTS AND MAIN RESULTS

Infants with gestation-appropriate birthweight (n = 3,462) had significantly better lung function at 8-9 years of age than those with IUGR (i.e., birthweight <10th centile [n = 576] [SD differences and confidence intervals adjusted for sex, gestation, maternal smoking during pregnancy, and social class: FEV(1), -0.198 (-0.294 to -0.102), FVC, -0.131 (-0.227 to -0.036), forced midexpiratory flow between 25 and 75% of vital capacity -0.149 (-0.246 to -0.053)]). Both groups had similar respiratory symptoms. All spirometry measurements were higher in children with IUGR who had weight catch-up growth (n = 430) than in those without (n = 146), although the differences were not statistically significant. Both groups remained significantly lower than control subjects. Growth-retarded asymmetric and symmetric children had similar lung function.

CONCLUSIONS

IUGR is associated with poorer lung function at 8-9 years of age compared with control children. Although the differences were not statistically significant, spirometry was higher in children who showed weight catch-up growth, but remained significantly lower than the control children.

Is there a link between wheezing in early childhood and adverse birth outcomes? A systematic review

We aimed to provide a summary of the existing published knowledge on the association between adverse birth outcomes and the development of wheezing during the first two years of life. We carried out a systematic review of epidemiological studies within the MEDLINE database. Epidemiological studies on human subjects, published in English, were included in the review. A comprehensive literature search yielded 72 studies for further consideration. Following the application of the eligibility criteria we identified nine studies. A positive association and an excess risk of wheezing during the first two years of life were revealed for adverse birth outcomes.

[Perinatal exposure to tobacco and respiratory and allergy symptoms in first years of life]

BACKGROUND AND OBJECTIVES

To analyse the relationship between prenatal and postnatal tobacco exposure and the development of respiratory and allergy symptoms during the first 4 years of life.

PATIENTS AND METHODS

Prospective and multicentred cohort study that included the subjects belonging to AMICS (Asthma Multicentred Infant Cohort Study) located in Ashford (England), Barcelona and Minorca (Spain). We recruited 1611 children, followed from the pregnancy to the 4th year of life, whose parents annually answered a questionnaire on their tobacco consumption and their children's respiratory and allergy health. In the Barcelona cohort (n=487) a tobacco exposure biomarker (cotinine) was analysed on several matrices.

RESULTS

Prenatal tobacco exposure is associated with a greater risk of hospitalisation due to respiratory infection, particularly in the second year of life, whereas postnatal tobacco exposure is associated more strongly with the presence of late wheezing presence and increases in the chance of being diagnosed with asthma at 4 years of age. The children prenatally and postnatally exposed had more persistent wheezing, persistent rhoncus, early cough, a higher number of upper respiratory infections per year and a greater number were diagnosed with asthma. The higher the levels of cotinine measured, the higher was the risk for wheezing. No relationship was seen between tobacco exposure and atopic symptoms.

CONCLUSIONS

Passive smoke exposure during pregnancy and childhood has very distinct clinical respiratory effects in children. Therefore, smoking cessation of childbearing age women must be a priority of preventive medicine.

Birth weight and lung function in a cohort of Chinese school children

OBJECTIVE

Evidence on the association between birth weight and lung function is conflicting. We evaluated the children's lung function in relation to their birth weight in China.

METHODS

A prospective cohort study was conducted in 1,599 school children. Baseline data on birth weight and other potential confounding variables were obtained from self-administered questionnaires. Pulmonary function tests were performed with a standard procedure and repeated 6 months later.

RESULTS

There were no significant differences in the standard deviation score (SDS) of forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) between children with low birth weight (LBW) and those with normal birth weight (NBW). The growth rates in lung function between children with LBW and NBW were also insignificant.

CONCLUSIONS

No association between birth weight and lung function was found among Chinese school children.

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.

Birth weight and adult lung function: a within-pair analysis of twins followed up from birth

BACKGROUND

The aim of the study was to evaluate whether there is any association between intrauterine growth and later lung function or bronchial reactivity in early adulthood in line with Barker's hypothesis.

METHODS

Nineteen twin pairs with disproportionate intrauterine growth pattern were followed up from birth: either one of the pairs had intrauterine growth retardation (birth weight <2 SD) or the within-pair birth weight difference was >1.3 SD. Flow-volume spirometry, followed by isocapnic hyperventilation of cold air, was performed at the ages of 8-16 and 14-22 years in 1993 and 1999. Wilcoxon's matched-pairs analysis was used to compare smaller and larger twin pairs.

RESULTS

In 1993, there were no significant differences between the groups in either spirometry or cold air challenge. In 1999, such a difference was found in forced expiratory volume % (FEV%) and forced expiratory flow (FEF) at 25%-75%, the smaller twin pairs having lower values. In 1993, nine subjects reacted to cold air (>9% decrease in FEV in 1 second). In 1999, only four subjects reacted to cold air, and they all belonged to the group of smaller twins (P=0.04).

CONCLUSION

Lung function evaluated by FEV% and FEF25-75 was lower and responses to cold air were more common at the median age of 16 years in twins with impaired intrauterine growth.

Effects of Folate and Vitamin B12 Deficiencies During Pregnancy on Fetal, Infant, and Child Development

The importance of folate in reproduction can be appreciated by considering that the existence of the vitamin was first suspected from efforts to explain a potentially fatal megaloblastic anemia in young pregnant women in India. Today, low maternal folate status during pregnancy and lactation remains a significant cause of maternal morbidity in some communities. The folate status of the neonate tends to be protected at the expense of maternal stores; nevertheless, there is mounting evidence that inadequate maternal folate status during pregnancy may lead to low infant birthweight, thereby conferring risk of developmental and long-term adverse health outcomes. Moreover, folate-related anemia during childhood and adolescence might predispose children to further infections and disease. The role of folic acid in prevention of neural tube defects (NTD) is now established, and several studies suggest that this protection may extend to some other birth defects. In terms of maternal health, clinical vitamin B12 deficiency may be a cause of infertility or recurrent spontaneous abortion. Starting pregnancy with an inadequate vitamin B12 status may increase risk of birth defects such as NTD, and may contribute to preterm delivery, although this needs further evaluation. Furthermore, inadequate vitamin B12 status in the mother may lead to frank deficiency in the infant if sufficient fetal stores of vitamin B12 are not laid down during pregnancy or are not available in breastmilk. However, the implications of starting pregnancy and lactation with low vitamin B12 status have not been sufficiently researched.

Pulmonary testing using peak flow meters of very low birth weight children born in the perisurfactant era and school controls at age 10 years

We determined lung function at age 10 years in very low birthweight (VLBW, <or=1,500 g) children and controls, and compared the sensitivity to detect subgroup differences by peak expiratory flow (PEF), forced expiratory volume in one second (FEV(1)), forced vital capacity (FVC) and their diurnal variation. VLBW children were recruited across the perisurfactant era at admission to six NICUs in Wisconsin and Iowa, and controls from area classrooms. Two hundred sixty five VLBW children and 360 controls were tested by the Jaeger AM1 peak flow meter at age 10 years. Two hundred six VLBW and 79 controls had additional home monitoring. Abnormality was defined as observed/predicted ratio <0.8 for PEF, FEV(1), and FVC, and by criteria of Pelkonen for diurnal PEF variation. VLBW children were compared to controls, VLBW children with bronchopulmonary dysplasia (BPD) to those without, and those with respiratory conditions to those without. PEF and FEV(1) showed high reproducibility (intraclass correlations, ICC 0.75-0.83). Controls and VLBW children with and without BPD differed significantly on all measures. Baseline test results did not differ across birth years, but PEF variation was less after surfactant availability (P = 0.04). Observed over predicted FEV(1) was the most sensitive in detecting differences between groups (P < 0.001), with mean (s.d.) 0.97 (0.12) for controls, 0.88 (0.14) for VLBW children without BPD, and 0.78 (0.13) for those with BPD. Odds ratios for abnormality were especially high with respiratory medication use during the first 5 years of life, 4.4 (95% CI: 2.0-9.8) for FEV(1) and 5.1 (95% CI: 2.0-13.2) for diurnal PEF variation. Our results show that respiratory abnormalities persist to at least age 10 years for VLBW children born in the surfactant era.

Low birthweight and asthma among young urban children

OBJECTIVES

We assessed whether the association between low birthweight and early childhood asthma can be explained by an extensive set of individual- and neighborhood-level measures.

METHODS

A population-based sample of children born in large US cities during 1998-2000 was followed from birth to age 3 years (N=1803). Associations between low birthweight and asthma diagnosis at age 3 years were estimated using multilevel models. Prenatal medical risk factors and behaviors, demographic and socioeconomic characteristics, and neighborhood characteristics were controlled.

RESULTS

Low-birthweight children were twice as likely as normal birthweight children to have an asthma diagnosis (34% vs 18%). The fully adjusted association (OR= 2.36; P<.001) was very similar to the unadjusted association (OR= 2.48; P<.001). Rates of renter-occupied housing and vacancies at the census tract-level were strong independent predictors of childhood asthma.

CONCLUSIONS

Very little of the association between low birthweight and asthma at age 3 can be explained by an extensive set of demographic, socioeconomic, medical, behavioral, and neighborhood characteristics. Associations between neighborhood housing characteristics and asthma diagnosis in early childhood need to be further explored.

Respiratory function at age 8-9 years in extremely low birthweight/very preterm children born in Victoria in 1991-1992

Our aim was to determine respiratory function at 8 years of age in extremely low birth weight (ELBW; birth weight, < 1,000 g)/very preterm (< 28 weeks of gestation) children born in the 1990s compared with normal birth weight (NBW; birth weight, >2,499 g) controls. The ELBW/very preterm subjects comprised 298 consecutive survivors with either birth weight < 1,000 g or gestational age < 28 weeks born in the state of Victoria during 1991-1992. Controls comprised 262 randomly selected NBW survivors. Respiratory function was measured on 81% (240/298) of the ELBW/very preterm children and 79% (208/262) of the NBW controls. Respiratory function variables reflecting airflow were substantially diminished in ELBW/very preterm children compared with NBW controls. Moreover, the proportions with clinically important reductions in airflow were higher in the ELBW/very preterm group (e.g., forced expired volume in 1 sec, < 75%; ELBW/very preterm, 19.7%; NBW, 2.4%; P < 0.0001). Within the ELBW/very preterm group, children who had bronchopulmonary dysplasia (BPD) in the newborn period and those who had later asthma had significantly reduced respiratory function in variables reflecting airflow. In conclusion, the abnormalities in respiratory function in ELBW/very preterm children compared with NBW subjects described in the presurfactant era persisted in the 1990s, especially in those who had BPD in the newborn period.

Respiratory Function in Adolescence in Relation to Low Birth Weight, Preterm Delivery, and Intrauterine Growth Restriction

OBJECTIVES

To study the associations between respiratory function in 18-year-old male subjects and birth weight, preterm delivery, and intrauterine growth restriction (IUGR).

METHODS

Population-based birth cohort. Subsamples of 118 male subjects with low birth weight (LBW) [< 2,500 g] and 236 male subjects with normal birth weight were examined at the age of 18 years.

RESULTS

In the crude analysis, subjects with LBW showed reductions in FEV1 and FVC of 0.166 L and 0.141 L, respectively, compared to those born weighing > or = 2,500 g. These differences were not significant after adjustment for confounding. When subjects with LBW were stratified into those with preterm delivery and those with IUGR, the latter presented a significant reduction in both FEV1 and FVC, when compared to the reference group. These differences also disappeared after adjustment for confounders. Preterm delivery per se was also not associated with poor lung function.

CONCLUSIONS

In this population, LBW was not associated with respiratory function in 18-year-old male subjects.

Low preconception body mass index is associated with birth outcome in a prospective cohort of Chinese women

Low maternal prepregnancy BMI is associated with adverse birth outcomes, but the BMI at which risk increases is not well defined. We assessed whether the relationship between prepregnancy BMI and birth outcomes is influenced by the extent to which mothers were underweight in a prospective study in Anhui, China. The women (n = 575) were 20-34 y old, married, nulliparous and nonsmokers. All measures of infant growth increased with increasing maternal BMI until a plateau was reached at a BMI of 22-23 kg/m2. Infants born to the 27% of women who were severely underweight before pregnancy (BMI < or = 18.5 kg/m2) were at increased risk for fetal growth deficits associated with infant morbidity. Compared with a normal BMI, being severely underweight was associated with mean (+/- SEM) reductions of 219 +/- 40 g in infant birthweight and 6.7 +/- 1.3% in the birthweight ratio and an 80% increase in risk of intrauterine growth restriction [odds ratio (OR) 1.8; 95% CI: 1.0, 3.3; P = 0.05]. Being severely underweight was also associated with smaller infant head circumference and lower ponderal index. Being moderately underweight (18.5 < BMI < 19.8 kg/m2) was not significantly associated with adverse pregnancy outcomes. Gestational age and risk of preterm birth were not associated with maternal BMI. More than half of the women in this study were underweight before pregnancy. Although being moderately underweight was not associated with increased risk of adverse pregnancy outcomes, being severely underweight was an important risk factor for reduced fetal growth.

Association between self-reported childhood socioeconomic position and adult lung function: findings from the British Women's Heart and Health Study

BACKGROUND

A study was undertaken to assess the associations between indicators of early life socioeconomic position and lung function in older adulthood.

METHODS

The associations of self-reported indicators of childhood socioeconomic position with adult lung function (forced expiratory volume in 1 second (FEV(1)), forced vital capacity (FVC), and forced expiratory flow rate during mid expiration (FEF(25-75)), all measured using standard procedures) were assessed in a cross sectional study of 3641 British women aged 60-79 years.

RESULTS

In confounder adjusted analyses, each individual indicator of childhood circumstances was inversely associated with each measure of lung function. In the fully adjusted models (including mutual adjustment for each of the other indicators of childhood socioeconomic circumstances), only childhood occupational social class and access to a car were associated with lung function in adulthood. However, there were strong linear trends of worsening lung function with greater numbers of indicators of childhood poverty (all p values <0.001).

CONCLUSIONS

Childhood poverty is associated with poorer lung function in women aged 60-79 years. Adverse childhood circumstances that affect both lung growth and development and cardiovascular disease in later life may explain some of the well known associations between poor lung function and cardiovascular disease, or lung function may be an important mediating factor in this association.

Chronic maternal nicotine exposure during gestation and lactation and the development of the lung parenchyma in the offspring

THE AIM OF THIS STUDY WAS TO INVESTIGATE THE EFFECT OF MATERNAL NICOTINE EXPOSURE DURING GESTATION AND LACTATION ON: (1) the development of the gas exchange area of the lungs of the offspring; and (2) to determine whether these effects are reversible. Pregnant rats received daily nicotine (subcutaneously 1mgkg(-1) body weight) during gestation and lactation. Nicotine administration started 1 day after mating and lasted until weaning on postnatal day 21. The offspring were exposed to nicotine via the placenta and mother's milk only. The lung tissue of the neonates was collected on postnatal days 14, 21, 35 and 42 and prepared for morphometry. The results obtained show that maternal nicotine exposure resulted in bigger alveolar volumes and suppressed alveolarisation in the lungs of the offspring. Flattening of the alveoli occurred as the animals aged and as a consequence the internal surface area available for gas exchange decreased; a condition that resembles panlobular emphysema. It is unlikely that these effects of maternal nicotine exposure during gestation and lactation on lung development in the offspring was due to a lower birth weight, or a reduction in the period of gestation, or a poor supply of nutrients to the offspring. The changes in the gas-exchange region of the nicotine-exposed rat pups appear to be irreversible.

Preconception homocysteine and B vitamin status and birth outcomes in Chinese women

BACKGROUND

The associations between homocysteine, B vitamin status, and pregnancy outcomes have not been examined prospectively.

OBJECTIVE

We assessed the associations of preconception homocysteine and B vitamin status with preterm birth and birth of low-birth-weight (LBW) and small-for-gestational-age (SGA) infants in Chinese women.

DESIGN

This was a case-control study of women aged 21-34 y. Preterm cases (n = 29) delivered living infants at <37 wk gestation; term controls (n = 405) delivered infants at > or =37 wk. LBW cases (n = 33) had infants weighing <2500 g; normal-birth-weight controls (n = 390) had infants weighing > or =2500 g. SGA cases (n = 65) had infants below the 10th percentile of weight-for-gestational-age; appropriate-for-gestational-age controls (n = 358) had infants above this cutoff. Nonfasting plasma concentrations of homocysteine, folate, and vitamins B-6 and B-12 were measured before conception.

RESULTS

Elevated homocysteine (> or =12.4 micro mol/L) was associated with a nearly 4-fold higher risk of preterm birth (OR: 3.6; 95% CI: 1.3, 10.0; P < 0.05). The risk of preterm birth was 60% lower among women with vitamin B-12 > or =258 pmol/L than among vitamin B-12-deficient women (OR: 0.4; 95% CI: 0.2, 0.9; P < 0.05) and was 50% lower among women with vitamin B-6 > or =30 nmol/L than among vitamin B-6-deficient women (OR: 0.5; 95% CI: 0.2, 1.2; NS). Folate status was not associated with preterm birth, and homocysteine and B vitamin status were not associated with LBW or SGA status.

CONCLUSIONS

Elevated homocysteine and suboptimal vitamin B-12 and B-6 status may increase the risk of preterm birth. These results need to be confirmed in larger prospective studies.

Pregnancy and immunology: selected aspects

LEARNING OBJECTIVES

This article reviews current concepts of the immunology of pregnancy and of the diagnosis and management of certain allergic conditions in the pregnant woman: asthma, rhinitis, immunotherapy, and hereditary angioedema (HAE).

DATA SOURCES

Current texts, reviews, and individual studies were picked from the National Library of Medicine database.

RESULTS AND CONCLUSIONS

Knowledge concerning the immunologic paradox of pregnancy continues to evolve. Although the answer is not definitive, attention is being paid to the role of a Th-2 shift in the pregnant uterus. Extensive studies, both epidemiologic and therapeutic, are clarifying the influence of pregnancy on asthma and rhinitis (and vice versa) and the best methods for treatment of these conditions in the pregnant woman. A brief guideline to the handling of hereditary angioedema in pregnancy is presented.

Effects of glutathione-S-transferase M1, T1, and P1 on childhood lung function growth

The effects of glutathione-S-transferase (GST) M1, GSTT1, and GSTP1 genotypes on lung function growth were investigated in 1,940 children enrolled in the Children's Health Study as fourth graders (aged 8-11 years) in two cohorts during 1993 and 1996 and were followed annually over a 4-year period. Genotypes for GSTM1 and GSTT1 and GSTP1 codon 105 variants (ile105 and val105) were determined using DNA from buccal cell specimens. We used two-level regression models to estimate the effects of GSTM1, GSTT1, and GSTP1 genotypes on the adjusted annual average lung function growth. GSTM1 null was associated with deficits in annual growth rates for FVC (-0.21%; 95% confidence interval [CI], -0.40, -0.03) and FEV(1) (-0.27%; 95% CI, -0.50, -0.04). Children who were homozygous for the GSTP1 val105 allele had slower lung function growth (FVC -0.35%; 95% CI, -0.62, -0.07; and FEV(1) -0.34%; 95% CI, -0.68, 0.00) than children with one or more ile105 alleles. Children with asthma who were homozygous for the GSTP1 val105 allele had substantially larger deficits in FVC, FEV(1), and maximal mid-expiratory flow than children without asthma. The deficits in FVC and FEV(1) growth associated with both GSTM1 null and the GSTP1 val105 allele were largest and were statistically significant in non-Hispanic white children. We conclude that GSTM1 and GSTP1 genotypes are associated with lung function growth in school children.

Influence of intrauterine growth restriction on airway development in fetal and postnatal sheep

Epidemiologic studies suggest that intrauterine growth restriction (IUGR) can lead to impaired lung function, yet little information exists on the effects of IUGR on airway development. Our objectives were to characterize morphometrically effects of IUGR on airway structure in the fetus and to determine whether alterations persist into postnatal life. We used two groups of sheep, each with appropriate controls; a fetal group was subjected to IUGR by restriction of placental function from 120 to 140 d (term approximately 147 d), and a postnatal group, killed 8 wk after birth, was subjected to IUGR from 120 d to birth at term. In both fetuses and postnatal lambs, IUGR did not alter lung weight relative to body weight. In IUGR fetuses, the luminal areas and basement membrane perimeters of the trachea and larger bronchi (generations 0-8, trachea = 0) were smaller than in controls. Airway wall areas, relative to basement membrane perimeters, were reduced in IUGR fetuses compared with controls, largely due to reduced areas of cartilage and epithelium. At 8 wk after birth, there were no significant differences in airway dimensions between IUGR and control lambs. However, the number of profiles of bronchial submucosal glands, relative to basement membrane perimeters, was lower in IUGR lambs than in controls and the area of epithelial mucin was increased. We conclude that restriction of fetal growth during late gestation impairs the growth of bronchial walls that could affect airway compliance in the immediate postnatal period. Although airway growth deficits are reversed by 8 wk, alterations in mucus elements persist.

Does low birth weight help to explain the increased prevalence of asthma among African-Americans?

BACKGROUND

Racial disparities in asthma prevalence are not fully explained. Previous studies have reported an association between low birth weight (LBW) and asthma. African-Americans are at a heightened risk for both conditions.

OBJECTIVE

The objective of this analysis was to study a sample of suburban schoolchildren to determine if increased asthma prevalence in African-Americans could be explained by report of LBW.

METHODS

Logistic regression was used to analyze telephone survey and clinical data for a sample of 126 children, aged 6 to 8 years.

RESULTS

African-Americans reported asthma (12.5% vs 5.3%) and LBW (16.6% vs 3.9%) more frequently than non-African-Americans. After adjusting for LBW, the odds ratio for the association of African-American race to asthma was reduced from 2.6 to 1.8, whereas LBW remained independently associated with asthma, adjusted odds ratio = 5.1 (95% CI:1.4 to 18.9). The adjusted population risk for asthma due to LBW was 0.31.

CONCLUSIONS

High rates of LBW for African-Americans may contribute to racial disparities in asthma prevalence.

Prevalence of respiratory symptoms in school children and salivary IgA--an epidemiological study in a rural area of Northrhine-Westphalia, Germany

An elevated frequency of wheezing was found in school children in a rural area of Northrhine-Westphalia, Germany (Duhme and Keil, Institut für Epidemiologie und Sozialmedizin, Universität Münster, Münster, Germany 1997). In this study the prevalence of wheezing was reinvestigated by including main influencing factors. A cross-sectional survey was performed in all school children visiting school classes 1, 2 and 7, 8 (n = 1161). Two corresponding questionnaires were used: a parental questionnaire and a questionnaire for self-completion by the children aged 12-15. The latter included the ISAAC video questionnaire. The levels of immunoglobulins A, G and M were determined in 995 saliva samples. Testing of lung function (whole body plethysmography before and after physical exercise) was performed in children with and without parent-reported wheezing in the last 12 months (n = 377). Response rate (questionnaire: 93%) and participation rates (saliva samples: 86%, lung function tests: 93%) were high. Our study confirmed higher prevalence of asthmatic symptoms in children aged 6-8 in Ochtrup (13.2%) compared to children of the same age in Muenster (8.5% (Duhme et al., Eur. Respir. J. 11, 840-847, 1998)). However, in the age group 12-15 years the prevalence was significantly lower in Ochtrup (9.8%), when compared to the former investigation and in comparison to Muenster (former survey: 17.9%; Muenster: 13.1%). Prevalence of wheezing was consistently higher in families with atopic disease. Additionally, history of respiratory disease, premature birth and presence of pets during 1st year of life showed a positive association with prevalence of wheezing. Mean salivary IgA levels were 61.4 (SD (standard deviation) 35.1, median: 53.7) mg/l in children aged 6-8 years and 83.4 (SD 39.0, median: 76.3) mg/l in children aged 12-15 years. No significant association between salivary immunoglobulins and wheezing was detected.