The effects of antenatal smoking on lung function and respiratory symptoms in infants and children

Prenatal exposure to ambient fine particulate matter and child lung function in the CANDLE cohort

BACKGROUND

Ambient fine particulate matter (PM2.5) exposure adversely impacts child airway health; however, research on prenatal PM2.5 exposure, and child lung function is limited. We investigated these associations in the ECHO-PATHWAYS Consortium, focusing on the role of exposure timing during different phases of fetal lung development.

METHODS

We included 675 children in the CANDLE cohort born between 2007 and 2011 in Memphis, TN, USA. Prenatal exposure to ambient PM2.5 was estimated using a spatiotemporal model based on maternal residential history and averaged over established prenatal periods of lung development. Forced expiratory volume in the first second (FEV1) and forced vital capacity (FVC) were measured by spirometry at age 8-9 years. We used linear regression and Bayesian Distributed Lag Interaction Models (BDLIM) to estimate associations between exposure and lung function z-scores, adjusting for maternal/child characteristics, prenatal/postnatal tobacco exposure, and birth year/season, and evaluating effect modification by child sex and allergic sensitization.

RESULTS

The average ambient concentration of PM2.5 during pregnancy was 11.1 µg/m3 (standard deviation:1.0 µg/m3). In the adjusted linear regression and BDLIM models, adverse, but not statistically significant, associations were observed between exposure during the pseudoglandular (5-16 weeks of gestation) and saccular (24-36 weeks) phases of lung development and FEV1 and FVC. The strongest association was between a 2 μg/m3 higher concentration of PM2.5 during the saccular phase and FEV1 z-score (-0.176, 95% Confidence Interval [CI]: -0.361, 0.010). The FEV1/FVC ratio was not associated with PM2.5 in any exposure window. No effect modification by child sex or allergic sensitization was observed.

CONCLUSIONS

We did not find strong evidence of associations between prenatal ambient PM2.5 exposure and child lung function in a large, well-characterized study sample. However, there was a suggested adverse association between FEV1 and exposure during late pregnancy. The saccular phase of lung development might be an important window for exposure to PM2.5.

Effect of maternal cigarette smoke exposure on COPD progression in offspring mice

OBJECTIVE

To investigate the impact of maternal smoking on chronic obstructive pulmonary disease (COPD) progression in offspring.

METHODS

Using female C57BL/6 J mice, a maternal cigarette smoke exposure (CSE) model was established. Mice were exposed to cigarette smoke for 2 hours/day, 7 days/week, with a minimum 4-hour interval between exposures. Experimental groups included control (Con), pregnancy exposure (AS), pre-pregnancy exposure (SA), and pre-pregnancy + pregnancy exposure (SS). Lung function tests (Penh, PAU, TVb, EF50, Tr) were conducted on male offspring at 7 weeks. Histopathology, electron microscopy, and protein level changes were examined.

RESULTS

Lung function tests revealed significant impairments in Penh, PAU, TVb, EF50, and Tr in offspring across all exposure scenarios. Specifically, AS experienced significant lung function impairment and mitochondrial dysfunction in offspring, with noticeable pulmonary lesions and increased apoptosis. SA showed similar or even more severe lung function impairment and cellular apoptosis. SS exhibited the most pronounced effects, with the highest levels of lung dysfunction, mitochondrial damage, and apoptosis. Histopathological analysis showed pulmonary lesions in offspring exposed to maternal CSE. Flow cytometry revealed increased apoptosis and reduced mitochondrial membrane potential in offspring lung cells. Electron microscopy confirmed mitochondrial dysfunction. Upregulation of apoptotic proteins and downregulation of anti-apoptotic protein Bcl-2 were found in offspring lung tissue exposed to maternal CSE.

CONCLUSION

Maternal smoking induces impaired lung function, pulmonary lesions, and mitochondrial dysfunction in offspring, regardless of exposure timing and duration. Additionally, it alters expression of apoptosis-related proteins in offspring lung tissue, potentially contributing to COPD susceptibility.

Prenatal cigarette smoke exposure sensitizes acetaminophen-induced liver injury by modulating miR-34a-5p in male offspring mice

Introduction: Cigarette smoke (CS) exacerbates the severity of diseases not only in lungs, but also in systemic organs having no direct contact with smoke. In addition, smoking during pregnancy can have severe health consequences for both the mother and the fetus. Therefore, our aim was to evaluate effects of prenatal exposure to CS on acetaminophen (APAP)-induced acute liver injury (ALI) in offspring. Methods: Female C57BL/6 mice on day 6 of gestation were exposed to mainstream CS (MSCS) at 0, 150, 300, or 600 μg/L for 2 h a day, 5 days a week for 2 weeks using a nose-only exposure system. At four weeks old, male offspring mice were injected intraperitoneally with a single dose of APAP at 300 mg/kg body weight to induce ALI. Results: Maternal MSCS exposure significantly amplified pathological effects associated with ALI as evidenced by elevated serum alanine aminotransferase levels, increased hepatocellular apoptosis, higher oxidative stress, and increased inflammation. Interestingly, maternal MSCS exposure reduced microRNA (miR)-34a-5p expression in livers of offspring. Moreover, treatment with a miR-34a-5p mimic significantly mitigated the severity of APAP-induced hepatotoxicity. Overexpression of miR-34a-5p completely abrogated adverse effects of maternal MSCS exposure in offspring with ALI. Mechanistically, miR-34a-5p significantly decreased expression levels of hepatocyte nuclear factor 4 alpha, leading to down-regulated expression of cytochrome P450 (CYP)1A2 and CYP3A11. Discussion: Prenatal exposure to MSCS can alter the expression of miRNAs, even in the absence of additional MSCS exposure, potentially increasing susceptibility to APAP exposure in male offspring mice.

Prenatal smoking and drinking are associated with altered newborn autonomic functions

BACKGROUND

Prenatal smoking and drinking are associated with sudden infant death syndrome and neurodevelopmental disorders. Infants with these outcomes also have altered autonomic nervous system (ANS) regulation. We examined the effects of prenatal smoking and drinking on newborn ANS function.

METHODS

Pregnant women were enrolled in Northern Plains, USA (NP) and Cape Town (CT), South Africa. Daily drinking and weekly smoking data were collected prenatally. Physiological measures were obtained during sleep 12-96 h post-delivery.

RESULTS

In all, 2913 infants from NP and 4072 from CT were included. In active sleep, newborns of mothers who smoked throughout pregnancy, compared to non-smokers, had higher breathing rates (2.2 breaths/min; 95% CI: 0.95, 3.49). Quit-early smoking was associated with reductions in beat-to-beat heart rate variability (HRV) in active (-0.08 s) and quiet sleep (-0.11 s) in CT. In girls, moderate-high continuous smoking was associated with increased systolic (3.0 mmHg, CI: 0.70, 5.24) and diastolic blood pressure (2.9 mmHg, CI: 0.72, 5.02). In quiet sleep, low-continuous drinking was associated with slower heart rate (-4.5 beat/min). In boys, low-continuous drinking was associated with a reduced ratio of low-to-high frequency HRV (-0.11, CI: -0.21, -0.02).

CONCLUSIONS

These findings highlight potential ANS pathways through which prenatal drinking and smoking may contribute to neurodevelopment outcomes.

IMPACT

In this prospective cohort study of 6985 mother-infant dyads prenatal drinking and smoking were associated with multiple ANS parameters. Smoking was associated with increased neonatal breathing rates among all infants, and heart rate variability (HRV) and blood pressure (BP) among girls. Drinking was associated with reductions in HR and BP among all newborns, and reductions in the ratio of low to-high frequency HRV among boys. These findings suggest that prenatal smoking and drinking alter newborn ANS which may presage future neurodevelopmental disorders.

Prenatal tobacco exposure and risk of asthma and allergy outcomes in childhood

BACKGROUND

Harmful effects of prenatal tobacco exposure and possible interaction with 17q12-21 genetic variants have been shown for some asthma outcomes in childhood, whereas findings related to allergy outcomes are more inconsistent. This study aimed to examine the effect of prenatal tobacco exposure and relation to 17q12-21 genotype on a wide array of asthma and allergy-related outcomes in early childhood.

METHODS

Prenatal tobacco exposure was determined by maternal smoking during the third trimester (yes/no) in 411 children from the phenotyped Copenhagen Prospective Studies on Asthma in Childhood 2000 (COPSAC2000) birth cohort with clinical follow-up to age 7 years. The rs7216389 single nucleotide polymorphism was used as main representative of the 17q12-21 locus. Asthma end-points included asthma diagnosis, exacerbations, episodes with troublesome lung symptoms and lower respiratory tract infections, spirometry, plethysmography, bronchial responsiveness to methacholine, exercise and cold dry air. Allergy-related endpoints included aeroallergen sensitisation, allergic rhinitis, fractional exhaled nitric oxide, blood eosinophil count and urine eosinophil protein X levels. Statistical analyses were done using Cox regression, linear regression, logistic regression and quasi-Poisson regression.

RESULTS

Prenatal tobacco exposure increased the risk of asthma (adjusted hazard ratio (aHR) 2.05, 95% CI 1.13-3.73; p=0.02), exacerbations (aHR 3.76, 95% CI 2.05-6.91; p<0.001), number of LRTIs (adjusted incidence rate ratio 1.87, 95% CI 1.34-2.55; p<0.001), and was associated with decreased spirometry indices (forced expiratory volume in 1 s (FEV1) adjusted mean difference (aMD) -0.07 L, 95% CI -0.13- -0.005 L, p=0.03; maximal mid-expiratory flow aMD -0.19 L·s-1, -0.34- -0.04 L·s-1, p=0.01) and increased bronchial responsiveness to methacholine (provocative dose of methacholine causing a 20% drop in FEV1 adjusted geometric mean ratio 0.55, 95% CI 0.31-0.96; p=0.04). In contrast, there was no association with any allergy-related end-points. The effect on asthma depended on 17q12-21 genotype with an increased risk only among children without risk alleles.

CONCLUSION

Prenatal tobacco exposure was associated with asthma dependent on 17q12-21 genotype and with exacerbations, lung function and bronchial responsiveness, but not with any allergy-related outcomes. This suggests that tobacco exposure in utero leads to adverse lung developmental/structural effects rather than susceptibility to develop allergy and type 2 inflammation.

Socioecological Mapping of Barriers and Enablers to Smoking Cessation in Indigenous Australian Women During Pregnancy and Postpartum: A Systematic Review

BACKGROUND

With a high prevalence of smoking during pregnancy and limited Indigenous-specific evidence for treatment, we used socioecological mapping to identify multilevel barriers and enablers to smoking cessation related to Indigenous Australian pregnant and postpartum women.

METHODS

Nine electronic databases were searched. Original studies except interventions and trials, published in English, up to February 29, 2020 were included. Studies were appraised using the QualSyst tool. Evidence was narratively synthesized. The review protocol was registered with PROSPERO (CRD42019135543).

RESULTS

A total of 15 studies (10 quantitative, 5 qualitative) were included, covering 1306 women, 3 partners/family members, 234 health professionals (HP), and 2755 patient records. Complex and overlapping barriers were identified at individual, family, community, societal, and system levels. Socioeconomic disadvantages, inequality, and pervasive racism as legacies of colonization, combined with personal, family, and community circumstances intensified individual experiences of stress, which may be heightened during pregnancy. Inadequate smoking cessation care (SCC), inconsistent antitobacco messages, and ineffectual HP interventions underscore a need for service enhancement and further evidence to develop culturally relevant messages. High motivation of pregnant women to quit, resilience, and supports available in the family and community are strengths that warrant attention in future interventions.

CONCLUSIONS

SCC without ameliorating the social disadvantages and the disparities in health determinants between Indigenous and non-Indigenous Australian women may limit the effectiveness of SCC. A comprehensive approach is required that includes policy changes for addressing external stressors the women experience, engagement of family and community, and better training of HP and provision of free pharmacotherapy.

IMPLICATIONS

To systematically address barriers to smoking cessation at multiple levels, initiatives to ameliorate social disadvantages and discrepancies in social determinants of health between Indigenous and non-Indigenous Australians are required to be taken in tandem with SCC. Initiatives may include making relevant policy changes and allocating more resources for education, employment, housing, and community development. Enhancement of knowledge, skills, and confidence of HP regarding the provision of high-quality SCC for Indigenous women and their families is warranted. Future interventions may build on high motivation, resilience, and strengths of individual women, and incorporate support strategies engaging family and community.

The Role of Maternal Smoking in Sudden Fetal and Infant Death Pathogenesis

Maternal smoking is a risk factor for both sudden infant death syndrome (SIDS) and sudden intrauterine unexplained death syndrome (SIUDS). Both SIDS and SIUDS are more frequently observed in infants of smoking mothers. The global prevalence of smoking during pregnancy is 1.7% and up to 8.1% of women in Europe smoke during pregnancy and worldwide 250 million women smoke during pregnancy. Infants born to mothers who smoke have an abnormal response to hypoxia and hypercarbia and they also have reduced arousal responses. The harmful effects of tobacco smoke are mainly mediated by release of carbon monoxide and nicotine. Nicotine can enter the fetal circulation and affect multiple developing organs including the lungs, adrenal glands and the brain. Abnormalities in brainstem nuclei crucial to respiratory control, the cerebral cortex and the autonomic nervous system have been demonstrated. In addition, hypodevelopment of the intermediolateral nucleus in the spinal cord has been reported. It initiates episodic respiratory movements that facilitate lung development. Furthermore, abnormal maturation and transmitter levels in the carotid bodies have been described which would make infants more vulnerable to hypoxic challenges. Unfortunately, smoking cessation programs do not appear to have significantly reduced the number of pregnant women who smoke.

Host, Gender, and Early-Life Factors as Risks for Chronic Obstructive Pulmonary Disease

Although smoking results in lung pathology in many, still not all smokers develop chronic obstructive pulmonary disease (COPD). Roughly a quarter of patients with COPD have never smoked. An understanding of both host and environmental factors beyond smoking that contribute to disease development remain critical to understanding disease prevention and ultimately effectively intervene. In this article, we summarize host factors, including genetics and gender, as well as early-life events that contribute to the development of COPD.

Lung functional development and asthma trajectories

Early life environmental risk factors are associated with chronic respiratory morbidity in child- and adulthood. A possible mechanism for this sustained effect is their influence on early life lung functional growth and development, a susceptible phase of rapid lung growth with increased plasticity. We summarize evidence of hereditary and environmental ante-, peri-, and early postnatal factors on lung functional development, such as air pollution, tobacco exposure, nutrition, intrauterine growth retardation, prematurity, early life infections, microbiome, and allergies and their effect on lung functional trajectories. While some of the factors (e.g., prematurity) directly impair lung growth, the influence of many environmental factors is mediated through inflammatory processes (e.g., recurrent infections or oxidative stress). The timing and nature of these influences and their impact result in degrees of impaired maximal lung functional capacity in early adulthood; and they potentially impact future long-term respiratory morbidity such as chronic asthma or chronic obstructive airway disease (COPD). We discuss possibilities to prevent or modify such early abnormal lung functional growth trajectories and the need for future studies and prevention programs.

Predicting Lung Health Trajectories for Survivors of Preterm Birth

Rates of preterm birth (<37 weeks of gestation) are increasing worldwide. Improved perinatal care has markedly increased survival of very (<32 weeks gestation) and extremely (<28 weeks gestation) preterm infants, however, long term respiratory sequalae are common among survivors. Importantly, individual's lung function trajectories are determined early in life and tend to track over the life course. Preterm infants are impacted by antenatal, postnatal and early life perturbations to normal lung growth and development, potentially resulting in significant shifts from the "normal" lung function trajectory. This review summarizes what is currently known about the long-term lung function trajectories in survivors of preterm birth. Further, this review highlights how antenatal, perinatal and early life factors are likely to contribute to individual lung health trajectories across the life course.

Oxidative stress and mitochondrial dysfunction in parafacial respiratory group induced by maternal cigarette smoke exposure in rat offspring

Cigarette smoke (CS) exposure negatively affects neurodevelopment. We established a CS exposure rat model to determine how maternal CS exposure induces oxidative stress and mitochondrial dysfunction in parafacial respiratory group (pFRG) essential to central chemoreceptive regulation of normal breathing. Pregnant rats were exposed to CS during gestational days 1-20, and the offspring were studied on postnatal day 2. Our data showed that maternal CS exposure resulted in elevated accumulation of ROS, which left a footprint on DNA and lipid with increases in 8-hydroxy-2'-deoxyguanosine and malondialdehyde contents. Furthermore, maternal CS exposure induced decreases in manganese superoxide dismutase, catalase and glutathione reductase activities as well as reduction in glutathione content in pFRG in the offspring. Moreover, maternal exposure to CS led to mitochondrial ultrastructure changes, mitochondrial swelling, reduction in ATP generation, loss of mitochondrial membrane potential and increase in mitochondrial DNA copy number. These findings suggest that maternal exposure to CS alters normal development of pFRG that is critical for normal respiratory control.

Longitudinal assessment of lung function in extremely prematurely born children

OBJECTIVES

To assess longitudinally small airway function in children born extremely prematurely and whether there was a correlation between airway function in infancy and at 11-14 years.

WORKING HYPOTHESES

There would be tracking of airways obstruction and small airway function would deteriorate during childhood in those born extremely prematurely.

STUDY DESIGN

A longitudinal study.

PATIENT-SUBJECT SELECTION

Thirty-five children with a mean gestational age of 26 weeks had lung function assessed at 1 year corrected and 11-14 years of age.

METHODOLOGY

Lung volumes were measured by helium gas dilution (FRC_He ) and plethysmography (FRC_pleth ) and small airway function assessed by calculating the FRC_He :FRC_pleth ratio. Airway function was assessed at 1 year corrected by measurement of airway resistance (R_aw ) and at 11-14 years by assessment of R_aw , forced expiratory flow from 75% of vital capacity (FEF₇₅ ), and forced expiratory volume at one second (FEV₁ ).

RESULTS

At the first assessment, the children had a mean (SD) FRC_He :FRC_pleth of 0.90 (0.13) and at the second, 0.83 (0.12) (P = 0.035). There was a significant 0.54% decrease (95%CI: -1.02%, -0.06%) in FRC_He :FRC_pleth for increased age per year after adjusting for birth weight, gestational age, sex, and bronchopulmonary dysplasia (P = 0.027). There were significant correlations between R_aw at the first assessment and R_aw (P = 0.012), FEF₇₅ (P = 0.034), and FEV₁ (P = 0.04) at 11-14 years.

CONCLUSIONS

These results demonstrate in those born extremely prematurely there is tracking of airway function during childhood.

Effect of long-term maternal smoking on the offspring's lung health

Maternal smoking during pregnancy contributes to long-term health problems in offspring, especially respiratory disorders that can manifest in either childhood or adulthood. Receptors for advanced glycation end products (RAGE) are multiligand receptors abundantly localized in the lung, capable of responding to by-products of reactive oxygen species and proinflammatory responses. RAGE signaling is a key regulator of inflammation in cigarette smoking-related pulmonary diseases. However, the impact of maternal cigarette smoke exposure on lung RAGE signaling in the offspring is unclear. This study aims to investigate the effect of maternal cigarette smoke exposure (SE), as well as mitochondria-targeted antioxidant [mitoquinone mesylate (MitoQ)] treatment, during pregnancy on the RAGE-mediated signaling pathway in the lung of male offspring. Female Balb/c mice (8 wk) were divided into a sham group (exposed to air), an SE group (exposed to cigarette smoke), and an SE + MQ group (exposed to cigarette smoke with MitoQ supplement from mating). The lungs from male offspring were collected at 13 wk. RAGE and its downstream signaling, including nuclear factor-κB and mitogen-activated protein kinase family consisting of extracellular signal-regulated kinase 1, ERK2, c-JUN NH2-terminal kinase (JNK), and phosphorylated JNK, in the lung were significantly increased in the SE offspring. Mitochondrial antioxidant manganese superoxide dismutase was reduced, whereas IL-1β and oxidative stress response nuclear factor (erythroid-derived 2)-like 2 were significantly increased in the SE offspring. Maternal MitoQ treatment normalized RAGE, IL-1β, and Nrf-2 levels in the SE + MQ offspring. Maternal SE increased RAGE and its signaling elements associated with increased oxidative stress and inflammatory cytokines in offspring lungs, whereas maternal MitoQ treatment can partially normalize these changes.

Maternal smoking in pregnancy and its influence on childhood asthma

Maternal smoking in pregnancy (MSP) is a large modifiable risk factor for pregnancy related mortality and morbidity and also the most important known modifiable risk factor for asthma. This review summarises the effects of MSP throughout infancy, childhood and adolescence with regards to asthma (development and severity). Firstly, the direct damage caused by nicotine on fetal lung development, fetal growth and neuronal differentiation is discussed, as well as the indirect effects of nicotine on placental functioning. Secondly, the effects of MSP on later immune functioning resulting in increased infection rate are summarised and details are given on the effects of MSP modulating airway hyperreactivity, reducing lung function and therefore increasing asthma morbidity. Furthermore, epigenetic effects are increasingly being recognised. These can also result in transgenerational detrimental effects induced by cigarette smoke. In summary, the causal relationship between MSP and asthma development is well documented and presents a major health problem for generations to come. The high prevalence of MSP is alarming and epigenetic effects of nicotine on immune functioning potentiate this danger. A considerable part of the increase in asthma prevalence worldwide is due to MSP.

Intrauterine exposure to smoking and wheezing in adolescence: the 1993 Pelotas Birth Cohort

Previous studies have suggested an association between maternal smoking during pregnancy and asthma symptoms such as wheezing during childhood. However, few have evaluated this association in adolescence, especially in populations with high prevalence of wheezing as in Brazil. Using the 1993 Pelotas birth cohort, a longitudinal study set in southern Brazil of 5249 urban live births, we aimed to evaluate the association between maternal and the partner's smoking during pregnancy and wheezing at 11 and 15 years of age. We evaluated smoking during pregnancy using number of cigarettes/day, and our main outcomes were as follows: wheezing in the last year and number of wheezing crises, at both 11 and 15 years of age, as well as persistent wheezing (having crises at 11 and 15 years of age) and medical asthma diagnosis at age 15. In addition, other socio-demographic variables were included as possible confounders and mediators of this association. We used Poisson regression models to evaluate crude and adjusted associations. Of the 5249 live births in 1993, 87.5% and 85.7% were followed-up to 11 and 15 years of age, respectively. Maternal smoking during pregnancy showed a dose-response association with number of wheezing crises at age 15 (P = 0.023), presence of persistent wheezing (P = 0.034) and asthma diagnosis (P = 0.023). Partner's smoking was not associated with any wheezing variables. Maternal smoking during pregnancy appears to exert an effect on respiratory morbidity of adolescents, evaluated by wheezing symptoms.

Is the growth of the fetus of a non-smoking mother influenced by the smoking of either grandmother while pregnant?

Background

There are animal data that indicate that prenatal environmental exposures have sex-specific effects on subsequent generations. In humans, an increase in birthweight has been reported if the maternal grandmother had smoked in the pregnancy giving rise to the mother. Here we assess whether prenatal exposure of either parent to cigarette smoke has a sex-specific effect on the grandchild's birth measurements.

Methods

Information from 12707 maternal and 9677 paternal grandmothers of children in the Avon Longitudinal Study of Parents and Children (ALSPAC) concerned whether they had smoked while expecting the study parent. Study children were weighed and measured at birth. Analyses to test effects of grandmaternal prenatal smoking used multiple regression allowing for several potential confounders; analyses were restricted to births to non-smoking study mothers.

Findings

After adjustment, the average birthweight, birth length and BMI measurements of the grandsons (but not granddaughters) were greater if the maternal grandmother smoked prenatally: birthweight  = +61 [95% CI +30, +92] g; birth length  = +0·19 [95% CI +0·02, +0·35] cm; BMI  = +1·6 [95% CI +0·6, +2·6] g/m². Similar effects were seen in births to primiparae and multiparae. Additional allowance for maternal birthweight resulted in an average increase in boys to +100 g [95% CI +61, +140] g. There were no fetal growth differences if the paternal grandmother had smoked prenatally.

Conclusions

The evidence from this study suggests that when the mother does not smoke in pregnancy the maternal grandmother's smoking habit in pregnancy has a positive association with her grandson's fetal growth.

Exercise-induced bronchoconstriction in school-aged children who had chronic lung disease in infancy

OBJECTIVES

To assess for exercise-induced bronchoconstriction in 8- to 12-year-old children who had chronic lung disease (CLD) in infancy, and to evaluate the response of bronchoconstriction to bronchodilation with albuterol in comparison with preterm and term controls.

STUDY DESIGN

Ninety-two children, including 29 with CLD, 33 born preterm at ≤32 weeks' gestation, and 30 born at term, underwent lung spirometry before and after cycle ergometry testing and after postexercise bronchodilation with albuterol.

RESULTS

Doctor-diagnosed asthma and exercise-induced wheeze were reported more frequently in the CLD group than in the preterm and term groups, but only 10% were receiving a bronchodilator. There were no differences among the groups in peak minute ventilation, oxygen uptake, or carbon dioxide output at maximum exercise. After maximal exercise, predicted forced expiratory volume in 1 second (FEV1) decreased from a mean baseline value of 81.9% (95% CI, 76.6-87.0%) to 70.8% (95% CI, 65.5-76.1%) after exercise in the CLD group, from 92.0% (95% CI, 87.2-96.8%) to 84.3% (95% CI, 79.1-89.4%) in the preterm group, and from 97.5% (95% CI, 92.5-102.6%) to 90.3% (95% CI, 85.1-95.5%) in the term group. After albuterol administration, FEV1 increased to 86.8% (95% CI, 81.7-92.0%) in the CLD group, 92.1% (95% CI, 87.3-96.9%) in the preterm group, and 97.1% (95% CI, 92.0-102.3%) in the term group. The decrease in predicted FEV1 after exercise and increase in predicted FEV1 after bronchodilator use were greatest in the CLD group (-11.0% [95% CI, -18.4 to -3.6%] and 16.0% [95% CI, 8.6-23.4%], respectively; P < .005 for both), with differences of <8% in the 2 control groups.

CONCLUSION

School-age children who had CLD in infancy had significant exercise-induced bronchoconstriction that responded significantly to bronchodilation. Reversible exercise-induced bronchoconstriction is common in children who experienced CLD in infancy and should be actively assessed for and treated.

Maternal nicotine effects on vascular endothelial growth factor expression and morphometry in rat lungs

AIMS

Maternal smoking during pregnancy may impair pulmonary function in infants, and the exact mechanisms underlying these changes are unknown. We evaluated the effects of maternal nicotine exposure on lung VEGF expression and morphometry during the postnatal period in rats.

METHODS AND RESULTS

Timed pregnant Sprague-Dawley rats were injected subcutaneously with nicotine at a dose of 2 mg/kg/day from Day 3 to Day 21 of gestation. A control group was injected with saline. Body weight, lung weight, and lung volume were comparable between control and nicotine-exposed rats. Plasma vascular endothelial growth factor (VEGF) levels and lung VEGF mRNA expression decreased with advancing age, and nicotine exposure insignificantly decreased plasma VEGF levels and lung VEGF mRNA expression, compared with the control rats during the study period. Nicotine exposure caused a significant decrease in vascular endothelial growth factor receptor (VEGFR)-2 mRNA expression, compared with the level of the control rats on Postnatal Day 1. On Postnatal Day 1, nicotine-exposed rats exhibited a significantly lower volume fraction of alveolar airspace and alveolar surface area and a significantly higher alveolar wall volume fraction than did the control rats.

CONCLUSIONS

Maternal nicotine exposure during pregnancy decreases VEGF and VEGFR-2 mRNA expression and alters lung structure in the lungs of postnatal rats. Because angiogenesis is vital for alveolarization during normal lung development, these results suggest that decreased VEGF expression might be involved in the structural alterations of the developing lung after exposure to antenatal nicotine.

Effects of prenatal exposure to cigarette smoke on use of xanthine and pneumogram evaluation at discharge in premature infants

OBJECTIVE

Prenatal exposure to cigarette smoke is associated with an increased risk of sudden infant death syndrome and possible rate increase of obstructive apnea in full-term infants but unknown in premature infants. Therefore, the objective was to study the effect of prenatal exposure to cigarette smoke on the use of methylxanthines and discharge pneumograms in premature infants.

METHODS

Preterm infants [gestational age (GA) ≤34 weeks] born between January 1997 and September 2007 were studied. A four-channel pneumogram was performed at discharge. Relevant clinical data were collected from the infant's records. Infants with prenatal exposure to cigarette smoke were compared with infants not exposed (controls).

RESULTS

A total of 1656 infants were studied: 263 infants {birth weight (BW) (mean ± SD) 1682 ± 566 g, GA 31.0 ± 2.8 weeks} exposed to prenatal cigarette smoke and 1393 infants (BW 1638 ± 575 g, GA 31.1 ± 2.7 weeks) not exposed. Baseline patient characteristics were similar between the two groups. When comparing the smoking versus control groups, there was no significant difference in the infants for the following: xanthine therapy and abnormal pneumograms; presence of central, obstructed or mixed apnea and home discharge on monitors, oxygen and xanthines.

CONCLUSIONS

Prenatal exposure to cigarette smoke was not associated with increased use of xanthines or abnormal pneumogram in premature infants.

Early-onset chronic obstructive pulmonary disease is associated with female sex, maternal factors, and African American race in the COPDGene Study

RATIONALE

The characterization of young adults who develop late-onset diseases may augment the detection of novel genes and promote new pathogenic insights.

METHODS

We analyzed data from 2,500 individuals of African and European ancestry in the COPDGene Study. Subjects with severe, early-onset chronic obstructive pulmonary disease (COPD) (n=70, age < 55 yr, FEV1 < 50% predicted) were compared with older subjects with COPD (n =306, age >64 yr, FEV1 <50% predicted).

MEASUREMENTS AND MAIN RESULTS

Subjects with severe, early-onset COPD were predominantly females (66%), P =0.0004. Proportionally,early-onset COPD was seen in 42% (25 of 59) of African Americans versus 14% (45 of 317) of non-Hispanic whites, P <0.0001. Other risk factors included current smoking (56 vs. 17%, P < 0.0001) and self-report of asthma (39 vs. 25%, P =0.008). Maternal smoking (70 vs. 44%, P=0.0001) and maternal COPD (23 vs.12%, P=0.03) were reported more commonly in subjects with early-onset COPD. Multivariable regression analysis found association with African American race, odds ratio (OR), 7.5 (95% confidence interval [CI], 2.3–24; P ¼=0.0007); maternal COPD, OR, 4.7 (95% CI,1.3–17; P=0.02); female sex, OR, 3.1 (95% CI, 1.1–8.7; P=0.03); and each pack-year of smoking, OR, 0.98 (95% CI, 0.96–1.0; P ¼ 0.03).

CONCLUSIONS

These observations support the hypothesis that severe, early-onset COPD is prevalent in females and is influenced by maternal factors. Future genetic studies should evaluate (1) gene-by-sex interactions to address sex-specific genetic contributions and (2) gene-by-race interactions.

Respiratory morbidity, healthcare utilisation and cost of care at school age related to home oxygen status

The aim of the study was to determine whether respiratory morbidity, lung function, healthcare utilisation and cost of care at school age in prematurely born children who had bronchopulmonary dysplasia (BPD) were influenced by use of supplementary oxygen at home after neonatal intensive care unit discharge. Healthcare utilisation and cost of care in years 5 to 7 and respiratory morbidity (parent-completed respiratory questionnaire) and lung function measurements at least at age 8 years were assessed in 160 children. Their median gestational age was 27 (range 22-31) weeks and 65 of them had received supplementary oxygen when discharged home (home oxygen group). The home oxygen group had more outpatient attendances (p = 0.0168) and respiratory-related outpatient attendances (p = 0.0032) with greater related cost of care (p = 0.0186 and p = 0.0030, respectively), their cost of care for prescriptions (p = 0.0409) and total respiratory related cost of care (p = 0.0354) were significantly greater. There were, however, no significant differences in cough, wheeze or lung function results between the two groups.

CONCLUSION

Prematurely born children who had BPD and supplementary oxygen at home after discharge had increased healthcare utilisation at school age. Whether such children require greater follow, in the absence of excess respiratory morbidity, merits investigation.

The influence of neonatal lung function on rhinovirus-associated wheeze

RATIONALE

Several studies have shown that the occurrence of wheezing illnesses during the first year of life is associated with lower levels of lung function shortly after birth and before any respiratory illness. It has been suggested that reduced lung function early in life predisposes infants to wheezing during viral respiratory infections, but the association between neonatal lung function and subsequent confirmed viral infections has never been investigated.

OBJECTIVES

To study the influence between neonatal lung function and the occurrence of human rhinovirus (HRV)-associated wheeze.

METHODS

In a prospective birth cohort study, infants were followed from birth through the first year of life with daily questionnaires about respiratory symptoms. Neonatal lung function was performed within the first 2 months of life. Nose and throat swabs were collected during episodes with respiratory symptoms. Polymerase chain reaction was used to detect single HRV infections.

MEASUREMENTS AND MAIN RESULTS

In 176 of the 202 infants (87%) with a single HRV infection, valid lung function measurements were obtained. The risk of wheeze was 1.49 times higher for each SD increase of airway resistance. The adjusted risk (corrected for possible important confounders) for wheeze was 1.77 (95% confidence interval, 1.16-2.69; P = 0.01) times higher for each SD increase of airway resistance. Maternal smoking during pregnancy was independently associated with wheeze (odds ratio 4.42; 95% confidence interval, 1.27-15.5; P = 0.02).

CONCLUSIONS

This study showed that total lung resistance is clearly associated with HRV-associated wheeze. Moreover, HRV-associated wheeze might be the first sign to recognize infants with reduced neonatal lung function.

Comprehensive integrated spirometry using raised volume passive and forced expirations and multiple-breath nitrogen washout in infants

With the rapid somatic growth and development in infants, simultaneous accurate measurements of lung volume and airway function are essential. Raised volume rapid thoracoabdominal compression (RTC) is widely used to generate forced expiration from an airway opening pressure of 30 cmH(2)O (V(30)). The (dynamic) functional residual capacity (FRC(dyn)) remains the lung volume most routinely measured. The aim of this study was to develop comprehensive integrated spirometry that included all subdivisions of lung volume at V(30) or total lung capacity (TLC(30)). Measurements were performed on 17 healthy infants aged 8.6-119.7 weeks. A commercial system for multiple-breath nitrogen washout (MBNW) to measure lung volumes and a custom made system to perform RTC were used in unison. A refined automated raised volume RTC and the following two novel single maneuvers with dual volume measurements were performed from V(30) during a brief post-hyperventilation apneic pause: (1) the passive expiratory flow was integrated to produce the inspiratory capacity (IC) and the static (passive) FRC (FRC(st)) was estimated by initiating MBNW after end-passive expiration; (2) RTC was initiated late during passive expiration, flow was integrated to produce the slow vital capacity ((j)SVC) and the residual volume (RV) was measured by initiating MBNW after end-expiration while the jacket (j) was inflated. Intrasubject FRC(dyn) and FRC(st) measurements overlapped (p=0.6420) but neither did with the RV (p<0.0001). Means (95% confidence interval) of FRC(dyn), IC, FRC(st), (j)SVC, RV, forced vital capacity and tidal volume were 21.2 (19.7-22.7), 36.7 (33.0-40.4), 21.2 (19.6-22.8), 40.7 (37.2-44.2), 18.1 (16.6-19.7), 40.7 (37.1-44.2) and 10.2 (9.6-10.7)ml/kg, respectively. Static lung volumes and capacities at V(30) and variables from the best forced expiratory flow-volume curve were dependent on age, body length and weight. In conclusion, we developed a comprehensive physiologically integrated approach for in-depth investigation of lung function at V(30) in infants.

Prenatal factors in the development of chronic lung disease

Chronic lung disease (CLD), defined as chronic oxygen dependency, is a common outcome of neonatal intensive care. It occurs most frequently in infants born very prematurely, but also in infants born at term who had severe lung disease and those with abnormal antenatal lung growth due particularly to reduction in fetal breathing movements, amniotic fluid volume or intrathoracic space. There are, however, other causes and the importance of antenatal infection/inflammation regarding impairment of antenatal lung growth is increasingly recognised. Affected infants can suffer chronic respiratory morbidity including an excess of respiratory symptoms and lung function abnormalities even in adulthood. Antenatal interventions directed at improving lung growth are available, but require testing inappropriately designed trials with pulmonary function at follow-up as an outcome.

Cross-sectional survey of risk factors for asthma in 6-7-year-old children in New Zealand: International Study of Asthma and Allergy in Childhood Phase Three

AIM

To identify risk factors for asthma in primary school-aged children in New Zealand.

METHODS

A cross-sectional survey of 10,873 6-7-year-old children in Auckland, Bay of Plenty, Nelson and Christchurch (a response rate of 85.2%). A questionnaire was completed by the parent or care giver.

RESULTS

22.2% of children wheezed in the last 12 months (current wheeze). Maori children were at greater risk of current wheeze compared with European children (adjusted odds ratio (adjOR) = 1.37; 95% confidence interval = 1.18-1.59). Antibiotics and paracetamol used in the first year of life were associated with an increased risk of current wheeze (adjOR = 1.78 (1.56-2.04) and adjOR = 1.31 (1.06-1.61), respectively). Watching television for 5 or more hours per day was associated with an increased risk of current wheeze (adjOR = 1.44 (1.13-1.83)). Milk and egg consumption in the last 12 months was associated with a reduced risk of current wheeze.

CONCLUSIONS

 This study has identified risk factors for asthma in children aged 6-7 years, although causal pathways cannot be established. These associations have important public health implications if causal.

Tobacco-related practices and policies in residential perinatal drug treatment programs

Despite serious health consequences from high rates of smoking among perinatal women, smoking cessation and/or nicotine treatment practices have yet to be broadly adopted into perinatal substance abuse treatment settings. This correlational cross-sectional survey examined tobacco-related policies, practices, knowledge, and attitudes of 31 directors of perinatal residential substance abuse treatment programs in California. We found that the directors' programs had limited on-site adoption of evidence-based practices for smoking cessation, and that directors had gaps in their knowledge of perinatal tobacco effects. Implications for tobacco policy initiatives in perinatal substance abuse treatment are discussed.

Smoking cessation in pregnancy

BACKGROUND

Pregnant women who continue to smoke expose their developing fetus to a wide range of risks. Assisting these patients to stop smoking can be an important intervention for the health of the baby and the mother. The management of pregnant smokers can be challenging, due to the potential risks of pharmacotherapy. There are a number of options available to the clinician to aid smoking cessation in non pregnant women. These include nicotine replacement therapy (NRT), bupropion, varenicline, and a range of non-drug therapies.

OBJECTIVE

To provide guidance to prescribers on the best way to manage smoking cessation in the pregnant patient, reviewing the risks and efficacy of the different approaches.

METHODS

An extensive literature search was carried out to find original studies which examined issues surrounding the safety and efficacy of methods of smoking cessation in pregnancy.

RESULTS/CONCLUSION

NRT is the agent of choice for smoking cessation in pregnancy as the safety of other therapies in pregnancy have not yet been proved.

Variation in the GST mu locus and tobacco smoke exposure as determinants of childhood lung function

RATIONALE

The glutathione S-transferases (GSTs) are important detoxification enzymes.

OBJECTIVES

To investigate effects of variants in GST mu genes on lung function and assess their interactions with tobacco smoke exposure.

METHODS

In this prospective study, 14,836 lung function measurements were collected from 2,108 children who participated in two Southern California cohorts. For each child, tagging single nucleotide polymorphisms in GSTM2, GSTM3, GSTM4, and GSTM5 loci were genotyped. Using principal components and haplotype analyses, the significance of each locus in relation to level and growth of FEV1, maximum midexpiratory flow rate (MMEF), and FVC was evaluated. Interactions between loci and tobacco smoke on lung function were also investigated.

MEASUREMENTS AND MAIN RESULTS

Variation in the GST mu family locus was associated with lower FEV1 (P = 0.01) and MMEF (0.04). Two haplotypes of GSTM2 were associated with FEV1 and MMEF, with effect estimates in opposite directions. One haplotype in GSTM3 showed a decrease in growth for MMEF (-164.9 ml/s) compared with individuals with other haplotypes. One haplotype in GSTM4 showed significantly decreased growth in FEV1 (-51.3 ml), MMEF (-69.1 ml/s), and FVC (-44.4 ml), compared with all other haplotypes. These results were consistent across two independent cohorts. Variation in GSTM2 was particularly important for FVC and FEV(1) among children whose mothers smoked during pregnancy.

CONCLUSIONS

Genetic variation across the GST mu locus is associated with 8-year lung function growth. Children of mothers who smoked during pregnancy and had variation in GSTM2 had lower lung function growth.