Maternal smoking during pregnancy and lower respiratory tract illness in early life

Perinatal Nicotine Exposure Disrupts Hematopoietic Stem Cell Development and Elevates Influenza Susceptibility in Adulthood

Tobacco use during pregnancy has many deleterious health consequences for not only the smoking mother, but also on the unborn fetus. Children of smoking mothers are reported to have higher frequency and severity of respiratory diseases later in life; however, the mechanisms driving this increased vulnerability are not clearly understood. One potential cause of increased disease susceptibility is an altered immune system, originating in epigenetically maladaptive hematopoietic stem cells (HSCs). Here, we show that perinatal nicotine exposure (PNE) alters the establishment of HSCs and fetal-derived non-traditional tissue immune cells, with no alterations in circulating immune cell numbers. Suppression of HSCs and lung immune cells persisted for weeks after PNE had ceased. Strikingly, PNE led to increased disease susceptibility and severity upon challenge with influenza A virus in adulthood. This was associated with significant and highly selective alterations in lung immune cells, emphasizing the importance of cellular mechanisms in resilience to infections. Together, these experiments demonstrate that perinatal exposures that have deleterious consequences on hematopoietic establishment can impair immune function for life and identify the cellular mechanisms by which perinatal nicotine exposure predisposes the offspring to a weakened defense against respiratory pathogens.

Health effects associated with exposure to secondhand smoke: a Burden of Proof study

Despite a gradual decline in smoking rates over time, exposure to secondhand smoke (SHS) continues to cause harm to nonsmokers, who are disproportionately children and women living in low- and middle-income countries. We comprehensively reviewed the literature published by July 2022 concerning the adverse impacts of SHS exposure on nine health outcomes. Following, we quantified each exposure-response association accounting for various sources of uncertainty and evaluated the strength of the evidence supporting our analyses using the Burden of Proof Risk Function methodology. We found all nine health outcomes to be associated with SHS exposure. We conservatively estimated that SHS increases the risk of ischemic heart disease, stroke, type 2 diabetes and lung cancer by at least around 8%, 5%, 1% and 1%, respectively, with the evidence supporting these harmful associations rated as weak (two stars). The evidence supporting the harmful associations between SHS and otitis media, asthma, lower respiratory infections, breast cancer and chronic obstructive pulmonary disease was weaker (one star). Despite the weak underlying evidence for these associations, our results reinforce the harmful effects of SHS on health and the need to prioritize advancing efforts to reduce active and passive smoking through a combination of public health policies and education initiatives.

Dietary and Antioxidant Vitamins Limit the DNA Damage Mediated by Oxidative Stress in the Mother-Newborn Binomial

During pregnancy, appropriate nutritional support is necessary for the development of the foetus. Maternal nutrition might protect the foetus from toxic agents such as free radicals due to its antioxidant content. In this study, 90 mothers and their children were recruited. DNA damage mediated by oxidative stress (OS) was determined by the levels of 8-hidroxy-2′-deoxyguanosine (8-OHdG) in the plasma of women and umbilical cord blood. The mothers and newborns were categorised into tertiles according to their 8-OHdG levels for further comparison. No relevant clinical differences were observed in each group. A strong correlation was observed in the mother−newborn binomial for 8-OHdG levels (Rho = 0.694, p < 0.001). In the binomial, a lower level of 8-OHdG was associated with higher consumption of calories, carbohydrates, lipids, and vitamin A (p < 0.05). In addition, the levels of 8-OHdG were only significantly lower in newborns from mothers with a higher consumption of vitamin A and E (p < 0.01). These findings were confirmed by a significant negative correlation between the 8-OHdG levels of newborns and the maternal consumption of vitamins A and E, but not C (Rho = −0.445 (p < 0.001), −0.281 (p = 0.007), and −0.120 (p = 0.257), respectively). Multiple regression analysis showed that the 8-OHdG levels in mothers and newborns inversely correlated with vitamin A (β = −1.26 (p = 0.016) and −2.17 (p < 0.001), respectively) and pregestational body mass index (β = −1.04 (p = 0.007) and −0.977 (p = 0.008), respectively). In conclusion, maternal consumption of vitamins A and E, but not C, might protect newborns from DNA damage mediated by OS.

Prenatal and Postnatal Cigarette Smoke Exposure Is Associated With Increased Risk of Exacerbated Allergic Airway Immune Responses: A Preclinical Mouse Model

Increased exposure to household air pollution and ambient air pollution has become one of the world’s major environmental health threats. In developing and developed countries, environmental cigarette smoke (CS) exposure is one of the main sources of household air pollution (HAP). Moreover, results from different epidemiological and experimental studies indicate that there is a strong association between HAP, specifically CS exposure, and the development of allergic diseases that often persists into later life. Here, we investigated the impact of prenatal and postnatal CS exposure on offspring susceptibility to the development of allergic airway responses by using a preclinical mouse model. Pregnant BALB/c mice were exposed to either CS or air during pregnancy and lactation and in order to induce allergic asthma the offspring were sensitized and challenged with house dust mite (HDM). Decreased lung function parameters, like dynamic compliance and pleural pressure, were observed in PBS-treated offspring born to CS-exposed mothers compared to offspring from air-exposed mothers. Maternal CS exposure significantly increased the HDM-induced airway eosinophilia and neutrophilia in the offspring. Prenatal and postnatal CS exposure increased the frequency of Th2 cells in the lungs of HDM-treated offspring compared to offspring born to air-exposed mothers. Offspring born to CS-exposed mothers showed increased levels of IL-4, IL-5 and IL-13 in bronchoalveolar lavage fluid compared to offspring from air-exposed mothers. Ex-vivo restimulation of lung cells isolated from HDM-treated offspring born to CS-exposed mothers also resulted in increased IL-4 production. Finally, serum immunoglobulins levels of HDM-specific IgE and HDM-specific IgG1 were significantly increased upon a HDM challenge in offspring born to CS-exposed mothers compared to offspring from air-exposed mothers. In summary, our results reveal a biological plausibility for the epidemiological studies indicating that prenatal and postnatal CS exposure increases the susceptibility of offspring to allergic immune responses.

Nicotine replacement therapy and e-cigarettes in pregnancy and infant respiratory outcomes

BACKGROUND

Nicotine replacement therapy (NRT) and e-cigarettes are recommended to pregnant women who wish to stop smoking. Albeit eliminating other harmful components of cigarettes, those alternatives still expose the developing fetus to nicotine. The lungs may be particularly vulnerable to damage by nicotine as there is widespread nicotinic-acetylcholine receptor expression in the lungs. There is, however, a paucity of information about the effect of NRT and e-cigarette use in pregnancy on infant respiratory outcomes.

AIMS

To explore the effect of NRT and e-cigarettes on the developing lung.

STUDY DESIGN

A literature search was undertaken to examine the use and safety of nicotine-replacement strategies in pregnancy, with a focus on infant respiratory outcomes. This included experimental studies investigating the effect of isolated "gestational" nicotine on the developing lung.

OUTCOME MEASURES

Respiratory outcomes in animal studies and infants.

RESULTS

Animal studies investigating the effect of gestational nicotine exposure on fetal lung development demonstrated abnormal lung growth; including abnormal airway branching and alveolar development. Consequently, offspring display altered pulmonary mechanics, including both increased respiratory rate and airway resistance. These findings mirror respiratory pathology observed in infants born to smoking mothers. Human trials of NRT and e-cigarette use in pregnancy have not identified adverse perinatal outcomes regarding reduced birthweight or prematurity, but have not considered infant and childhood respiratory outcomes.

CONCLUSIONS

Nicotine can impair fetal lung development, leading to concerns regarding the safety of NRT and e-cigarettes in pregnancy. Studies have yet to explore the impact of these nicotine-containing products on infant respiratory outcomes.

Maternal Smoking during Pregnancy and the Risk for Childhood Infectious Diseases in the Offspring: A Population-Based Cohort Study

OBJECTIVE

Infectious diseases account for up to 43% of childhood hospitalizations. Given the magnitude of infection-related hospitalizations, we aimed to evaluate the effect of maternal smoking during pregnancy on the risk for long-term childhood infectious morbidity.

STUDY DESIGN

This is a population-based cohort analysis comparing the long-term risk for infectious diseases, in children born to mothers who smoked during pregnancy versus those who did not. Infectious diseases were predefined based on International Classification of Diseases, Ninth Revision codes. Deliveries occurred between the years 1991 and 2014.

RESULTS

A total of 246,854 newborns met the inclusion criteria; 2,986 (1.2%) were born to mothers who smoked during pregnancy. Offspring of smokers had significantly higher risk for several infectious diseases during childhood (upper respiratory tract, otitis, viral infections, and bronchitis) as well as increased risk for total infection-related hospitalizations (odds ratio = 1.5, 95% confidence interval [CI]: 1.3-1.7; p = 0.001). Cumulative incidence of infection-related hospitalizations was significantly higher in offspring of smokers (log-rank test, p = 0.001). Controlling for maternal age, diabetes, hypertensive disorders, and gestational age at index delivery, smoking remained an independent risk factor for infectious diseases during childhood (adjusted hazard ratio = 1.5, 95% CI: 1.3-1.6; p = 0.001).

CONCLUSION

Intrauterine exposure to maternal smoking may create an environment leading to an increased future risk for long-term pediatric infectious morbidity of the offspring.

Effects of parental smoking and indoor tobacco smoke exposure on respiratory outcomes in children

The extensive literature has reported adverse effects on environmental tobacco smoke (ETS) on children's health. We aim to analyze associations of ETS with dry night cough, croup, pneumonia, and frequent common cold and to disentangle the effects of prenatal, infancy and childhood exposure by multilevel logistic regression. A cross-sectional study was conducted among 41,176 children aged 3-8 years in 8 major cities of China during 2010-2011, and obtained demographic information, smoke exposure information, and respiratory outcomes. Parents' smoking habit and indoor tobacco smoke odor were considered as two indicators of ETS. The prevalences of respiratory outcomes were 6.0% for croup, 9.5% for frequency common cold, 17.1% for dry night cough and 32.3% for pneumonia respectively in the study. The associations between respiratory outcomes and parental smoking were not obvious, while indoor tobacco smoke odor was clearly and strongly associated with most respiratory outcomes, with adjusted odds ratios ranging from 1.06 to 1.95. Both infancy and childhood exposure to tobacco smoke odor were independent risk factors, but infancy exposure had a higher risk. The results explore that ETS increased the risk of respiratory outcomes in children, highlighting the need for raising awareness about the detrimental effects of tobacco smoke exposure.

Oral Vitamin C (500 mg/d) to Pregnant Smokers Improves Infant Airway Function at 3 Months (VCSIP). A Randomized Trial

Rationale: We reported a randomized trial demonstrating daily supplemental vitamin C to pregnant smokers significantly improved newborn pulmonary function tests. The current study tests these results in a new cohort using infant pulmonary function tests. Objectives: To determine if infants of pregnant smokers randomized to daily supplemental vitamin C would have improved forced expiratory flows (FEFs) at 3 months of age compared with those randomized to placebo, and to investigate the association of the α5 nicotinic acetylcholine receptor. Methods: A randomized, double-blind, placebo-controlled trial was conducted at three centers. Two hundred fifty-one pregnant smokers were randomized at 13-23 weeks of gestation: 125 randomized to vitamin C (500 mg/d) and 126 to placebo. Measurements and Main Results: The primary outcome was FEF75 at 3 months of age performed with the raised volume rapid thoracic compression technique (Jaeger/Viasys). FEF50 and FEF25-75 obtained from the same expiratory curves were prespecified secondary outcomes. The infants of pregnant smokers randomized to vitamin C (n = 113) had the following FEFs at 3 months of age compared with those randomized to placebo (n =  109) as measured by FEF75 (200.7 vs. 188.7 ml/s; adjusted 95% confidence interval [CI] for difference, -3.33 to 35.64; P = 0.10), FEF50 (436.7 vs. 408.5 ml/s; adjusted 95% CI for difference, 6.10-61.30; P = 0.02), and FEF25-75 (387.4 vs. 365.8 ml/s; adjusted 95% CI for difference, 0.92-55.34; P = 0.04). Infant FEFs seemed to be negatively associated with the maternal risk alleles for the α5 nicotinic acetylcholine receptor (rs16969968). Conclusions: Although the primary outcome of FEF75 was not improved after vitamin C supplementation to pregnant smokers, the predetermined secondary outcomes FEF50 and FEF25-75 were significantly improved. These results extend our previous findings and demonstrate improved airway function (FEF50 and FEF25-75) at 3 months of age in infants after vitamin C supplementation to pregnant smokers. Clinical trial registered with www.clinicaltrials.gov (NCT01723696).

Cost effectiveness of vitamin c supplementation for pregnant smokers to improve offspring lung function at birth and reduce childhood wheeze/asthma

OBJECTIVE

To determine the implications of supplemental vitamin C for pregnant tobacco smokers and its effects on the prevalence of pediatric asthma, asthma-related mortality, and associated costs.

STUDY DESIGN

A decision-analytic model built via TreeAge compared the outcome of asthma in a theoretical annual cohort of 480,000 children born to pregnant smokers through 18 years of life. Vitamin C supplementation (500 mg/day) with a standard prenatal vitamin was compared to a prenatal vitamin (60 mg/day). Model inputs were derived from the literature. Deterministic and probabilistic sensitivity analyses assessed the impact of assumptions.

RESULT

Additional vitamin C during pregnancy would prevent 1637 cases of asthma at the age of 18 per birth cohort of pregnant smokers. Vitamin C would reduce asthma-related childhood deaths and save $31,420,800 in societal costs over 18 years per birth cohort.

CONCLUSION

Vitamin C supplementation in pregnant smokers is a safe and inexpensive intervention that may reduce the economic burden of pediatric asthma.

Vitamin C to Decrease the Effects of Smoking in Pregnancy on Infant Lung Function (VCSIP): Rationale, design, and methods of a randomized, controlled trial of vitamin C supplementation in pregnancy for the primary prevention of effects of in utero tobacco smoke exposure on infant lung function and respiratory health

Despite strong anti-smoking efforts, at least 12% of American women cannot quit smoking when pregnant resulting in >450,000 smoke-exposed infants born yearly. Smoking during pregnancy is the largest preventable cause of childhood respiratory illness including wheezing and asthma. Recent studies have shown a protective effect of vitamin C supplementation on the lung function of offspring exposed to in utero smoke in a non-human primate model and an initial human trial. Vitamin C to Decrease the Effects of Smoking in Pregnancy on Infant Lung Function (VCSIP) is a randomized, double-blind, placebo-controlled trial to evaluate pulmonary function at 3months of age in infants delivered to pregnant smokers randomized to 500mg/day of vitamin C versus placebo during pregnancy. Secondary aims evaluate the incidence of wheezing through 12months and pulmonary function testing at 12months of age. Women are randomized between 13 and 23weeks gestation from clinical sites in Portland, Oregon at Oregon Health & Science University and PeaceHealth Southwest Medical Center and in Indianapolis, Indiana at Indiana University and Wishard Hospital. Vitamin C supplementation occurs from randomization to delivery. Monthly contact with participants and monitoring of medical records is performed to document medication adherence, changes in smoking and medical history, and adverse events. Pulmonary function testing of offspring occurs at 3 and 12months of age and incidence of wheezing and respiratory illness through 12months is captured via at least quarterly questionnaires. Ancillary studies are investigating the impact of vitamin C on placental blood flow and DNA methylation.

Pulmonary Effects of Maternal Smoking on the Fetus and Child: Effects on Lung Development, Respiratory Morbidities, and Life Long Lung Health

Maternal smoking during pregnancy is the largest preventable cause of abnormal in-utero lung development. Despite well known risks, rates of smoking during pregnancy have only slightly decreased over the last ten years, with rates varying from 5-40% worldwide resulting in tens of millions of fetal exposures. Despite multiple approaches to smoking cessation about 50% of smokers will continue to smoke during pregnancy. Maternal genotype plays an important role in the likelihood of continued smoking during pregnancy and the degree to which maternal smoking will affect the fetus. The primary effects of maternal smoking on offspring lung function and health are decreases in forced expiratory flows, decreased passive respiratory compliance, increased hospitalization for respiratory infections, and an increased prevalence of childhood wheeze and asthma. Nicotine appears to be the responsible component of tobacco smoke that affects lung development, and some of the effects of maternal smoking on lung development can be prevented by supplemental vitamin C. Because nicotine is the key agent for affecting lung development, e-cigarette usage during pregnancy is likely to be as dangerous to fetal lung development as is maternal smoking.

The Role of Nicotine in the Effects of Maternal Smoking during Pregnancy on Lung Development and Childhood Respiratory Disease. Implications for Dangers of E-Cigarettes

Use of e-cigarettes, especially among the young, is increasing at near-exponential rates. This is coupled with a perception that e-cigarettes are safe and with unlimited advertising geared toward vulnerable populations, the groups most likely to smoke or vape during pregnancy. There is now wide appreciation of the dangers of maternal smoking during pregnancy and the lifelong consequences this has on offspring lung function, including the increased risk of childhood wheezing and subsequent asthma. Recent evidence strongly supports that much of the effect of smoking during pregnancy on offspring lung function is mediated by nicotine, making it highly likely that e-cigarette use during pregnancy will have the same harmful effects on offspring lung function and health as do conventional cigarettes. In fact, the evidence for nicotine being the mediator of harm of conventional cigarettes may be most compelling for its effects on lung development. This raises concerns about both the combined use of e-cigarettes plus conventional cigarettes by smokers during pregnancy as well as the use of e-cigarettes by e-cigarette-only users who think them safe or by those sufficiently addicted to nicotine to not be able to quit e-cigarette usage during pregnancy. Thus, it is important for health professionals to be aware of the risks of e-cigarette usage during pregnancy, particularly as it pertains to offspring respiratory health.

SmokeHaz: Systematic Reviews and Meta-analyses of the Effects of Smoking on Respiratory Health

BACKGROUND

Smoking tobacco increases the risk of respiratory disease in adults and children, but communicating the magnitude of these effects in a scientific manner that is accessible and usable by the public and policymakers presents a challenge. We have therefore summarized scientific data on the impact of smoking on respiratory diseases to provide the content for a unique resource, SmokeHaz.

METHODS

We conducted systematic reviews and meta-analyses of longitudinal studies (published to 2013) identified from electronic databases, gray literature, and experts. Random effect meta-analyses were used to pool the findings.

RESULTS

We included 216 articles. Among adult smokers, we confirmed substantially increased risks of lung cancer (risk ratio (RR), 10.92; 95% CI, 8.28-14.40; 34 studies), COPD (RR, 4.01; 95% CI, 3.18-5.05; 22 studies), and asthma (RR, 1.61; 95% CI, 1.07-2.42; eight studies). Exposure to passive smoke significantly increased the risk of lung cancer in adult nonsmokers and increased the risks of asthma, wheeze, lower respiratory infections, and reduced lung function in children. Smoking significantly increased the risk of sleep apnea and asthma exacerbations in adult and pregnant populations, and active and passive smoking increased the risk of tuberculosis.

CONCLUSIONS

These findings have been translated into easily digestible content and published on the SmokeHaz website.

Impact of Tobacco Smoke and Nicotine Exposure on Lung Development

Tobacco smoke and nicotine exposure during prenatal and postnatal life can impair lung development, alter the immune response to viral infections, and increase the prevalence of wheezing during childhood. The following review examines recent discoveries in the fields of lung development and tobacco and nicotine exposure, emphasizing studies published within the last 5 years. In utero tobacco and nicotine exposure remains common, occurring in approximately 10% of pregnancies within the United States. Exposed neonates are at increased risk for diminished lung function, altered central and peripheral respiratory chemoreception, and increased asthma symptoms throughout childhood. Recently, genomic and epigenetic risk factors, such as alterations in DNA methylation, have been identified that may influence the risk for long-term disease. This review examines the impact of prenatal tobacco and nicotine exposure on lung development with a particular focus on nicotinic acetylcholine receptors. In addition, this review examines the role of prenatal and postnatal tobacco smoke and nicotine exposure and its association with augmenting infection risk, skewing the immune response toward a T-helper type 2 bias and increasing risk for developing an allergic phenotype and asthmalike symptoms during childhood. Finally, this review outlines the respiratory morbidities associated with childhood secondhand smoke and nicotine exposure and examines genetic and epigenetic modifiers that may influence respiratory health in infants and children exposed to in utero or postnatal tobacco smoke.

Early-life Exposure to Widespread Environmental Toxicants and Health Risk: A Focus on the Immune and Respiratory Systems

Evidence has accumulated that exposure to widespread environmental toxicants, such as heavy metals, persistent organic pollutants, and tobacco smoke adversely affect fetal development and organ maturation, even after birth. The developing immune and respiratory systems are more sensitive to environmental toxicants due to their long-term physical development, starting from the early embryonic stage and persisting into early postnatal life, which requires complex signaling pathways that control proliferation and differentiation of highly heterogeneous cell types. In this review, we summarize the effect of early-life exposure to several widespread environmental toxicants on immune and lung development before and after birth, including the effects on immune cell counts, baseline characteristics of cell-mediated and humoral immunity, and alteration of lung structure and function in offspring. We also review evidence supporting the association between early-life exposure to environmental toxicants and risk for immune-related diseases and lung dysfunction in offspring in later life.

Understanding the Association of Human Rhinovirus with Asthma

Human rhinoviruses are ubiquitous seasonal pathogens. They have known associations with first onset of wheezing illnesses in children and with asthma exacerbations in patients of all ages. It is not yet certain whether human rhinoviruses play a direct role in the pathogenesis of asthma by activating deleterious inflammatory responses or if they only serve as a catalyst to accelerate the disease in genetically predisposed individuals. There have been previously demonstrated reductions in the development of the asthmatic phenotype with passive immunization against respiratory syncytial virus; however, in the case of rhinovirus, there are barriers to effective vaccine development, such as the lack of a common antigenic target due to alterations of surface markers among subtypes. It remains to be determined whether certain subtypes of human rhinovirus are more asthmagenic and therefore worthy of greater attention as vaccine candidates, but several studies have suggested that RV-C and certain RV-A strains may be more strongly linked with asthma.

Physical, behavioral, and cognitive effects of prenatal tobacco and postnatal secondhand smoke exposure

The purpose of this review is to examine the rapidly expanding literature regarding the effects of prenatal tobacco and postnatal secondhand smoke (SHS) exposure on child health and development. Mechanisms of SHS exposure are reviewed, including critical periods during which exposure to tobacco products appears to be particularly harmful to the developing fetus and child. The biological, biochemical, and neurologic effects of the small fraction of identified components of SHS are described. Research describing these adverse effects of both in utero and childhood exposure is reviewed, including findings from both animal models and humans. The following adverse physical outcomes are discussed: sudden infant death syndrome, low birth weight, decreased head circumference, respiratory infections, otitis media, asthma, childhood cancer, hearing loss, dental caries, and the metabolic syndrome. In addition, the association between the following adverse cognitive and behavioral outcomes and such exposures is described: conduct disorder, attention-deficit/hyperactivity disorder, poor academic achievement, and cognitive impairment. The evidence supporting the adverse effects of SHS exposure is extensive yet rapidly expanding due to improving technology and increased awareness of this profound public health problem. The growing use of alternative tobacco products, such as hookahs (a.k.a. waterpipes), and the scant literature on possible effects from prenatal and secondhand smoke exposure from these products are also discussed. A review of the current knowledge of this important subject has implications for future research as well as public policy and clinical practice.

Possible role of the α7 nicotinic receptors in mediating nicotine's effect on developing lung - implications in unexplained human perinatal death

Background

It is well known that maternal smoking during pregnancy is very harmful to the fetus. Prenatal nicotine absorption, in particular, is associated with alterations in lung development and functions at birth and with respiratory disorders in infancy. Many of the pulmonary disorders are mediated by the interaction of nicotine with the nicotinic receptors (nAChRs), above all with the α7 nAChR subunits that are widely expressed in the developing lung. To determine whether the lung hypoplasia frequently observed in victims of sudden fetal and neonatal death with a smoker mother may result from nicotine interacting with lung nicotinic receptors, we investigated by immunohistochemistry the possible presence of the α7 nAChR subunit overexpression in these pathologies.

Methods

In lung histological sections from 45 subjects who died of sudden intrauterine unexplained death syndrome (SIUDS) and 15 subjects who died of sudden infant death syndrome (SIDS), we applied the radial alveolar count (RAC) to evaluate the degree of lung maturation, and the immunohistochemical technique for nAChRs, in particular for the α7 nAChR subunit identification. In the same cases, an in-depth study of the autonomic nervous system was performed to highlight possible developmental alterations of the main vital centers located in the brainstem.

Results

We diagnosed a “lung hypoplasia”, on the basis of RAC values lower than the normal reference values, in 63% of SIUDS/SIDS cases and 8% of controls. In addition, we observed a significantly higher incidence of strong α7 nAChR immunostaining in lung epithelial cells and lung vessel walls in sudden fetal and infant death cases with a smoker mother than in age-matched controls. Hypoplasia of the raphe, the parafacial, the Kölliker-Fuse, the arcuate and the pre-Bötzinger nuclei was at the same time present in the brainstem of these victims.

Conclusions

These findings demonstrate that when crossing the placenta, nicotine can interact with nicotinic receptors of both neuronal and non-neuronal cells, leading to lung and nervous system defective development, respectively. This work stresses the importance of implementing preventable measures to decrease the noxious potential of nicotine in pregnancy.

Risky substance exposure during pregnancy: a pilot study from Lebanese mothers

BACKGROUND

The harmful effects of medication and licit substance use during pregnancy may potentially constitute a major public health concern. Our study aims to assess risky exposure of Lebanese pregnant women to drugs, tobacco, caffeine, and alcohol, and to determine their effect on postnatal outcomes.

METHODS

Women at term were addressed after delivery in five university hospitals of Beirut and Mount Lebanon between February and June 2012. A standardized questionnaire was administered to them. Moreover, medical files of both mothers and their respective newborns were checked to confirm information given by mothers, and to assess the health outcome of the babies.

RESULTS

Among the interviewed 350 women, active and passive smoking of tobacco (cigarette or water pipe), and consumption of category C, D, and X drugs were common during pregnancy in Lebanon; they were shown to negatively affect the neonatal outcome in multivariate analyses: they significantly decreased Apgar scores and increased the risk of underweight and medical complications of babies (P < 0.05).

CONCLUSION

Our study demonstrated that Lebanese women were exposed during pregnancy to multiple medications and licit substances that affected the neonates' health. Our findings have implications for clinical obstetric practice and prevention programs in Lebanon. Efforts should be made to decrease exposure to harmful substances during pregnancy.

In utero exposure to low dose arsenic via drinking water impairs early life lung mechanics in mice

BACKGROUND

Exposure to arsenic via drinking water is a significant environmental issue affecting millions of people around the world. Exposure to arsenic during foetal development has been shown to impair somatic growth and increase the risk of developing chronic respiratory diseases. The aim of this study was to determine if in utero exposure to low dose arsenic via drinking water is capable of altering lung growth and postnatal lung mechanics.

METHODS

Pregnant C57BL/6 mice were given drinking water containing 0, 10 (current World Health Organisation (WHO) maximum contaminant level) or 100 μg/L arsenic from gestational day 8 to birth. Birth outcomes and somatic growth were monitored. Plethysmography and the forced oscillation technique were used to collect measurements of lung volume, lung mechanics, pressure-volume curves and the volume dependence of lung mechanics in male and female offspring at two, four, six and eight weeks of age.

RESULTS

In utero exposure to low dose arsenic via drinking water resulted in low birth weight and impaired parenchymal lung mechanics during infancy. Male offspring were more susceptible to the effects of arsenic on growth and lung mechanics than females. All alterations to lung mechanics following in utero arsenic exposure were recovered by adulthood.

CONCLUSIONS

Exposure to arsenic at the current WHO maximum contaminant level in utero impaired somatic growth and the development of the lungs resulting in alterations to lung mechanics during infancy. Deficits in growth and lung development in early life may contribute to the increased susceptibility of developing chronic respiratory disease in arsenic exposed human populations.

Association of maternal smoking during pregnancy with infant hospitalization and mortality due to infectious diseases

BACKGROUND

Maternal smoking is associated with infant respiratory infections and with increased risk of low birth weight infants and preterm birth. This study assesses the association of maternal smoking during pregnancy with both respiratory and nonrespiratory infectious disease (ID) morbidity and mortality in infants.

METHODS

We conducted 2 retrospective case-control analyses of infants born in Washington State from 1987 to 2004 using linked birth certificate, death certificate and hospital discharge records. One assessed morbidity--infants hospitalized due to IDs within 1 year of birth (47,404 cases/48,233 controls). The second assessed mortality--infants who died within 1 year due to IDs (627 cases/2730 controls).

RESULTS

Maternal smoking was associated with both hospitalization (adjusted odds ratio [AOR] = 1.52; 95% confidence interval [CI]: 1.46, 1.58) and mortality (AOR = 1.51; 95% CI: 1.17, 1.96) due to any ID. In subgroup analyses, maternal smoking was associated with hospitalization due to a broad range of IDs including both respiratory (AOR = 1.69; 95% CI: 1.63, 1.76) and nonrespiratory IDs (AOR = 1.27; 95% CI: 1.20, 1.34). Further stratification by birth weight and gestational age did not appreciably change these estimates. In contrast, there was no association of maternal smoking with ID infant mortality when only low birth weight infants were considered.

CONCLUSIONS

Maternal smoking was associated with a broad range of both respiratory and nonrespiratory ID outcomes. Despite attenuation of the mortality association among low birth weight infants, ID hospitalization was found to be independent of both birth weight and gestational age. These findings suggest that full-term infants of normal weight whose mothers smoked may suffer an increased risk of serious ID morbidity and mortality.

Perinatal exposure to environmental tobacco smoke (ETS) enhances susceptibility to viral and secondary bacterial infections

Studies suggest childhood exposure to environmental tobacco smoke (ETS) leads to increased incidence of infections of the lower respiratory tract. The objective of this study was to determine whether perinatal exposure to ETS increases the incidence, morbidity and severity of respiratory influenza infection and whether a secondary bacterial challenge at the peak of a pre-existing viral infection creates an enhanced host-pathogen susceptibility to an opportunistic infection. Timed-pregnant female Balb/c mice were exposed to either ETS for 6 h/day, 7 d/week beginning on gestation day 14 and continuing with the neonates to 6 weeks of age. Control animals were exposed to filtered air (FA). At the end of exposure, mice were intranasally inoculated with a murine-adapted influenza A. One week later, an intranasal inoculation of S. aureus bacteria was administered. The respective treatment groups were: bacteria only, virus only or virus+bacteria for both FA and ETS-exposed animals for a total of six treatment groups. Animal behavior and body weights were documented daily following infection. Mice were necropsied 1-day post-bacterial infection. Bronchoalveolar lavage fluid (BALF) cell analysis demonstrated perinatal exposure to ETS, compared to FA, leads to delayed but enhanced clinical symptoms and enhanced total cell influx into the lungs associated with viral infection followed by bacterial challenge. Viral infection significantly increases the number of neutrophils entering the lungs following bacterial challenge with either FA or ETS exposure, while the influx of lymphocytes and monocytes is significantly enhanced only by perinatal ETS exposure. There is a significant increase in peribronchiolar inflammation following viral infection in pups exposed to ETS compared with pups exposed to FA, but no change is noted in the degree of lung injury between FA and ETS-exposed animals following bacterial challenge. The data suggests perinatal exposure to ETS alters the response of neonates to the timing and severity of infection as well as ETS alters the pattern of inflammation and cellular influx into the lungs due to viral and bacterial infection.

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.

[The Fetal Tobacco Syndrome - A statement of the Austrian Societies for General- and Family Medicine (ÖGAM), Gynecology and Obstetrics (ÖGGG), Hygiene, Microbiology and Preventive Medicine (ÖGHMP), Pediatrics and Adolescence Medicine (ÖGKJ) as well as Pneumology (ÖGP)]

Over more than 50 years, the nocuous effects of smoking in pregnancy on the fetus are well known. In the first years of science the focus was primarily on restricted fetal growth while in more recent years over 10.000 studies investigated the incomparably big sum of detrimental effects for the unborn's health. In this statement we want to present the recent scientific findings on this topic. The statement is aimed to show all doctors who treat pregnant women the present situation and evidence. In the beginning we give a short overview about the epidemiological situation in Europe. Then we present step by step the health effects with regards to pathophysiology and clinics. Furthermore the reader will learn about possibilities for smoking cessation in pregnancy. The problem of passive-smoking in pregnancy will be dealt with in a separate chapter. At present there is strong evidence that pregnant smoking has a detrimental effect on birth-weight, placenta-associated disease, stillbirth, sudden infant death syndrome (SIDS), childhood overweight, clefts, lung function, asthma, cardiovascular diseases and mental developmental disorders. These factors can be summarized by the term Fetal Tobacco Syndrome. There is supply for more studies for less investigated health effects. Pregnancy is a chance to stop smoking as most women show a high motivation in this period. Hence doctors of all disciplines should inform pregnant women about the detrimental effects of smoking on their unborn child and show them possibilities for smoking cessation.

Immunohistochemical detection and regulation of α5 nicotinic acetylcholine receptor (nAChR) subunits by FoxA2 during mouse lung organogenesis

Background

α₅ nicotinic acetylcholine receptor (nAChR) subunits structurally stabilize functional nAChRs in many non-neuronal tissue types. The expression of α₅ nAChR subunits and cell-specific markers were assessed during lung morphogenesis by co-localizing immunohistochemistry from embryonic day (E) 13.5 to post natal day (PN) 20. Transcriptional control of α₅ nAChR expression by FoxA2 and GATA-6 was determined by reporter gene assays.

Results

Steady expression of α₅ nAChR subunits was observed in distal lung epithelial cells during development while proximal lung expression significantly alternates between abundant prenatal expression, absence at PN4 and PN10, and a return to intense expression at PN20. α₅ expression was most abundant on luminal edges of alveolar type (AT) I and ATII cells, non-ciliated Clara cells, and ciliated cells in the proximal lung at various periods of lung formation. Expression of α₅ nAChR subunits correlated with cell differentiation and reporter gene assays suggest expression of α₅ is regulated in part by FoxA2, with possible cooperation by GATA-6.

Conclusions

Our data reveal a highly regulated temporal-spatial pattern of α₅ nAChR subunit expression during important periods of lung morphogenesis. Due to specific regulation by FoxA2 and distinct identification of α₅ in alveolar epithelium and Clara cells, future studies may identify possible mechanisms of cell differentiation and lung homeostasis mediated at least in part by α₅-containing nAChRs.

The morphology and mineralization of dental hard tissue in the offspring of passive smoking rats

OBJECTIVE

To study the effects of maternal passive smoking on the morphology and mineralization of dental hard tissue in offspring rats.

DESIGN

We have established a maternal passive smoking model. Offspring rats were sacrificed on the 20th day of gestation (E20) or the 3rd (D3) or 10th day (D10) after birth. We observed hard tissue morphology using Haematoxylin-Eosin (H&E) staining sections, used micro computer tomography (Micro-CT) to measure hard tissue thickness and volume on the mandibular first molars of the offspring rats, and used Micro-CT and energy dispersive X-ray spectroscopy with scanning electron microscopy (SEM/EDS) to determine the hard tissue mineral density and the ratio of calcium atom number/calcium atom+phosphorus atom number (Ca(2+)/P(3-)+Ca(2+)).

RESULTS

Overall, the development of dental hard tissue was delayed in the offspring of passive smoking rats. The thickness and volume of hard tissue were lower in the offspring of the maternal passive smoking group than in the offspring of the control group. Mineral density of the hard tissue and the ratio of (Ca(2+)/P(3-)+Ca(2+)) were also reduced in the offspring of the maternal passive smoking group.

CONCLUSION

Maternal passive smoking inhibits the morphological development and mineralization level of hard tissue on the mandibular first molars of offspring rats.

Parental and household smoking and the increased risk of bronchitis, bronchiolitis and other lower respiratory infections in infancy: systematic review and meta-analysis

BACKGROUND

Passive smoke exposure increases the risk of lower respiratory infection (LRI) in infants, but the extensive literature on this association has not been systematically reviewed for nearly ten years. The aim of this paper is to provide an updated systematic review and meta-analysis of studies of the association between passive smoking and LRI, and with diagnostic subcategories including bronchiolitis, in infants aged two years and under.

METHODS

We searched MEDLINE and EMBASE (to November 2010), reference lists from publications and abstracts from major conference proceedings to identify all relevant publications. Random effect pooled odds ratios (OR) with 95% confidence intervals (CI) were estimated.

RESULTS

We identified 60 studies suitable for inclusion in the meta-analysis. Smoking by either parent or other household members significantly increased the risk of LRI; odds ratios (OR) were 1.22 (95% CI 1.10 to 1.35) for paternal smoking, 1.62 (95% CI 1.38 to 1.89) if both parents smoked, and 1.54 (95% CI 1.40 to 1.69) for any household member smoking. Pre-natal maternal smoking (OR 1.24, 95% CI 1.11 to 1.38) had a weaker effect than post-natal smoking (OR 1.58, 95% CI 1.45 to 1.73). The strongest effect was on bronchiolitis, where the risk of any household smoking was increased by an OR of 2.51 (95% CI 1.96 to 3.21).

CONCLUSIONS

Passive smoking in the family home is a major influence on the risk of LRI in infants, and especially on bronchiolitis. Risk is particularly strong in relation to post-natal maternal smoking. Strategies to prevent passive smoke exposure in young children are an urgent public and child health priority.

TTF-1 regulates α5 nicotinic acetylcholine receptor (nAChR) subunits in proximal and distal lung epithelium

BACKGROUND

Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels comprised of five similar subunits that influence signal transduction and cell turnover. α5 is a structural subunit detected in many non-neuronal tissues; however, its function during pulmonary development is unknown.

RESULTS

α5 was assessed by immunohistochemistry and RT-PCR in mouse lungs from embryonic day (E)13.5 to post-natal day (PN)20. From E13.5 to E18.5, α5 expression was primarily observed in primitive airway epithelial cells while mesenchymal expression was faint and sporadic. α5 expression was detected throughout the proximal lung at PN1 and extensively expressed in the peripheral lung at PN4, an early stage of murine alveologenesis. An interesting shift occurred wherein α5 expression was almost undetectable in the proximal lung from PN4-PN10, but significant localization was again observed at PN20. Transcriptional control of α5 was determined by assessing the activity of reporters containing 2.0-kb and 850-bp of the mouse α5 promoter. Because perinatal expression of α5 was abundant in bronchiolar and alveolar epithelium, we assessed transcriptional control of α5 in Beas2B cells, a human bronchiolar epithelial cell line, and A-549 cells, an alveolar type II cell-like human epithelial cell line. Thyroid Transcription Factor-1 (TTF-1), a key transcription regulator of pulmonary morphogenesis, significantly increased α5 transcription by acting on both the 2.0-kb and 850-bp α5 promoters. Site-directed mutagenesis revealed that TTF-1 activated α5 transcription by binding specific TTF-1 response elements. Exogenous TTF-1 also significantly induced α5 transcription.

CONCLUSIONS

These data demonstrate that α5 is specifically controlled in a temporal and spatial manner during pulmonary morphogenesis. Ongoing research may demonstrate that precise regulation of α5 is important during normal organogenesis and misexpression correlates with tobacco related lung disease.

From the American Academy of Pediatrics: Technical report--Secondhand and prenatal tobacco smoke exposure

Secondhand tobacco smoke (SHS) exposure of children and their families causes significant morbidity and mortality. In their personal and professional roles, pediatricians have many opportunities to advocate for elimination of SHS exposure of children, to counsel tobacco users to quit, and to counsel children never to start. This report discusses the harms of tobacco use and SHS exposure, the extent and costs of tobacco use and SHS exposure, and the evidence that supports counseling and other clinical interventions in the cycle of tobacco use. Recommendations for future research, policy, and clinical practice change are discussed. To improve understanding and provide support for these activities, the harms of SHS exposure are discussed, effective ways to eliminate or reduce SHS exposure are presented, and policies that support a smoke-free environment are outlined.

[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.

Maternal exposure to secondhand cigarette smoke primes the lung for induction of phosphodiesterase-4D5 isozyme and exacerbated Th2 responses: rolipram attenuates the airway hyperreactivity and muscarinic receptor expression but not lung inflammation and atopy

Airway hyperreactivity (AHR), lung inflammation, and atopy are clinical signs of allergic asthma. Gestational exposure to cigarette smoke (CS) markedly increases the risk for childhood allergic asthma. Muscarinic receptors regulate airway smooth muscle tone, and asthmatics exhibit increased AHR to muscarinic agonists. We have previously reported that in a murine model of bronchopulmonary aspergillosis, maternal exposure to mainstream CS increases AHR after acute intratracheal administration of Aspergillus fumigatus extract. However, the mechanism by which gestational CS induces allergic asthma is unclear. We now show for the first time that, compared with controls, mice exposed prenatally to secondhand CS exhibit increased lung inflammation (predominant infiltration by eosinophils and polymorphs), atopy, and airway resistance, and produce proinflammatory cytokines (IL-4, IL-5, IL-6, and IL-13, but not IL-2 or IFN-gamma). These changes, which occur only after an allergen (A. fumigatus extract) treatment, are correlated with marked up-regulated lung expression of M1, M2, and M3 muscarinic receptors and phosphodiesterase (PDE)4D5 isozyme. Interestingly, the PDE4-selective inhibitor rolipram attenuates the increase in AHR, muscarinic receptors, and PDE4D5, but fails to down-regulate lung inflammation, Th2 cytokines, or serum IgE levels. Thus, the fetus is extraordinarily sensitive to CS, inducing allergic asthma after postnatal exposure to allergens. Although the increased AHR might reflect increased PDE4D5 and muscarinic receptor expression, the mechanisms underlying atopy and lung inflammation are unrelated to the PDE4 activity. Thus, PDE4 inhibitors might ease AHR, but are unlikely to attenuate lung inflammation and atopy associated with childhood allergic asthma.

Early wheezing phenotypes and severity of respiratory illness in very early childhood: study on intrauterine exposure to fine particle matter

The main goal of the paper was to assess the pattern of risk factors having an impact on the onset of early wheezing phenotypes in the birth cohort of 468 two-year olds and to investigate the severity of respiratory illness in the two-year olds in relation to both wheezing phenotypes, environmental tobacco smoke (ETS) and personal PM(2.5) exposure over pregnancy period (fine particulate matter). The secondary goal of the paper was to assess possible association of early persistent wheezing with the length of the baby at birth. Pregnant women were recruited from ambulatory prenatal clinics in the first and second trimester of pregnancy. Only women 18-35 years of age, who claimed to be non-smokers, with singleton pregnancies, without illicit drug use and HIV infection, free from chronic diseases were eligible for the study. In the statistical analysis of respiratory health of children multinomial logistic regression and zero-inflated Poisson regression models were used. Approximately one third of the children in the study sample experienced wheezing in the first 2 years of life and in about two third of cases (67%) the symptom developed already in the first year of life. The early wheezing was easily reversible and in about 70% of infants with wheezing the symptom receded in the second year of life. The adjusted relative risk ratio (RRR) of persistent wheezing increased with maternal atopy (RRR=3.05; 95%CI: 1.30-7.15), older siblings (RRR=3.05; 95%CI: 1.67-5.58) and prenatal ETS exposure (RRR=1.13; 95%CI: 1.04-1.23), but was inversely associated with the length of baby at birth (RRR=0.88; 95%CI: 0.76-1.01). The adjusted incidence risk ratios (IRR) of coughing, difficult breathing, runny/stuffy nose and pharyngitis/tonsillitis in wheezers were much higher than that observed among non-wheezers and significantly depended on prenatal PM(2.5) exposure, older siblings and maternal atopy. The study shows a clear inverse association between maternal age or maternal education and respiratory illnesses and calls for more research efforts aiming at the explanation of factors hidden behind proxy measures of quality of maternal care of babies. The data support the hypothesis that burden of respiratory symptoms in early childhood and possibly in later life may be programmed already in prenatal period when the respiratory system is completing its growth and maturation.

Length at birth and effect of prenatal and postnatal factors on early wheezing phenotypes. Kraków epidemiologic cohort study

The main goal of the study was to assess the pattern of risk factors having an impact on the onset of early wheezing phenotypes in the birth cohort of 468 two-year-olds. A secondary objective was to investigate a possible association between early persistent wheezing and infant's length at birth. Approximately one third of the children in the study sample experienced wheezing in the first two years of life, and in about two third of cases (67%), the symptom developed within the first year of life. The early wheezing was easily reversible and in about 70% of the affected infants, the symptom receded in the second year of life. The adjusted relative risk ratio (RRR) of persistent wheezing increased with maternal atopy (RRR = 3.13; 95% CI: 1.35-7.27), house dampness (RRR = 3.94; 95% CI: 1.26-12.3), parity (RRR = 2.56; 95% CI: 1.51-4.32) and prenatal ETS exposure (RRR = 1.13; 95% CI: 1.05-1.22), but was inversely associated with the infant's length at birth (RRR = 0.87; 95% CI: 0.76-0.99). The data support the hypothesis that wheezing phenotypes in early childhood and possibly later in life may already be programmed in the prenatal and early postnatal period when the respiratory system is completing its growth and maturation.

Smoking in pregnancy

During nine months of pregnancy, a woman who smokes 20 cigarettes each day will inhale nicotine, tar and carbon monoxide more than 50 000 times. This smoke contains chemicals known to be mutagenic and carcinogenic and will interfere with the normal growth and development of her child. Recent studies have revealed disturbing long-term consequences for the offspring. This article reviews the constituents of cigarette smoke, the effects of tobacco usage on the pregnancy, child and placenta, and strategies by which smoking during pregnancies may be prevented.

Smoking and reproduction

In the Netherlands, approximately 30% of all women of reproductive age smoke, compared with 36% of men.

Cigarette smoking is associated in women with a dose-related reduction in fecundity and fertility and in men with a reduction in semen quality. Smoking has a negative effect on pregnancy: increased rates of antepartum bleeding and placenta praevia have been described. Smoking is also associated with increases in the rates of spontaneous abortion, low birth weight and perinatal death. Some tobacco-related perinatal deaths are due to an increased risk of serious malformation. Children of mothers who smoke are admitted twice as often to hospital for pulmonary problems. However, studies on maternal smoking and childhood cancer have proved inconclusive.

Fetal exposure to secondhand tobacco smoke assessed by maternal self-reports and cord blood cotinine: prospective cohort study in Krakow

OBJECTIVES

While the validity of self-reported smoking habits is generally judged as satisfactory, objective markers of secondhand smoke (SHS) exposure may be more useful in validating the causal links between prenatal SHS and health effects. The cohort study in Krakow provided an opportunity for comparative assessment of fetal exposure to SHS based upon questionnaires and cord blood cotinine measurements.

METHODS

The study sample included 467 newborns born to women recruited in the first and second trimester of pregnancy. To compare the validity of self-reported SHS and cord blood cotinine levels in assessing the association between fetal passive smoking and health effects of newborns, we separately examined the regression coefficients of birthweight on self-reported number of cigarettes smoked by other household members during the entire pregnancy and cord blood cotinine levels.

RESULTS

In the non-exposed newborns the geometric mean of cord blood cotinine was 0.077 ng/ml and was significantly lower than in newborns with a maternal report of SHS. Cord cotinine levels were more highly correlated with a self-reported number of cigarettes smoked daily at home in the third trimester of pregnancy. The two measures of SHS (number of cigarettes and number of hours of daily exposure) were equally well correlated with cord blood cotinine levels. Using cotinine as the exposure variable, overall the association was not significant; but among the subgroup with cord cotinine levels above the median (> or =0.083 ng/ml), the association with birthweight was significant (beta coefficient = -113.65, P = 0.041).

CONCLUSION

The study provides evidence that the assessment of fetal SHS exposure based on cord blood cotinine produced better estimates of the association between exposure and birth outcomes.

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

We highlight evidence demonstrating antenatal smoking exposure is an important risk factor for increased respiratory symptoms and lung function abnormalities in infants and children. Epidemiological studies have demonstrated an excess both of wheezing in the first two years after birth and asthma and persistent wheezing in older children. Lung function testing in children exposed to antenatal smoking has demonstrated a reduction in airway function. Antenatal exposure of nicotine to animal models results in pulmonary hypoplasia, fewer but larger alveoli and altered airway morphology. Pulmonary function testing, however, has not demonstrated that infant lung volume is affected by antenatal smoking exposure, other than due to the expected effect of smoking on somatic growth, but there is an adverse effect on airway development. There is no evidence that antenatal smoking exposure increases bronchial hyperreactivity, rather it may be associated with a diminished response to both bronchoconstrictors and bronchodilators in infants.

Perinatal risk factors for hospitalization for pneumococcal disease in childhood: a population-based cohort study

OBJECTIVE

The objective of this study was to examine the relation of factors that are present at birth to subsequent hospitalization for childhood pneumococcal disease.

METHODS

We conducted a cohort study of all singletons born in 3 counties in western Denmark from 1980 through 2001, using population-based registries to obtain data on pregnancy- and birth-related variables and hospitalizations through age 12. We calculated incidence rates of pneumococcal disease hospitalization overall and within strata of study variables and used Poisson regression to estimate rate ratios for pneumococcal disease hospitalization while accounting for other birth characteristics.

RESULTS

Among 338,504 eligible births, 1052 children were later hospitalized for pneumococcal disease. Pneumonia accounted for most hospitalizations (81.9%). The pneumococcal disease hospitalization rate was highest among 7- to 24-month-olds, followed by 0- to 6-month-olds and 25- to 60-month-olds. The highest rates, typically over 200 hospitalizations per 100,000 person-years, were in 0- to 6- and 7- to 24-month-old children who were born preterm or with low birth weight, a low 5-minute Apgar score, or birth defects. The hospitalization rate was lower for first-born children at 0 to 6 months but not at older ages. At older ages, hospitalization rates were not substantially different for children whose mothers smoked during pregnancy, but at 0 to 6 months, the rate was higher for children of multiparous nonsmokers than for others. Adjusted rate ratios were elevated across all age categories for several variables, including low birth weight, presence of birth defects, and low 5-minute Apgar. For several others, including preterm birth, maternal multiparity, age < or = 20 years, and non-Danish/European Union citizenship, adjusted rate ratios were elevated only for 0- to 6-month-olds.

CONCLUSIONS

This large cohort study of hospitalization for childhood pneumococcal disease clarifies the roles of some gestation and birth factors while raising new questions about how these factors work.

The effects of in-utero tobacco-toxin exposure on the respiratory system in children

PURPOSE OF REVIEW

Promotion of cigarettes to children and women has resulted in unacceptably high rates of smoking during pregnancy in most developed countries and the potential to greatly increase smoking by mothers in developing countries. The risks of smoking during pregnancy to mothers and unborn children are well known and include growth retardation, respiratory diseases and sudden infant death syndrome. Determining the effects of exposure on the fetus depends upon accurate assessment of maternal smoking, both active and involuntary, and this can be done using self-reports and a variety of biomarkers in the mother and/or newborn.

RECENT FINDINGS

The evidence is clear that most of the excess respiratory morbidity in children born to smoking mothers is due to in-utero exposure and that deficits in lung function measured soon after birth persist in children and adults. Recent studies have also indicated that some children are genetically predisposed to adverse outcomes in response to in-utero exposure.

SUMMARY

Although many women attempt to quit during pregnancy and effective interventions are available, ultimately the respiratory health of future generations will depend upon effective public health and tobacco control measures designed to prevent smoking uptake by youth and in particular girls and young women.

Environmental tobacco smoke exposure: prevalence and mechanisms of causation of infections in children

BACKGROUND AND OBJECTIVES

Environmental tobacco smoke (ETS) exposure is probably one of the most important public health hazards in our community. Our aim with this article is to (1) review the prevalence of ETS exposure in the United States and how this prevalence is often measured in practice and (2) summarize current thinking concerning the mechanism by which this exposure may cause infections in young children.

METHODS

We conducted a Medline search to obtain data published mainly in peer-reviewed journals.

RESULTS

There is still a very high prevalence of ETS exposure among US children ranging from 35% to 80% depending on the method of measurement used and the population studied. The mechanism by which ETS may be related to these infections is not entirely clear but may be through suppression or modulation of the immune system, enhancement of bacterial adherence factors, or impairment of the mucociliary apparatus of the respiratory tract, or possibly through enhancement of toxicity of low levels of certain toxins that are not easily detected by conventional means.

CONCLUSIONS

The prevalence of ETS exposure in the United States is still very high, and its role in causing infections in children is no longer in doubt even if still poorly understood. Research, therefore, should continue to focus on the various mechanisms of causation of these infections and how to best reduce the exposure levels.