Association between prenatal and postnatal tobacco smoke exposure and allergies in young children

Smoke exposure and childhood atopic eczema and food allergy: A systematic review and meta-analysis

BACKGROUND

There is no consensus on the effect of timing and type of smoke exposure on early allergy development. This study aimed to determine the relationship between early eczema or food allergy/hypersensitivity development in children by firstly investigating the effect of smoke exposure across critical development periods and secondly by analyzing effects of parental atcive or passive smoking.

METHODS

Four databases (PubMed, Web of Science, Scopus and Embase) were searched in May 2022 and assessed by two independent reviewers. Case-control, cross-sectional or cohort studies reporting on smoke exposure from preconception to postnatal periods and atopic eczema, food allergy and/or hypersensitivity outcomes by age 3 years were included. The Newcastle-Ottawa Scale was used to assess study quality. Random effects model was used to estimate the pooled risk ratios.

RESULTS

From 1689 identified records, 32 studies with nearly 190,000 subjects were included. Parental smoking during preconception, pregnancy and postnatal periods was generally not associated with the risk of eczema, food allergy and food sensitisation development by age 3 years. Maternal active smoking during pregnancy was negatively associated with self-reported doctor diagnosis of eczema (RR = 0.87, 95% CI 0.77-0.98; I2  = 50.56) and maternal passive smoking during pregnancy was positively associated with clinician assessment of eczema in one study (RR = 1.38; 95% CI 1.06-1.79).

CONCLUSION

Our findings highlighted the importance of in utero programming in early-life allergy development. Despite the weak evidence, our results suggest pregnant women should minimise their contact with second-hand smoke to prevent offspring eczema development. There is a need for greater utilisation of objective allergy assessments in future studies.

Perinatal smoking exposure and risk of asthma in the first three years of life: A prospective prebirth cohort study

BACKGROUND

There is limited evidence on the association between prenatal smoking exposure and the risk of asthma in children. The aim of this prebirth cohort study was to investigate the association between prenatal and postnatal tobacco smoke exposure and the risk of asthma in Japanese children.

METHODS

Study subjects were 1304 mother-child pairs. Information on the variables under study was obtained using repeated questionnaires that were completed by mothers, first prior to delivery, then shortly after birth and subsequently around 4, 12, 24, and 36 months after delivery. Ever asthma was defined as a maternal report of physician-diagnosed asthma at any time since birth. Current asthma was defined as the use of asthma medication at the time of the sixth survey.

RESULTS

Logistic regression models revealed that maternal active smoking, either before pregnancy or during pregnancy, was not associated with the risk of ever asthma or current asthma. Further, no association was observed between postnatally living with at least one household smoker and the risk of asthma. Among children whose mothers are never smokers, maternal second-hand smoke (SHS) exposure at work and/or at home during pregnancy increased the risk of ever asthma and current asthma in children; adjusted odds ratio (95% confidence intervals) for ever asthma and current asthma were 2.41 (1.13-5.05) and 4.82 (1.68-13.43), respectively.

CONCLUSIONS

Our findings suggest that maternal SHS exposure during pregnancy might be associated with an increased risk of ever asthma and current asthma in young children whose mothers have never smoked.

Pre- and Postnatal Smoking Exposure and Risk of Atopic Eczema in Young Japanese Children: A Prospective Prebirth Cohort Study

Introduction

Epidemiological evidence regarding the effect of perinatal smoking exposure on atopic eczema in children continues to be inconclusive. The aim of this prospective prebirth cohort study was to investigate the association between prenatal smoking exposure and postnatal living with household smokers and the risk of atopic eczema in Japanese children aged 23 to 29 months.

Methods

Study subjects were 1354 Japanese mother-child pairs. Information on the variables under study was obtained through questionnaires which were completed by mothers, first prior to delivery, then shortly after birth and subsequently around 4, 12, and 24 months after delivery. Eczema in the last 12 months was defined according to the criteria of the International Study of Asthma and Allergies in Childhood. Physician-diagnosed atopic eczema was considered present if reported by mothers.

Results

Compared with no perinatal smoking exposure, prenatal smoking exposure only was associated with an increased risk of physician-diagnosed atopic eczema (adjusted odds ratio = 7.11, 95% confidence interval: 1.43 to 27.8). Postnatal living with at least one household smoker only was not associated with the risk of physician-diagnosed atopic eczema; neither was the combination of both prenatal smoking exposure and postnatal living with at least one household smoker. No association was observed between perinatal smoking exposure status and the risk of eczema as defined according to the International Study of Asthma and Allergies in Childhood criteria.

Conclusions

Our findings suggest that maternal smoking during pregnancy may increase the risk of atopic eczema in young children.

Implication

In the present prebirth cohort study, we assessed the independent and additive effects of pre- and postnatal exposure to tobacco smoking on atopic eczema in children. Compared with no perinatal smoking exposure, prenatal smoking exposure only was significantly associated with an increased risk of atopic eczema. Postnatal smoking exposure only was not associated with the risk of atopic eczema; neither was the combination of both pre- and postnatal smoking exposure. This is the first epidemiological study to show a positive association between prenatal smoking exposure only and the risk of atopic eczema.

Fetal Tobacco Smoke Exposure in the Third Trimester of Pregnancy Is Associated with Atopic Eczema/Dermatitis Syndrome in Infancy

The manifestation of atopic dermatitis (AD) is initially nonatopic eczema in early infancy; the manifestations subsequently change in age-specific stages. Since allergen-specific T-helper 2 cells appear in the fetus primarily after the third trimester of pregnancy and rapidly mature during the first 6 months of life, different timings of tobacco smoke exposure may have different effects on AD. In this study, we investigated whether the timing of fetal or/and infantile tobacco smoke exposure affects the cumulative incidence of atopic eczema/dermatitis syndrome (AEDS) in infants in Japan. This cross-sectional study enrolled 1,177 parent-infant pairs, in which the infants were >6 months old. Parental allergic history, number of older siblings, physician-diagnosed AEDS and food allergy (FA), and the perinatal fetal and/or infantile tobacco smoke exposure timing after 28 weeks gestation and during the first 6 months of life were assessed using self-completed questionnaires. Fetal tobacco smoke exposure after 28 weeks gestation was significantly associated with higher cumulative incidence of AEDS in exposed infants than in unexposed infants: AEDS in all infants, 41.4% versus 34.0% (Chi-squared, P = 0.020; adjusted odds ratio, 5.21; 95% confidence interval, 1.08-25.15); AEDS in those without parental allergic history, 38.0% versus 26.6% (Chi-squared, P = 0.024). Postnatal infantile tobacco smoke exposure timing was not significantly associated with cumulative incidence of AEDS. No significant associations were observed between any tobacco smoke exposure timings and the cumulative incidence of FA. Fetal tobacco smoke exposure during the third trimester of pregnancy was positively associated with AEDS in infancy and might induce epigenetic changes in the fetal allergen-specific immune responses.

Gingival Pigmentation Affected by Smoking among Different Age Groups: A Quantitative Analysis of Gingival Pigmentation Using Clinical Oral Photographs

The presence of any age-related differences in gingival pigmentation associated with smoking, particularly in a young population, remains to be fully investigated. The purpose of this study was to determine the age-related differences in smoking gingival pigmentation. Gingival pigmentation was analyzed using the gingival melanosis record (GMR) and Hedin’s classification with frontal oral photographs taken at 16 dental offices in Japan. Participants were categorized into 10-year age groups, and their baseline photographs were compared. In addition, to evaluate the effect of smoking cessation on gingival pigmentation, subjects were divided into a former smoker group (stopped smoking) and current smoker group. A total of 259 patients 19 to 79 years of age were analyzed. People in their 30s showed the most widespread gingival pigmentation. In addition, subjects in their 20s showed a weak effect of smoking cessation on gingival pigmentation. These findings suggested that the gingival pigmentation induced by smoking was more remarkable in young people than in middle-aged people. This information may be useful for anti-smoking education, especially among young populations with a high affinity for smoking.

Secondhand smoke exposure and risk of wheeze in early childhood: a prospective pregnancy birth cohort study

Background

Evidence regarding the independent and additive effects of both pre- and postnatal smoking exposure on the risk of wheeze in children is limited. The purpose of this prospective pregnancy birth cohort study was to examine the association between prenatal and postnatal tobacco smoke exposure during the first year of life and the risk of wheeze in Japanese children aged 23 to 29 months.

Methods

Study subjects were 1354 Japanese mother-child pairs. Information on the variables under study was obtained using repeated questionnaires that were completed by mothers, first prior to delivery, then shortly after birth and subsequently around 4, 12, and 24 months after delivery. Wheeze was defined according to the criteria of the International Study of Asthma and Allergies in Childhood.

Results

Compared with no maternal smoking during pregnancy, maternal smoking throughout pregnancy was significantly associated with an increased risk of wheeze in children, yet there were no associations between maternal smoking in the first trimester only or in the second and/or third trimesters and the risk of wheeze. No association was observed between postnatally living with at least one household smoker and the risk of wheeze. An analysis to assess the additive effect of prenatal and postnatal smoking exposure revealed that, compared with children not exposed to maternal smoking during pregnancy and not postnatally living with at least one household smoker, those who were both exposed to maternal smoking during pregnancy and postnatally living with at least one household smoker had twofold odds of developing wheeze.

Conclusions

Our findings suggest that maternal smoking throughout pregnancy might be associated with an increased risk of wheeze in children. There is also the possibility of a positive additive effect of pre- and postnatal smoking exposure on the risk of childhood wheeze.

Electronic supplementary material

The online version of this article (doi:10.1186/s12971-017-0138-7) contains supplementary material, which is available to authorized users.

Association of atopic dermatitis with smoking: A systematic review and meta-analysis

BACKGROUND

Tobacco exposure might be a modifiable risk factor for atopic dermatitis (AD).

OBJECTIVE

We examine the association between AD and exposure to tobacco smoke.

METHODS

We performed a systematic review and meta-analysis of observational studies (n = 86) in MEDLINE, EMBASE, Scopus, and Cochrane Library (1823-2015). Quality of evidence was assessed using the Newcastle-Ottawa Scale (NOS). A meta-analysis was performed using random-effects models to estimate pooled odds ratios (OR). Subset analyses were performed for different ages (children, adult), regions, study designs (cross-sectional, longitudinal), study sizes (<5000, ≥5000), study quality (NOS score <6, ≥6), and amount of smoking (mild, extensive).

RESULTS

A diagnosis of AD was associated with higher odds of active smoking (OR 1.87, 95% confidence interval 1.32-2.63) and exposure to passive smoke (OR 1.18, 95% confidence interval 1.01-1.38), but not maternal smoking during pregnancy (OR 1.06, 95% confidence interval 0.80-1.40). The association between active smoking and AD remained significant in children and adults, all continents studied, and study sizes, but all were cross-sectional designs and had NOS score 6 or greater. Passive smoke was associated with AD in children and adults, cross-sectional studies, South/Central American and African studies, study size less than 5000, and NOS score less than 6.

LIMITATIONS

AD severity and distribution were not assessed.

CONCLUSIONS

Active and passive exposure to smoke are associated with increased AD prevalence.

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.

Lifetime prevalence of childhood eczema and the effect of indoor environmental factors: Analysis in Hispanic and non-Hispanic white children

BACKGROUND

The prevalence of eczema varies markedly across the globe. It is unclear whether the geographic variation is due to race and/or ethnic differences, environmental exposures, or genetic factors.

OBJECTIVE

We investigated the effects of ethnicity and environmental exposures on eczema in Hispanic white and non-Hispanic white children who participated in the Southern California Children's Health Study.

METHODS

We performed a cross-sectional study with sociodemographic predictors and environmental exposures among Hispanic white and non-Hispanic white children ages 4-8 years enrolled in the Children's Health Study, 2002-2003.

RESULTS

Eczema prevalence differed by ethnicity: Hispanic whites showed lower prevalence (13.8%) compared with non-Hispanic whites (20.2%), and adjustment for sociodemographic factors did not account for the ethnic difference (odds ratio [OR] 0.79 [95% confidence interval {CI}, 0.65-0.95]). Parental history of allergic disease had a larger effect in Hispanic whites than in non-Hispanic whites (p for interaction = 0.005). High maternal education level (OR 1.46 [95% CI, 1.14-1.87]), parental history of allergic disease (OR 2.21 [95% CI, 1.78-2.76]), and maternal smoking during pregnancy (OR 1.44 [95% CI, 1.06-1.95]) increased the risk of eczema. Indoor environmental factors (e.g., mold, water damage, humidifier use) increased the risk of eczema in non-Hispanic whites independent of a parental history of allergic disease, but, in Hispanic whites, increased risks were observed, primarily in children without a parental history of allergic disease.

CONCLUSION

Hispanic white children in southern California had a lower prevalence of eczema than non-Hispanic whites, and this ethnic difference was not accounted for by sociodemographic differences. The effects of a parental history of allergic disease and indoor environmental exposures on eczema varied by ethnicity, which indicated that the etiology of eczema may differ in Hispanic whites and in non-Hispanic whites.

Policies to restrict secondhand smoke exposure: American College of Preventive Medicine Position Statement

Secondhand smoke (SHS) exposure poses serious health risks for all nonsmokers, especially children and pregnant women. SHS is estimated to contribute to heart attacks in nonsmokers and nearly 53,800 deaths in the U.S. annually. A literature review of English-language articles was performed using PubMed, organizational websites, and pertinent review articles. Over the past 25 years, smokefree policies have protected nearly half the U.S. population from the adverse health effects of SHS. Smokefree policies have been shown to improve health outcomes with no consequences to local businesses. As of April 2013, a total of 24 states and 561 municipalities and territories, including the District of Columbia, New York City, Puerto Rico, and the U.S. Virgin Islands, have established laws that require nonhospitality workplaces, restaurants, and bars to be 100% smokefree. Four other states-Florida, Indiana, Louisiana, and Nevada-have smokefree laws that cover restaurants but provide an exemption for stand-alone bars. At least 14 states have no smokefree laws. This paper describes the benefits of policies that reduce SHS and concludes with recommendations for future directions. The American College of Preventive Medicine (ACPM) recommends expanded clean indoor air policies for workplaces, stand-alone bars, restaurants, and multi-use family housing such as apartment buildings. ACPM recommends clean air policies for all university campuses, secondary school campuses, primary schools, child care centers, and city landmarks to further shift social norms and protect the health of children, adolescents, and adults. ACPM recommends closing existing gaps in clean indoor air policies.

Association between breastfeeding and dental caries in Japanese children

BACKGROUND

Studies investigating the impact of breastfeeding on dental caries have produced contradictory results. This cross-sectional study investigated the relationship between breastfeeding and the prevalence of dental caries in young Japanese children.

METHODS

The study subjects were 2056 Japanese children aged 3 years. Information on breastfeeding was obtained by means of a questionnaire. Children were classified as having caries if 1 or more deciduous teeth were decayed, missing, or had been filled at the time of examination.

RESULTS

The prevalence of dental caries was 20.7%. As compared with breastfeeding for less than 6 months, breastfeeding for 18 months or longer was associated with a significantly higher prevalence of dental caries. The relation was J-shaped: the adjusted prevalence ratios for less than 6 months, 6 to 11 months, 12 to 17 months, and 18 months or longer were 1.0, 0.79 (95% confidence interval [CI]: 0.60-1.05), 0.86 (95% CI: 0.66-1.13), and 1.66 (95% CI: 1.33-2.06), respectively (P for linear trend <0.0001, P for quadratic trend <0.0001).

CONCLUSIONS

Breastfeeding for 18 months or longer was positively associated with the prevalence of dental caries, while breastfeeding for 6 to 17 months was nonsignificantly inversely associated with the prevalence of dental caries.