Environmental tobacco smoke and fetal health: systematic review and meta-analysis

[Smoking cessation during pregnancy]

Smoking during pregnancy is associated with negative pregnancy and perinatal health outcomes. Physiological and societal particularities can modify the smoking behavior of pregnant women. Pregnancy is a teachable moment for smoking cessation. Increased nicotine clearance may lead to exacerbated tobacco withdrawal symptoms and desire to smoke, which need to be taken into account when helping pregnant smokers to quit. Although most pregnant smokers try to quit on their own, 12% of pregnant women in France reported smoking in 2021 during the 3rd trimester of pregnancy. Health care professionals should screen for tobacco consumption and assess the level of addiction. Management of smoking cessation can be multidisciplinary, including non-pharmacological support such as counselling, behavioral support, financial reward contingent on abstinence, and medication (nicotine replacement therapies). Assessment and limitation of secondhand smoke exposure (SHS) is needed because SHS can also have negative maternal and fetal consequences. Management of relapse during the postpartum period is also to be anticipated; in 2021, it concerned 22.4% of women who had stopped smoking during pregnancy. While electronic cigarette use is increasing overall and among pregnant women who smoke (5.4 before pregnancy, 1.3% during the 3rd trimester in 2021), well-conducted smoking cessation studies are necessary to assess its benefits and potential risks in this specific group of smokers.

Associations of Organophosphate Ester Flame Retardant Exposures during Pregnancy with Gestational Duration and Fetal Growth: The Environmental influences on Child Health Outcomes (ECHO) Program

BACKGROUND

Widespread exposure to organophosphate ester (OPE) flame retardants with potential reproductive toxicity raises concern regarding the impacts of gestational exposure on birth outcomes. Previous studies of prenatal OPE exposure and birth outcomes had limited sample sizes, with inconclusive results.

OBJECTIVES

We conducted a collaborative analysis of associations between gestational OPE exposures and adverse birth outcomes and tested whether associations were modified by sex.

METHODS

We included 6,646 pregnant participants from 16 cohorts in the Environmental influences on Child Health Outcomes (ECHO) Program. Nine OPE biomarkers were quantified in maternal urine samples collected primarily during the second and third trimester and modeled as log 2 -transformed continuous, categorized (high/low/nondetect), or dichotomous (detect/nondetect) variables depending on detection frequency. We used covariate-adjusted linear, logistic, and multinomial regression with generalized estimating equations, accounting for cohort-level clustering, to estimate associations of OPE biomarkers with gestational length and birth weight outcomes. Secondarily, we assessed effect modification by sex.

RESULTS

Three OPE biomarkers [diphenyl phosphate (DPHP), a composite of dibutyl phosphate and di-isobutyl phosphate (DBUP/DIBP), and bis(1,3-dichloro-2-propyl) phosphate] were detected in > 85 % of participants. In adjusted models, DBUP/DIBP [odds ratio (OR) per doubling = 1.07 ; 95% confidence interval (CI): 1.02, 1.12] and bis(butoxyethyl) phosphate (OR for high vs. nondetect = 1.25 ; 95% CI: 1.06, 1.46), but not other OPE biomarkers, were associated with higher odds of preterm birth. We observed effect modification by sex for associations of DPHP and high bis(2-chloroethyl) phosphate with completed gestational weeks and odds of preterm birth, with adverse associations among females. In addition, newborns of mothers with detectable bis(1-chloro-2-propyl) phosphate, bis(2-methylphenyl) phosphate, and dipropyl phosphate had higher birth weight-for-gestational-age z -scores (β for detect vs. nondetect = 0.04 - 0.07 ); other chemicals showed null associations.

DISCUSSION

In the largest study to date, we find gestational exposures to several OPEs are associated with earlier timing of birth, especially among female neonates, or with greater fetal growth. https://doi.org/10.1289/EHP13182.

Impact of indoor environment on children's pulmonary health

INTRODUCTION

A child's living environment has a significant impact on their respiratory health, with exposure to poor indoor air quality (IAQ) contributing to potentially lifelong respiratory morbidity. These effects occur throughout childhood, from the antenatal period through to adolescence. Children are particularly susceptible to the effects of environmental insults, and children living in socioeconomic deprivation globally are more likely to breathe air both indoors and outdoors, which poses an acute and long-term risk to their health. Adult respiratory health is, at least in part, determined by exposures and respiratory system development in childhood, starting in utero.

AREAS COVERED

This narrative review will discuss, from a global perspective, what contributes to poor IAQ in the child's home and school environment and the impact that indoor air pollution exposure has on respiratory health throughout the different stages of childhood.

EXPERT OPINION

All children have the right to a living and educational environment without the threat of pollution affecting their health. Action is needed at multiple levels to address this pressing issue to improve lifelong respiratory health. Such action should incorporate a child's rights-based approach, empowering children, and their families, to have access to clean air to breathe in their living environment.

Association between periodontal disease and osteoporosis in postmenopausal women: A systematic review and meta-analysis

Objective

To evaluate the relationship between periodontitis and postmenopausal osteoporosis.

Methods

This research was carried out according to the principles laid down by the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guideline statement. We searched the Web of Science, Embase, PubMed, The Cochrane Library, CNKI, VIP, and WanFang databases from inception to July 1, 2023 to collect all relevant publications, with no restrictions on publication date or Languages. Cochrane's tool for assessing RoB was used to evaluate the RoB for RCTs. The Newcastle-Ottawa Scale was used to assess the RoB for cohort studies and case-control studies. Mean differences (MD) with 95 % confidence intervals (CI) were used for analysis of continuous data. Heterogeneity was measured using the I2 statistic. Revman 5.4 software was used for the meta-analysis.

Results

28 observational studies with 19611 patients, including 5813 cases in the postmenopausal osteoporosis group and 13798 cases in the non-osteoporosis group. The studies showed that the degrees of clinical attachment loss (CAL), probing depth (PD), gingival recession (GR), simplified oral hygiene index (OHIS), and percentage of sites with bleeding on probing (BOP) in the postmenopausal osteoporosis group were higher than those in the non-osteoporosis group[CAL(MD = 0.89(mm), 95 % CI [0.48,1.30], p < 0.00001), PD (MD = 0.27(mm), 95 % CI [0.13, 0.41], p = 0.0001), GR (MD = 0.28(mm), 95 % CI [0.20, 0.35], p < 0.00001), OHIS (MD = 1.32,95 % CI [1.12,1.51], p < 0.00001), BOP(MD = 12.71(%), 95 % CI [3.24,22.18], p = 0.009)]. Eleven studies found that bone mineral density (BMD) in the postmenopausal osteoporosis group was lower than that in non-osteoporosis group (MD = -0.41(U/cm2), 95 % CI [-0.77,-0.05], p = 0.03). The combined analysis results of the studies in the two groups showed that there were no significant differences in the loss of alveolar crestal height (ACH)[(MD = -1.76(%),95%CI [-3.64,0.12], p = 0.07)].

Conclusion

Postmenopausal osteoporosis patients are more likely to suffer from periodontitis, and the condition is easily aggravated.

Identifying critical windows of air pollution exposure during preconception and gestational period on birthweight: a prospective cohort study

BACKGROUND

Few studies have assessed air pollution exposure association with birthweight during both preconception and gestational periods.

METHODS

Leveraging a preconception cohort consisting of 14220 pregnant women and newborn children in Shanghai, China during 2016-2018, we aim to assess associations of NO2 and PM2.5 exposure, derived from high-resolution spatial-temporal models, during preconception and gestational periods with outcomes including term birthweight, birthweight Z-score, small-for-gestational age (SGA) and large-for-gestational age (LGA). Linear and logistic regressions were used to estimate 3-month preconception and trimester-averaged air pollution exposure associations; and distributed lag models (DLM) were used to identify critical exposure windows at the weekly resolution from preconception to delivery. Two-pollutant models and children's sex-specific associations were explored.

RESULTS

After controlling for covariates, one standard deviation (SD) (11.5 μg/m3, equivalent to 6.1 ppb) increase in NO2 exposure during the second and the third trimester was associated with 13% (95% confidence interval: 2 - 26%) and 14% (95% CI: 1 - 29%) increase in SGA, respectively; and one SD (9.6 μg/m3) increase in PM2.5 exposure during the third trimester was associated with 15% (95% CI: 1 - 31%) increase in SGA. No association have been found for outcomes of birthweight, birthweight Z-score and LGA. DLM found that gestational weeks 22-32 were a critical window, when NO2 exposure had strongest associations with SGA. The associations of air pollution exposure tended to be stronger in female newborns than in male newborns. However, no significant associations of air pollution exposure during preconception period on birthweight outcomes were found.

CONCLUSION

Consistent with previous studies, we found that air pollution exposure during mid-to-late pregnancy was associated with adverse birthweight outcomes.

Association Between Smoking and Hypertension in Pregnancy Among Japanese Women: A Meta-analysis of Birth Cohort Studies in the Japan Birth Cohort Consortium (JBiCC) and JECS

BACKGROUND

Recent literature suggest the effect of maternal smoking on risk of hypertensive disorders in pregnancy (HDP) and preeclampsia may differ by ethnicity; however, studies on Asians are limited.

METHODS

We investigated the association of maternal smoking with HDP and preeclampsia using a common analysis protocol to analyze the association in six birth cohorts participating in a Japanese consortium of birth cohorts (JBiCC). Results were compared with-published results from cohorts not included in this consortium, and, where possible, we produced a meta-analysis including these studies.

RESULTS

Meta-analysis of four cohort studies including 28,219 participants produced an odds ratio (OR) of 1.24 (95% confidence interval [CI], 0.88-1.87) for the effect of smoking beyond early pregnancy compared to women who did not smoke during pregnancy. These results combined with those from the Japan Environment and Children's Study (JECS) yielded an OR of 1.19 (95% CI, 1.00-1.43, P = 0.056). Meta-analysis results for categories of smoking volume were insignificant, but when combined with JECS yielded an OR of 0.86 (95% CI, 0.65-1.12) for smoking 1-4 cigarettes, 1.25 (95% CI, 0.98-1.60) for smoking 5-9 cigarettes, and 1.27 (95% CI, 1.04-1.54) for smoking 10 or more cigarettes per day. All effects were insignificant for preeclampsia.

CONCLUSION

Our results suggest that the protective effects of smoking longer and smoking more on HDP and preeclampsia repeatedly observed among Europeans and North Americans likely do not hold for the Japanese.

Are Babies Born Preterm High-Risk Asthma Candidates?

Among preterm infants, the risk of developing asthma is a matter of debate. This review discusses the state of the art of poorly understood prematurity-associated asthma. Impaired pulmonary function is common in children born prematurely. Preterm infants are prone to developing viral respiratory tract infections, bronchiolitis in the first year of life, and recurrent viral wheezing in preschool age. All of these conditions may precede asthma development. We also discuss the role of both atopic sensitization and intestinal microbiome and, consequently, immune maturation. Diet and pollution have been considered to better understand how prematurity could be associated with asthma. Understanding the effect of factors involved in asthma onset may pave the way to improve the prediction of this asthma phenotype.

Active or passive maternal smoking increases the risk of low birth weight or preterm delivery: Benefits of cessation and tobacco control policies

In France, maternal smoking, active or passive, remains one of the highest in Europe. At the same time, there is an increase in the number of low birth weight (<2500 g) and premature (<37 weeks of amenorrhea) newborns. The objective of this narrative review is to examine the impact of active or passive maternal smoking on birth weight or prematurity rates, and to consider the benefits of policies to stop or control smoking. This is a narrative review that analyzes and discusses the major articles published over the past 20 years regarding the role of active or passive maternal smoking on the risk of low birth weight or preterm delivery. Articles were selected using the following keywords: maternal smoking, low birth weight, preterm birth, smoking cessation, passive smoking, exhaled carbon monoxide, tobacco control policies. Active smoking is associated, in a dose-response relationship, with increased risks of low birth weight and preterm delivery. Passive smoking, mainly related to the presence of a smoking spouse, increases the risk of low birth weight and preterm birth. Our review confirmed also the benefits of smoking cessation, even in the third trimester, in reducing the risk of small for gestation age or fetal growth restriction and preterm birth. Several studies of tobacco control policies have been shown to be effective in significantly reducing maternal smoking. There is sufficient evidence to infer a causal link between active or passive maternal smoking and low birth weight or preterm delivery. This causal link is compelling and sufficient to justify intensifying efforts to promote rapid progress in tobacco control policies, with the vision of a tobacco-free generation, and smoking cessation with best practices during preconception or pregnancy.

Smoking Ban Law in Chile: Impact in Newborns' Birth Weight by Women's Age Groups and by City Population Density

Objectives: We examined the short-term impact of the Smoking Ban Law (SBL) enacted in Chile in 2013 on low birth weight (LBW) rates in cities and its differential effects by different maternal age groups and city density. Methods: We included 885,880 live births from 21 Chilean cities of ≥100,000 inhabitants. We examined the smoking and LBW prevalence distribution before and after the SBL. Through Poisson mixed effect models, we determined whether a meaningful change in LBW rate occurred after SBL implementation in the whole sample and stratified by city population density and maternal age group. Results: LBW prevalence remained stable before and after the SBL implementation (6.1% and 6.3%, respectively), while women's smoking prevalence had a relative reduction of 25.9% (p < 0.00001). No significant changes in LBW rate occurred after the implementation of SBL in the total sample or stratified by city density tertiles or maternal age groups. Conclusion: SBL implementation did not show short-term impact on LBW rate in Chile. Further studies need to examine long-term impact of SBL on low birthweight.

Evaluating association of smoking status during pregnancy with adverse birth outcomes using urinary cotinine concentration: The Japan environment and Children's study (JECS)

Urinary cotinine concentration (UCC) reflects smoking status. However, in pregnant women, its association with adverse birth outcomes related to fetal growth is not widely known. Thus, we aimed to explore this relationship by focusing on dose-response relationships. We investigated 86,638 pregnant women enrolled between 2011 and 2014 in a prospective cohort study in Japan and observed three birth outcomes (preterm birth, low birth weight, and small-for-gestational age). We measured UCC in the second or third trimester, and categorized the participants using cut-off values (negative cotinine concentration, passive cotinine concentration, and active cotinine concentration corresponding to non-smokers, passive smokers, and active smokers, respectively). Logistic regression analyses were conducted to evaluate the risks, and dose-response relationships were visualized using restricted cubic spline curves. Analyses based on self-reported smoking status were also performed. We found that in low active and highly active cotinine concentrations, the adjusted odds ratios (aORs) of birth outcomes were significantly increased (preterm birth, 1.24 [95% CI 1.06-1.46], 1.39 [95% CI 1.19-1.62]; low birth weight, 1.40 [95% CI 1.24-1.58], 2.27 [95% CI 2.05-2.53]; small-for-gestational age, 1.35 [95% CI 1.19-1.52], 2.39 [95% CI 2.16-2.65]). Restricted cubic spline curves demonstrated risk elevations in the active cotinine concentration range. Our research revealed dose-response relationships between UCC during pregnancy and the risks of preterm birth, low birth weight, and small-for-gestational age. Measurement of UCC to ascertain smoking status during pregnancy may be a useful approach for predicting the risks of these birth outcomes.

Predictors of Poor Neonatal Outcomes among Pregnant Women in Indonesia: A Systematic Review and Meta-Analysis

OBJECTIVES

This study aimed to examine the association between maternal health behaviors and neonatal outcomes among the Indonesian population.

METHODS

Articles were collected from PubMed, EBSCO, ProQuest, DOAJ, and GARUDA. Funnel plots and Egger's tests analyzed indications of publication bias. A Mantel-Haenszel random-effects model was used to see the overall effect size of exposures on outcomes. Heterogeneity was seen based on I2. Data collected from articles included the author, year of publication, location of the study, study design, number of samples, risk factors, and effect sizes.

RESULTS

We identified 24 relevant studies, including eight from the primary databases and 16 from an additional database. A total of 12 studies were included in the meta-analysis, examining the association between maternal health behaviors and neonatal outcomes. The pooled odds ratio (OR) for passive smoking and low-birth-weight (LBW) was 3.41 (95% CI: 1.75-6.63, I2 = 40%, four studies). The pooled OR for incomplete antenatal care (ANC) and LBW was 6.29 (95% CI: 2.11-18.82, I2 = 70%, four studies). The pooled OR for incomplete ANC and neonatal mortality was 2.59 (95% CI: 1.01-6.66, I2 = 93%, four studies).

CONCLUSIONS

The results indicated that pregnant women with incomplete ANC had a higher risk of LBW and neonatal mortality, and those who were passively exposed to smoking had a higher risk of LBW. Further investigations are needed, considering the high heterogeneity found, and additional meta-analyses should be based on the variations of socio-demographic conditions.

“If the social circle is engaged, more pregnant women will successfully quit smoking”: a qualitative study of the experiences of midwives in the Netherlands with smoking cessation care

Background

If smoking is common within a pregnant woman’s social circle, she is more likely to smoke and her chances of succeeding in quitting smoking are reduced. It is therefore important to encourage smoking cessation in a pregnant woman’s social circle. Midwives are ideally positioned to help pregnant women and members of their social circle quit smoking but there is currently little knowledge about if and how midwives approach smoking cessation with pregnant women’s social circles.

Methods

In 2017 and 2018, semi-structured interviews were conducted with 14 birth care providers in the Netherlands. Interviews were inductively coded; data were analyzed thematically.

Results

In the interviews, midwives reported that they don’t commonly provide smoking cessation support to members of pregnant women’s social circles. The respondents noted that they primarily focused on mothers and weren’t always convinced that advising the partners, family, and friends of pregnant women to quit smoking was their responsibility. Data from the interviews revealed that barriers to giving advice to the social circle included a lack of a trusting relationship with the social circle, concerns about raising the topic and giving unwanted advice on cessation to members of the social circle and a lack of opportunity to discuss smoking.

Conclusions

Midwives in the Netherlands were reluctant to actively provide smoking cessation advice to the social circle of pregnant women. To overcome barriers to addressing cessation to the social circle, educational programs or new modules for existing programs could be used to improve skills related to discussing smoking. Clear guidelines and protocols on the role of midwives in providing cessation support to the social circle could help midwives overcome ambivalence that they might have.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12913-022-08472-7.

Tobacco use during pregnancy

The use of tobacco during pregnancy is the leading preventable cause of pregnancy complications and adverse birth outcomes. In high-income countries, around one in 10 pregnant women smokes tobacco, while smokeless tobacco is the primary form of tobacco used in many low- and middle-income countries. Although the risk of tobacco-related harms can be reduced substantially if mothers cease smoking in the first trimester of pregnancy, the proportion of women who successfully quit smoking during pregnancy remains modest. Psychosocial interventions are first-line treatment, with some high-quality evidence showing that counselling is effective in promoting smoking cessation among pregnant women. There is insufficient evidence regarding the efficacy and safety of smoking cessation pharmacotherapies when used during pregnancy, although in some countries nicotine replacement therapy is recommended for pregnant women who have been unable to quit without pharmacological assistance. E-cigarettes are increasingly being used as a smoking cessation aid in the general population of smokers, but more research is needed to determine if e-cigarettes are a safe and effective treatment option for pregnant women.

Effects of household environmental exposure and ventilation in association with adverse birth outcomes: A prospective cohort study in rural China

Prenatal exposure to outdoor air pollution have been associated with birth outcomes. However, there is limited evidence on the adverse effects of household indoor air pollution worldwide, much less in rural areas of China. This study aimed to explore the associations of household environmental factors (primary cooking fuel, housing renovation, and home ventilation) with four adverse birth outcomes (preterm birth (PTB), small for gestational age (SGA), low birth weight (LBW), and term low birth weight (T-LBW)). We conducted a cohort study involving 10,324 pregnancies in women who delivered a live-born infant from 2015 to 2018 in Guangxi, China. Risk ratios and 95% confidence intervals (CI) were estimated with control for reproductive history, lifestyle, home environmental confounders, and other potential confounders. A total of 5.4% of the infants were PTB, 10.7% were SGA, 5.5% had LBW, and 3.0% had T-LBW. Household-use induction cookers as the primary cooking fuel during pregnancy was associated with SGA (RR = 1.31, 95% CI: 1.07-1.60), LBW (1.41, 1.09-1.82), and T-LBW(1.62, 1.16-2.26), as compared with household-use gas as the primary cooking fuel. Housing renovation within one year before pregnancy was associated with PTB (1.45, 1.06-1.98) and LBW (1.56, 1.17-2.09), while housing renovation during pregnancy was associated with a higher risk of SGA only in moderate home ventilation conditions (3.74, 1.69-8.28). Our findings suggested that household-use induction cookers as the primary cooking fuel increased the risks of SGA, LBW, and T-LBW. In addition, housing renovation within one year before pregnancy increased the risks of PTB and LBW. Proper home ventilation may reduce the effect on the association between housing renovation during pregnancy and SGA.

Prevalence and socio-structural determinants of tobacco exposure in young women: Data from the Healthy Trajectories Initiative (HeLTI) study in urban Soweto, South Africa

BACKGROUND

Tobacco use is a major public health risk worldwide, which has increased on the African continent over the past 40 years. Socio-economic factors impact tobacco use and exposure, but little is known about the scope of this problem in young women living in an urban, historically disadvantaged township in contemporary South Africa. This study aimed to identify the prevalence of tobacco use in a cohort of young South African women using serum cotinine, and to assess the association between a number of socio-economic and social factors and tobacco use in this setting.

METHODS

Secondary analysis was conducted on cross-sectional data from the Healthy Life Trajectories Initiative (HeLTI) study. Serum cotinine was measured and a cut-off of ≥ 10 ng/mL was classified as tobacco use. Household socio-economic, socio-demographic and health information were collected by an interviewer-administered questionnaire.

RESULTS

Cotinine data was available for 1508 participants, of whom 29.2% (n = 441) had cotinine levels indicative of tobacco use. In regression analyses, moderate to severe socio-economic vulnerability (score 2-3 OR 1.66, p = 0.008; score ≥4: OR 1.63, p = 0.026) and multiparity (OR 1.74, p = 0.013) were associated with tobacco use. In addition, alcohol dependence (OR 3.07, p < 0.001) and drug use (OR 4.84, p < 0.001) were associated with tobacco use.

CONCLUSION

Young women with multiple children, moderate to severe socio-economic vulnerability, and alcohol and drug use were identified as more likely to use tobacco, indicating the need for targeted anti-tobacco interventions to curb the impact of tobacco on the growing burden of noncommunicable diseases in this setting.

A Systematic Review of Prospective Memory Interventions Across Stages of Dementia-Related Disorders

BACKGROUND

There is a critical need to develop effective interventions for cognitive impairments associated with dementia-related disorders (i.e., Alzheimer's disease, frontotemporal dementia, mild cognitive impairment). Prospective memory (PM), or the ability to create and carry out future intentions, is one cognitive domain that is impaired in individuals with dementia-related disorders. Effective treatment of PM could significantly improve daily functioning, level of independence, and quality of life.

OBJECTIVE

To date, there have been a number of studies investigating potential interventions, but these interventions have not been comprehensively reviewed and compared across the stages of dementia-related disorders, as is the aim of the current review.

METHODS

This review examined 21 studies on the success of intervention strategies for prospective memory in patients with dementia-related disorders.

RESULTS

All the studies demonstrated positive effects of intervention on PM abilities, but there are questions concerning ecological validity, length of positive effects on PM, and a lack of diversity of interventions across the different stages of dementia-related disorders.

CONCLUSION

Future research should address these issues by incorporating daily functioning activities and caregiver support into the intervention process, as well as investigating these interventions at more severe stages of dementia-related disorders.

Environmental tobacco smoke and carotid intima-media thickness in healthy children and adolescents: a systematic review

Thicker carotid intima-media thickness (CIMT) has been a valid predictor for atherosclerosis development. A significant association between environmental tobacco smoke (ETS) and thickening of CIMT has been demonstrated in adults, whereas such association has scarcely been reviewed in paediatric population. The dominate electronic databases, including MEDLINE (Ovid), PubMed, Embase, CINAHL, Web of Science, Scopus, were searched from inception. Reference lists of retrieved articles were further scanned as to avoid any missing literatures. Newcastle-Ottawa scale was used to assess the quality of the included studies. Qualitative synthesis analyses were performed on the selected studies. 331 articles were retrieved, and 4 were finally selected. All four studies investigated the association between postnatal ETS and CIMT in children, and three of them reported a statistically significant positive association. Three studies investigated the association between prenatal maternal ETS and CIMT, and one of the three found a positive association. Two studies explored the association between postnatal maternal ETS and CIMT, one reported a positive association. Two studies used serum cotinine measurement to quantify ETS and demonstrated potential dose-response relationship with CIMT. ETS exposure may play an independent role in the development of cardiovascular risks in healthy children and adolescents. In the consideration of the great burden of respiratory and cardiovascular diseases, there is an urgent need of effective surveillance for paediatric population's ETS exposure to reduce smoke exposure.

Exposure to polycyclic aromatic hydrocarbons during pregnancy and breast tissue composition in adolescent daughters and their mothers: a prospective cohort study

BACKGROUND

Polycyclic aromatic hydrocarbons (PAH), which are found in air pollution, have carcinogenic and endocrine disrupting properties that might increase breast cancer risk. PAH exposure might be particularly detrimental during pregnancy, as this is a time when the breast tissue of both the mother and daughter is undergoing structural and functional changes. In this study, we tested the hypothesis that ambient PAH exposure during pregnancy is associated with breast tissue composition, measured one to two decades later, in adolescent daughters and their mothers.

METHODS

We conducted a prospective analysis using data from a New York City cohort of non-Hispanic Black and Hispanic mother-daughter dyads (recruited 1998-2006). During the third trimester of pregnancy, women wore backpacks containing a continuously operating air sampling pump for two consecutive days that measured ambient exposure to eight carcinogenic higher molecular weight nonvolatile PAH compounds (Σ8 PAH) and pyrene. When daughters (n = 186) and mothers (n = 175) reached ages 11-20 and 29-55 years, respectively, optical spectroscopy (OS) was used to evaluate measures of breast tissue composition (BTC) that positively (water content, collagen content, optical index) and negatively (lipid content) correlate with mammographic breast density, a recognized risk factor for breast cancer. Multivariable linear regression was used to evaluate associations between ambient PAH exposure and BTC, overall and by exposure to household tobacco smoke during pregnancy (yes/no). Models were adjusted for race/ethnicity, age, and percent body fat at OS.

RESULTS

No overall associations were found between ambient PAH exposure (Σ8 PAH or pyrene) and BTC, but statistically significant additive interactions between Σ8 PAH and household tobacco smoke exposure were identified for water content and optical index in both daughters and mothers (interaction p values < 0.05). Σ8 PAH exposure was associated with higher water content (β_daughters = 0.42, 95% CI = 0.15-0.68; β_mothers = 0.32, 95% CI = 0.05-0.61) and higher optical index (β_daughters = 0.38, 95% CI = 0.12-0.64; β_mothers = 0.38, 95% CI = 0.12-0.65) in those exposed to household tobacco smoke during pregnancy; no associations were found in non-smoking households (interaction p values < 0.05).

CONCLUSIONS

Exposure to ambient Σ8 PAH and tobacco smoke during pregnancy might interact synergistically to impact BTC in mothers and daughters. If replicated in other cohorts, these findings might have important implications for breast cancer risk across generations.

OUP accepted manuscript

STUDY QUESTION

Is periconceptional maternal smoking associated with embryonic morphological development in ongoing pregnancies?

SUMMARY ANSWER

Smoking during the periconceptional period is associated with a delayed embryonic morphological development which is not fully recuperated beyond the first trimester of pregnancy.

WHAT IS KNOWN ALREADY

Smoking during pregnancy decreases prenatal growth, increasing the risk of preterm birth, small for gestational age (GA) and childhood obesity.

STUDY DESIGN, SIZE, DURATION

Between 2010 and 2018, 689 women with ongoing singleton pregnancies were periconceptionally enrolled in a prospective cohort study with follow-up until 1 year after delivery.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Between 7 + 0 and 10 + 3 weeks, GA serial three-dimensional transvaginal ultrasound scans were performed. Embryonic morphological development as assessed by the Carnegie developmental stages was evaluated using Virtual Reality techniques. In the absence of fetal morphology classification methods beyond the embryonic period, fetal ultrasound measurements at around 20 weeks’ GA, and birth weight were used to assess fetal growth. Linear mixed models were used to evaluate the association between smoking and the Carnegie stages. Regarding first-trimester morphological development, we additionally stratified our findings for mode of conception. Multiple linear regression models were used to study the association between smoking, fetal growth and birth weight. To investigate to which extent delayed embryonic morphological development mediated the effect of smoking, contemporary mediation analysis was used. Adjustments were made for potential confounders and other covariates.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 689 singleton ongoing pregnancies were included and 1210 Carnegie stages were determined. Maternal periconceptional smoking represented by the number of cigarettes/day was associated with a slight non-significant delay of the Carnegie stages (β_{cigarettes/day} = −0.058, 95% CI −0.122; 0.007, P = 0.080). Smoking of ≥10 cigarettes/day showed the strongest association (β_{≥10 cigarettes/day} = −0.352, 95% CI −0.648; −0.057, P = 0.019), as reflected by a 0.9-day delay in reaching the final Carnegie stage. Stratification for mode of conception showed a stronger negative association between the number of cigarettes/day in the IVF/ICSI group (β_{cigarettes/day} = −0.126, 95% CI −0.200; −0.051, P = 0.001) compared to naturally conceived pregnancies (β_{cigarettes/day} = 0.009, 95% CI −0.093; 0.111, P = 0.867). In the IVF/ICSI group, periconceptional smoking of ≥10 cigarettes/day was associated with in a 1.6 day delay in reaching the final Carnegie stage (β_{≥10 cigarettes/day} = −0.510, 95% CI −0.834; −0.186, P = 0.002). In the second trimester, periconceptional smoking was associated with a smaller femur length (β_{cigarettes/day} = −0.077, 95% CI −0.147; −0.008, P = 0.029) and a larger head circumference (β_{1–9 cigarettes/day} = 0.290, 95% CI 0.065; 0.514, P = 0.012). Smoking was associated with a lower birth weight, with a dose-response effect (β_{cigarettes/day} = −0.150, 95% CI −0.233; −0.068, P < 0.001). Furthermore, using the unadjusted model, 40–60% of the association between smoking and fetal ultrasound parameters and 6.3% of the association between smoking and birth weight can be explained by a delayed embryonic morphology.

LIMITATIONS, REASONS FOR CAUTION

The study population was recruited from a tertiary referral center. Smoking habits were explored using self-reported questionnaires and checked for consistency by trained researchers.

WIDER IMPLICATIONS OF THE FINDINGS

This study shows that the association of periconceptional maternal smoking and human morphological development can already be detected early in the first trimester of pregnancy using embryonic morphology as outcome. One of the key messages of this study is that the delay, or dysregulation, in embryonic morphology is associated with allometric growth reflected by smaller fetal measurements at 20 weeks gestation and lower weight at birth. The delay in embryonic morphology, measured in early pregnancy, cannot be recuperated during the pregnancy. The results of this study emphasize the importance of smoking intervention programs prior to conception. More research is warranted to assess the association between periconceptional smoking cessation and embryonic development.

STUDY FUNDING/COMPETING INTEREST(S)

The work was funded by the Department of Obstetrics and Gynaecology, Erasmus MC, University Medical Centre, Rotterdam, The Netherlands. The authors declare no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Risk Assessment of Passive Smoking Based on Analysis of Hair Nicotine and Cotinine as Exposure Biomarkers by In-Tube Solid-Phase Microextraction Coupled On-Line to LC-MS/MS

Passive smoking due to environmental tobacco smoke is a serious public health concern because it increases the risk of lung cancer and cardiovascular disease. However, the current status and effect of passive smoking in various lifestyles are not fully understood. In this study, we measured hair nicotine and cotinine levels as exposure biomarkers in non-smokers and assessed the risk from the actual situation of passive smoking in different lifestyle environments. Nicotine and cotinine contents in hair samples of 110 non-smoker subjects were measured by in-tube solid-phase microextraction with on-line coupling to liquid chromatography-tandem mass spectrometry, and self-reported lifestyle questionnaires were completed by the subjects. Nicotine and cotinine were detected at concentrations of 1.38 ng mg⁻¹ and 12.8 pg mg⁻¹ respectively in the hair of non-smokers, with levels significantly higher in subjects who reported being sensitive to tobacco smoke exposure. These levels were also affected by type of food intake and cooking method. Nicotine and cotinine in hair are useful biomarkers for assessing the effects of passive smoking on long-term exposure to environmental tobacco smoke, and our analytical methods can measure these exposure levels in people who are unaware of passive smoking. The results of this study suggest that the environment and places of tobacco smoke exposure and the lifestyle behaviors therein are important for the health effects of passive smoking.

Association between early gestation passive smoke exposure and neonatal size among self-reported non-smoking women by race/ethnicity: A cohort study

Understanding implications of passive smoke exposure during pregnancy is an important public health issue under the Developmental Origins of Health and Disease paradigm. In a prospective cohort of low-risk non-smoking pregnant women (NICHD Fetal Growth Studies—Singletons, 2009–2013, N = 2055), the association between first trimester passive smoke exposure and neonatal size was assessed by race/ethnicity. Plasma biomarker concentrations (cotinine, nicotine) assessed passive smoke exposure. Neonatal anthropometric measures included weight, 8 non-skeletal, and 2 skeletal measures. Linear regression evaluated associations between continuous biomarker concentrations and neonatal anthropometric measures by race/ethnicity. Cotinine concentrations were low and the percent above limit of quantification varied by maternal race/ethnicity (10% Whites; 14% Asians; 15% Hispanics; 49% Blacks). The association between cotinine concentration and infant weight differed by race/ethnicity (P_interaction = 0.034); compared to women of the same race/ethnicity, per 1 log-unit increase in cotinine, weight increased 48g (95%CI -44, 139) in White and 51g (95%CI -81, 183) in Hispanic women, but decreased -90g (95%CI -490, 309) in Asian and -93g (95%CI -151, -35) in Black women. Consistent racial/ethnic differences and patterns were found for associations between biomarker concentrations and multiple non-skeletal measures for White and Black women (P_interaction<0.1). Among Black women, an inverse association between cotinine concentration and head circumference was observed (−0.20g; 95%CI −0.38, −0.02). Associations between plasma cotinine concentration and neonatal size differed by maternal race/ethnicity, with increasing concentrations associated with decreasing infant size among Black women, who had the greatest biomarker concentrations. Public health campaigns should advocate for reducing pregnancy exposure, particularly for vulnerable populations.

Association between environmental tobacco smoke exposure in early life and autistic-like behaviors in Chinese preschoolers

OBJECTIVE

Few studies have evaluated the association between children's exposure to environmental tobacco smoke (ETS) in early life (during pregnancy, from birth to one year and from one to three years) and autistic-like behaviors. This study aimed to explore this association.

METHODS

This cross-sectional study analyzed data collected in 2017 as part of the Longhua Child Cohort Study. Autistic-like behaviors were measured using the Autism Behavior Checklist (ABC). Data on ETS exposure and autistic-like behaviors of children were collected via self-administered questionnaires completed by the mothers. Multivariate logistic regression models were undertaken to assess the associations.

RESULTS

Of the 65,243 participants included in this study, 1958 children met criteria for having autistic-like behaviors. The results showed that children were more likely to exhibit autistic-like behaviors when they were exposed to ETS in early life (AOR = 1.38; 95% CI = 1.26-1.52), compared to preschoolers without ETS exposure at any period of their early life. Compared with their unexposed counterparts, children who were exposed to ETS during gestation (AOR = 1.42; 95% CI = 1.29-1.57), or from birth to one year old (AOR = 1.42; 95% CI = 1.19-1.69) had significantly increased risk of autistic-like behaviors. In addition, with the increase in duration of exposure and average number of cigarettes smoked in the child's immediate environment, the risk of autistic-like behaviors increased.

CONCLUSION

Our study indicated that children's ETS exposure in early life was significantly associated with autistic-like behaviors. When children's exposure to cigarettes in early life increased in duration and number, the likelihood of the presence of autistic-like behaviors was higher.

Wildfire exposure during pregnancy and the risk of adverse birth outcomes: A systematic review

BACKGROUND

Maternal wildfire exposure (e.g., smoke, stress) has been associated with poor birth outcomes with effects potentially mediated through air pollution and psychosocial stress. Despite the recent hike in the intensity and frequency of wildfires in some regions of the world, a critical appraisal of the evidence on the association between maternal wildfire exposure and adverse birth outcomes has not yet been undertaken. We conducted a systematic review that evaluated the scientific evidence on the association between wildfire exposure during pregnancy and the risk of adverse birth outcomes.

METHODS

Comprehensive searches in nine bibliographic databases were conducted from database inception up to June 2020. Observational epidemiological studies that evaluated associations between exposure to wildfire during pregnancy and adverse birth outcomes were eligible for inclusion. Studies were assessed using the National Toxicology Program's Office of Health Assessment and Translation (NTP OHAT) risk of bias tool and certainty of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) framework. Screening of retrieved articles, data extraction, and risk of bias assessment were performed by two independent reviewers. Study results were synthesized descriptively.

RESULTS

Eight epidemiological studies conducted in four countries and involving 1,702,252 births were included in the review. The exposure to wildfire during pregnancy was assessed in individual studies by measurement of PM_2.5 (n = 2), PM₁₀ (n = 1), Total Ozone Mapping Spectrometer (TOMS)aerosol index (n = 1), heat spots (n = 1), and by proximity of maternal residence to wildfire-affected areas (n = 3). There is some evidence indicating that maternal wildfire exposure associates with birth weight reduction (n = 7) and preterm birth (n = 4), particularly when exposure to wildfire smoke occurred in late pregnancy. The association between wildfire exposure and small for gestational age (n = 2) and infant mortality (n = 1) was inconclusive.

CONCLUSION

Current evidence suggests that maternal exposure to wildfire during late pregnancy is linked to reduced birth weight and preterm birth. Well-designed comprehensive studies are needed to better understand the perinatal effects of wildfires.

Effects of active and/or passive smoking during pregnancy and the postpartum period

INTRODUCTION

Tobacco smoking may cause adverse effects during pregnancy and postpartum. The aim of this study was to evaluate several repercussions of active and/or passive smoking by the mother at home, during pregnancy, at delivery, as well as for the newborn baby and breastfeeding, including the effect of quitting smoking in the first trimester of pregnancy.

METHODS

A prospective longitudinal study was carried out with a sample of 800 pregnant women. Four evaluations were made: first and third trimester of pregnancy, and 2 and 6/8 months postpartum. Sociodemographic, obstetric, health and tobacco consumption details were collected, with biochemical tests being performed to confirm the self-reported abstinence.

RESULTS

Being an active and passive smoker predicted suffering complications in pregnancy (OR 2.50; 95% CI; 1.42-4.35) and delivery (OR 3.10; 95% CI; 1.75-5.51), and also tended not to breastfeed (OR 2.44; 95% CI; 1.35-4.42). Being an active smoker predicted complications at childbirth (OR 5.58; 95% CI; 2.64-7.77), for the baby (OR 3.77; 95% CI; 1.53-9.36) and not breastfeeding at 2 (OR 25.73; 95% CI; 11.95-55.40), and 6/8 months postpartum (OR 6.61; 95% CI; 3.21-13.58). Being a passive smoker reduces the intend to breastfeed (OR 1.81; 95% CI; 1.11-2.95), and the practice of breastfeeding at 2 months postpartum (OR 1.94; 95% CI; 1.11-3.37). Women who quit smoking are less likely to suffer complications in pregnancy and childbirth, and are more likely to attend antenatal and breastfeeding classes, and to have babies with higher birth weight.

CONCLUSIONS

Active and passive tobacco consumption has significant implications during pregnancy and postpartum period. Smoking cessation at the beginning of pregnancy reverses much of these effects.

Association between Self-Reported Survey Measures and Biomarkers of Second-Hand Tobacco Smoke Exposure in Non-Smoking Pregnant Women

Second-hand tobacco smoke (SHS) causes adverse health outcomes in adults. Further studies are needed to evaluate psychosocial SHS exposure measures in comparison to SHS exposure biomarkers, particularly in pregnant women. This study aimed to compare self-reported SHS exposure to urinary cotinine levels in pregnant women. A cross-sectional correlation design was conducted using a convenience sample of 70 non-smoking pregnant women. Measures included self-reported questionnaires and laboratory confirmation of cotinine levels in the urinary samples. Multiple regression analysis was used to assess the correlation after controlling for potential confounding variables. The average level of urinary cotinine among non-smoking pregnant women was 6.77 ng/mL. Medium-strength correlations were found among psychosocial SHS exposure measures and urine cotinine levels. Questions regarding ‘instances of smoking in front of the individual’ and ‘subjective perceived frequency of SHS exposure in past 7 days’ are feasible items for pregnant women in clinics (particularly the first question). Hence, we suggest that these simple questions should be used to assist pregnant women in reducing the harm associated with SHS exposure.

Vaping in Pregnancy: A Systematic Review

INTRODUCTION

Smoking in pregnancy increases the risk of negative health outcomes. Vaping can be effective for smoking cessation in nonpregnant populations. We conducted a systematic review of vaping in pregnancy, covering prevalence, patterns of use, reasons for use, smoking cessation, and health effects.

METHODS

Five academic databases were searched on 17 February 2020. Studies reporting prevalence, patterns, reasons, cessation, or health effects of vaping in pregnancy were included; animal and in vitro studies were excluded. A narrative review was used, with risk of bias assessed using Hoy and colleague's tool, the Newcastle-Ottawa scale, and the Consolidated Criteria for reporting Qualitative Research.

RESULTS

Twenty-three studies were identified: 11 survey, 7 qualitative, 3 cohort, and 2 secondary analyses of randomized clinical trials. Prevalence of vaping in pregnancy (four studies) was between 1.2% and 7.0% overall, and <1% among nonsmokers. Twelve studies reported patterns of use, but findings were inconsistent. Twelve of 14 studies asking why pregnant women vaped reported that most vaped to reduce or quit smoking. Mixed findings were reported from six studies on smoking cessation. Of three studies with health-related outcomes, two were underpowered and one reported similar birthweights for babies born to nonsmokers and women who vaped, with both higher (p < .0001) than the birthweight of babies born to smokers.

CONCLUSIONS

There were insufficient data to draw conclusions about prevalence, patterns, and effects of vaping in pregnancy on smoking cessation. The limited literature suggests that vaping in pregnancy has little or no effect on birthweight.

IMPLICATIONS

Smoking causes many negative health outcomes for pregnant women and to babies born to people who smoke. There remains a paucity of research on the effects of vaping in pregnancy. There is, however, the potential for vaping products to reduce the negative health outcomes associated with smoking. More research is needed to develop an evidence base in this area.

Burden of disease from exposure to secondhand smoke in children in Europe

BACKGROUND

Secondhand smoke (SHS) exposure at home and fetal SHS exposure during pregnancy are a major cause of disease among children. The aim of this study is quantifying the burden of disease due to SHS exposure in children and in pregnancy in 2006-2017 for the 28 European Union (EU) countries.

METHODS

Exposure to SHS was estimated using a multiple imputation procedure based on the Eurobarometer surveys, and SHS exposure burden was estimated with the comparative risk assessment method using meta-analytical relative risks. Data on deaths and disability-adjusted life years (DALYs) were collected from National statistics and from the Global Burden of Disease Study.

RESULTS

Exposure to SHS and its attributable burden stalled in 2006-2017; in pregnant women, SHS exposure was 19.8% in 2006, 19.1% in 2010, and 21.0% in 2017; in children it was 10.1% in 2006, 9.6% in 2010, and 12.1% in 2017. In 2017, 35,633 DALYs among children were attributable to SHS exposure in the EU, mainly due to low birth weight.

CONCLUSIONS

Comprehensive smoking bans up to 2010 contributed to reduce SHS exposure and its burden in children immediately after their implementation; however, SHS exposure still occurs, and in 2017, its burden in children was still relevant.

IMPACT

Exposure to secondhand smoke at home and in pregnancy is a major cause of disease among children. Smoking legislation produced the adoption of voluntary smoking bans in homes; however, secondhand smoke exposure at home still occurs and its burden is substantial. In 2017, the number of deaths and disability-adjusted life years in children attributable to exposure to secondhand smoke in the European Union countries were, respectively, 335 and 35,633. Low birth weight caused by secondhand smoke exposure in pregnancy showed the largest burden. Eastern European Union countries showed the highest burden.

Associations between Residential Proximity to Oil and Gas Drilling and Term Birth Weight and Small-for-Gestational-Age Infants in Texas: A Difference-in-Differences Analysis

BACKGROUND

Oil and natural gas extraction may produce environmental pollution at levels that affect reproductive health of nearby populations. Available studies have primarily focused on unconventional gas drilling and have not accounted for local population changes that can coincide with drilling activity.

OBJECTIVE

Our study sought to examine associations between residential proximity to oil and gas drilling and adverse term birth outcomes using a difference-in-differences study design.

METHODS

We created a retrospective population-based term birth cohort in Texas between 1996 and 2009 composed of mother-infant dyads (n=2,598,025) living <10km from an oil or gas site. We implemented a difference-in-differences approach to estimate associations between drilling activities and infant health: term birth weight and term small for gestational age (SGA). Using linear and logistic regression, we modeled interactions between births before (unexposed) or during (exposed) drilling activity and residential proximity near (0-1, 1-2, or 2-3km) or far (3-10km) from an active or future drilling site, adjusting for individual- and neighborhood-level characteristics.

RESULTS

The adjusted mean difference in term birth weight for mothers living 0-1 vs. 3-10km from a current or future drilling site was -7.3g [95% confidence interval (CI): -11.6, -3.0] for births during active vs. future drilling. The corresponding adjusted odds ratio for SGA was 1.02 (95% CI: 0.98, 1.06). Negative associations with term birth weight were observed for the 1-2 and 2-3km near groups, and no consistent differences were identified by type of drilling activity. Larger, though imprecise, adverse associations were found for infants born to Hispanic women, women with the lowest educational attainment, and women living in cities.

CONCLUSIONS

Residing near oil and gas drilling sites during pregnancy was associated with a small reduction in term birth weight but not SGA, with some evidence of environmental injustices. Additional work is needed to investigate specific drilling-related exposures that might explain these associations. https://doi.org/10.1289/EHP7678.

Effect of Grandmaternal Smoking on Body Size and Proportions at Birth

Many long-term adverse effects of smoking during pregnancy are known. Increasingly, adverse effects in the grandchild after grandmaternal smoking during pregnancy are reported. We explored this in a birth cohort of 24,000 grandmother–mother–child triads identified from the Finnish Medical Birth Register in 1991–2016. Multiple logistic regression was used to analyze the association between any smoking during pregnancy by both grandmother and mother, or only grandmother or mother on adverse birth outcomes. No smoking by neither grandmother nor mother was used as the reference. As endpoints, preterm birth, low birth weight, small for gestational age (birth weight, birth length, head circumference), and body proportionality (low ponderal index, high brain-to-body ratio, high head-to-length ratio) were included. Smoking by both grandmother and mother was consistently associated with higher risks than smoking only by the mother. Birth length and weight were especially sensitive to (grand)maternal smoking. In conclusion, the combined effect of grandmaternal and maternal smoking is associated with higher risks than only maternal smoking.

A single-center, prospective, observational study on maternal smoking during pregnancy in Greece: The HELENA study

INTRODUCTION

The unequivocal association between exposure to smoke and numerous complications of pregnancy, demonstrated in the last decades, has led to a significant decrease of smoking rates in pregnancy. The aim of the present study was to determine the prevalence of maternal smoking and to elucidate factors predisposing to it among pregnant women in Athens, Greece.

METHODS

A population of 1700 pregnant women (mean age: 31.2±5.5 years) who visited consecutively the Cardiology Department of Helena Venizelou Maternity Hospital in Athens, Greece, between September 2016 and August 2017, was prospectively analyzed. Data regarding changes in the future mother’s smoking habit as well as different sociodemographic factors potentially related to these changes were recorded.

RESULTS

Of the 1700 participants, 704 (41.4%) were smokers, and of those 52.4% quit smoking after knowledge of their pregnancy status. The overall prevalence of smoking in pregnancy was 19.7%. Prevalence was higher in women who were aged <20 years (p=0.038), were multipara (p=0.032), had ≤12 years of education (p=0.044) and had a partner who was a smoker (p=0.047). Women aged ≤20 years were more likely to be persistent smokers at the beginning of pregnancy and demonstrated a higher prevalence of smoking during pregnancy (42.2% vs 19.7% in the overall study population).

CONCLUSIONS

Our data demonstrate that maternal smoking during pregnancy still remains a major public health issue in Greece with a prevalence higher than most other industrialized countries.

Environmental Risk Factors and Health: An Umbrella Review of Meta-Analyses

Background: Environmental health is a growing area of knowledge, continually increasing and updating the body of evidence linking the environment to human health. Aim: This study summarizes the epidemiological evidence on environmental risk factors from meta-analyses through an umbrella review. Methods: An umbrella review was conducted on meta-analyses of cohort, case-control, case-crossover, and time-series studies that evaluated the associations between environmental risk factors and health outcomes defined as incidence, prevalence, and mortality. The specific search strategy was designed in PubMed using free text and Medical Subject Headings (MeSH) terms related to risk factors, environment, health outcomes, observational studies, and meta-analysis. The search was limited to English, Spanish, and French published articles and studies on humans. The search was conducted on September 20, 2020. Risk factors were defined as any attribute, characteristic, or exposure of an individual that increases the likelihood of developing a disease or death. The environment was defined as the external elements and conditions that surround, influence, and affect a human organism or population’s life and development. The environment definition included the physical environment such as nature, built environment, or pollution, but not the social environment. We excluded occupational exposures, microorganisms, water, sanitation and hygiene (WASH), behavioral risk factors, and no-natural disasters. Results: This umbrella review found 197 associations among 69 environmental exposures and 83 diseases and death causes reported in 103 publications. The environmental factors found in this review were air pollution, environmental tobacco smoke, heavy metals, chemicals, ambient temperature, noise, radiation, and urban residential surroundings. Among these, we identified 65 environmental exposures defined as risk factors and 4 environmental protective factors. In terms of study design, 57 included cohort and/or case-control studies, and 46 included time-series and/or case-crossover studies. In terms of the study population, 21 included children, and the rest included adult population and both sexes. In this review, the largest body of evidence was found in air pollution (91 associations among 14 air pollution definitions and 34 diseases and mortality diagnoses), followed by environmental tobacco smoke with 24 associations. Chemicals (including pesticides) were the third larger group of environmental exposures found among the meta-analyses included, with 19 associations. Conclusion: Environmental exposures are an important health determinant. This review provides an overview of an evolving research area and should be used as a complementary tool to understand the connections between the environment and human health. The evidence presented by this review should help to design public health interventions and the implementation of health in all policies approach aiming to improve populational health.

The effect of active and passive maternal smoking before and during pregnancy on neonatal weight at birth

INTRODUCTION

Smoking during pregnancy is a risk factor for adverse pregnancy outcomes. Data on the correlation between passive maternal smoking and pregnancy outcomes remain limited. We investigated the effect of active smoking and environmental tobacco smoke (ETS) during pregnancy on neonatal birthweight, including the risk for low birthweight (LBW).

MATERIAL AND METHODS

The study was conducted between 2010 and 2012. A group of 8625 women were surveyed during postpartum hospitalization. Outcome measures included mean birthweight of newborns. Additionally, odds ratios with confidence intervals were calculated to investigate the risk for LBW in active and passive smoking groups of mothers.

RESULTS

Lower birthweight (46 g - 307 g; p < 0.05) and a higher risk for LBW (OR = 1.35, 95% CI: 1.05-1.75; p < 0.05) were observed in all infants born to smoking mothers. A negative effect of ETS in pregnancy on the reduction of mean birthweight was also found. Additionally, we analyzed the cumulative effect of active and passive smoking on neonatal birthweight. A statistically significant reduction in neonatal weight at birth was found in a group of women who smoked actively and passively during pregnancy (130 g; p < 0.05).

CONCLUSIONS

Smoking is associated with decreased birthweight and in a group of active smoking mothers increased risk for LBW. This effect is dose-dependent and is also present in a group of women who smoked before pregnancy. There is also a cumulative effect of active smoking and ETS causing decreased neonatal birthweight and increased risk for low birthweight.

Early life exposures and risk of adult respiratory disease during 50 years of follow-up

Adult health is influenced by factors during fetal life affecting organ development and birth weight. We aimed to study such factors in relation to adult respiratory disease (ARD) risk. The Helsingborg Birth Cohort, Sweden, contributed baseline data collected by medical staff through clinical examination and questionnaires on maternal and birth characteristics 1964-1967. Register linkages were performed with completions of data on ARD by ICD 8-10 classifications (1969-2016), and/or ARD-related drug usage (2005-2016) enabling a 50-year follow-up time. Cox proportional hazard regression analyses were made to adjust for potential confounders, adjusted hazard ratio (aHR). A total of 3675 mothers and their offspring were included. Female offspring showed higher frequency of ARD than males, aHR 1.5 (95% CI 1.3-1.8). Maternal use of sedatives during second trimester, aHR 2.2 (95% CI 1.4-3.4), and maternal smoking during most of pregnancy, aHR 1.2 (95% CI 1.0-1.4), were associated with offspring ARD. Stratified by sex, large-for-gestational-age, aHR 1.4 (95% CI 1.0-1.9), was significantly associated with ARD in female offspring along with maternal sedative use during second trimester and maternal smoking during most of pregnancy. Maternal sedative use during second trimester or all trimesters were the only significant risk factors for male offspring. In conclusion, maternal sedative use in second trimester was independently associated with subsequent respiratory disease in adult offspring irrespective of sex.

The association between maternal exposure to secondhand smoke during pregnancy and their children's cerebral palsy, Shandong, China

INTRODUCTION

Tobacco use poses a threat to the health of pregnant women and their children. Our study assessed the association between maternal exposure to secondhand smoke (SHS) during pregnancy and children's cerebral palsy (CP) in Shandong, China.

METHODS

In our observational study, 5067 mother-child pairs were included from Shandong Province, China. Mothers filled in questionnaires about exposure to SHS during pregnancy. Statistical analysis and logistic regression models were built in R program to estimate the association in adjusted odds ratio (AOR) between SHS exposure during pregnancy and risk of children's CP, after adjustment for potential confounders including delivery mode and baby's birthweight.

RESULTS

Exposure to SHS was noted among 3663 (72.3%) of the 5067 non-smoking mothers during their pregnancy. Of the 239 CP children within the study, 192 (80.3%) were exposed to SHS during pregnancy. Children born to mothers exposed to SHS during pregnancy had a higher risk of CP (AOR=1.44; 95% CI: 1.02-2.04) than those born to non-exposed mothers, the risk increased by exposure time in the logistic regression model. The association between SHS exposure during pregnancy and CP children remained significant when adjusting for delivery mode and infant's birthweight due to their significant association with CP, with an AOR of 1.46 (95% CI: 1.13-1.91) for 1-4 days/week and 1.63 (95% CI: 1.22-2.01) for 5-7 days/week exposure to SHS.

CONCLUSIONS

Our study suggests that maternal exposure to secondhand smoke during pregnancy is associated with children's CP. Future preventive interventions of CP should include strategies that target the antenatal women who are exposed to SHS.

Are AAMA and GAMA Levels in Urine after Childbirth a Suitable Marker to Assess Exposure to Acrylamide from Passive Smoking during Pregnancy?-A Pilot Study

Introduction: Acrylamide (AA) is a “probably carcinogenic to humans” monomer that can form in heated starchy food and in tobacco smoke. N-Acetyl-S-(2-carbamoylethyl)-L-cysteine (AAMA) and N-Acetyl-S-(2-carbamoyl-2-hydroxyethyl)-L-cysteine (GAMA), acrylamide metabolites in urine, are recognized as good markers of exposure to acrylamide. Aim: The aim of the study is a preliminary assessment whether the levels of AAMA and GAMA in urine after childbirth are good markers of acrylamide exposure due to passive smoking during pregnancy. Material and method: The study group consisted 67 non-smokers and 10 passive-smoker women during pregnancy. AAMA and GAMA levels in urine samples were determined using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Results: The median AAMA levels in urine of non-smoking and passively smoking women were 30.7 μg/g creatinine and 25.2 μg/g creatinine, respectively. Much lower values were determined for GAMA: 11.4 μg/g creatinine and 10.3 μg/g creatinine, respectively. There is no significant difference between AAMA and GAMA content in urine samples between both groups of women as well as in the anthropometric parameters of newborns between those two groups of mothers. Conclusion: Our pilot study did not confirm that postpartum AAMA and GAMA concentrations in urine are good markers of exposure to acrylamide from passive smoking during pregnancy. It is probably due to the different ways of acrylamide absorption from tobacco smoke by active and passive smokers. Exposure of pregnant women to acrylamide from passive smoking requires further research.

Innovations in parental smoking cessation assistance delivered in the child healthcare setting

Addressing parental smoking in the child healthcare setting improves the health of all family members. Innovative approaches, such as mobilizing technology-based platforms, may streamline screening and motivate acceptance of behavioral health services to treat tobacco use and dependence. The obective of this study was to describe innovations added to the CEASE intervention and to track 2 year post-intervention implementation data on families who were screened for tobacco use. Child healthcare practices in five states (IN, NC, OH, TN, and VA) used an electronic tablet screener to identify tobacco use within families and deliver tobacco cessation assistance to smokers. Motivational/educational videos on cessation were displayed via the screener to enhance its utility. Five CEASE intervention practices screened 50,111 family members for tobacco use and identified 6,885 families with children exposed to tobacco smoke. The mean number of screeners per practice per month was 417; the mean number of households with smokers identified per month was 57. Of 2,764 smokers who were at visits and consented, 57% indicated that they wanted a prescription to reduce or quit smoking; 94% of these were given preprinted prescriptions. Of 41% who requested connection to the quitline, 93% were given enrollment forms. Electronic screening was used to routinely identify tobacco users, leading to increased potential for offering cessation assistance to all household members who smoke. Improved delivery of smoking cessation services to families may be achieved by integrating technological innovations into routine pediatric practice. CLINICAL TRIALS REGISTRATION: Trial Number NCT01882348.

[Effects of active and/or passive smoking during pregnancy and the postpartum period]

INTRODUCTION

Tobacco smoking may cause adverse effects during pregnancy and postpartum. The aim of this study was to evaluate several repercussions of active and/or passive smoking by the mother at home, during pregnancy, at delivery, as well as for the new born baby and breastfeeding, including the effect of quitting smoking in the first trimester of pregnancy.

METHODS

A prospective longitudinal study was carried out with a sample of 800 pregnant women. Four evaluations were made: first and third trimester of pregnancy, and 2 and 6/8 months postpartum. Sociodemographic, obstetric, health and tobacco consumption information was collected, with biochemical tests being performed to confirm the self-reported abstinence.

RESULTS

Being an active and passive smoker predicted suffering complications in pregnancy (OR 2.50; 95% CI; 1.42-4.35) and delivery (OR 3.10; 95% CI; 1.75-5.51), and also intend not to breastfeed (OR 2.44; 95% CI; 1.35-4.42). Being an active smoker predicted complications at childbirth (OR 5.58; 95% CI; 2.64-7.77), for the baby (OR 3.77; 95% CI; 1.53-9.36) and not breastfeeding at 2 (OR 25.73; 95% CI; 11.95-55.40), and 6/8 months postpartum (OR 6.61; 95% CI; 3.21-13.58). Being a passive smoker reduces the intention to breastfeed (OR 1.81; 95% CI; 1.11-2.95), and the practice of breastfeeding at 2 months postpartum (OR 1.94; 95% CI; 1.11-3.37). Women who quit smoking are less likely to suffer complications in pregnancy and childbirth, and are more likely to attend antenatal and breastfeeding classes, and to have babies with higher birth weight.

CONCLUSIONS

Active and passive tobacco consumption has significant implications during pregnancy and postpartum period. Smoking cessation at the beginning of pregnancy reverses much of these effects.

Preterm birth and secondhand smoking during pregnancy: A case-control study from Vietnam

Background

The relationship between women who are exposed to secondhand smoke and preterm birth is still controversial. The present study aimed to examine the association between maternal secondhand smoking (SHS) during pregnancy and preterm birth.

Methods

A 1:1 case-control study was conducted at delivery room of The Women’s and Children’s Hospital of An Giang, Vietnam. A total of 288 cases of preterm birth and 288 controls included in this study. A structured questionnaire in a face-to-face interview was used to assess SHS and potential confounders (maternal age, body mass index, occupation, education level, parity, antenatal care visits, history of preterm birth, prenatal bleeding and preeclampsia/eclampsia).

Results

SHS was reported more frequently by women who delivered preterm babies compared with women of term deliveries (67.4% vs. 51.0%; P <0.001). After controlling all potential confounders, multivariable logistic regression analysis showed a relationship between SHS during pregnancy and preterm delivery (adjusted Odds ratio: 1.92; 95% CI 1.31, 2.81)

Conclusions

Our findings suggest that exposure to household tobacco smoke during pregnancy is associated with preterm birth.

Factors Associated with Prenatal Smoking Cessation Interventions among Public Health Nurses in Japan

This study aimed to identify the factors associated with prenatal smoking cessation interventions based on the 5As model among public health nurses (PHNs) in Japan. A nationwide cross-sectional study was conducted from December 2019 to February 2020 via a self-administered questionnaire. The study subjects were 1988 PHNs working in 431 health centers of municipalities and special wards across the country. Of the 1988 questionnaires mailed, 521 responses (26.2%) were included in the analysis. Of the 521 responses, most of the respondents were female (98.1%) and the mean age was 37.5 years. There were statistically significant differences on age, work regions, experience years working as a PHN and smoking cessation training after becoming a PHN in implementing the 5As. Self-efficacy, professional development competency, research utilization competency, age and experience years working as a PHN were positively associated with the 5As. Social nicotine dependence was negatively associated with the 5As. Furthermore, self-efficacy mediated the relationship between the 5As and professional development competency, research utilization competency, social nicotine dependence, age and experience years working as a PHN. In the future, smoking cessation intervention training should be widely implemented to improve self-efficacy and prenatal smoking cessation interventions among Japanese PHNs.

Determination of Urinary Cotinine Cut-Off Concentrations for Pregnant Women in the Japan Environment and Children's Study (JECS)

Few studies have assessed the accuracy of self-reported questionnaires to determine smoking habits relative to urinary biomarkers. This study investigated urinary cotinine cut-off concentrations distinguishing active, passive and non-smokers among pregnant women who participated in the Japan Environment and Children's Study, a nationwide birth cohort study. Pregnant participants with measured urinary cotinine concentrations (UCCs) and who completed self-reported questionnaires on smoking status were included (n = 89,895). The cut-off values (COVs) for active and passive smokers were calculated by fitting mixed normal distribution functions to UCCs. The sensitivity and specificity of the questionnaires were subsequently evaluated. The median (interquartile range) UCC was 0.24 (0.083-0.96) µg/g-creatinine, with the detection rate of 89%. The COV for distinguishing active smokers from passive and non-smokers was 36.8 µg/g-creatinine. When this COV was considered to represent the true condition, the questionnaire had a sensitivity of 0.523, a specificity of 0.998, a positive predictive value (PPV) of 0.967 and a negative predictive value (NPV) of 0.957. The COV for distinguishing passive smokers from non-smokers was 0.31 µg/g-creatinine, with the questionnaire having a sensitivity of 0.222, a specificity of 0.977, a PPV of 0.868 and an NPV of 0.644. As many as 78% of passive smokers might be misclassified as non-smokers.

Influence of Environmental Tobacco Smoke and Air Pollution on Fetal Growth: A Prospective Study

Exposure to air pollution during pregnancy leads to adverse pregnancy outcomes. Few studies have evaluated the influences of air quality, including environmental tobacco smoke (ETS) and particulate matter (PM), on fetal development, which this study examined. This longitudinal correlation study used multiple linear regression data analysis of PM_2.5/PM₁₀, self-reported ETS exposure, urinary cotinine level, maternal characteristics, and birth parameters (gestational week, body weight, body length, head, and chest circumferences) with the effect of air quality on fetal growth. The study included 74 pregnant women (mean age 31.9 ± 4.2 years, body mass index 23.6 ± 3.8 kg/m², average gestational duration 38.5 ± 0.8 weeks). ETS exposure decreased birth length by ≥1 cm, and potentially is an independent risk factor for fetal growth restriction, and pregnant women should avoid indoor and outdoor ETS. However, neither PM_2.5/PM₁₀ nor ETS was associated with low birth weight or small for gestational age. This study adds to the evidence base that ETS exposure of nonsmoking pregnant women affects the fetal birth length. Family members should refrain from smoking near expectant mothers, although smoking in the vicinity of their residential surroundings potentially exposes mothers and their fetuses to ETS. Public pollution and childbirth education classes should include details of indoor ETS.

Stepped-wedge cluster randomised trial of a smoking cessation counselling training programme for midwives treating women with functional health illiteracy and low socioeconomic status (PROMISE): a study protocol

Background

In the Netherlands, midwives are required to use the ‘V-MIS’ (Minimal Intervention Strategy for Midwives) smoking cessation counselling protocol to help pregnant women quit smoking. This counselling protocol is often poorly implemented in midwifery practices. It may also be less suitable for pregnant woman with low socioeconomic status or functional health illiteracy. We created an adapted version of the V-MIS protocol that is intended to facilitate implementation in midwifery practices: PROMISE (PROtocol for growing up smokefree using a Minimal smoking cessation Intervention Strategy in the Early stages of life). For this adapted protocol, midwives use carbon monoxide meters, storyboard leaflets, and specific communication techniques for women with functional health illiteracy. They will receive a face-to-face training in using these materials and communication techniques.

Methods

The effectiveness and implementation of PROMISE will be tested in a stepped-wedge cluster randomised controlled trial. We will randomise clusters of midwifery practices and departments in hospitals. We will then train them, subsequently, at regular intervals (‘steps’). At each step, practices that will receive training cross over from the control condition to the experimental condition. We will measure how well the PROMISE protocol has been implemented by assessing the rate of pregnant women that received detailed smoking cessation counselling from their midwives (primary outcome). Our secondary target group is pregnant women with functional health illiteracy and low socioeconomic status. Among them, we will assess smoking status and health-related outcome before and after pregnancy.

Discussion

The PROMISE smoking cessation counselling protocol is intended to help midwives, OB-GYNs, and other obstetrics professionals to support pregnant women with smoking cessation.

Trial registration

Dutch Trial Registry: NTR 6305/NL6158. Registered on 20 December 2016.

[Passive Smoking and Pregnancy - CNGOF-SFT Expert Report and Guidelines for Smoking Management during Pregnancy]

OBJECTIVE

The objective of this chapter is to evaluate the risks of second-hand-smoke during pregnancy and to assess the benefits of antenatal care.

METHODS

Bibliographical research in French and English using the Medline and Cochrane databases and the recommendations of international societies.

RESULTS

Exposure to second-hand smoke appears to be higher at home and in the car, with potential consequences for pregnancy, especially prematurity (NP3). Complete avoidance of smoking at home significantly reduces exposure to passive smoking compared to incomplete avoidance (NP4). The more numerous the sources, the higher the intoxication is (NP4). The major risk factor associated with passive smoking is the presence of a spouse who smokes. Other associated factors are the presence of a smoker at home or in the car, young population (<25 years), low level of education, old smoking (NP4). Passive smoking is associated with an increased risk of fetal death in utero, fetal malformations, prematurity and birth weight under 2500g (NP2). No specific management is recommended for all pregnant women. Nevertheless, in a specific population of pregnant women with vulnerabilities, a behavioral approach aimed at teaching them to negotiate with their entourage may be beneficial in order to reduce the effects of passive smoking on pregnancy (NP2).

CONCLUSION

It is recommended to advise women and their family (especially spouses) to create a smoke-free environment, especially at home and in the car (professional consensus). It is recommended to provide a minimum amount of smoking cessation advice to pregnant women's entourage (professional consensus).

Maternal iodine status, intrauterine growth, birth outcomes and congenital anomalies in a UK birth cohort

BACKGROUND

Severe iodine insufficiency in pregnancy has significant consequences, but there is inadequate evidence to indicate what constitutes mild or moderate insufficiency, in terms of observed detrimental effects on pregnancy or birth outcomes. A limited number of studies have examined iodine status and birth outcomes, finding inconsistent evidence for specific outcomes.

METHODS

Maternal iodine status was estimated from spot urine samples collected at 26-28 weeks' gestation from 6971 mothers in the Born in Bradford birth cohort. Associations with outcomes were examined for both urinary iodine concentration (UIC) and iodine-to-creatinine ratio (I:Cr). Outcomes assessed included customised birthweight (primary outcome), birthweight, small for gestational age (SGA), low birthweight, head circumference and APGAR score.

RESULTS

There was a small positive association between I:Cr and birthweight in adjusted analyses. For a typical participant, the predicted birthweight centile at the 25th percentile of I:Cr (59 μg/g) was 2.7 percentage points lower than that at the 75th percentile of I:Cr (121 μg/g) (99% confidence interval (CI) 0.8 to 4.6), birthweight was predicted to be 41 g lower (99% CI 13 to 69) and the predicted probability of SGA was 1.9 percentage points higher (99% CI 0.0 to 3.7). There was no evidence of associations using UIC or other birth outcomes, including stillbirth, preterm birth, ultrasound growth measures or congenital anomalies.

CONCLUSION

Lower maternal iodine status was associated with lower birthweight and greater probability of SGA. Whilst small, the effect size for lower iodine on birthweight is comparable to environmental tobacco smoke exposure. Iodine insufficiency is avoidable, and strategies to avoid deficiency in women of reproductive age should be considered.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03552341. Registered on June 11, 2018.

Reducing Secondhand Smoke Exposure Among Nonsmoking Pregnant Women: A Systematic Review

Introduction

Exposure to secondhand smoke (SHS) in pregnancy leads to an increased risk of stillbirths, congenital malformations, and low birth weight. There is a lack of evidence about how best to achieve reductions in SHS exposure among nonsmoking pregnant women. This work systematically reviews individual or household interventions to reduce pregnant women’s exposure to SHS.

Methods

MEDLINE, EMBASE, and CINAHL databases were searched from their dates of inception to April 17, 2019. Studies were included if: participants were nonsmoking pregnant women; involved an intervention to reduce SHS exposure or encourage partner quitting; and measured SHS exposure of pregnant women and/or recorded quit rates among partners. The UK National Institute for Health & Care Excellence (NICE) Quality Appraisal checklist was used to determine internal and external validity.

Results

Nine studies met the inclusion criteria. Educational interventions were primarily targeted at the pregnant woman to change her or others’ behavior, with only two studies involving the partner who smoked. Intervention delivery was mixed, spanning brief discussions through to more involving sessions with role play. The effective interventions involved multiple follow-ups. There was no standardized method of assessing exposure to SHS. Many of the included studies had moderate to high risk of bias.

Conclusion

There is mixed evidence for interventions aimed at reducing pregnant women’s exposure to SHS, though multi-component interventions seem to be more effective. The effectiveness of family-centered approaches involving creating smoke-free homes alongside partner smoking cessation, perhaps involving pharmacological support and/or financial incentives, should be explored.

Implications

• Measures to protect nonsmoking pregnant women from SHS tend to place the responsibility for “avoidance” on the woman.

• There is little work that seeks to involve the smoking partner or other smokers in protecting pregnant women from SHS.

• Interventions to create smoke-free homes and/or smoking partner cessation need to be developed: pharmacological and financial support should be explored.

Maternal smoking as an independent risk factor for the development of severe retinopathy of prematurity in very preterm infants

BACKGROUND/OBJECTIVES

Retinopathy of prematurity (ROP) is a severe neonatal complication potentially leading to visual impairment and blindness. Known risk factors include preterm birth, low birth weight and respiratory support. Limited and contradictory data exist on the risk of maternal smoking during pregnancy on the development of ROP. This study aims to investigate smoking as an independent risk factor for the development of severe ROP (≥stage 3).

SUBJECTS/METHODS

This is a single centre retrospective case-control study of prospectively collected clinical data of infants born before 32 weeks of gestation between 2001 and 2012 at a tertiary care university hospital. The association between maternal smoking during pregnancy and the development of severe ROP was analyzed by multivariate logistic regression.

RESULTS

In total, n = 751 infants born < 32 weeks of gestation were included in this study. In total, 52.9% (n = 397) were diagnosed with ROP and 10.8% (n = 81) developed ROP ≥ stage 3. In total, 8.4% (n = 63) mothers presented with a history of smoking during pregnancy, which was associated to a higher rate of ROP (OR 2.59, 95% CI 1.10-6.12). Low gestational age, low birth weight and prolonged respiratory support were confirmed as independent risk factors for the development of severe ROP.

CONCLUSIONS

To date, this is the largest study evaluating the effect of maternal smoking on the development of ROP. Maternal smoking during pregnancy is identified as an independent risk factor for the development of severe ROP in preterm infants born < 32 weeks of gestation.

Air pollutants disrupt iron homeostasis to impact oxidant generation, biological effects, and tissue injury

Air pollutants cause changes in iron homeostasis through: 1) a capacity of the pollutant, or a metabolite(s), to complex/chelate iron from pivotal sites in the cell or 2) an ability of the pollutant to displace iron from pivotal sites in the cell. Through either pathway of disruption in iron homeostasis, metal previously employed in essential cell processes is sequestered after air pollutant exposure. An absolute or functional cell iron deficiency results. If enough iron is lost or is otherwise not available within the cell, cell death ensues. However, prior to death, exposed cells will attempt to reverse the loss of requisite metal. This response of the cell includes increased expression of metal importers (e.g. divalent metal transporter 1). Oxidant generation after exposure to air pollutants includes superoxide production which functions in ferrireduction necessary for cell iron import. Activation of kinases and phosphatases and transcription factors and increased release of pro-inflammatory mediators also result from a cell iron deficiency, absolute or functional, after exposure to air pollutants. Finally, air pollutant exposure culminates in the development of inflammation and fibrosis which is a tissue response to the iron deficiency challenging cell survival. Following the response of increased expression of importers and ferrireduction, activation of kinases and phosphatases and transcription factors, release of pro-inflammatory mediators, and inflammation and fibrosis, cell iron is altered, and a new metal homeostasis is established. This new metal homeostasis includes increased total iron concentrations in cells with metal now at levels sufficient to meet requirements for continued function.

Effects of maternal smoking on body size and proportions at birth: a register-based cohort study of 1.4 million births

OBJECTIVES

The aim of our work was to analyse the effect of maternal smoking on body size and body proportions of newborns when the mother had smoked only during the first trimester, in comparison with continued smoking after the first trimester. Furthermore, we have evaluated how growth restriction associated with maternal smoking contributes to changes in body proportions.

DESIGN

Register-based cohort study SETTING: Maternal Exposure (MATEX) cohort identified from the Finnish Medical Birth Register.

PARTICIPANTS

Singleton births without congenital anomalies and missing data (1.38 million) from 1 January 1991 to 31 December 2016.

METHODS

Logistic regression was used to quantify the effect of maternal smoking, stratified by the maternal smoking status.

OUTCOME MEASURES

Body proportions indicated by low brain-to-body ratio (defined as <10th percentile); high ponderal index and high head-to-length ratio (defined as >90th percentile); small body size for gestational age at birth (defined as weight, length or head circumference <10th percentile) and preterm birth (<37 weeks) and low birth weight (2500 g).

RESULTS

Continued smoking after the first trimester was associated with high ponderal index (OR 1.26, 95% CI 1.23 to 1.28), low brain-to-body ratio (1.11, 1.07-1.15) and high head-to-length ratio (1.22, 1.19-1.26), corresponding with absolute risks of 22%, 10% and 19%, respectively). The effects were slightly lower when smoking had been quit during the first trimester. Similar effects were seen for the body size variables and low birth weight. Preterm birth was not associated with smoking only during first trimester.

CONCLUSIONS

Maternal smoking, independent of smoking duration during pregnancy, was associated with abnormal body proportions resulting from larger reduction of length and head circumference in comparison to weight. The effects of having quit smoking during the first trimester and having continued smoking after the first trimester were similar, suggesting the importance of early pregnancy as a sensitive exposure window.