Measuring prenatal secondhand smoke exposure in mother-baby couplets

A Comparison of Measured Airborne and Self-Reported Secondhand Smoke Exposure in the MADRES Pregnancy Cohort Study

INTRODUCTION

Secondhand smoke (SHS) exposure during pregnancy is linked to adverse birth outcomes, such as low birth weight and preterm birth. While questionnaires are commonly used to assess SHS exposure, their ability to capture true exposure can vary, making it difficult for researchers to harmonize SHS measures. This study aimed to compare self-reported SHS exposure with measurements of airborne SHS in personal samples of pregnant women.

METHODS

SHS was measured on 48-hour integrated personal PM2.5 Teflon filters collected from 204 pregnant women, and self-reported SHS exposure measures were obtained via questionnaires. Descriptive statistics were calculated for airborne SHS measures, and analysis of variance tests assessed group differences in airborne SHS concentrations by self-reported SHS exposure.

RESULTS

Participants were 81% Hispanic, with a mean (standard deviation [SD]) age of 28.2 (6.0) years. Geometric mean (SD) personal airborne SHS concentrations were 0.14 (9.41) µg/m3. Participants reporting lower education have significantly higher airborne SHS exposure (p = .015). Mean airborne SHS concentrations were greater in those reporting longer duration with windows open in the home. There was no association between airborne SHS and self-reported SHS exposure; however, asking about the number of smokers nearby in the 48-hour monitoring period was most correlated with measured airborne SHS (Two + smokers: 0.30 µg/m3 vs. One: 0.12 µg/m3 and Zero: 0.15 µg/m3; p = .230).

CONCLUSIONS

Self-reported SHS exposure was not associated with measured airborne SHS in personal PM2.5 samples. This suggests exposure misclassification using SHS questionnaires and the need for harmonized and validated questions to characterize this exposure in health studies.

IMPLICATIONS

This study adds to the growing body of evidence that measurement error is a major concern in pregnancy research, particularly in studies that rely on self-report questionnaires to measure SHS exposure. The study introduces an alternative method of SHS exposure assessment using objective optical measurements, which can help improve the accuracy of exposure assessment. The findings emphasize the importance of using harmonized and validated SHS questionnaires in pregnancy health research to avoid biased effect estimates. This study can inform future research, practice, and policy development to reduce SHS exposure and its adverse health effects.

Association between objective measures and parent-reported measures of child tobacco smoke exposure: A secondary data analysis of four trials

INTRODUCTION

Tobacco smoke exposure (TSE) harms children and adults. Studies of childhood TSE exposure often relies on parental reports, but may benefit from objective measures. The objective of our study was to study the relationship between reported and objective measures of TSE.

METHODS

We analyzed data from four intervention trials, conducted in clinical or community settings, to identify objective measures most closely associated with parent-reported measures and the optimal set of parent-reported measures for predicting objective measures. We also assessed whether there was a learning curve in reported exposure over time, and the importance of replicate biomarker measures.

RESULTS

Correlations between objective and parent-reported measures of child TSE were modest at best, ranging from zero to 0.41. Serum cotinine and urinary cotinine were most strongly associated with parental reports. Parental questions most closely related to biomarkers were number of cigarettes and home smoking rules; together these formed the best set of predictive questions. No trial included all objective measures and all questions, precluding definitive statements about relative advantages. Within-subject repeatability of biomarker measures varied across studies, suggesting that direct pilot data are needed to assess the benefit of replicate measurements.

CONCLUSIONS

Improvements in objective and parent-reported child exposure measurements are needed to accurately monitor child TSE, evaluate efforts to reduce such exposure, and better protect child health.

Hair and nail nicotine levels of mothers and their infants as valid biomarkers of exposure to intrauterine tobacco smoke

INTRODUCTION

Tobacco use remains the single most modifiable cause of adverse pregnancy outcomes. It is crucial to be able to accurately quantify the burden of tobacco exposure on both the mother and fetus to have better measures of efficacy with interventions being studied.

METHODS

This is a descriptive and exploratory study conducted within a randomized controlled trial. Pregnant smoking and non-smoking women were followed from ≤22 weeks' gestation through delivery with monthly maternal smoking questionnaires, urine cotinine levels, and collection of maternal and infant hair and nail samples, at delivery. Nicotine was extracted and measured (ng/mg) using high-performance liquid chromatography with electrochemical detection.

RESULTS

Forty-six mother-infant dyads (34 pregnant smokers and 12 pregnant non-smokers) had successful completion of maternal and infant hair and nails samples. The median hair nicotine levels of the smoking mothers and their infants was significantly higher than those of the non-smokers (1.015 vs 0.037 ng/ mg, p<0.05 for the mothers; 0.445 vs 0.080 ng/mg, p<0.01 for the infants). Similarly, the median nail nicotine levels for smoking mothers and their infants were significantly higher than the non-smokers (2.130 vs 0.056 ng/mg, p<0.01 for the mothers; 0.594 vs 0.132 ng/mg, p<0.05 for the infants). We found a moderate but significant correlation between maternal hair and nail nicotine (r=0.64, p<0.001), infant hair and nail nicotine (r=0.64; p<0.001), maternal and infant hair nicotine (r=0.61, p<0.001), and maternal and infant nail nicotine levels (r=0.58, p<0.001).

CONCLUSIONS

Our study shows that both infant hair and nail nicotine levels are valid biomarkers of intrauterine tobacco smoke exposure, and can be used to identify prenatal smoke exposure, correlating well with the level of maternal nicotine exposure.

At the Origins of Tobacco-Smoking and Tea Consumption in a Virgin Population (Yakutia, 1650–1900 A.D.): Comparison of Pharmacological, Histological, Economic and Cultural Data

(1) Background: The way tobacco and tea spread among virgin populations is of major interest our understanding of how ancient economic and cultural practices could have influenced current habits. (2) Methods: hair concentrations of theobromine, theophylline, caffeine, nicotine, and cotinine were measured in hair samples from 47 frozen bodies of people from eastern Siberia, dated from the contact with Europeans to the assimilation of people into Russian society. (3) Results: hair concentration of theobromine, theophylline, and caffeine vary with the type of beverage consumed: green, black, or local herbal teas. Shortly after the first contacts, a few heavy consumers of tobacco were found among light or passive consumers. Tobacco-related co-morbidities began to be recorded one century after and heavy tea users were only found from the 19th century (4) Conclusions: Economic factors and social and family contacts seem to have played a decisive role in tobacco consumption very early on. Behavioral evolution governed the process of substance integration into Siberian culture and was a determinant for the continuity of its use across long periods of time. Analyzing the respective contributions of social and economic processes in the use of these substances opens avenues of investigation for today’s public health.

Secondhand tobacco smoke exposure among children under 5 years old: questionnaires versus cotinine biomarkers: a cohort study

OBJECTIVES

Cotinine is the gold standard to estimate prevalence of secondhand tobacco smoke (SHS) exposure, and assay limit of detection (LOD) cut-points are typically used regardless of age. Our aim was to compare the concordance between mother-reported SHS exposure and serum cotinine categorising children as exposed with the assay LOD or age-specific cut-points.

DESIGN

Data from the Health Outcomes and Measures of the Environment (HOME) Study, a prospective pregnancy and birth cohort.

SETTING

Hospital or participants' homes.

PARTICIPANTS

389 pregnant women aged 18 years and older, between 13 and 19 weeks of gestation, living in a five-county region of the Cincinnati, Ohio metropolitan area, and with follow-up on their children at birth and ages 12, 24, 36 and 48 months.

PRIMARY AND SECONDARY OUTCOME MEASURES

Children's serum cotinine, mother-reported active smoking and SHS exposure were available at birth and during follow-up visits. We used Cohen's kappa index to assess concordance between maternal self-report and child's serum cotinine concentrations. We estimated optimal age-specific cut-points, their sensitivity-specificity and positive-negative predictive values with receiver operating characteristic curves.

RESULTS

Self-reported exposure and cotinine data were available for 280 women who gave birth to singleton child. When applying the assay LOD (0.015 ng/mL), concordance between maternal report and serum cotinine, without accounting for age, was below 0.23 at all times. When using age-specific cut-points (12 months: 0.11 ng/mL; 24 months: 0.08 ng/mL; 36 months: 0.05 ng/mL and 48 months: 0.04 ng/mL), concordance improved, being low at 12 months (0.39), moderate at 24 and 36 months (0.47 and 0.43) and high at 48 months (0.62).

CONCLUSIONS

Concordance between mother-reported SHS exposure among children under 5 years and serum cotinine improved considerably after applying the cohort-specific and age-specific cut-points. Future studies are necessary to verify these results.

Association Between Chronic Exposure to Tobacco Smoke and Accumulation of Toxic Metals in Hair Among Pregnant Women

Tobacco smoke contains various toxic heavy metals that individuals are exposed to when they smoke. Despite the presence of heavy metals in tobacco smoke, the relationship between smoking and the accumulation of toxic metals in pregnant women after long-term exposure remains under discussion. We examined the association between long-term exposure to tobacco smoke and the accumulation of toxic metals in the hair of female participants. Our study recruited 252 women from the Shanxi and Hebei provinces of Northern China; these participants were self-reported non-active smokers, and had previously delivered healthy babies without birth defects. Scalp hair was collected and analyzed for nicotine and cotinine and five potentially toxic metals (specifically, silver, chromium, cadmium, mercury, and lead). Our results showed significant positive correlations between cotinine and four metals, including silver (r = 0.369, p < 0.001), cadmium (r = 0.185, p < 0.01), mercury (r = 0.161, p < 0.05), and lead (r = 0.243, p < 0.001). Significant positive correlations were also found between nicotine and three metals-specifically silver (r = 0.331, p < 0.001), cadmium (r = 0.176, p < 0.01), and lead (r = 0.316, p < 0.001). A logistic regression model showed significant associations between cotinine and potentially toxic metals including mercury, silver, and lead (with or without adjusting for potential confounders). We thus conclude that long-term passive smoking could potentially increase the exposure level of toxic metals including lead, silver, and mercury in our study, which are especially harmful for pregnant women and their unborn fetus.

Perinatal Biochemical Confirmation of Smoking Status by Trimester

Introduction:

Tobacco use during pregnancy is the most modifiable risk factor associated with poor pregnancy outcomes. Self-reported tobacco use has been demonstrated to have high misclassification rates. The aims were to examine misclassification rates of perinatal tobacco use during each trimester of pregnancy and 8 weeks postpartum, and to evaluate characteristics associated with misclassification of tobacco use status.

Methods:

This is secondary analysis of a prospective, multicenter trial of pregnant women, and it includes participants who were biochemically identified as tobacco users during their first trimester (N = 103). Each trimester and once postpartum, tobacco use was assessed via self-report and validated using a cutoff of 100 ng/mL for urine cotinine via NicAlert test strips to indicate current use. Those who self-reported as nonusers but were identified as users via urine cotinine were considered misclassified; misclassification rates were determined for each time period. Logistic regression assessed maternal factors associated with misclassification status.

Results:

Misclassification rates declined from 35.0% at first trimester to 31.9% and 26.6% at the second and third; the postpartum rate was 30.4%. These rates did not differ significantly from each other at the 0.05 level. Race/ethnicity was associated with misclassification status; white/non-Hispanic women were 87% less likely to be misclassified (p < .001).

Conclusion:

Misclassification of prenatal smoking status decreases as pregnancy progresses, though the observed rate change was not significant. Minority women may be at particular risk for non-disclosure of tobacco use. Biochemical validation should be considered when assessing perinatal tobacco use via self-report, given high misclassification rates throughout the perinatal period.

Implications:

These results demonstrate that regardless of trimester, more than one-quarter of tobacco-using pregnant women may not disclose tobacco use throughout pregnancy and early postpartum. Although the rate of misclassification decreased from first to third trimester and then increased in the immediate postpartum, these changes in misclassification rates were not significant. Minority groups may be at particular risk of misclassification compared with white/non-Hispanic women. Biochemical validation is warranted throughout pregnancy to encourage cessation as tobacco use is one of the most easily-modified risk factors for poor birth outcomes.

Advertising exposure and use of e-cigarettes among female current and former tobacco users of childbearing age

OBJECTIVE

The study examined the relationship between exposure to e-cigarette advertising and e-cigarette use by pregnancy status, including use of flavored e-cigarette products, among women of childbearing age.

DESIGN

A cross-sectional, correlational design was used.

SUBJECTS

Female current or former tobacco users in Central and Eastern Kentucky, 18-45 years old (N = 194, 52% pregnant).

MEASURES

Demographics, pregnancy status, cigarette and e-cigarette use, and exposure to e-cigarette advertising.

RESULTS

Younger age, white non-Hispanic race, and greater exposure to e-cigarette advertising were associated with a higher likelihood of ever using e-cigarettes (p < .05 for each variable). Pregnancy was not associated with ever use (p = .11). Younger age was associated with use of flavored e-cigarettes (p = .0027). Among e-cigarette users, those who used flavored products were more likely to have seen advertisements or information about e-cigarettes on social media, compared to those who used unflavored e-cigarettes only (p = .016).

CONCLUSION

There is a link between advertising exposure and ever use of e-cigarettes. Pregnancy status is not significantly associated with ever use. Use of flavored e-cigarettes is associated with younger age. E-cigarette users with greater exposure to advertising on social media were more likely to use flavored products.

Growth Models of Maternal Smoking Behavior: Individual and Contextual Factors

BACKGROUND

Persistent maternal smoking during pregnancy, reduction or cessation during pregnancy, and smoking initiation or resumption postpartum impel further research to understand these behavioral patterns and opportunities for intervention.

OBJECTIVES

We investigated heterogenous longitudinal patterns of smoking quantity to determine if these patterns vary across three maternal age groups, and whether the influence of individual and contextual risk factors varies by maternal age.

METHODS

Separate general growth mixture models were estimated for mothers ages 15-25, 26-35, and 36+, allowing different empirical patterns of an ordinal measure of smoking behavior at six time points, from preconception through child entry to kindergarten.

RESULTS

We identify five classes for mothers ages 15-25, four classes for ages 26-35, and three classes for ages 36+. Each age group presents classes of nonsmokers and persistent heavy smokers. Intermediate to these ends of the spectrum, each age group exhibited its own smoking classes characterized by the extent of pregnancy smoking reductions and postpartum behavior. In all three age groups, class membership can be distinguished by individual sociodemographic and behavioral characteristics. Co-resident smokers predicted nearly all smoking classifications across age groups, and selected neighborhood characteristics predicted classification of younger (15-25) and older (36+) mothers.

CONCLUSIONS

The design, timing, and delivery of smoking prevention and cessation services, for women seeking to become pregnant and for women presenting for prenatal or pediatric care, are best guided by individual characteristics, particularly maternal age, preconception alcohol consumption, and postpartum depression, but neighborhood characteristics merit further attention for mothers at different ages.

Women’s longitudinal smoking patterns from preconception through child’s kindergarten entry: profiles of biological mothers of a 2001 US birth cohort

To identify longitudinal patterns of women’s smoking during the pre-conception, perinatal, and early parenting period and describe risk factors distinguishing the different profiles. We conducted longitudinal latent class analysis of maternal smoking status over a 6–7 year period in a sample of 8,650 biological mothers of the Early Childhood Longitudinal Study-Birth Cohort, nationally representative of US births in 2001. Five latent classes were identified: pregnancy-inspired quitters (4.3 %), delayed initiators (5.1 %), persistent smokers (8.5 %), temporary quitters (10.4 %), and nonsmokers (71.7 %). These classes were distinguished by age, race/ethnicity, education, poverty status, marital status, parity, drinking behavior, and depression. For example, when compared to those with college degrees, those with less than a high school degree were at least five times as likely to be in the delayed initiator, temporary quitter, or persistent smoker classes (vs. the nonsmoker class). Heterogeneous longitudinal smoking patterns indicate the need for both prevention messages and cessation treatment continuing past parturition, tailored to fit individual profiles in order to achieve better health outcomes for both mothers and children.

Factors associated with second-hand smoke exposure in non-smoking pregnant women in Spain: self-reported exposure and urinary cotinine levels

The aim of this study was to evaluate the main sources of and sociodemographic factors associated with second-hand smoke (SHS) exposure, assessed both by questionnaire and by urinary cotinine (UC) levels, in non-smoking pregnant women. We conducted a cross-sectional study in pregnant women from 4 different regions in Spain. A total of 1783 non-smoking pregnant women completed a questionnaire about their previous smoking habit and SHS exposure in their 3rd trimester of pregnancy and provided a urine sample for measuring UC levels. We used logistic regression models to assess the relationship between several sociodemographic variables and some potential sources of SHS exposure. In addition, we analysed the association of several sociodemographic variables and the SHS exposure according to UC levels, using Tobit regression analysis. More than half of women (55.5%) were exposed to SHS in their 3rd trimester of pregnancy. The following variables were associated with SHS exposure: having smoked previously, low educational level, and being primiparous. Data collection after the first law banning smoking in public places was associated with lower risk of SHS exposure in restaurants and at work. UC levels were higher among women exposed to more than one source. Having a partner who smoked at home was the source of SHS with the greatest impact on UC levels, followed by having a partner who smoked but not at home, other people smoking in the household, being exposed during leisure time, at work and at restaurants. The most important source of SHS exposure was exposure at home. Prevention of SHS exposure should be addressed not only with pregnant women but also with their families.

The effectiveness of breath carbon monoxide analyzer in screening for environmental tobacco smoke exposure in Saudi pregnant women

BACKGROUND:

Exposure to environmental tobacco smoke (ETS) has harmful effects on the pregnancy outcomes similar to those observed in actively smoking pregnant women. The aim of this study was to estimate the sensitivity and specificity of the breath carbon monoxide (BCO) analysis in the assessment of smoking status among Saudi pregnant women, including ETS exposure compared to self-reported tobacco smoke exposure.

METHODS:

A cross-sectional design was used during January 2012, 560 pregnant women, irrespective of their gestational age, agreed to undergo BCO testing and completed the data collection sheet for the study. Sensitivity, specificity, positive and negative predictive values were calculated to compare the BCO test with self-reported exposure to ETS.

RESULTS:

Of the study population 151 (27%) women self-reported ETS exposure during the index pregnancy, 409 (73%) self-reported non-exposure. Sensitivity of the test was 32.5% (95% CI; 25.2-40.3%), the Specificity was much higher at 69.2% (95% CI; 64.4-73.5%), the positive predictive value was 28% (95% CI, 21.9-35.1%), and the negative predictive value was 73.5% (95% CI; 68.9-77.7%).

CONCLUSION:

The BCO test is an ineffective tool to detect the level of ETS exposure among Saudi pregnant women.

Ethnicity, smoking status, and preterm birth as predictors of maternal locus of control

A woman's psychological health can affect prenatal behaviors. The purpose of this study was to examine the relationship between maternal beliefs, prenatal behaviors, and preterm birth (PTB) in a multiethnic population. This was a planned secondary analysis of a cross-sectional trial of postpartum women with singleton gestation. In all, 210 participants were given the Fetal Health Locus of Control (FHLC) scale to measure three primary maternal beliefs that influenced their prenatal behaviors (Internal Control, Chance, Powerful Others). Women who experienced preterm delivery and those who smoked during pregnancy scored the Chance category significantly higher than those who delivered term infants (p = .05; p = .004, respectively). This suggests those who smoked during pregnancy had a greater degree of belief that Chance influenced their infant's health status. Cultural differences also emerged specific to the impact of health care providers on PTB; with Hispanic women scoring Powerful Others the highest among the groups (p = .02). Nurses can plan a critical role in identifying at-risk women (smoking, strong Chance beliefs) while providing a clear message that taking action and modifying high-risk behaviors can reduce risk for adverse pregnancy outcome.

Smoking ban and small-for-gestational age births in Ireland

Background

Ireland introduced a comprehensive workplace smoke-free legislation in March, 2004. Smoking-related adverse birth outcomes have both health care and societal cost implications. The main aim of this study was to determine the impact of the Irish smoke-free legislation on small-for-gestationa- age (SGA) births.

Methods and Findings

We developed a population-based birthweight (BW) percentile curve based on a recent study to compute SGA (BW <5^th percentile) and very SGA (vSGA - BW<3^rd percentile) for each gestational week. Monthly births born between January 1999 and December 2008 were analyzed linking with monthly maternal smoking rates from a large referral maternity university hospital. We ran individual control and CUSUM charts, with bootstrap simulations, to pinpoint the breakpoint for the impact of ban implementation ( = April 2004). Monthly SGA rates (%) before and after April 2004 was considered pre and post ban period births, respectively. Autocorrelation was tested using Durbin Watson (DW) statistic. Mixed models using a random intercept and a fixed effect were employed using SAS (v 9.2). A total of 588,997 singleton live-births born between January 1999 and December 2008 were analyzed. vSGA and SGA monthly rates declined from an average of 4.7% to 4.3% and from 6.9% to 6.6% before and after April 2004, respectively. No auto-correlation was detected (DW = ∼2). Adjusted mixed models indicated a significant decline in both vSGA and SGA rates immediately after the ban [(−5.3%; 95% CI −5.43% to −5.17%, p<0.0001) and (−0.45%; 95% CI: −0.7% to −0.19%, p<0.0007)], respectively. Significant gradual effects continued post the ban periods for vSGA and SGA rates, namely, −0.6% (p<0.0001) and −0.02% (p<0.0001), respectively.

Conclusions

A significant reduction in small-for-gestational birth rates both immediately and sustained over the post-ban period, reinforces the mounting evidence of the positive health effect of a successful comprehensive smoke-free legislation in a vulnerable population group as pregnant women.

Prenatal hair nicotine analysis in homes with multiple smokers

Prenatal exposure to secondhand smoke (SHS) is responsible for adverse perinatal outcomes, including preterm birth. Smoking at home is the primary source of exposure to women during pregnancy. Hair nicotine analysis of mothers and infants was used to describe the relationship between prenatal SHS exposure and number of household smokers. Maternal hair nicotine was strongly correlated with the number of household smokers and was a more sensitive measure of household smoking than infant hair. Home smoking bans and focused public media campaigns on the harmful effects of SHS exposure are necessary prevention strategies to avoid adverse perinatal outcomes.

Effect of prenatal tobacco smoke exposure on fetal growth potential

AIM

to determine the independent effect of prenatal tobacco smoke exposure on fetal growth using customized birthweight norms.

METHODS

demographic characteristics and data on exposure to tobacco smoke during pregnancy were obtained from singleton neonates ≥ 34 weeks' gestation. Centile Calculator software v62.2 (www.gestation.net) was used for calculating customized birthweight percentiles.

RESULTS

of the 3227 neonates studied, 30.9% were exposed to maternal smoking during pregnancy, whereas involuntary maternal exposure was reported in 20.1%. Growth restriction was noted in 350 (10.8%). The odds ratio (OR) for fetal growth restriction was 1.49 (1.10-1.91) in passive smokers, and 2.34 (1.81-2.96) in smokers. A decrease in birthweight and an increase in the prevalence of growth restriction with the increasing number of cigarette consumption was observed. This effect was evident even in cases of a "minimal" consumption of 1-5 cigarettes per day.

CONCLUSION

an essential adverse effect of tobacco smoke exposure on fetal growth in pregnancies exposed to passive smoking, as well as in those with "minimal" maternal cigarette consumption, was found. Since approximately 30% of growth restricted neonates could be independently attributed to active or passive maternal exposure, these findings reinforce the need for smoking preventive strategies in pregnant women and their environment.

The effects of prenatal secondhand smoke exposure on preterm birth and neonatal outcomes

OBJECTIVE

To examine the relationship between prenatal secondhand smoke (SHS) exposure, preterm birth and immediate neonatal outcomes by measuring maternal hair nicotine.

DESIGN

Cross-sectional, observational design.

SETTING

A metropolitan Kentucky birthing center.

PARTICIPANTS

Two hundred and ten (210) mother-baby couplets.

METHODS

Nicotine in maternal hair was used as the biomarker for prenatal SHS exposure collected within 48 hours of birth. Smoking status was confirmed by urine cotinine analysis.

RESULTS

Smoking status (nonsmoking, passive smoking, and smoking) strongly correlated with low, medium, and high hair nicotine tertiles (ρ=.74; p<.001). Women exposed to prenatal SHS were more at risk for preterm birth (odds ratio [OR]=2.3; 95% Confidence Interval [CI] [.96, 5.96]), and their infants were more likely to have immediate newborn complications (OR=2.4; 95% CI [1.09, 5.33]) than nonexposed women. Infants of passive smoking mothers were at increased risk for respiratory distress syndrome (RDS) (OR=4.9; 95% CI [1.45, 10.5]) and admission to a Neonatal Intensive Care Unit (NICU) (OR=6.5; CI [1.29, 9.7]) when compared to infants of smoking mothers (OR=3.9; 95% CI [1.61, 14.9]; OR=3.5; 95% CI [2.09, 20.4], respectively). Passive smokers and/or women with hair nicotine levels greater than .35 ng/ml were more likely to deliver earlier (1 week), give birth to infants weighing less (decrease of 200-300 g), and deliver shorter infants (decrease of 1.1-1.7 cm).

CONCLUSIONS

Prenatal SHS exposure places women at greater risk for preterm birth, and their newborns are more likely to have RDS, NICU admissions, and immediate newborn complications.