Perinatal Biochemical Confirmation of Smoking Status by Trimester

Rural-urban differences in substance use during pregnancy

PURPOSE

Drug overdoses are now a leading cause of pregnancy-related deaths in the United States. Despite evidence of rural-urban disparities in substance use, there has not yet been a nationally representative examination of rural-urban differences in perinatal substance use. This study provides a comprehensive examination of rural-urban disparities in perinatal substance use.

METHODS

This study uses cross-sectional data to examine 3499 pregnant women from the 2015-2019 National Survey on Drug Use and Health (NSDUH). Rural (nonmetro)-urban (metro) differences in past-month tobacco use, alcohol use, binge drinking, illicit drug use, and marijuana use were examined using Rao-Scott chi-square tests and multivariable logistic regression using complex survey weights.

FINDINGS

In 2015-2019, past-month tobacco use varied geographically, as rural pregnant participants were more likely to have used tobacco than those in small and large urban areas (24.7% vs. 15.2% and 8.2%, respectively, p < 0.0001). After controlling for sociodemographic and health care needs, rural pregnant women were more likely to report tobacco use (adjusted odds ratio [aOR]: 2.32, 95% confidence interval [CI]: 1.66, 3.25) but were less likely to report alcohol use (aOR: 0.58, 95% CI: 0.34, 0.98) than their large urban counterparts. There were no rural-urban differences in the odds of binge drinking, illicit drug use, or marijuana-only use in the past month.

CONCLUSIONS

Geographic variations in perinatal substance use highlight the need for tailored interventions targeting substance use prevention during pregnancy, prioritizing tobacco in rural areas and alcohol in urban areas.

Assessing tobacco use in Swedish young adults from self-report and urinary cotinine: a validation study using the BAMSE birth cohort

OBJECTIVES

Studies on health effects of tobacco often rely on self-reported exposure data, which is subjective and can lead to misclassification. The aim of this study was to describe the prevalence of cigarette smoking, snus and e-cigarette use, as well as to validate self-reported tobacco use among young adults in Sweden.

METHOD

Participants of a population-based Swedish cohort (n=3052), aged 22-25 years, assessed their tobacco use in a web questionnaire. Urinary cotinine was analysed in a subsample of the study population (n=998). The agreement between self-reported tobacco use and urinary cotinine was assessed using Cohen's Kappa coefficient (κ) at a cut-off level of 50 ng/mL.

RESULTS

Patterns of tobacco use differed between men and women. Among men, 20.0% reported daily snus use, 5.8% daily cigarette smoking and 5.6% any e-cigarette use. In contrast, 3.2% of the women reported daily snus use, 9.0% daily cigarette smoking and 2.4% any e-cigarette use. Among the tobacco use categories, daily snus users had the highest levels of cotinine. Of reported non-tobacco users, 3.5% had cotinine levels above the cut-off, compared with 68.0% among both occasional cigarette smokers and snus users, 67.5% among all e-cigarette users and 94.7% and 97.8% among daily cigarette smokers and snus users, respectively. Agreement between self-reported tobacco use and urinary cotinine was classified as strong for daily use of cigarettes (κ=0.824) and snus (κ=0.861), while moderate to weak for occasional smoking (κ=0.618), occasional snus use (κ=0.573) and any e-cigarette use (κ=0.576).

CONCLUSIONS

We found high validity of self-reported tobacco use in our study population, particularly for daily tobacco use. Further, we found that daily snus users were exposed to high levels of cotinine. Together with previous findings, our results indicate good validity of self-reported tobacco use among young adults.

The Understanding of Maternal Smoking among Women who were Smoking or had Quit Smoking during Pregnancy

BACKGROUND

Maternal tobacco smoking during pregnancy is associated with adverse health effects for the woman, fetus, and child, including such serious effects as preterm birth, low birth weight, stillbirth, and neonatal and sudden infant death. Smoking cessation during pregnancy reduces health risks.

PURPOSE

In order to support pregnant women to quit smoking, it is essential to know determinants of quitting smoking in pregnancy. The purpose of this research was to examine women's understanding of maternal smoking, in terms of their beliefs, in relation to quitting smoking during pregnancy.

METHODS

The study was a cross-sectional survey with anonymous questionnaires. The sample consisted of 161 pregnant and postnatal women who were continuing or had continued to smoke during pregnancy or had quit smoking during pregnancy. Logistic regression was used to determine the impact of women's understanding of maternal smoking on quitting smoking in pregnancy.

RESULTS

A large majority of the women had low to moderate understanding of maternal smoking. Those with higher levels of understanding were more likely to quit smoking during pregnancy than were those with a low level of understanding. Not having children prior to the current pregnancy or childbirth also increased the likelihood of quitting smoking during pregnancy while being without a partner combined with having a longer duration of smoking decreased the likelihood of quitting smoking during pregnancy.

CONCLUSION

As a modifiable factor, pregnant women's understanding of maternal smoking can be readily targeted with informational interventions in an effort to help them quit smoking.

Pregnant and postnatal women's experiences of interacting with health care providers about their tobacco smoking: a qualitative systematic review

OBJECTIVE

The objective of this review was twofold: (i) to comprehensively identify the best available evidence about the experiences of women who smoked tobacco during pregnancy or postnatally (or both) concerning health care providers' interactions with them about their smoking, when such interactions occurred during contact for prenatal or postnatal health care in any health care setting; and (ii) to synthesize the research findings for recommendations to strengthen health care providers' interventions regarding smoking during pregnancy and smoking during the postnatal period.

INTRODUCTION

Maternal tobacco smoking during pregnancy and maternal tobacco smoking postnatally pose serious health risks for the woman, fetus, and offspring, whereas maternal smoking cessation has beneficial health effects. Given the importance of health care providers' interactions with pregnant and postnatal women for smoking cessation care, it is essential to understand women's experiences of such interactions.

INCLUSION CRITERIA

Studies considered for this review had qualitative research findings about the experiences of women who smoked tobacco during pregnancy or postnatally (or both) in relation to health care providers' interactions with them about their smoking.

METHODS

The review was conducted using the JBI approach to qualitative systematic reviews. Published studies were sought through 6 academic databases (eg, CINAHL, MEDLINE). Unpublished studies were searched in 6 gray literature sources (eg, ProQuest Dissertations and Theses, Google Scholar). Reference lists of retrieved records were also searched. The searches occurred in October and November 2020; no country, language, or date limits were applied. Study selection involved title and abstract screening, full-text examination, and critical appraisal of all studies that met the inclusion criteria for the review. Study characteristics and research findings were extracted from the included studies. Study selection and extraction of findings were conducted by two reviewers independently; differences between reviewers were resolved through consensus. The research findings were categorized, and the categories were aggregated into a set of synthesized findings. The synthesized finding were assigned confidence scores. The categories and finalized synthesized findings were agreed upon by all reviewers.

RESULTS

The 57 included studies varied in qualitative research designs and in methodological quality (from mostly low to high). There were approximately 1092 eligible participants, and 250 credible and unequivocal research findings. The research findings yielded 14 categories and 6 synthesized findings with low to very low confidence scores. Some women who smoked tobacco during pregnancy and some women who smoked tobacco postnatally lacked supportive interactions by health care providers regarding their smoking; other women experienced supportive interactions by health care providers. Women were adversely impacted when health care providers' interactions lacked supportiveness, and were beneficially impacted when interactions were supportive. Women varied in openness to health care providers' interactions regarding their smoking, from not being receptive to being accepting, and some women wanted meaningful health care provider interactions.

CONCLUSIONS

Although confidence in the synthesized findings is low to very low, the evidence indicates that supportive health care provider interactions may facilitate positive smoking behavior change in pregnancy and postnatally. It is recommended that health care providers implement accepted clinical practice guidelines with women who smoke prenatally or postnatally, using an approach that is person-centered, emotionally supportive, engaging (eg, understanding), and non-authoritarian.

SYSTEMATIC REVIEW REGISTRATION NUMBER

PROSPERO CRD42020178866.

Municipal smoke-free laws and preterm birth

BACKGROUND

Smoking during pregnancy and prenatal secondhand smoke exposure increase the risk of preterm birth. As Kentucky has the second highest rate of smoking in the United States and no statewide smoke-free law, an examination of the effect of municipal smoke-free legislation on preterm birth is warranted.

OBJECTIVE

This study used state-level live birth data and county-level municipal smoke-free legislation status to assess the association between the presence and strength of smoke-free laws and the likelihood of preterm birth. Moreover, this study hypothesized that pregnant persons living in counties with comprehensive municipal smoke-free laws prohibiting smoking inside all workplaces and enclosed public places would exhibit a lower likelihood of preterm birth than those living in counties with weak or moderate laws (ie, smoke-free laws with exemptions that do not cover all workplaces and enclosed public places) or no smoke-free law.

STUDY DESIGN

Using live birth data from the Kentucky Office of Vital Statistics with birth years ranging from 2004 to 2020, a total of 894,372 live births were recorded that indicated that a childbearing person was between the ages of 18 and 49 years and a resident of Kentucky; these live births formed the sample for the study. Municipal ordinances implemented during a given calendar year were coded in the model as present starting with the following calendar year, as the birth records were time deidentified except for the year of birth. This lagged law convention maximized the likelihood that pregnant persons included in the study were exposed to the smoke-free policy for at least a portion of their pregnancy. Multilevel logistic regression was used to assess the effect of smoke-free ordinances on the likelihood of preterm birth, with personal- and county-level variables included as potential covariates and pregnant persons nested within the county of residence. Data analysis was conducted using SAS (version 9.4; SAS Institute, Cary, NC), with an alpha level of .05.

RESULTS

Nearly all personal-level variables were associated with preterm birth status. Personal factors associated with an increased likelihood of preterm birth included being older (relative to 18-24 years old; odds ratios [95% confidence intervals]: 1.02 [1.01-1.04] and 1.27 [1.24-1.31] for ages 25-34 and 35-49 years, respectively); having a history of preterm birth (odds ratio, 4.65; 95% confidence interval, 4.53-4.78); and smoking before pregnancy (odds ratio, 1.14; 95% confidence interval, 1.12-1.16). Pregnant persons living in counties with comprehensive laws were 9% less likely to have a preterm birth than those living in counties without a smoke-free ordinance (odds ratio, 0.91; 95% confidence interval, 0.89-0.94; P<.001). There was no difference in the likelihood of preterm birth between those living in counties with moderate or weak laws and those unprotected by any smoke-free ordinance in their county of residence.

CONCLUSION

This study demonstrated that comprehensive municipal smoke-free laws are associated with reduced risk of preterm birth and that moderate or weak smoke-free laws are not. The findings have major implications for public health policy and underscore the potential influence of healthcare providers' advocacy for strong smoke-free policies, prohibiting smoking in all workplaces (including restaurants, bars, and casinos), to support healthy pregnancies.

Simultaneous quantification of urinary tobacco and marijuana metabolites using solid-supported liquid-liquid extraction coupled with liquid chromatography tandem mass spectrometry

Co-exposure to tobacco and marijuana has become common in areas where recreational marijuana use is legal. To assist in the determination of the combined health risks of this co-exposure, an analytical method capable of simultaneously measuring tobacco and marijuana metabolites is needed to reduce laboratory costs and the required sample volume. So far, no such analytical method exists. Thus, we developed and validated a method to simultaneously quantify urinary levels of trans-3'-hydroxycotinine (3OH-COT), cotinine (COT), and 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (COOH-THC) to assess co-exposure to tobacco and marijuana. Urine (200 µL) was spiked with labelled internal standards and enzymatically hydrolyzed to liberate the conjugated analytes before extraction using solid-supported liquid-liquid extraction (SLE) with ethyl acetate serving as an eluent. The target analytes were separated on a C18 (4.6 × 100 mm, 5 μm) analytical column with a gradient mobile phase elution and analyzed using tandem mass spectrometry with multiple reaction monitoring of target ion transitions. Positive electrospray ionization (ESI) was used for 3OH-COT and COT, while negative ESI was used for COOH-THC. The total run time was 13 min. The extraction recoveries were 18.4-23.9 % (3OH-COT), 65.1-96.8 % (COT), and 80.6-95.4 % (COOH-THC). The method limits of quantification were 5.0 ng/mL (3OH-COT) and 2.5 ng/mL (COT and COOH-THC). The method showed good accuracy (82.5-98.5 %) and precision (1.22-6.21 % within-day precision and 1.42-6.26 % between-day precision). The target analytes were stable for at least 144 h inside the autosampler (10 °C). The analyses of reference materials and 146 urine samples demonstrated good method performance. The use of a 96-well plate for preparation makes the method useful for the analysis of large numbers of samples.

A biomarker-based study of prenatal smoking exposure and autism in a Finnish national birth cohort

Maternal exposure to tobacco smoke during pregnancy is a common and persistent exposure linked to adverse neurodevelopmental outcomes in the offspring. However, previous studies provide mixed evidence regarding the relationship between prenatal smoking and offspring autism. This study used cotinine level, a biomarker for nicotine, to investigate the relationship between prenatal smoking and autism. The authors conducted a population-based case-control study nested in a national cohort of all births in Finland from 1987 to 2005. Cases diagnosed with childhood autism (ICD-10/9 code F84.0/299.0) through 2007 were identified using data from linked national registers. Each case was matched with a control on date of birth (±30 days), sex, and place of birth (N = 962 pairs). Maternal serum cotinine levels were prospectively measured in first- to early second-trimester serum samples archived in a national biobank using a quantitative immunoassay. Data were analyzed using conditional logistic regression. Prenatal maternal levels of serum cotinine were not associated with the odds of autism, whether cotinine was classified continuously, by deciles, or using previously defined categories corresponding to probable maternal smoking status. After adjusting for maternal age, paternal age, previous births, and any history of parental psychiatric disorder, the odds ratio for categorical high versus low cotinine, using a 3-level exposure variable, was 0.98 (95% CI = 0.76, 1.26; p = 0.88). In conclusion, this national birth cohort-based study does not provide evidence for an association between maternal cotinine, a biomarker of maternal smoking, and risk of autism. LAY SUMMARY: This study explored whether prenatal exposure to tobacco smoke in mothers is related to the diagnosis of autism in their children, by measuring the levels of cotinine, a biomarker for tobacco exposure, in stored serum samples drawn from mothers during pregnancy. The levels of cotinine in the mothers of children diagnosed with autism were similar to those in the mothers of control children of similar age and gender distribution.

Pregnant and postnatal women's experiences of interacting with health care providers about their tobacco smoking: a qualitative systematic review protocol

OBJECTIVE

The objective of this review is to comprehensively identify and synthesize the best available evidence about the experiences of women who smoked tobacco during pregnancy or postnatally (or both) concerning their health care providers' interactions with them about their smoking.

INTRODUCTION

Smoking tobacco during pregnancy and postnatally continue to be important global public health challenges. Maternal smoking poses risks to the woman's general health and causes pregnancy complications and serious adverse health effects for the fetus and child. Hence, it is essential that health care providers support pregnant and postnatal women to achieve smoking cessation and not relapse. Learning about these women's experiences of health care provider interactions may inform recommendations for health care provider best practice in interpersonal approach.

INCLUSION CRITERIA

The participants of interest are women who smoked tobacco during pregnancy, the postnatal period, or both, with the phenomenon of interest being their experiences of health care provider interactions with them about their smoking. The context is any setting globally. Studies for consideration will have qualitative data, including any mixed methods studies.

METHODS

This qualitative systematic review will be conducted according to JBI methodology. Databases to be searched for published studies include CINAHL, PubMed, APA PsycINFO, Embase, Sociological Abstracts, and SocINDEX. Gray literature will be searched for unpublished studies. The authors will conduct an initial screening and then a full-text review of studies for congruence with the inclusion criteria. A critical appraisal will be performed on eligible studies and data will be extracted from included studies. Meta-aggregation will be used to yield synthesized findings, which will be assigned confidence scores.

SYSTEMATIC REVIEW REGISTRATION NUMBER

PROSPERO CRD42020178866.

Behavioral and Enhanced Perinatal Intervention (B-EPIC): A randomized trial targeting tobacco use among opioid dependent pregnant women

BACKGROUND

Opioid use during pregnancy is a significant public health issue. The standard of care for treating opioid use disorder during pregnancy includes medications for opioid disorder (MOUD). However, tobacco use often goes unaddressed among pregnant women on MOUD. In 2018, our team received a National Institute on Drug Abuse (NIDA) funded R34 to conduct a three year-randomized trial to test the feasibility of a novel tobacco intervention for pregnant women receiving MOUD.

AIMS

The aims of this study are: (1) to determine the impact of the B-EPIC intervention on maternal tobacco use and stage of change; (2) to determine the impact of B-EPIC on tobacco-related maternal and infant health outcomes including gestational age at birth, birthweight, NAS diagnosis and severity, and number of ear and respiratory infections during the first six months; (3) to compare healthcare utilization and costs incurred by pregnant patients that receive the B-EPIC intervention versus TAU.

METHODS

We plan to enroll 100 pregnant women on MOUD for this randomized controlled trial (B-EPIC intervention n = 50 and treatment as usual n = 50). A major strength of this study is its wide range of health and economic outcomes assessed on mother, neonate and the infant.

CONCLUSIONS

Despite the very high rates of smoking among pregnant women with OUD, there are few tobacco treatment interventions that have been tailored for this high - risk population. The overall goal of this study is to move towards a tobacco treatment standard for pregnant women receiving treatment for OUD.

Challenges Experienced by Women Who Smoke During Pregnancy or Postnatally

Maternal smoking during pregnancy and maternal smoking postnatally are important public health concerns worldwide. Smoking adversely affects the woman's general health and is causally related to pregnancy complications and serious health outcomes for the child, such as stillbirth, preterm delivery, low birth weight, and sudden infant death. The purpose of this research was to examine maternal smoking through a quantitative descriptive survey of 164 women, 120 who were pregnant and 44 who were postnatal. Women experienced barriers to quitting smoking, including dealing with stress, being exposed to smokers, not being ready to quit, not knowing how to quit, not looking for or not being able to find information about smoking or quitting smoking, and lacking adequate social and healthcare provider support. On the other hand, women revealed characteristics that suggest they might have had improved potential for quitting smoking, including having negative feelings about smoking, having cut down on smoking, smoking at a low level, having made quit attempts, thinking it would not be hard to quit smoking, being in the preparation stage of behavioral change, and thinking their healthcare providers (HCPs) would help them if they decided to quit. Taken together, those findings suggest that HCPs could offer important assistance to help women achieve smoking cessation. However, more research needs to be conducted to clarify the role and effectiveness of various HCPs in smoking cessation interventions and to identify measures to strengthen their provision of such interventions.

Smoking Status and Symptoms of Depression During and After Pregnancy Among Low-Income Women

OBJECTIVE

To describe the point prevalence rates, relapse rates, smoking status, and symptoms of depression and to examine the relationship between smoking status and symptoms of depression from early pregnancy to 12 months after childbirth among low-income women.

DESIGN

Secondary data analysis.

SETTING

Data from the national Nurse-Family Partnership program.

PARTICIPANTS

Women who were enrolled in the national Nurse-Family Partnership program between 2011 and 2016 with histories of smoking 3 months before pregnancy (N = 1,554).

METHODS

We used smoking status and Edinburgh Postnatal Depression Scale scores in early pregnancy, late pregnancy, and 12 months after childbirth to identify point prevalence rates, relapse rates, smoking status, and symptoms of depression. We used chi-square and additional analyses to examine the relationship between smoking status and symptoms of depression.

RESULTS

The prevalence of smoking was 30.12% (n = 468) in early pregnancy, 24.39% (n = 379) in late pregnancy, and 50.58% (n = 786) 12 months after childbirth. Prevalence rates of a positive depression screening result were 30.31% (n = 471), 20.46% (n = 318), and 18.08% (n = 281), respectively. Smoking relapse rates were 2.45% (n = 38) during the third trimester and 27.86% (n = 433) at 12 months after childbirth. Eight distinct patterns of smoking and depression were identified. Women who smoked were significantly more likely to also have positive depression screening results during the third trimester and at 12 months after childbirth compared with nonsmoking women (OR = 1.37, 95% confidence interval [1.04, 1.81] and OR = 1.93, 95% confidence interval [1.47, 2.51], respectively).

CONCLUSION

Prevalence rates of smoking, relapse, and positive depression screening results were great in this sample of low-income women during and after pregnancy. Pivotal time points exist where the trajectory of smoking and depression screening patterns may change. It is important for smoking cessation interventions to incorporate mental health assessment and treatment.

Perceptions, Characteristics, and Behaviors of Cigarette and Electronic Cigarette Use among Pregnant Smokers

INTRODUCTION

Smoking during pregnancy is a primary risk factor for adverse perinatal outcomes. Although electronic cigarette (e-cigarette) use has increased, reasons for and behaviors of use are not fully understood. The purpose of this study, composed exclusively of pregnant current smokers, was to describe perceptions of health risks associated with e-cigarette use among pregnant women, describe the use patterns of pregnant dual users (defined as those who simultaneously use conventional/combustible cigarettes and e-cigarettes), and examine smoking-related behaviors between conventional-only (defined as those smoking combustible cigarettes but not e-cigarettes) and dual users.

METHODS

Cross-sectional data from a larger study of pregnant conventional-only and dual users were analyzed. A brief survey measured perceptions of prenatal e-cigarette use and smoking behaviors. Analysis included descriptive statistics, bivariate analysis, and logistic and linear regression analysis.

RESULTS

Among 176 pregnant smokers (38% dual users), more than one-half of participants believed e-cigarettes were harmful to women (56%) and posed harm to the fetus (53%). Among dual users, 41% used their e-cigarette daily, on average eight times per day. Eleven percent of dual users smoked a pack of cigarettes per day, compared with 5% of conventional-only smokers, and dual users scored significantly higher (p = .026) on the Penn State Cigarette Dependence Index. The most common e-cigarette liquid flavor was fruit (64%), and the most frequently reported e-cigarette nicotine concentration was 1-6 mg.

CONCLUSIONS

Characterizing perceptions and behaviors of e-cigarette use during pregnancy is foundational for future research to explore the association between product use and maternal and infant outcomes.

Opportunities for evaluating chemical exposures and child health in the United States: the Environmental influences on Child Health Outcomes (ECHO) Program

The Environmental Influences on Child Health Outcomes (ECHO) Program will evaluate environmental factors affecting children's health (perinatal, neurodevelopmental, obesity, respiratory, and positive health outcomes) by pooling cohorts composed of >50,000 children in the largest US study of its kind. Our objective was to identify opportunities for studying chemicals and child health using existing or future ECHO chemical exposure data. We described chemical-related information collected by ECHO cohorts and reviewed ECHO-relevant literature on exposure routes, sources, and environmental and human monitoring. Fifty-six ECHO cohorts have existing or planned chemical biomonitoring data for mothers or children. Environmental phenols/parabens, phthalates, metals/metalloids, and tobacco biomarkers are each being measured by ≥15 cohorts, predominantly during pregnancy and childhood, indicating ample opportunities to study child health outcomes. Cohorts are collecting questionnaire data on multiple exposure sources and conducting environmental monitoring including air, dust, and water sample collection that could be used for exposure assessment studies. To supplement existing chemical data, we recommend biomonitoring of emerging chemicals, nontargeted analysis to identify novel chemicals, and expanded measurement of chemicals in alternative biological matrices and dust samples. ECHO's rich data and samples represent an unprecedented opportunity to accelerate environmental chemical research to improve the health of US children.

A gestational vulnerability window for smoking exposure and the increased risk of preterm birth: how timing and intensity of maternal smoking matter

BACKGROUND

Reducing the incidence of preterm birth is a national priority. Maternal cigarette smoking is strongly and consistently associated with preterm birth. The objective of this study was to examine prenatal exposure based on combined measures of timing (by trimester) and intensity level (the number of cigarettes smoked per day) of maternal smoking to identify a pregnancy period with the highest risk of preterm birth.

METHODS

A sample of 2,485,743 singleton births was drawn from the 2010 National Center of Health Statistics (NCHS) linked birth/infant death file of US residents in 33 states that implemented the revised 2003 birth certificate. Nine mutually exclusive smoking status categories were created to assess prenatal exposure across pregnancy in association with preterm birth. Gestational age was based on the obstetric estimate. Multiple logistic regression analyses were conducted to compare the odds of preterm birth among women who smoked at different intensity levels in the second or third trimester with those who smoked only in the first trimester.

RESULTS

Overall, 7.95% of women had a preterm birth; 8.90% of low intensity (less than a pack/day) smokers in the first trimester only, 12.99% of low and 15.38% of high intensity (pack a day or more) smokers in the first two trimesters, and 10.56% of low and 11.35% of high intensity smokers in all three trimesters delivered preterm. First and second trimester high (aOR 1.85, 95% CI: 1.66, 2.06) and low intensity smokers (aOR 1.51, 95% CI: 1.41, 1.61) had higher odds of preterm birth compared to those who smoked less than a pack a day only in the first trimester, but the odds did not increase for all three trimester smokers relative to the first and second trimester smokers. In sensitivity analysis, adjustment for exposure misclassification error corrected data and testing for effect modification by maternal race/ethnicity found no significant interaction.

CONCLUSIONS

This study documented a biologically plausible vulnerability window for smoking exposure and the increased risk of preterm birth. For women who do not modify their smoking behavior preconception, preterm birth risk of smoking remains low until late in the first trimester.

Discrepancy between Self-Reported and Urine Cotinine-Verified Environmental Tobacco Smoke Exposure among Rural Pregnant Women in China

Prenatal exposure to environmental tobacco smoke (ETS) is the most modifiable risk factor associated with adverse child-health outcomes. However, few longitudinal studies are implemented to compare the rates of discrepancy between self-reported (SR) and urinary cotinine (UC)-verified ETS exposure during the three trimesters of pregnancy, especially in rural areas. The objectives of this study were to assess the discrepancy between SR and UC-verified ETS exposure among rural women employing three measures throughout pregnancy, and to explore predictors related to these differences. This study used a prospective prenatal cohort consisting of 420 pregnant women whose ETS exposure was entirely evaluated by both SR and UC verification across three trimesters of pregnancy. Environmental tobacco exposure was assessed via SR verification, and was validated using the limit of detection for UC. The discrepancy rates were determined for each trimester. Multivariate logistic regression was used to assess the predictors associated with these differences. The discrepancy rates between SR and UC verification were 25.2%, 17.1%, and 20.5% (first, second, and third trimester, respectively). The highest inconsistency occurred in the first trimester. After adjusting for confounding factors, the following variables were found to have statistically significant associations with the discrepancy rate between SR and UC-verified ETS exposure: the number of smokers in the family and household income for all three trimesters, township site for the second and third trimester, and gravidity for the last trimester. The SR rate of ETS exposure among rural pregnant women is underreported, while the UC-verified rate is higher. More smokers in the family and gravidity may increase the risk of ETS exposure for pregnant women. Biochemical validation is warranted throughout pregnancy for the adoption of home-smoking bans and the promotion of community-based smoke-free programs.