Prenatal environmental tobacco smoke exposure and early childhood body mass index

Maternal smoking during pregnancy is associated with increased risk of childhood overweight body mass index (BMI). Less is known about the association between prenatal secondhand tobacco smoke (SHS) exposure and childhood BMI. We followed 292 mother-child dyads from early pregnancy to 3 years of age. Prenatal tobacco smoke exposure during pregnancy was quantified using self-report and serum cotinine biomarkers. We used linear mixed models to estimate the association between tobacco smoke exposure and BMI at birth, 4 weeks, and 1, 2 and 3 years. During pregnancy, 15% of women reported SHS exposure and 12% reported active smoking, but 51% of women had cotinine levels consistent with SHS exposure and 10% had cotinine concentrations indicative of active smoking. After adjustment for confounders, children born to active smokers (self-report or serum cotinine) had higher BMI at 2 and 3 years of age, compared with unexposed children. Children born to women with prenatal serum cotinine concentrations indicative of SHS exposure had higher BMI at 2 (mean difference [MD] 0.3 [95% confidence interval -0.1, 0.7]) and 3 (MD 0.4 [0, 0.8]) years compared with unexposed children. Using self-reported prenatal exposure resulted in non-differential exposure misclassification of SHS exposures that attenuated the association between SHS exposure and BMI compared with serum cotinine concentrations. These findings suggest active and secondhand prenatal tobacco smoke exposure may be related to an important public health problem in childhood and later life. In addition, accurate quantification of prenatal secondhand tobacco smoke exposures is essential to obtaining valid estimates.     

Prenatal Smoking in Two Consecutive Pregnancies: Georgia, 1989–1992

Objective: To explore the patterns of prenatal smoking among women whose first and second pregnancies ended in live births. Methods: We used population-based data to explore prenatal smoking among 14,732 white and 8968 black Georgia residents whose first and second pregnancies ended in live births during 1989–1992. Smoking status was obtained from birth certificates linked for individual mothers. Because of demographic differences, we analyzed white and black women separately. Results: Approximately 15% (2253) of white women and 4% (318) of black women smoked during their first pregnancy. Of those smokers, 69% (1551) of white women and 58% (184) of black women also smoked during their second pregnancy. For both white and black nonsmokers during the first pregnancy, low education was the most significant predictor of smoking during the second pregnancy, after adjusting for consistency of the father's name on the birth certificate, prenatal care, birth interval, mother's county of residence, and birth outcome. Conclusions: The prevalence of smoking in this study may be low because of underreporting of prenatal smoking on birth certificates. The majority of women who smoked during their first pregnancy also smoked during their second, suggesting that these women exposed their first infant to tobacco smoke both in utero and after delivery. Practitioners should offer smoking cessation programs to women during, as well as after, pregnancy. Pediatricians should educate parents on the health risks to young children of exposure to environmental tobacco smoke and refer smoking parents to smoking cessation programs.     

Fetal Exposure to Secondhand Tobacco Smoke Assessed by Maternal Self-reports and Cord Blood Cotinine: Prospective Cohort Study in Krakow

Objectives While the validity of self-reported smoking habits is generally judged as satisfactory, objective markers of secondhand smoke (SHS) exposure may be more useful in validating the causal links between prenatal SHS and health effects. The cohort study in Krakow provided an opportunity for comparative assessment of fetal exposure to SHS based upon questionnaires and cord blood cotinine measurements. Methods The study sample included 467 newborns born to women recruited in the first and second trimester of pregnancy. To compare the validity of self-reported SHS and cord blood cotinine levels in assessing the association between fetal passive smoking and health effects of newborns, we separately examined the regression coefficients of birthweight on self-reported number of cigarettes smoked by other household members during the entire pregnancy and cord blood cotinine levels. Results In the non-exposed newborns the geometric mean of cord blood cotinine was 0.077 ng/ml and was significantly lower than in newborns with a maternal report of SHS. Cord cotinine levels were more highly correlated with a self-reported number of cigarettes smoked daily at home in the third trimester of pregnancy. The two measures of SHS (number of cigarettes and number of hours of daily exposure) were equally well correlated with cord blood cotinine levels. Using cotinine as the exposure variable, overall the association was not significant; but among the subgroup with cord cotinine levels above the median (≥0.083 ng/ml), the association with birthweight was significant (beta coefficient = −113.65, P = 0.041). Conclusion The study provides evidence that the assessment of fetal SHS exposure based on cord blood cotinine produced better estimates of the association between exposure and birth outcomes. The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention.     

The discrepancy between self-reported smoking status and urine continine levels among women enrolled in prenatal care at four publicly funded clinical sites.

The discrepancy between self-reported smoking behavior and actual urine cotinine values among prenatal patients at four municipally operated clinical sites was examined. Face-to-face interview and birth certificate information about smoking behavior during pregnancy was compared with laboratory urine cotinine values for 74 patients. Almost three of every four (73%) self-reported nonsmokers had continine values greater than 80 ng/mL; one-half (48%) had values exceeding 100 ng/mL. Self-reported prenatal smoking behavior seems to be an unreliable indicator of actual smoking status among low-income prenatal patients, resulting in missed opportunities to lower tobacco-related exposure/risk among women with the poorest birth outcomes.     

Newborn infant urinary cotinine and birth outcomes in the Jerusalem Environment Mother and Child Cohort Study

BackgroundEnvironmental tobacco smoke (ETS) exposure during pregnancy can cause preterm delivery and childhood cancer. The aim of this study was to measure ETS exposure in pregnant women and in newborn infants in Israel using urinary cotinine measurements, to assess predictors of ETS exposure in these vulnerable groups, and to assess associations with birth effects (birth weight, birth length, head circumference) in newborn infants.MethodsWe analyzed urinary cotinine and creatinine in 265 non-smoking pregnant women and 97 newborns, and analyzed associations with self-reported exposure to ETS, paternal smoking, sociodemographic variables and with birth outcomes (birth weight, birth length, head circumference).Results37.7% of pregnant women and 29.0% of infants had urinary cotinine concentrations above the level of quantification (LOQ) of 1 μg/L, whereas 63.8% and 50.5%, respectively, had urinary cotinine concentrations above the level of detection (LOD) of 0.5 μg/L. Median unadjusted and creatinine adjusted urinary concentrations of cotinine in pregnant women were 0.7 μg/L, and 0.9 μg/g creatinine, respectively, and in newborn infants were 0.5 μg/L, and 1.3 μg/g creatinine, respectively. We did not find an association between maternal and infant urinary cotinine level. Maternal (but not infant) urinary cotinine was significantly associated with paternal smoking (p < 0.05). Infant (but not maternal) cotinine above the LOQ was negatively associated with birth weight (p < 0.05).ConclusionsIn this high socioeconomic cohort, almost a third of newborn infants born to non-smoking mothers had quantifiable levels of urinary cotinine. This is the first study showing that newborns with quantifiable urinary cotinine levels have lower birth weight.     

Cord serum cotinine as a biomarker of fetal exposure to cigarette smoke at the end of pregnancy

This study investigated the association between biomarkers of fetal exposure to cigarette smoke at the end of pregnancy, cotinine in cord serum and in maternal and newborn urine samples, and quantitative measurement of smoking intake and exposure evaluated by maternal self-reported questionnaire. Study subjects were 429 mothers and their newborns from a hospital in Barcelona, Spain. A questionnaire including smoking habits was completed in the third trimester of pregnancy and on the day of delivery. Cotinine concentration in cord serum was associated with daily exposure to nicotine in nonsmokers and with daily nicotine intake in smokers. The geometric mean of cotinine concentration in cord serum statistically discriminated between newborns from nonexposed and exposed nonsmoking mothers, and between these two classes and smokers, and furthermore was able to differentiate levels of exposure to tobacco smoke and levels of intake stratified in tertiles. Urinary cotinine levels in newborns from nonsmoking mothers exposed to more than 4 mg nicotine daily were statistically different from levels in two other categories of exposure. Cotinine concentration in urine from newborns and from mothers did not differentiate between exposure and nonexposure to environmental tobacco smoke (ETS) in nonsmoking mothers. Cord serum cotinine appeared to be the most adequate biomarker of fetal exposure to smoking at the end of pregnancy, distinguishing not only active smoking from passive smoking, but also exposure to ETS from nonexposure.     

Smoking during pregnancy--United States, 1990-2002

Cigarette smoking during pregnancy adversely affects the health of both mother and child. The risk for adverse maternal conditions (e.g., premature rupture of membranes, abruptio placentae, and placenta previa) and poor pregnancy outcomes (e.g., neonatal mortality and stillbirth, preterm delivery, and sudden infant death syndrome) is increased by maternal smoking. Infants born to mothers who smoke weigh less than other infants, and low birthweight (<2,500 grams) is a key predictor for infant mortality. Infertility and conception delay also might be elevated by smoking. National health objectives for 2010 target an increase in cessation to 30% among pregnant smokers during the first trimester and abstinence from cigarettes by 99% of women giving birth. To assess progress toward these goals, CDC analyzed state-specific trends in maternal smoking during 1990-2002 by using data collected on birth certificates. This report summarizes the results of those analyses, which indicated that whereas participating areas observed a significant decline in maternal smoking during the surveillance period, 10 states reported recent increases in smoking by pregnant teens. Although the widespread public health message to abstain from smoking during pregnancy has helped decrease maternal smoking, to reduce prevalence further, implementation of additional interventions are required.     

Tea drinking, passive smoking, smoking deception and serum cotinine in the Scottish heart health study

Following a recent claim that the use of cotinine in body fluids, to assess passive smoking and smoking “deception”, was confounded by metabolic individuality, and by non-tobacco sources of dietary nicotine, particularly tea, data were examined from a large cross-sectional survey in a tea-drinking population. In 3383 men and women aged 44–59 years from the Scottish Heart Health Study, defined as non-smokers, both by self-report and by low thiocyanate and expired air carbon monoxide levels, serum cotinine showed minimal association with self-reported daily average tea consumption. However, there was a strong correlation between degree of self-reported passive tobacco smoke exposure and median serum cotinine level. In the same survey, serum cotinine in 4144 self-reported non-smokers and in 3326 smokers showed entirely different distributions, but the same range, suggesting heavy nicotine intake in some “non-smokers”. These analyses confirm that cotinine levels in true non-smokers reflect far more the nicotine in inhaled ambient tobacco smoke than they do nicotine in tea. Some smoking “deceivers” have the same degree of exposure to nicotine as heavy smokers. Despite individual variability, the claim of confounding is poorly supported, and cotinine is confirmed as an indicator both of passive smoking and of smoking deception.     

Adjusting for multiple-misclassified variables in a study using birth certificates

PurposeBirth certificates are a convenient source of population data for epidemiologic studies. It is well documented, however, that birth certificate data can be highly inaccurate. Nonetheless, studies based on birth certificates are routinely analyzed without accounting for sources of data errors. We focused on the association between maternal cigarette smoking and cleft lip and palate based on birth certificate data.MethodsWe adjusted odds ratio estimates simultaneously for exposure and outcome misclassification. We also calculated odds ratios adjusted for exposure misclassification only and outcome misclassification only.ResultsAdjustment for both maternal smoking during pregnancy and clefting resulted in adjusted odds ratios that ranged from less than 1.0 to much greater than the unadjusted estimate of 1.16, with most adjusted estimates outside of the 95% confidence limits (1.01, 1.33).ConclusionsBecause of the potentially large impact of birth certificate classification errors, we suggest that inferences from these or similar records employ quantitative methods for incorporating uncertainties caused by data errors.     

Changes in Maternal Cigarette Smoking Among Pregnant WIC Participants in Rhode Island

Objectives To describe the relationship between the timing of entry into the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) among pregnant women in Rhode Island (RI) and changes in maternal cigarette smoking (MCS) during pregnancy. Methods MCS data gathered by WIC were analyzed for pregnant women who self-identified as smokers at the onset of pregnancy between the years 2001–2005. Bivariate and multivariate analyses were performed to examine the relationship between timing of WIC entry and both increased and decreased/quit MCS during pregnancy. Results Self-reports from smokers indicated that 9.5% quit smoking, 24.6% decreased MCS, 26.8% experienced no change, 33.5% increased MCS, and 5.6% attempted to quit MCS but failed during pregnancy. The adjusted odds ratio for smokers with 1st trimester WIC entry and increased MCS was 0.64 (95% CI 0.52, 0.79). Among smokers with 1st trimester PNC entry, the adjusted odds ratio for smokers with 1st trimester WIC entry and decreased/quit MCS was 1.51 (95% CI 1.17, 1.96). Conclusions Early WIC entry appears to be associated with improvements in MCS. Participants who entered WIC in the first trimester of pregnancy were less likely to increase smoking during pregnancy, and if they also had first trimester prenatal care, were more likely to decrease/quit smoking compared to those who entered WIC later. Programs that increase the rates of first trimester WIC entry may contribute to lower rates of MCS in the WIC population.     

Factors Associated with Prenatal Smoking Among Black Women in Eastern North Carolina

Objectives: The objective of this research was to explore prenatal smoking behaviors among Black women attending prenatal clinics. Despite the racial disparities in poor pregnancy outcomes, and the well-known association of smoking with harmful outcomes, little research has been conducted about prenatal smoking among Black women. Methods: Women were enrolled in the study and interviewed at the time of the first prenatal visit. The interview contained items to assess prenatal smoking and cessation, depressive symptoms, demographic factors, and beliefs about smoking. Reports of smoking cessation were verified using urinary cotinine. Results: The sample consisted of 811 Black women. Fourteen percent of the women were self-reported smokers, 12.6% reported cessation and 73% were nonsmokers. Twenty percent of the self-reported quitters had elevated cotinine; when these women were reclassified, 17% of the women were smokers. Factors associated with smoking in logistic regression analysis included elevated maternal depressive symptoms (OR = 1.7, 95% CI: 1.1–2.6), maternal age 20 years or older (OR = 1.94; 95% CI: 1.1, 3.3), less than a high school education (OR = 2.2; 95% CI: 1.2, 3.8), unmarried/not living with a partner (OR = 1.9; 95% CI: 1.0, 3.6), and allowing smoking in the home (OR = 5.5; 95% CI: 3.4, 8.6). Conclusions: The prevalence of maternal prenatal smoking was much higher among women in this sample than has been previously reported. The rate of nondisclosure of smoking among self-reported quitters was also high. Maternal behavioral (allowing smoking in the home) and psychosocial factors (depressive symptoms) were associated with prenatal smoking.     

Stressful life events, smoking behavior, and intentions to smoke among and multiethnic sample of sixth graders

Objectives. Adolescent smoking has been associated with stressful life events. However, few studies have examined the associations between stress, smoking intentions, and smoking behavior among a multiethnic sample of adolescents. Methods. We compiled a checklist of stressful life events relevant to multiethnic youth and administered it to 1,074 sixth-grade students in urban Los Angeles. Results. The most frequently reported stressful events were similar across ethnic groups and generations in the USA: test taking, chores, and arguments with friends. The events reported as the most severe were disturbances in family life, such as: death, arguments between parents, and illness or injury. Whites and Latinos had reported higher levels of ever smoking and intentions to smoke than Asian/Pacific Islanders (PIs). On the positive family-related events scale Latinos scored higher than did whites or Asian/PIs. Whites scored higher than Latinos or Asian/PIs on both negative peer-related and negative personal-related events. Associations were observed between total stress, stressful life events, and smoking behavior and intention to smoke. Total stress was associated with ever smokers, smoking intentions within the next year and in high school over the entire sample. Negative peer-related events were associated with intention to smoke within the next year, among Latinos. Among Asian/PIs negative peer-related events were associated with intention to smoke within the next year and in high school. Negative school-related events were significantly associated with ever smoking and intentions to smoke in the next year and marginally associated with intentions to smoke in high school among children born in the USA whose parents were also born in the USA. Negative peer-related events and positive personal-related events were significantly associated with intentions to smoke in the next year among children born in the USA whose parents were immigrants. Conclusions. Results suggest that negative peer- and school-related events may lead to increased risk of smoking behavior and intentions to smoke among multicultural adolescents.     

Perceived risks and reasons to smoke cigarettes during pregnancy among Alaska native women

Objective: The purpose of this study was to explore perceptions of the risks of smoking and reasons Alaska Native women give for smoking during pregnancy.

Design: A total of 118 women (54 smokers, 64 non-smokers) enrolled in a biomarker study and completed a baseline interview asking about their concerns regarding tobacco use while pregnant and reasons why pregnant women might smoke during pregnancy. Responses were collapsed into six categories of perceived risks of smoking and eight categories of reasons to smoke during pregnancy.

Results: The majority of both pregnant non-smokers and smokers (72.6% and 60.4%) agreed that smoking during pregnancy could negatively impact the health of their baby. However, non-smokers were more likely than smokers (77.4% vs. 58.5%) to view smoking during pregnancy as a risk factor for the baby’s development (p?=?.029). Both non-smokers and smokers identified addiction as a reason for smoking during pregnancy (82.8% and 63%); however, non-smokers were more likely than smokers to state this was a reason for use (p?=?.015). Seventy-three percent of the entire sample reported a reason to smoke in pregnancy was to help manage negative affect.

Conclusion: Results from this work may be helpful in advancing research by identifying targets for intervention specific to Alaska Native women receiving prenatal care in Anchorage, Alaska.     

Factors Associated With Quitting Smoking During Pregnancy Among Women Veterans

IntroductionLittle is known about the rates of smoking among pregnant veterans. Our objective was to examine rates of smoking during pregnancy and factors associated with quitting smoking during pregnancy.MethodsWe used data from a cohort study of pregnant veterans from 15 Veterans Health Administration facilities nationwide. Veterans who reported smoking during pregnancy were included in this analysis. Poisson regression models were used to estimate the relative risk (RR) of quitting smoking during pregnancy.ResultsOverall, 133 veterans reported smoking during pregnancy. Among this group of women who smoked, the average age was 31.6 years, 20% were Black, and 14% were Hispanic/Latino. More than one-half of women (65%) who reported smoking at the start of pregnancy quit smoking during pregnancy. Multivariable models, adjusted for history of deployment and age, indicated that prenatal care initiation at 12 or fewer weeks compared with more than 13 weeks (relative risk [RR], 2.06; 95% confidence interval [CI], 1.18–3.58), living without household smokers compared with any household smokers (RR, 1.58; 95% CI, 1.14–2.17), and first pregnancy (RR, 1.51; 95% CI, 1.17–1.95) were significant predictors of quitting versus persistent smoking during pregnancy.ConclusionsWomen veterans who quit smoking may be different than those who continue to smoke during pregnancy. Establishing prenatal care early in pregnancy, which likely includes counseling about smoking cessation, seems to be an important factor in quitting. Those for whom it is not a first pregnancy and who live with other smokers may especially benefit from such counseling.     

Estimates of Smoking Before and During Pregnancy,and Smoking Cessation During Pregnancy: Comparing Two Population-Based Data Sources

Objectives

We compared three measures of maternal smoking status—-prepregnancy, during pregnancy, and smoking cessation during pregnancy—between the Pregnancy Risk Assessment Monitoring System (PRAMS) questionnaire and the 2003 revised birth certificate (BC).

Methods

We analyzed data from 10,485 women with live births in eight states from the 2008 PRAMS survey, a confidential, anonymous survey administered in the postpartum period that is linked to select BC variables. We calculated self-reported prepregnancy and prenatal smoking (last trimester only) prevalence based on the BC, the PRAMS survey, and the two data sources combined, and the percentage of smoking cessation during pregnancy based on the BC and PRAMS survey. We used two-sided t-tests to compare BC and PRAMS estimates.

Results

Prepregnancy smoking prevalence estimates were 17.3% from the BC, 24.4% from PRAMS, and 25.4% on one or both data sources. Prenatal smoking prevalence estimates were 11.3% from the BC, 14.0% from PRAMS, and 15.2% on one or both data sources. The percentages of prepregnancy smokers who indicated that they quit smoking by the last trimester were 35.1% from the BC and 42.6% from PRAMS. The PRAMS estimates of prepregnancy and prenatal smoking, and smoking cessation during pregnancy were statistically higher than the corresponding BC estimates (t-tests, p<0.05).

Conclusions

PRAMS captured more women who smoked before and during the last trimester than the revised BC. States implementing PRAMS and the revised BC should consider information from both sources when developing population-based estimates of smoking before pregnancy and during the last trimester of pregnancy.Prenatal smoking remains one of the most common preventable causes of infant morbidity and mortality. Smoking may cause reduced fertility and delayed conception among women and is associated with an increased risk of cleft lip and palate.^1,2 Smoking during pregnancy causes placental abruption, placenta previa, preterm delivery, low birthweight, Sudden Infant Death Syndrome (SIDS), and preterm-related death.² In the United States, an estimated 5%–8% of preterm deliveries, 13%–19% of full-term low birthweight deliveries, 23%–34% of SIDS deaths, and 5%–7% of preterm-related deaths could be averted if prenatal smoking was eliminated.³Healthy People 2020 goals include reducing the smoking prevalence before and during pregnancy and increasing smoking cessation during pregnancy.⁴ Most states can measure progress in achieving these goals by using two population-based data sources, the Pregnancy Risk Assessment Monitoring System (PRAMS) and the revised 2003 birth certificate (BC). PRAMS surveys women with live births and collects information on smoking in the three months before pregnancy, during the last three months of pregnancy, and approximately four months after delivery. PRAMS data are linked to each infant''s BC. As of 2011, 40 states and New York City were implementing PRAMS, representing 75% of U.S. live births.⁵ Unlike the 1989 version of the BC, which ascertains whether a woman smoked during pregnancy without specifying in which trimester, the 2003 revised BC collects data on smoking status during the three months before pregnancy and during the first, second, and third trimesters. As of 2011, 38 states had implemented the revised BC, representing 86% of U.S. live births (Personal communication, Joyce Martin, National Center for Health Statistics, October 2011).Two previous studies compared the BC and PRAMS in ascertaining self-reported smoking during pregnancy only and found that using PRAMS resulted in higher estimates of prenatal smoking than using the BC.^6,7 In the Allen et al. study,⁶ only two of the 24 states had implemented the revised BC in 2004. To our knowledge, no studies have compared BC and PRAMS estimates of smoking in the three months before pregnancy and the percentage of women who quit smoking during pregnancy. Thus, our study is an update and expansion of findings from previous work.The purpose of this study was to compare estimates of prepregnancy and prenatal smoking using PRAMS, the BC, and both sources combined, and to compare the percentage of smokers who quit by the last trimester of pregnancy estimated using PRAMS with the percentage estimated using the BC. A secondary goal was to assess whether smokers identified by only one data source had similar or different demographic characteristics than smokers identified by both data sources.     

Self-Reported and Serum Cotinine-Validated Smoking in Pregnant Women in Estonia

Objectives: Although widely used in epidemiological studies, self-report has been shown to underestimate the prevalence of smoking among pregnant women. Objectives of this study were to examine the discrepancy between self-reported and cotinine-validated smoking status, and the sociodemographic characteristics associated with the misclassification of real smoking status among pregnant women in Tallinn, the capital of Estonia. Methods: Serum cotinine assays were performed on a subsample (n= 1360) of the pregnant women, who had participated in a recent study of human papillomavirus type 16 (HPV-16) seroprevalence in Estonia. In the present study, serum concentrations ≥15 ng/ml were used to distinguish current smokers from nonsmokers. The serum-validated smoking level was compared with the self-reported level in the records of the Estonian Medical Birth Registry. For the group of self-reported non-smokers, the differences between the cotinine-validated smokers and the cotinine-validated nonsmokers, with respect to their sociodemographic characteristics (age, ethnicity, educational level, employment status, marital status, parity), were estimated by logistic regression. Results: Of 1239 women who reported being nonsmokers, 259 (20.9%) had serum cotinine levels ≥15 ng/ml, and can be regarded as current smokers. Among self-reported nonsmokers, nondisclosure of current smoking was significantly more frequent in non-Estonian, less educated, socially inactive, cohabiting and multiparous women. Conclusions: Self-reported data on smoking in pregnant women underestimates the real smoking prevalence in Estonia. Maternal unwillingness to declare smoking during pregnancy needs to be taken into account in the practice of maternal and child health to better target prenatal smoking cessation interventions.     

Measures of maternal tobacco exposure and infant birth weight at term

This study was undertaken to determine the relation between self-reported number of cigarettes smoked per day and urine cotinine concentration during pregnancy and to examine the relations between these two measures of tobacco exposure and birth weight. Data were obtained from the Smoking Cessation in Pregnancy project, conducted between 1987 and 1991. Cigarette smoking information and urine cotinine concentration were collected for 3,395 self-reported smokers who were receiving prenatal care at public clinics in three US states (Colorado, Maryland, and Missouri) and who delivered term infants. General linear models were used to quantify urine cotinine variability explained by the number of cigarettes smoked per day and to generate mean adjusted birth weights for women with different levels of tobacco exposure. Self-reported number of cigarettes smoked per day explained only 13.9% of the variability in urine cotinine concentration. Birth weight declined as tobacco exposure increased; however, the relation was not linear. The sharpest declines in birth weight occurred at low levels of exposure. Furthermore, urine cotinine concentration did not explain more variability in birth weight than did number of cigarettes smoked. These findings should be considered by researchers studying the effects of smoking reduction on birth outcomes.     

Psychopathology Symptoms are Associated with Prenatal Health Practices in Pregnant Women with Heavy Smoking Levels

Purpose

Smoking during pregnancy may be linked to other problematic prenatal health behaviors in women. We examined interrelationships among prenatal smoking, prenatal health behaviors and mental health. The objective of this study was to examine factors that may contribute to variations in prenatal health practices among women who smoke during pregnancy.

Methods

Birth mothers from an adoption study (N?=?912) were interviewed about prenatal smoking, health behaviors, and mental health symptoms at 5 months postpartum.

Results

One-quarter of participants (N?=?222) reported smoking 6 or more cigarettes daily for at least 1 trimester. For mothers who smoked more than 6 cigarettes daily, higher levels of antisocial behaviors (β?=????.14, p?=?.03) and depressive symptoms (β?=????.17, p?=?.03) were associated with less frequent prenatal folate use; antisocial behaviors and depressive symptoms were not associated for prenatal folate use among women who did not smoke more than 6 cigarettes daily. For mothers who did not smoke more than 6 cigarettes daily, more depressive symptoms were associated with fewer prenatal care visits (β?=?.12, p?=?.01). Antisocial behaviors and anxiety symptoms were not associated with prenatal care visits in either group of mothers.

Conclusions for Practice

Maternal antisocial behaviors and depressive symptoms during pregnancy may be markers for poorer adherence to recommendations for folate supplementation among women who smoke 6 or more cigarettes daily during pregnancy, independent of adequacy of prenatal care.

     

Self-reported smoking, cotinine levels, and patterns of smoking in pregnancy

Non-pregnant adult smokers generally exhibit fairly stable smoking behaviour over time. In studies of this population, cotinine assays are considered a 'gold standard' measure of exposure to cigarette smoke; current smoking status can be validated with high sensitivity and specificity. In contrast, there is substantial within-person fluctuation in pregnancy smoking, as women try repeatedly to quit or cut down. As a result, cotinine measures may be of limited use for validation of amount smoked, as they are informative only about recent exposure, vary with individual smoking topography and are dependent on time lapsed since the last cigarette smoked. Thus, in reproductive epidemiology, where timing, intensity and duration of exposure are critical, self-reported history of cigarette consumption may be a more relevant fetal exposure than current smoking status. If there were substantial within-person variation over the course of pregnancy, numerous measures of cotinine would be needed to characterise patterns of fetal exposure and would not be feasible in many studies. We examined self-reported smoking patterns and compared them to patterns of urinary cotinine levels in a prospective study of 998 pregnant women, recruited 1988-92. Fluctuations in smoking were considerable and, while cotinine measures and self-reported number of cigarettes were highly correlated at any given time point across women (r=0.70), the within-person correlation between the patterns of self-reported number of cigarettes and cotinine levels was weaker (r=0.33). For researchers interested in fetal outcomes in which intensity and timing of exposure are critical, we conclude that self-reported variations in smoking during pregnancy may be a valid way to characterise detailed patterns of fetal exposure in epidemiological studies.     

Adverse birth outcomes associated with maternal smoking and polymorphisms in the N-Nitrosamine-metabolizing enzyme genes NQO1 and CYP2E1

Maternal smoking during pregnancy can result in both pregnancy complications and reduced size of the fetus and neonate. Among women who smoke, genetic susceptibility to tobacco smoke also is a likely causative factor in adverse pregnancy outcomes. A prospective cohort study was conducted among 460 pregnant women who delivered live singletons in Sapporo, Japan, from 2002 to 2005. Multiple linear regression models were used to estimate associations of maternal smoking and polymorphisms in two genes encoding N-nitrosamine-metabolizing enzymes-NAD(P)H: quinone oxidoreductase 1 (NQO1) and cytochrome P-450 2E1 (CYP2E1)-with birth size. Among infants born to smokers with the NQO1 homozygous wild-type allele, birth weight, birth length, and birth head circumference were significantly reduced (p < 0.01 for each factor). For the homozygous wild-type CYP2E1 allele, birth weight was lower by an estimated 195 g (standard error, 55; p < 0.001) among smokers. These genotypes did not confer adverse effects among women who had never smoked or who quit smoking during the first trimester. The adverse effects of maternal smoking on infant birth size may be modified by maternal genetic polymorphisms in N-nitrosamine-metabolizing enzymes among Japanese subjects. These results may help in directing smoking cessation interventions during pregnancy, especially among susceptible women.