Smoking and pregnancy outcome among African-American and white women in central North Carolina

Social Determinants of Cigarette Smoking among American Women during Pregnancy

Educational attainment is among the most substantial protective factors against cigarette smoking, including during pregnancy. Although Minorities’ Diminished Returns (MDRs) of educational attainment, defined as weaker protective effect of education for racial and ethnic minority groups compared to Non-Hispanic Whites, has been demonstrated in previous studies; such MDRs are not tested for cigarette smoking during pregnancy. To better understand the relevance of MDRs to tobacco use during pregnancy, this study had three aims: firstly, to investigate the association between educational attainment and cigarette smoking in pregnant women; secondly, to compare racial and ethnic groups for the association between educational attainment and cigarette smoking; and thirdly, to explore the mediating effect of poverty status on such MDRs, among American adults during pregnancy. This cross-sectional study explored a nationally representative sample of pregnant American women (n = 338), which was taken from the Population Assessment of Tobacco and Health (PATH; 2013). Current smoking was the outcome. Educational attainment was the independent variable. Region and age were the covariates. Poverty status was the mediator. Race and ethnicity were the effect modifiers. Overall, a higher level of educational attainment (OR = 0.54, p < 0.05) was associated with lower odds of current smoking among pregnant women. Race (OR = 2.04, p < 0.05) and ethnicity (OR = 2.12, p < 0.05) both showed significant interactions with educational attainment on smoking, suggesting that the protective effect of educational attainment against smoking during pregnancy is smaller for Blacks and Hispanics than Non-Hispanic Whites. Poverty status fully mediated the above interactions. In the United States, highly educated pregnant Black and Hispanic women remain at higher risk of smoking cigarettes, possibly because they are more likely to live in poverty, compared to their White counterparts. The results suggest the role that labor market discrimination has in explaining lower returns of educational attainment in terms of less cigarette smoking by racial and ethnic minority pregnant women.

High Rates of Menthol Cigarette Use Among Pregnant Smokers: Preliminary Findings and Call for Future Research

INTRODUCTION

Smoking during pregnancy remains widespread and is causally associated with infant morbidity and mortality. Despite links between menthol cigarette use and decreased smoking cessation, little is known regarding rates or characteristics of pregnant menthol cigarette smokers.

METHODS

Participants were drawn from two low-income, racially/ethnically diverse cohorts of pregnant smokers recruited from 2006 to 2015 (N = 166, Mage = 25 ± 5). Demographics, menthol cigarette use, daily cigarette use, quit status, and consecutive weeks quit were assessed by prospective interviews. Nicotine dependence was assessed using the Fagerström Test of Nicotine Dependence. Nicotine levels were assessed via saliva cotinine.

RESULTS

High rates of menthol use were found in both cohorts (85% and 87%). Across both cohorts, menthol smokers were more likely to identify as racial/ethnic minorities, were less educated, and reported lower income than non-menthol smokers (ps < .03). Menthol smokers also reported fewer continuous weeks quit (8.4 vs. 14.5 weeks quit; p < .03) and a tendency toward decreased likelihood of quitting smoking over pregnancy (29% vs. 48%; p < .08) in unadjusted but not in covariate-adjusted analyses. No differences emerged in cigarettes per day, nicotine dependence or nicotine exposure.

CONCLUSIONS

We found very high rates of menthol cigarette use in pregnant smokers-particularly among racial/ethnic minority and low socioeconomic status smokers-and some evidence for associations with reduced smoking cessation in pregnancy. Consideration of pregnant smokers as a uniquely vulnerable population is warranted in evaluating regulation of menthol in cigarettes. Further research is needed regarding the impact of menthol on smoking persistence in pregnancy and on maternal and infant health outcomes.

IMPLICATIONS

This study highlights high rates of menthol cigarette use in pregnant women in the Northeast, United States, with evidence for higher rates of menthol use among racial/ethnic minority, less educated and low-income pregnant smokers, and preliminary evidence for associations between menthol cigarette use and reduced smoking cessation. Consideration of the effects of menthol on smoking persistence in pregnant women and on the health of their offspring is warranted in the development of regulations regarding menthol in cigarettes.

Maternal smoking and low family income during pregnancy as predictors of the relationship between depression and adiposity in young adults

There is an increasing incidence of overweight/obesity and mental health disorders in young adults and the two conditions often coexist. We aimed to investigate the influence of antenatal and postnatal factors that may underlie this association with a focus on maternal prenatal smoking, socio-economic status and gender. Data from the Western Australian Pregnancy Cohort (Raine) Study (women enrolled 1989-1991) including 1056 offspring aged 20 years (cohort recalled 2010-2012) were analyzed (2015-2016) using multivariable models for associations between offspring depression scores (DASS-21 Depression-scale) and body mass index (BMI), adjusting for pregnancy and early life factors and offspring behaviours. There was a significant positive relationship between offspring depression-score and BMI independent of gender and other psychosocial covariates. There was a significant interaction between maternal prenatal smoking and depression-score (interaction coefficient=0.096; 95% CI: 0.006, 0.19, P=0.037), indicating the relationship between depression-score and BMI differed according to maternal prenatal smoking status. In offspring of maternal prenatal smokers, a positive association between BMI and depression-score (coefficient=0.133; 95% CI: 0.05, 0.21, P=0.001) equated to 1.1 kg/m2 increase in BMI for every 1standard deviation (8 units) increase in depression-score. Substituting low family income during pregnancy for maternal prenatal smoking in the interaction (interaction coefficient=0.091; 95% CI: 0.01, 0.17, P=0.027) showed a positive association between BMI and depression score only among offspring of mothers with a low family income during pregnancy (coefficient=0.118; 95% CI: 0.06, 0.18, P<0.001). There were no significant effects of gender on these associations. Whilst further studies are needed to determine whether these associations are supported in other populations, they suggest potentially important maternal behavioural and socio-economic factors that identify individuals vulnerable to the coexistence of obesity and depression in early adulthood.

Impact of Smoking Ban on Passive Smoke Exposure in Pregnant Non-Smokers in the Southeastern United States

Prenatal passive smoke exposure raises risk for negative birth outcomes. Legislation regulating public smoking has been shown to impact exposure levels, though fewer studies involving pregnant women have been conducted within the U.S. where bans are inconsistent across regions. This study examined the effect of a ban enacted in the southeastern U.S. on pregnant women's cotinine levels. Additional analyses compared self-reported exposure to cotinine and identified characteristics associated with passive exposure. Pregnant women (N = 851) were recruited prospectively between 2005 and 2011 in North Carolina. Sociodemographic and health data were collected via surveys; maternal blood samples were assayed for cotinine. Among non-active smokers who provided self-report data regarding passive exposure (N = 503), 20% were inconsistent with corresponding cotinine. Among all non-smokers (N = 668), being unmarried, African American, and less educated were each associated with greater passive exposure. Controlling for covariates, mean cotinine was higher prior to the ban compared to after, F(1, 640) = 24.65, p < 0.001. Results suggest that banning smoking in public spaces may reduce passive smoke exposure for non-smoking pregnant women. These data are some of the first to examine the impact of legislation on passive smoke exposure in pregnant women within the U.S. using a biomarker and can inform policy in regions lacking comprehensive smoke-free legislation.

Association between Second-Hand Smoking and Laryngopathy in the General Population of South Korea

Purpose

The relationship between second-hand smoking and laryngopathy has not yet been reported. Thus, this study investigates the relationship between second-hand smoking and laryngopathy and suggests basic empirical data to prevent laryngopathy.

Methods

This study analyzed 1,905 non-smokers over the age of 19 (269 men and 1,636 women) who completed the health questionnaire, laryngeal endoscope test, and urine cotinine test in the 2008 Korea National Health and Nutrition Examination Survey (KNHANES). Second-hand smoking was defined as a urine cotinine concentration of 50ng/ml and over. Confounding factors included age, gender, education, household income, occupation, alcohol consumption, and coffee consumption. Risk ratios (RR) and 95% confidence intervals (CI) were presented for the relationship between second-hand smoking and laryngopathy by using Poisson regression analysis.

Results

There was a significant relationship between second-hand smoking and laryngopathy (p<0.05). After all compounding factors were adjusted, non-smokers exposed to second-hand smoking had a 2.5 times (RR = 2.47, 95% CI: 1.19–5.08) significantly higher risk of laryngopathy than non-smokers not exposed to second-hand smoking (p<0.05).

Conclusion

In this epidemiological study, there was a significant relationship between second-hand smoking and laryngopathy. More effective anti-smoking policies are required to protect the health of both non-smokers and smokers.

Prioritizing individual genetic variants after kernel machine testing using variable selection

Kernel machine learning methods, such as the SNP-set kernel association test (SKAT), have been widely used to test associations between traits and genetic polymorphisms. In contrast to traditional single-SNP analysis methods, these methods are designed to examine the joint effect of a set of related SNPs (such as a group of SNPs within a gene or a pathway) and are able to identify sets of SNPs that are associated with the trait of interest. However, as with many multi-SNP testing approaches, kernel machine testing can draw conclusion only at the SNP-set level, and does not directly inform on which one(s) of the identified SNP set is actually driving the associations. A recently proposed procedure, KerNel Iterative Feature Extraction (KNIFE), provides a general framework for incorporating variable selection into kernel machine methods. In this article, we focus on quantitative traits and relatively common SNPs, and adapt the KNIFE procedure to genetic association studies and propose an approach to identify driver SNPs after the application of SKAT to gene set analysis. Our approach accommodates several kernels that are widely used in SNP analysis, such as the linear kernel and the Identity by State (IBS) kernel. The proposed approach provides practically useful utilities to prioritize SNPs, and fills the gap between SNP set analysis and biological functional studies. Both simulation studies and real data application are used to demonstrate the proposed approach.

Association between Maternal Smoking during Pregnancy and Low Birthweight: Effects by Maternal Age

Background

Maternal smoking during pregnancy has been consistently related to low birthweight. However, older mothers, who are already at risk of giving birth to low birthweight infants, might be even more susceptible to the effects of maternal smoking. Therefore, this study aimed to examine the modified association between maternal smoking and low birthweight by maternal age.

Methods

Data were obtained from a questionnaire survey of all mothers of children born between 2004 and 2010 in Okinawa, Japan who underwent medical check-ups at age 3 months. Variables assessed were maternal smoking during pregnancy, maternal age, gestational age, parity, birth year, and complications during pregnancy. Stratified analyses were performed using a logistic regression model.

Results

In total, 92641 participants provided complete information on all variables. Over the 7 years studied, the proportion of mothers smoking during pregnancy decreased from 10.6% to 5.0%, while the prevalence of low birthweight did not change remarkably (around 10%). Maternal smoking was significantly associated with low birthweight in all age groups. The strength of the association increased with maternal age, both in crude and adjusted models.

Conclusions

Consistent with previous studies conducted in Western countries, this study demonstrates that maternal age has a modifying effect on the association between maternal smoking and birthweight. This finding suggests that specific education and health care programs for older smoking mothers are important to improve their foetal growth.

Failure time regression with continuous informative auxiliary covariates

In this paper we use Cox’s regression model to fit failure time data with continuous informative auxiliary variables in the presence of a validation subsample. We first estimate the induced relative risk function by kernel smoothing based on the validation subsample, and then improve the estimation by utilizing the information on the incomplete observations from non-validation subsample and the auxiliary observations from the primary sample. Asymptotic normality of the proposed estimator is derived. The proposed method allows one to robustly model the failure time data with an informative multivariate auxiliary covariate. Comparison of the proposed approach with several existing methods is made via simulations. Two real datasets are analyzed to illustrate the proposed method.

Blood cadmium levels are associated with a decline in lung function in males

BACKGROUND

Cadmium exposure was found to cause a decline in lung function among the general population, but these findings were limited to smokers and gender differences were not explored.

OBJECTIVES

To examine the relationship between cadmium and chronic obstructive pulmonary disease (COPD) according to gender and smoking status in Korea.

METHODS

Cross-sectional data from the Korean National Health and Nutrition Examination Survey from 2008 to 2011 were analyzed. COPD was defined by a pre-bronchodilator forced expiratory volume in 1s divided by forced vital capacity of <0.70. A logistic regression model was used to elucidate the association between blood cadmium levels and COPD according to gender and smoking status.

RESULTS

Among 3861 eligible participants, 3622 were included in the analysis. The prevalence of COPD demonstrated an increasing trend in males (P for trend<0.001), but not in females (P for trend=0.67). After adjusting for covariates, a higher blood cadmium level, but within the normal range, was associated with COPD in males, including those who had never-smoked (P for trend <0.001 and P for trend=0.008). However, a higher blood cadmium level was not significantly associated with COPD in females, including those who had never smoked (P for trend=0.39 and P for trend=0.43).

CONCLUSIONS

A higher blood cadmium level, within the normal range, was associated with COPD in males, including those who had never smoked. However, there was no significant association between blood cadmium levels and COPD in females.

Association between length of gestation and cervical DNA methylation of PTGER2 and LINE 1-HS

Worldwide, more than 1 in 10 infants is born prior to 37 weeks gestation. Preterm birth can lead to increased mortality risk and poor life-long health and neurodevelopmental outcomes. Whether environmental risk factors affect preterm birth through epigenetic phenomena is largely unstudied. We sought to determine whether preterm risk factors, such as smoke exposure and education, were associated with cervical DNA methylation in the prostaglandin E receptor 2 gene (PTGER2) and a repetitive element, long interspersed nuclear element-1 Homo sapiens-specific (LINE 1-HS). Second, we aimed to determine whether mid-pregnancy DNA methylation of these regions in cervical samples could predict the length of gestation. We obtained a cervical swab between 16-19 weeks gestation from 80 women participating in a Mexico City birth cohort, used pyrosequencing to analyze DNA methylation of PTGER2 and LINE 1-HS, and examined associations with maternal covariates. We used accelerated failure time models to analyze associations of DNA methylation with the length of gestation. DNA methylation of both sequences was associated with Pap smear inflammation. LINE 1-HS methylation was associated with smoke exposure, BMI and parity. In adjusted models, gestations were 3.3 days longer (95%CI 0.6, 6.0) for each interquartile range of PTGER2 DNA methylation. Higher LINE 1-HS methylation was associated with shorter gestations (-3.3 days, 95%CI -6.5, -0.2). In conclusion, cervical DNA methylation was associated with risk factors for preterm birth and the length of gestation.

Association of polymorphisms in natural killer cell-related genes with preterm birth

Inflammation is implicated in preterm birth, but genetic studies of inflammatory genes have yielded inconsistent results. Maternal DNA from 1,646 participants in the Pregnancy, Infection, and Nutrition Cohort, enrolled in Orange and Wake counties, North Carolina (1995-2005), were genotyped for 432 tag single-nucleotide polymorphisms (SNPs) in 30 candidate genes. Gene-level and SNP associations were modeled within strata of genetic ancestry. Six genes were associated with preterm birth among European Americans: interleukin 12A (IL12A); colony-stimulating factor 2 (CSF2); interferon γ receptor 2 (IFNGR2); killer cell immunoglobulin-like receptor, three domain, long cytoplasmic tail, 2 (KIR3DL2); interleukin 4 (IL4); and interleukin 13 (IL13). Of these, relatively strong single-SNP associations were seen in IFNGR2 and KIR3DL2. Among the 4 genes related to natural killer cell function, 2 (IL12A and CSF2) were consistently associated with reduced risk of prematurity for both European and African Americans. SNPs tagging a locus control region for IL4 and IL13 were associated with an increased risk of spontaneous preterm birth for European Americans (rs3091307; risk ratio = 1.9; 95% confidence interval: 1.4, 2.5). Although gene-level associations were detected only in European Americans, single-SNP associations among European and African Americans were often similar in direction, though estimated with less precision among African Americans. In conclusion, we identified novel associations between variants in the natural killer cell immune pathway and prematurity in this biracial US population.

Active and passive maternal smoking during pregnancy and birth outcomes: the Kyushu Okinawa maternal and child health study

BACKGROUND

In Western countries, active maternal smoking during pregnancy is recognized as the most important preventable risk factor for adverse birth outcomes. However, the effect of passive maternal smoking is less clear and has not been extensively studied. In Japan, there has been only one epidemiological study which examined the effects of active smoking during early pregnancy on birth outcomes although the effects of passive smoking were not assessed.

METHODS

Study subjects were 1565 mothers with singleton pregnancies and the babies born from these pregnancies. Data on active maternal smoking status in the first, second, and third trimesters and maternal environmental tobacco smoke (ETS) exposure at home and work were collected with self-administered questionnaires.

RESULTS

Compared with children born to mothers who had never smoked during pregnancy, children born to mothers who had smoked throughout their pregnancy had a significantly increased risk of small-for-gestational-age (SGA) (adjusted odd ratio [OR] = 2.87; 95% confidence interval: 1.11 - 6.56). However, active maternal smoking only in the first trimester and active maternal smoking in the second and/or third trimesters but not throughout pregnancy were not significantly associated with SGA. With regard to the risk of preterm birth, the adjusted ORs for the above-mentioned three categories were not significant; however, the positive linear trend was significant (P for trend = 0.048). No significant association was found between active maternal smoking during pregnancy and the risk of low birth weight. There was a significant inverse relationship between active maternal smoking during pregnancy and birth weight; newborns of mothers who had smoked throughout pregnancy had an adjusted mean birth weight reduction of 169.6 g. When classifying babies by gender, a significant positive association between active maternal smoking throughout pregnancy and the risk of SGA was found only in male newborns, however, the interaction was not significant. Maternal ETS exposure at home or work was not significantly associated with any birth outcomes.

CONCLUSIONS

This is the first study in Japan to show that active maternal smoking throughout pregnancy, but not during the first trimester, is significantly associated with an increased risk of SGA and a decrease in birth weight. Thus, women who smoke should quit smoking as soon as possible after conception.

Kernel machine SNP-set testing under multiple candidate kernels

Joint testing for the cumulative effect of multiple single-nucleotide polymorphisms grouped on the basis of prior biological knowledge has become a popular and powerful strategy for the analysis of large-scale genetic association studies. The kernel machine (KM)-testing framework is a useful approach that has been proposed for testing associations between multiple genetic variants and many different types of complex traits by comparing pairwise similarity in phenotype between subjects to pairwise similarity in genotype, with similarity in genotype defined via a kernel function. An advantage of the KM framework is its flexibility: choosing different kernel functions allows for different assumptions concerning the underlying model and can allow for improved power. In practice, it is difficult to know which kernel to use a priori because this depends on the unknown underlying trait architecture and selecting the kernel which gives the lowest P-value can lead to inflated type I error. Therefore, we propose practical strategies for KM testing when multiple candidate kernels are present based on constructing composite kernels and based on efficient perturbation procedures. We demonstrate through simulations and real data applications that the procedures protect the type I error rate and can lead to substantially improved power over poor choices of kernels and only modest differences in power vs. using the best candidate kernel.

Bioinformatic analysis of benzo-α-pyrene-induced damage to the human placental insulin-like growth factor-1 gene

INTRODUCTION

Intrauterine growth restriction (IUGR) has been associated with exposure to polyaromatic hydrocarbons (PAHs) which are released in the combustion of oil, fuel, gas, garbage, and tobacco. Pregnant women exposed to PAHs are at risk of the effects of these environmental toxins; for example, benzo-α-pyrene (BαP) is able to enter the blood stream and could contribute to IUGR or other developmental abnormalities via effects on the placental cells. Since IUGR has been associated with decreased cord blood concentrations of immunoreactive insulin-like growth factor 1 (ir-IGF-1) and IUGR has been associated with disordered development and fetal programming, we tested the effects of BαP on human placental trophoblast cells in culture.

EXPERIMENTAL

IGF-1 expression and activation was studied using an immortalized human placental trophoblast cell line (HTR-8). The cells were treated with vehicle control or 1 µmol/L BαP, or 5 µmol/L BαP for 12 hours. RNA was extracted and the exons of IGF-1 were amplified using reverse transcriptase-polymerase chain reaction (RT-PCR). The ir-IGF-1 expression levels were compared using gel electrophoresis. The PCR products were sequenced, and levels of mutation were measured with comparative sequence analysis. A computational protein analysis (computer simulation) was performed in order to assess the potential impact of BαP-associated mutation on IGF-1 protein function.

RESULTS

The IGF-1 expression decreased considerably in BαP-treated cells relative to untreated controls (P < .05), also in a dose-dependent manner. Comparative sequence analysis indicated that the level of BαP exposure correlated with the percentage of base pair mutations in IGF-1 nucleotide sequences for both treatment groups (P < .05). Shifts were observed in the open reading frame, indicating a possible change in the IGF-1 start codon. Protein folding simulation analysis indicated that the base pair changes induced by BαP weakened IGF-1-IGF binding protein (IGFBP) interaction.

CONCLUSIONS

In concordance with the previous findings, exposure of human placental trophoblast cells to BαP exposure results in reduction of IGF-1 expression and base pair mutations. The direct action of BαP on the placenta indicates that it may not be necessary for BαP to access other maternal tissues in order for gene abnormalities to occur. Given that PAHs are known to work through aryl hydrocarbon hydrolase (AHH), these results are likely due to the presence of AHH in HTR cells. Computational modeling of BαP actions on IGF1, substrate-ligand binding, supports the biological premise of this work and underlines the need to determine actual biological effects rather than equating immune to bioactivity of IGF1.

Low level maternal smoking and infant birthweight reduction: genetic contributions of GSTT1 and GSTM1 polymorphisms

BACKGROUND

Genetic susceptibility to tobacco smoke might modify the effect of smoking on pregnancy outcomes.

METHODS

We conducted a case-control study of 543 women who delivered singleton live births in Kaunas (Lithuania), examining the association between low-level tobacco smoke exposure (mean: 4.8 cigarettes/day) during pregnancy, GSTT1 and GSTM1 polymorphisms and birthweight of the infant. Multiple linear-regression analysis was performed adjusting for gestational age, maternal education, family status, body mass index, blood pressure, and parity. Subsequently, we tested for the interaction effect of maternal smoking, GSTT1 and GSTM1 genes polymorphisms with birthweight by adding all the product terms in the regression models.

RESULTS

The findings suggested a birthweight reduction among light-smoking with the GSTT1-null genotype (-162.9 g, P = 0.041) and those with the GSTM1-null genotype (-118.7 g, P = 0.069). When a combination of these genotypes was considered, birthweight was significantly lower for infants of smoking women the carriers of the double-null genotypes (-311.2 g, P = 0.008). The interaction effect of maternal smoking, GSTM1 and GSTT1 genotypes was marginally significant on birthweight (-234.5 g, P = 0.078). Among non-smokers, genotype did not independently confer an adverse effect on infant birthweight.

CONCLUSIONS

The study shows the GSTT1-null genotype, either presents only one or both with GSTM1-null genotype in a single subject, have a modifying effect on birthweight among smoking women even though their smoking is low level. Our data also indicate that identification of the group of susceptible subjects should be based on both environmental exposure and gene polymorphism. Findings of this study add additional evidence on the interplay among two key GST genes and maternal smoking on birth weight of newborns.

Pregnancy, smoking and birth outcomes

This review summarizes the epidemiology and consequences of maternal smoking in pregnancy, with emphasis on the adverse effects on birth outcomes. In developed countries, approximately 15%, and in developing countries, approximately 8% of women smoke cigarettes, and adolescents and women from lower socioeconomic groups are more likely than other women to smoke while pregnant. Maternal smoking during pregnancy is the largest modifiable risk factor for intrauterine growth restriction. A meta-analysis of recent studies showed that the pooled estimate for reduction of mean birthweight was 174 g (95% confidence limits 132-220 g). Other studies confirm a weaker association between maternal smoking and preterm birth. The population attributable risk of low birthweight due to maternal smoking in the UK is estimated to be 29-39%. Tobacco smoke toxins damage the placenta and may lead to placental abruption, abortion or placenta praevia. Infants of mothers who smoke in pregnancy are at an increased risk of respiratory complications including asthma, obesity and, possibly, behavioral disorders. These effects may be dose-related, as there is good evidence that mean birthweight decrements are greater with increased numbers of cigarettes smoked during pregnancy. Cotinine is a useful indicator of tobacco smoke exposure in pregnant women and higher levels in body fluids have been related to lower birthweights. Maternal genetic polymorphisms of the cytochrome P (CYP)450 and glutathione-S-transferase (GST) subfamilies of metabolic genes influence the magnitude of the effect of nicotine exposure on birth outcomes through their influence on nicotine metabolism. Greatly increased risk of cigarette smoke-induced diseases, including low birthweight, has been found in individuals with susceptible genotypes. Interventions to control maternal smoking are also considered.

Behavioral influences on preterm birth: integrated analysis of the pregnancy, infection, and nutrition study

Most previous studies of preterm birth have considered risk factors in isolation rather than examining the collective impact of multiple candidate determinants. In order to examine the combined impact of a set of behavioral risk factors on the risk of preterm birth, we analyzed data collected for the Pregnancy, Infection, and Nutrition Study on a range of sociodemographic, behavioral, and related factors. Women who received prenatal care at selected clinics in central North Carolina and gave birth in the period 1995-2005 were recruited into a prospective cohort study, with 4,251 women providing the required information on risk factors and pregnancy outcome. A number of demographic and behavioral attributes were modestly associated with preterm birth, with odds ratios of 1.3-1.5, including age >35, African-American ethnicity, height of 63 inches or less, parity 2+, and delivery at the academic medical center. Despite weak associations for individual risk factors, changes in a constellation of behaviors during pregnancy predict substantial shifts in the risk of preterm birth, suggesting a reduction from 8 to 3% preterm among those with a low-risk baseline profile, and a reduction from 18 to 7% preterm among those with a high-risk baseline profile. While inferences are limited by the incomplete range of available predictors, uncertainty regarding whether observed associations are causal, and substantial challenges in changing component behaviors, the possibility of substantial reduction in risk merits more serious consideration of whether behavioral interventions could markedly reduce the risk of preterm birth.

An integrated randomized intervention to reduce behavioral and psychosocial risks: pregnancy and neonatal outcomes

While biomedical risks contribute to poor pregnancy and neonatal outcomes in African American (AA) populations, behavioral and psychosocial risks (BPSR) may also play a part. Among low income AA women with psychosocial risks, this report addresses the impacts on pregnancy and neonatal outcomes of an integrated education and counseling intervention to reduce BPSR, as well as the contributions of other psychosocial and biomedical risks. Subjects were low income AA women ≥18 years living in the Washington, DC, metropolitan area and seeking prenatal care. Subjects (n = 1,044) were screened for active smoking, environmental tobacco smoke exposure (ETSE), depression, or intimate partner violence (IPV) and then randomized to intervention (IG) or usual care (UCG) groups. Data were collected prenatally, at delivery, and postpartum by maternal report and medical record abstraction. Multiple imputation methodology was used to estimate missing variables. Rates of pregnancy outcomes (miscarriage, live birth, perinatal death), preterm labor, Caesarean section, sexually transmitted infection (STI) during pregnancy, preterm birth (<37 weeks), low birth weight (<2,500 g), very low birth weight (<1,500 g), small for gestational age, neonatal intensive care unit (NICU) admission, and >2 days of hospitalization were compared between IG and UCG. Logistic regression models were created to predict outcomes based on biomedical risk factors and the four psychosocial risks (smoking, ETSE, depression, and IPV) targeted by the intervention. Rates of adverse pregnancy and neonatal outcomes were high and did not differ significantly between IG and UCG. In adjusted analysis, STI during the current pregnancy was associated with IPV (OR = 1.41, 95% CI 1.04-1.91). Outcomes such as preterm labor, caesarian section in pregnancy and preterm birth, low birth weight, small for gestational age, NICU admissions and >2 day hospitalization of the infants were associated with biomedical risk factors including preexisting hypertension and diabetes, previous preterm birth (PTB), and late initiation of prenatal care, but they were not significantly associated with active smoking, ETSE, depression, or IPV. Neither the intervention to reduce BPSR nor the psychosocial factors significantly contributed to the pregnancy and neonatal outcomes. This study confirms that biomedical factors significantly contribute to adverse outcomes in low income AA women. Biomedical factors outweighed psychosocial factors in contributing to adverse pregnancy and neonatal outcomes in this high-risk population. Early identification and management of hypertension, diabetes and previous PTB in low income AA women may reduce health disparities in birth outcomes. Level of evidence I.

Relationships between self-reported smoking, household environmental tobacco smoke exposure and depressive symptoms in a pregnant minority population

This study sought to examine relationships between depressive symptoms and prenatal smoking and/or household environmental tobacco smoke exposure (HH-ETSE) among urban minority women. We analyzed private, audio computer-assisted self interview data from a clinic-based sample of 929 minority pregnant women in Washington, DC. Depressive symptoms were assessed via the Beck Depression Inventory Fast Screen. HH-ETSE, current smoking, and former smoking were assessed via self-report. Depression levels and demographic characteristics were compared: (1) among nonsmokers, for those reporting HH-ETSE versus no HH-ETSE; and (2) among smokers, for those reporting current smoking (in last 7 days) versus former smokers. Measures associated with HH-ETSE/current smoking in bivariate analysis at P < 0.20 were included in adjusted logistic regression models. HH-ETSE, as a possible indicator of a social smoking network, was assessed as a mediator for the relationship between depression and current smoking.

RESULTS

Non-smokers reporting moderate-to-severe depressive symptoms showed significantly higher adjusted odds of prenatal HH-ETSE (AOR 2.5, 95% CI [1.2, 5.2]). Smokers reporting moderate-to-severe or mild depressive symptoms showed significantly higher adjusted odds of current smoking (AOR 1.9, 95% CI [1.1, 3.5] and AOR 1.8, 95% CI [1.1, 3.1], respectively). Among smokers, HH-ETSE was a significant mediator for the association between moderate-to-severe symptoms and current smoking. In conclusion, health care providers should be aware that depressed urban minority women are at risk of continued smoking/HH-ETSE during pregnancy. Interventions designed to encourage behavior change should include screening for depression, and build skills so that women are better able to address the social environment.

Exploratory quantile regression with many covariates: an application to adverse birth outcomes

Covariates may affect continuous responses differently at various points of the response distribution. For example, some exposure might have minimal impact on conditional means, whereas it might lower conditional 10th percentiles sharply. Such differential effects can be important to detect. In studies of the determinants of birth weight, for instance, it is critical to identify exposures like the one above, since low birth weight is a risk factor for later health problems. Effects of covariates on the tails of distributions can be obscured by models (such as linear regression) that estimate conditional means; however, effects on tails can be detected by quantile regression. We present 2 approaches for exploring high-dimensional predictor spaces to identify important predictors for quantile regression. These are based on the lasso and elastic net penalties. We apply the approaches to a prospective cohort study of adverse birth outcomes that includes a wide array of demographic, medical, psychosocial, and environmental variables. Although tobacco exposure is known to be associated with lower birth weights, the analysis suggests an interesting interaction effect not previously reported: tobacco exposure depresses the 20th and 30th percentiles of birth weight more strongly when mothers have high levels of lead in their blood compared with those who have low blood lead levels.

Associations of LINE-1 DNA Methylation with Preterm Birth in a Prospective Cohort Study

Preterm birth affects over 12% of all infants born in the US yet the biology of early delivery remains unclear, including whether epigenetic mechanisms are involved. We examined associations of maternal and umbilical cord blood long interspersed nuclear element-1 (LINE-1) DNA methylation with length of gestation and odds of preterm birth in singleton pregnancies in Project Viva. In white blood cells from maternal blood during 1(st) trimester (n=914) and 2(nd) trimester (n=922), and from venous cord blood at delivery (n=557), we measured LINE-1 by pyrosequencing (expressed as %5 methyl cytosines within the LINE-1 region analyzed [%5mC]). We ran linear regression models to analyze differences in gestation length, and logistic models for odds of preterm birth (<37 v. ≥37 weeks gestation), across quartiles of LINE-1. Mean(SD) LINE-1 levels were 84.3(0.6), 84.5(0.4), and 84.6(0.7) %5mC for 1(st) trimester, 2(nd) trimester and cord blood, respectively. Mean(SD) gestational age was 39.5(1.8) weeks, and 6.5% of infants were born preterm. After adjustment for maternal age, race/ethnicity, BMI, education, smoking status, and fetal sex, women with the highest vs. lowest quartile of 1(st) trimester LINE-1 had longer gestations (0.45 weeks [95% CI 0.12, 0.78]) and lower odds of preterm birth (OR 0.40 [0.17, 0.94]), whereas associations with cord blood LINE-1 were in the opposite direction (-0.45 weeks, -0.83, -0.08) and (OR 4.55 [1.18, 17.5]). In conclusion, higher early pregnancy LINE-1 predicts lower risk of preterm birth. In contrast, preterm birth is associated with lower LINE-1 in cord blood.

Extracellular matrix dynamics and fetal membrane rupture

The extracellular matrix (ECM) plays an important role in determining cell and organ function: (1) it is an organizing substrate that provides tissue tensile strength; (2) it anchors cells and influences cell morphology and function via interaction with cell surface receptors; and (3) it is a reservoir for growth factors. Alterations in the content and the composition of the ECM determine its physical and biological properties, including strength and susceptibility to degradation. The ECM components themselves also harbor cryptic matrikines, which when exposed by conformational change or proteolysis have potent effects on cell function, including stimulating the production of cytokines and matrix metalloproteinases (MMPs). Collectively, these properties of the ECM reflect a dynamic tissue component that influences both tissue form and function. This review illustrates how defects in ECM synthesis and metabolism and the physiological process of ECM turnover contribute to changes in the fetal membranes that precede normal parturition and contribute to the pathological events leading to preterm premature rupture of membranes (PPROM).

Preconceptional stress and racial disparities in preterm birth: an overview

OBJECTIVE

We reviewed the evidence for three theories of how preconceptional psychosocial stress could act as a contributing determinant of excess preterm birth risk among African American women: early life developmental plasticity and epigenetic programming of adult neuroendocrine systems; blunting, weathering, or dysfunction of neuroendocrine and immune function in response to chronic stress activation through the life course; individuals' adoption of risky behaviors such as smoking as a response to stressful stimuli.

METHODS

Basic science, clinical, and epidemiologic studies indexed in MEDLINE and Web of Science databases on preconceptional psychosocial stress, preterm birth and race were reviewed.

RESULTS

Mixed evidence leans towards modest associations between preconceptional chronic stress and preterm birth (for example common odds ratios of 1.2-1.4), particularly in African American women, but it is unclear whether this association is causal or explains a substantial portion of the Black-White racial disparity in preterm birth. The stress-preterm birth association may be mediated by hypothalamic-pituitary-adrenal axis dysfunction and susceptibility to bacterial vaginosis, although these mechanisms are incompletely understood. Evidence for the role of epigenetic or early life programming as a determinant of racial disparities in preterm birth risk is more circumstantial.

CONCLUSIONS

Preconceptional stress, directly or in interaction with host genetic susceptibility or infection, remains an important hypothesized risk factor for understanding and reducing racial disparities in preterm birth. Future studies that integrate adequately sized epidemiologic samples with measures of stress, infection, and gene expression, will advance our knowledge and allow development of targeted interventions.

Racial and ethnic disparities in United States: stillbirth rates: trends, risk factors, and research needs

As with most adverse health outcomes, there has been long standing and persistent racial and ethnic disparity for stillbirth in the United States. In 2005, the stillbirth rate (fetal deaths ≥ 20 weeks' gestation per 1000 fetal deaths and live births) for non-Hispanic blacks was 11.13 compared with 4.79 for non-Hispanic whites. Rates were intermediate for American Indian or Alaska Natives (6.17) and Hispanics (5.44). There is racial disparity for both early (< 28 weeks' gestation) and late stillbirths. We review available data regarding risk factors for stillbirth with a focus on those factors that are more prevalent in certain racial/ethnic groups and those factors that appear to have a more profound effect in certain racial/ethnic groups. Although many factors, including genetics, environment, stress, social issues, access to and quality of medical care and behavior, contribute to racial disparity in stillbirth, the reasons for the disparity remain unclear. Knowledge gaps and recommendations for further research and interventions intended to reduce racial disparity in stillbirth are highlighted.

Comparison of urine cotinine and the tobacco-specific nitrosamine metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and their ratio to discriminate active from passive smoking

OBJECTIVES

Cotinine is the most widely used biomarker to distinguish active versus passive smoking. However, there is an overlap in cotinine levels when comparing light or occasional smokers versus heavily exposed passive smokers. 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) is a tobacco-specific nitrosamine measurable in urine with a much longer half-life than cotinine. The aim of the study was to determine optimal cutoff points to discriminate active versus passive smokers and to compare sensitivity and specificity for the use of cotinine, NNAL, and the ratio of the NNAL/cotinine in urine.

METHODS

Cotinine and NNAL were measured in urine of 373 active smokers and 228 passive smokers.

RESULTS

Geometric mean cotinine levels were 2.03 ng/ml (interquartile interval: 0.43-8.60) and 1,043 ng/ml (658-2,251) and NNAL levels were 5.80 pg/ml (2.28-15.4) and 165 pg/ml (90.8-360) pg/ml in passive and active smokers, respectively. NNAL/cotinine ratio in urine was significantly higher for passive smokers when compared with active smokers (2.85 vs. 0.16, p < .01). The receiver operating characteristics analysis determined optimal cutoff points to discriminate passive versus active smokers: 31.5 ng/ml for cotinine (sensitivity: 97.1% and specificity: 93.9%), 47.3 pg/ml for NNAL (87.4% and 96.5%), and 0.74 x 10⁻³ for NNAL/cotinine ratio (97.3% and 87.3%).

CONCLUSIONS

Both urine cotinine and NNAL are sensitive and specific biomarkers for discriminating the source of tobacco smoke exposure. Cotinine is the best overall discriminator when biomarkers are measured while a person has ongoing exposure to tobacco smoke. NNAL because of its long half-life would be particularly useful when there is a delay between exposure and biomarker measurement. The NNAL/cotinine ratio provides similar sensitivity but poorer specificity at discriminating passive versus active smokers when compared with NNAL alone.

Epidemiology, determinants, and consequences of cigarette smoking in African American women: an integrative review

Tobacco smoking is a national public health problem that has been associated with numerous adverse health effects, including increased disease and cancer rates. Previous review articles on smoking in specific demographic populations have focused on smoking in women and on smoking in African Americans, but have not considered the dual roles of ethnicity and gender in smoking behavior. African American women (AAW) are an important subgroup to study because they are distinct from non-AAW and their male African American counterparts on biopsychosocial factors that are relevant to smoking behavior. The purpose of the present review paper is to integrate and summarize the current literature on the epidemiology, determinants, and consequences of cigarette smoking among AAW, by contrasting them to relevant comparison groups (non-AAW and African American men). Evidence suggests that AAW are generally more likely to be light smokers and initiate smoking later. The prevalence rates of AAW smokers have decreased over the past 25years, yet AAW are disproportionately affected by several smoking-related illnesses when compared to their ethnic and gender comparison groups. AAW smokers are distinct from relevant comparison groups in metabolic sensitivity to nicotine, aspects of smoking topography, and several psychosocial factors that influence smoking. Although a small literature on smoking in AAW is emerging, further empirical research of AAW smokers could inform the development of tailored interventions for AAW.

Infant birth size is not associated with maternal intake and status of folate during the second trimester in Norwegian pregnant women

Maternal folate status and smoking are potentially strong risk factors for infant birth size. We assessed the association of several folate indicators and smoking with birth outcomes in a subsample of participants in the Norwegian Mother and Child Cohort Study, consisting of 2934 singleton pregnancies in 2002-2003. Blood plasma folate and cotinine concentrations and self-reported intake of food folate and supplemental folic acid were measured during the second trimester (median 18 wk). Birth outcomes included gestational age, infant birth weight, head circumference, crown-heel length, and small for gestational age (SGA). Mean total dietary folate intake from foods (mean 268.0 microg/d) and supplements (mean 187.7 microg/d) was 455.7 microg/d. Smokers (plasma cotinine > or = 85 nmol/L) had substantially lower supplemental folic acid intake than nonsmokers, but they did not differ regarding folate intake from food only. Nevertheless, smoking was correlated with plasma folate both before and after adjusting for total dietary folate intake (both P < 0.001). We found no significant associations of food folate intake, supplemental folic acid use, total dietary folate intake, or plasma folate with the various birth outcomes after adjustment for potential confounders. Consistent with previous studies, infant birth size was strongly predicted by maternal smoking (adjusted odds ratio for SGA: 2.3; 95% CI: 1.6, 3.3). This study of well-nourished Norwegian pregnant women suggests that dietary folate and plasma folate during the second trimester are not risk factors for infant birth size.

Cigarette exposure induces changes in maternal vascular function in a pregnant mouse model

Smoking is associated with multiple adverse pregnancy outcomes, including fetal growth restriction. The objective of this study was to determine whether cigarette smoke exposure during pregnancy in a mouse model affects the functional properties of maternal uterine, mesenteric, and renal arteries as a possible mechanism for growth restriction. C57Bl/CJ mice were exposed to whole body sidestream smoke for 4 h/day. Smoke particle exposure was increased from day 4 of gestation until late pregnancy (day 16-19), with mean total suspended particle levels of 63 mg/m(3), representative of moderate-to-heavy smoking in humans. Uterine, mesenteric, and renal arteries from late-pregnant and virgin mice were isolated and studied in a pressure-arteriograph system (n = 23). Plasma cotinine was measured by ELISA. Fetal weights were significantly reduced in smoke-exposed compared with control fetuses (0.88 +/- 0.1 vs. 1.0 +/- 0.08 g, P < 0.02), while litter sizes were not different. Endothelium-mediated relaxation responses to methacholine were significantly impaired in both the uterine and mesenteric vasculature of pregnant mice exposed to cigarette smoke during gestation. This difference was not apparent in isolated renal arteries from pregnant mice exposed to cigarette smoke; however, relaxation was significantly reduced in renal arteries from smoke-exposed virgin mice. In conclusion, we found that passive cigarette smoke exposure is associated with impaired vascular relaxation of uterine and mesenteric arteries in pregnant mice. Functional maternal vascular perturbations during pregnancy, specifically impaired peripheral and uterine vasodilation, may contribute to a mechanism by which smoking results in fetal growth restriction.

Consequences of smoking and caffeine consumption during pregnancy in women with type 1 diabetes

OBJECTIVE

To test the hypothesis that, in women with type 1 diabetes, prenatal smoking and caffeine consumption during pregnancy are associated with an increased risk of adverse maternal and perinatal outcomes.

METHODS

A secondary analysis of data on pregnant women with type 1 diabetes from an interdisciplinary program of Diabetes in Pregnancy. Women were interviewed monthly, by a trained non-medical member of the research team, using a standardized questionnaire, to ascertain daily smoking habits and caffeine consumption.

RESULTS

Smoking and caffeine information were available on 191 pregnancies, 168 progressing beyond 20 weeks of gestation. Early pregnancy smoking (OR 3.3, 95% CI 1.2, 8.7) and caffeine consumption (OR 4.5, 95% CI 1.2, 16.8) were associated with increased risk of spontaneous abortion when controlling for age, years since diagnosis of diabetes, previous spontaneous abortion, nephropathy and retinopathy. Smoking throughout pregnancy was significantly associated with decreased birth weight and prolonged neonatal hospital stay. Smoking throughout pregnancy (OR 0.2, 95% 0.1, 1.0) and caffeine consumption after 20 weeks (OR 0.3, 95% CI 0.1, 1.0) were associated with reduced risk of pre-eclampsia.

CONCLUSIONS

Caffeine consumption during early pregnancy, regardless of glycemic control, increases the risk of spontaneous abortion. Smoking throughout pregnancy and caffeine consumption are associated with reduced risk of pre-eclampsia.

What causes racial disparities in very preterm birth? A biosocial perspective

Very preterm birth (<32 weeks' gestation) occurs in approximately 2% of livebirths but is a leading cause of infant mortality and morbidity in the United States. African-American women have a 2-fold to 3-fold elevated risk compared with non-Hispanic white women for reasons that are incompletely understood. This paper reviews the evidence for the biologic and social patterning of very preterm birth, with attention to leading hypotheses regarding the etiology of the racial disparity. A systematic review of the literature in the MEDLINE, CINAHL, PsycInfo, and EMBASE indices was conducted. The literature to date suggests a complex, multifactorial causal framework for understanding racial disparities in very preterm birth, with maternal inflammatory, vascular, or neuroendocrine dysfunction as proximal pathways and maternal exposure to stress, racial differences in preconceptional health, and genetic, epigenetic, and gene-environment interactions as more distal mediators. Interpersonal and institutionalized racism are mechanisms that may drive racially patterned differences. Current literature is limited in that research on social determinants and biologic processes of prematurity has been generally disconnected. Improved etiologic understanding and the potential for effective intervention may come with better integration of these research approaches.

Maternal smoking, GSTM1 and GSTT1 polymorphism and susceptibility to adverse pregnancy outcomes

The objective of the study was to investigate the association between maternal smoking, GSTM1, GSTT1 polymorphism, low birth weight (LBW, < 2,500 g) and intra-uterine growth restriction (IUGR, < 2,500 g and gestation ≥ 37 weeks) risk. Within a prospective cohort study in Kaunas (Lithuania), a nested case-control study on LBW and IUGR occurrence among 646 women with genotyping of GSTT1 and GSTM1 polymorphisms who delivered live singletons was conducted. Multivariate logistic regression analysis was used to study the association of maternal smoking and polymorphism in two genes metabolizing xenobiotics. Without consideration of genotype, light-smoking (mean 4.8 cigarettes/day) during pregnancy was associated with a small increase in LBW risk, adjusted OR 1.21; 95% CI 0.44 – 3.31. The corresponding odds for IUGR risk was 1.57; 95% CI 0.45 – 5.55. The findings suggested the greater LBW risk among light-smoking mothers with the GSTM1-null genotype (OR 1.91; 95% CI 0.43 – 8.47) compared to those with GSTM1-present genotype (OR 1.11; 95% CI 0.26 – 4.47). When both GSTM1 and GSTT1 genotypes were considered, the synergistic effect was found among smoking mothers: GSTT1-present and GSTM1-null genotype OR for LBW was 3.31; 95% CI 0.60–18.4 and that for IUGR was 2.47; 95% CI 0.31 – 13.1. However there was no statistically significant interaction between maternal smoking, GSTT1- present and GSTM1-null genotypes for LBW (OR 1.45; 95% CI 0.22 – 10.1, p = 0.66) and for IUGR (OR 1.10; 95% CI 0.10 – 12.6, p = 0.93). The results of this study suggested that smoking, even at a low-level, ought to be considered a potential risk factor for adverse birth outcomes and that genetic polymorphism may contribute to individual variation in tobacco smoke response.

Environmental tobacco smoke avoidance among pregnant African-American nonsmokers

BACKGROUND

Environmental tobacco smoke (ETS) exposure during pregnancy contributes to adverse infant health outcomes. Limited previous research has focused on identifying correlates of ETS avoidance. This study sought to identify proximal and more distal correlates of ETS avoidance early in pregnancy among African-American women.

METHODS

From a sample of low-income, black women (n=1044) recruited in six urban, prenatal care clinics (July 2001-October 2003), cotinine-confirmed nonsmokers with partners, household/family members, or friends who smoked (n=450) were identified and divided into two groups: any past-7-day ETS exposure and cotinine-confirmed ETS avoidance. Bivariate and multivariate logistic regression analyses identified factors associated with ETS avoidance. Data were initially analyzed in 2004. Final models were reviewed and revised in 2007 and 2008.

RESULTS

Twenty-seven percent of pregnant nonsmokers were confirmed as ETS avoiders. In multivariate logistic regression analysis, the odds of ETS avoidance were increased among women who reported household smoking bans (OR=2.96; 95% CI=1.83, 4.77; p<0.0001), that the father wanted the baby (OR=2.70; CI=1.26, 5.76; p=0.01), and that no/few family members/friends smoked (OR=3.15; 95% CI=1.58, 6.29; p<0.001). The odds were decreased among women who had a current partner (OR=0.42; 95% CI=0.23, 0.76; p<0.01), reported any intimate partner violence during pregnancy (OR=0.43; 95% CI=0.19, 0.95; p<0.05), and reported little social support to prevent ETS exposure (OR=0.50; 95% CI=0.30, 0.85; p=0.01). Parity, emotional coping strategies, substance use during pregnancy, partner/household member smoking status, and self-confidence in avoiding ETS were significant in bivariate, but not multivariate analyses.

CONCLUSIONS

Social contextual factors were the strongest determinants of ETS avoidance during pregnancy. Results highlight the importance of prenatal screening to identify pregnant nonsmokers at risk, encouraging household smoking bans, gaining support from significant others, and fully understanding the interpersonal context of a woman's pregnancy before providing behavioral counseling and advice to prevent ETS exposure.

Prenatal smoking exposure and asymmetric fetal growth restriction

BACKGROUND

Prenatal smoking exposure causes intrauterine fetal growth restriction (IUGR), although its effects on fetal proportionality are less clearly defined.

AIM

The present study assessed fetal proportionality in babies with IUGR using maternal salivary cotinine to indicate maternal smoking exposure.

SUBJECTS AND METHODS

A case-control study at the Liverpool Women's Hospital, UK of babies with asymmetric and symmetric IUGR and non-growth restricted babies was carried out.

RESULTS

270 white women including 90 IUGR cases and 180 controls were enrolled. Asymmetry presented in 52.2% of IUGR cases. Geometric mean maternal cotinine concentration was higher with asymmetric (p=0.002) than symmetric IUGR (p=0.07), when compared to controls. Maternal smoking exposure was independently associated with asymmetric IUGR (OR 2.4, 95% CI, 1.5-4.4, p</=0.001). Maternal anaemia was more frequent in babies with symmetric IUGR (OR 1.9, 1.3-3.4, p=0.002), but not in asymmetric babies. Rohrer's index ranged between 1.64 and 2.25 for asymmetric infants and significantly decreased with increasing maternal cotinine concentration in IUGR babies. Increased cotinine was not associated with shortened gestational age in IUGR babies.

CONCLUSIONS

Asymmetric IUGR occurred more frequently in heavy smokers. Stopping smoking even late in pregnancy may be beneficial for improved fetal outcomes. Symmetric IUGR was associated with maternal anaemia, highlighting the importance of prenatal nutritional status.

Neighbourhood deprivation and small-for-gestational-age term births in the United States

Residential context has received increased attention as a possible contributing factor to race/ethnic and socio-economic disparities in birth outcomes in the United States. Utilising vital statistics birth record data, this study examined the association between neighbourhood deprivation and the risk of a term small-for-gestational-age (SGA) birth among non-Hispanic whites and non-Hispanic blacks in eight geographical areas. An SGA birth was defined as a newborn weighing <10th percentile of the sex- and parity-specific birthweight distribution for a given gestational week. Multi-level random intercept logistic regression models were employed and statistical tests were performed to examine whether the association between neighbourhood deprivation and SGA varied by race/ethnicity and study site. The risk of term SGA was higher among non-Hispanic blacks (range 10.8-17.5%) than non-Hispanic whites (range 5.1-9.2%) in all areas and it was higher in cities than in suburban locations. In all areas, non-Hispanic blacks lived in more deprived neighbourhoods than non-Hispanic whites. However, the adjusted associations between neighbourhood deprivation and term SGA did not vary significantly by race/ethnicity or study site. The summary fully adjusted pooled odds ratios, indicating the effect of one standard deviation increase in the deprivation score, were 1.15 [95% CI 1.08, 1.22] for non-Hispanic whites and 1.09 [95% CI 1.05, 1.14] for non-Hispanic blacks. Thus, neighbourhood deprivation was weakly associated with term SGA among both non-Hispanic whites and non-Hispanic blacks.

African American adolescents and menthol cigarettes: smoking behavior among secondary school students

PURPOSE

This paper examines the impact of smoking menthol cigarettes among secondary students, primarily African Americans, across five measures of smoking behavior.

METHODS

Data were gathered from a 2006 survey of six secondary schools in a large urban area in the southeastern United States. Ordered logit analysis is employed to estimate race and menthol effects on cigarette consumption.

RESULTS

African American youth smoke at lower rates than white adolescents; menthol smokers consume cigarettes at higher rates irrespective of race. Most importantly, there is a strong interaction effect with black menthol smokers demonstrating the highest levels of cigarette consumption.

CONCLUSIONS

There is a need to provide adolescent and adult African Americans accurate information on the dangers of menthol cigarettes. Any proposed legislation should consider the special problems of menthol and its relationship to high cigarette consumption, especially for African American adolescents.

Maternal exposure to environmental tobacco smoke, GSTM1/T1 polymorphisms and oxidative stress

Environmental tobacco smoking (ETS) is known to be associated with adverse pregnancy outcomes. The purpose of this study was to investigate the relationship between maternal exposure to ETS and oxidative stress for neonates, as well as the effect of maternal genetic polymorphisms, glutathione-S-transferase M1 (GSTM1) and GSTT1, on this relationship. We used the radioimmunoassay to measure the urinary concentration of cotinine in 266 pregnant women who denied smoking cigarettes during pregnancy and in their singleton babies. In addition, the urinary concentration of malondialdehyde (MDA) and 8-hydroxy-2-deoxyguanosine (8-OH-dG) were assessed using high-performance liquid chromatography and enzyme-linked immunosorbent assay, respectively. We also extracted DNA from whole blood obtained from the mothers and then conducted polymerase chain reaction on the samples to determine the GSTM1 and GSTT1 genotypes. The maternal cotinine concentration was found to be significantly associated with the fetal cotinine concentration, particularly for mothers whose urine cotinine concentrations were above 120 microg/gcr (p<0.01). The fetal urine cotinine concentration was also found to be significantly associated with the fetal urine MDA concentration (p<0.01). When the null type maternal GSTM1 or the wild type GSTT1 was present, the maternal oxidative stress level increased significantly as the maternal continine concentration increased (MDA: p<0.01; 8-OH-dG: p<0.01). No significant relationships were found between maternal cotinine and fetal oxidative stress markers, however, the fetal MDA levels increased significantly as fetal cotinine levels increased. These results suggest that the maternal exposure to ETS affects the fetal urine cotinine concentration and induces production of maternal oxidative stress. In addition, maternal genetic polymorphisms of GSTM1 and GSTT1 may modify the oxidative stress by maternal exposure to ETS.

Smoking and risk of preterm birth among predominantly Puerto Rican women

PURPOSE

Studies of smoking during pregnancy and preterm birth among Hispanic women are sparse. Our goal was to evaluate the effect of cigarette smoking during pre-pregnancy, early pregnancy, and mid pregnancy on preterm birth among Hispanic women, the fastest growing ethnic group in the United States.

METHODS

We evaluated data from a prospective cohort study of 1,041 Hispanic (predominantly Puerto Rican) women recruited between 2000 and 2004 in Springfield, Massachusetts. At recruitment (mean = 15 weeks), women reported their smoking since pregnancy awareness (early pregnancy) and in the year prior to pregnancy (pre-pregnancy). Mid pregnancy smoking was collected at a second interview (mean = 28 weeks).

RESULTS

Smoking in pre-pregnancy was not associated with preterm birth. After adjustment for age, parity, education, and illicit drug use, women who smoked in early pregnancy had 1.6 times the risk of preterm birth (95% confidence interval [CI], 1.0-2.7) compared with nonsmokers. Women who smoked in mid pregnancy had 2.1 times the risk of preterm birth (95% CI, 1.0-4.2) compared with nonsmokers with a trend of increased risk of preterm birth with increasing levels of smoking (p trend, 0.03).

CONCLUSIONS

Smoking in early or mid pregnancy increased the risk of spontaneous preterm birth in a Hispanic population.

Within prisons, is there an association between the quantity of prenatal care and infant birthweight?

There is still controversy surrounding the effectiveness of prenatal care in reducing low birthweight. In addition, very few studies have assessed the relationship between prenatal care and infant birthweight among pregnant women within the prison system. We sought to ascertain whether there is an association between the quantity of prenatal care and infant birthweight among pregnant women within such a setting. We examined the prison medical records of 147 infants born to women delivering at term (37-41 weeks of gestation) between 1 January 2002 and 31 December 2004 who were incarcerated during pregnancy in Texas state prisons. Linear regression was used to evaluate the association between the number of prison prenatal care visits and infant birthweight while adjusting for potential confounders (age, gravidity, maternal education, maternal race, history of substance use, history of alcohol use, history of tobacco use and the presence of any chronic disease). We also adjusted for the interaction between the gestational age at admission to prison and the number of prison prenatal care visits. There was a statistically significant 120.5 g increase in adjusted mean birthweight with each additional prison prenatal care visit (P = 0.001) among study infants whose mothers entered prison during the first trimester. This trend was not observed among women who came in after the first trimester. There appears to be a positive association between the amount of prison prenatal care and infant birthweight among incarcerated pregnant women delivering at term, but this association appears to be limited to women entering prison during the first trimester of pregnancy.

Estimation of urinary cotinine cut-off points distinguishing non-smokers, passive and active smokers

An objective assessment of exposure to tobacco smoke may be accomplished by means of examining particular biomarkers in body fluids. The most common biomarker of tobacco smoke exposure is urinary, or serum, cotinine. In order to distinguish non-smokers from passive smokers and passive smokers from active smokers, it is necessary to estimate cotinine cut-off points. The objective of this article was to apply statistical distribution of urinary cotinine concentration to estimate cut-off points distinguishing the three above-mentioned groups. The examined group consisted of 327 volunteers (187 women and 140 men) who were ethnically homogenous inhabitants of the same urban agglomeration (Sosnowiec, Poland). The values which enabled differentiation of the examined population into groups and subgroups were as follows: 50 microg l(-1) (differentiation of non-smokers from passive smokers), 170 microg l(-1) (to divide the group of passive smokers into two subgroups: minimally and highly exposed to environmental tobacco smoke), 550 microg l(-1) (differentiation of passive smokers from active smokers), and 2100 microg l(-1) (to divide group of active smokers into two subgroups: minimally and highly exposed to tobacco smoke). The results suggest that statistical distribution of urinary cotinine concentration is useful for estimating urinary cotinine cut-off points and for assessing the smoking status of persons exposed to tobacco smoke.

Structured measurement error in nutritional epidemiology: applications in the Pregnancy, Infection, and Nutrition (PIN) Study

Preterm birth, defined as delivery before 37 completed weeks' gestation, is a leading cause of infant morbidity and mortality. Identifying factors related to preterm delivery is an important goal of public health professionals who wish to identify etiologic pathways to target for prevention. Validation studies are often conducted in nutritional epidemiology in order to study measurement error in instruments that are generally less invasive or less expensive than "gold standard" instruments. Data from such studies are then used in adjusting estimates based on the full study sample. However, measurement error in nutritional epidemiology has recently been shown to be complicated by correlated error structures in the study-wide and validation instruments. Investigators of a study of preterm birth and dietary intake designed a validation study to assess measurement error in a food frequency questionnaire (FFQ) administered during pregnancy and with the secondary goal of assessing whether a single administration of the FFQ could be used to describe intake over the relatively short pregnancy period, in which energy intake typically increases. Here, we describe a likelihood-based method via Markov Chain Monte Carlo to estimate the regression coefficients in a generalized linear model relating preterm birth to covariates, where one of the covariates is measured with error and the multivariate measurement error model has correlated errors among contemporaneous instruments (i.e. FFQs, 24-hour recalls, and/or biomarkers). Because of constraints on the covariance parameters in our likelihood, identifiability for all the variance and covariance parameters is not guaranteed and, therefore, we derive the necessary and suficient conditions to identify the variance and covariance parameters under our measurement error model and assumptions. We investigate the sensitivity of our likelihood-based model to distributional assumptions placed on the true folate intake by employing semi-parametric Bayesian methods through the mixture of Dirichlet process priors framework. We exemplify our methods in a recent prospective cohort study of risk factors for preterm birth. We use long-term folate as our error-prone predictor of interest, the food-frequency questionnaire (FFQ) and 24-hour recall as two biased instruments, and serum folate biomarker as the unbiased instrument. We found that folate intake, as measured by the FFQ, led to a conservative estimate of the estimated odds ratio of preterm birth (0.76) when compared to the odds ratio estimate from our likelihood-based approach, which adjusts for the measurement error (0.63). We found that our parametric model led to similar conclusions to the semi-parametric Bayesian model.

[The concentration of the chosen smoke toxicity biomarkers among smokers suffering from larynx cancer]

INTRODUCTION

An incidence of laryngeal cancer is strongly connected with exposure to tobacco smoke containing dozens of carcinogens. Genotoxic agents such as polycyclic aromatic hydrocarbons present in tobacco smoke are responsible for lesions of structure DNA and formation of DNA adducts by metabolically activated intermediates. Detecting the presence of DNA adducts in human tissues is therefore, a tool for studies of cancer. An evidence demonstrates that DNA adducts are useful markers of carcinogen exposure. The aim of this work was estimation of relationship between cigarette smoke exposure, determined as urinary cotinine and urinary 1-hydroxypyrene concentration, and number of aromatic-DNA adducts in blood lymphocytes.

MATERIAL AND METHODS

The study group consisted of 60 men at the age of 45 up to 65 years - 20 healthy non-smokers, 20 healthy current smokers and 20 current smokers with primary larynx cancer, which was classified histopathologically as squamous cell carcinoma. The cotinine and 1-hydroxypyrene were determined in the urine with high performance liquid chromatography. Analysis of DNA adducts was performed by the 32P - postlabelling method.

RESULTS

Urinary cotinine concentration in healthy smokers and cancer subjects in comparison with non-smokers was significant higher than in non-smokers, respectively, 29- and 31-fold higher but differences between healthy and sicks smokers were insignificant. Concentration of 1-hydroxypyrene in urine of healthy and cancer subjects was significantly higher (9- and 10-fold higher, respectively) compared with non-smokers. The highest level of aromatic-DNA adducts was found in lympfocytes of healthy smokers but differences between number of adducts in healthy smokers compared with non-smokers (+35%) and cancer subjects (+7,1%) were insignificant. The Pearson's coefficient (r) for the correlation between aromatic-DNA level and urinary cotinine or 1-hydroxypyrene concentration were significant only in cancer subjects group (r = 0,676, p = 0,011 and r = 0,465, p = 0,039, respectivelly).

CONCLUSIONS

The results suggest that cotinine and 1-hydroxypyrene concentration in urine are useful biomarkers of the tobacco smoke exposure. In contrast the levels of aromatic-DNA adducts in lymphocytes are not suitable for that purpose. It seems that none of investigated compounds are the risk predictor of larynx cancer.

Born too soon: the continuing challenge of preterm labor and birth in the United States

Prematurity is the single greatest cause of morbidity and mortality in obstetrics. Families, health care services, and education systems experience the impact of prematurity for the lifetime of the preterm-born child. Health care providers have tried to lower the preterm birth rate with prevention both before and during pregnancy and intervention for symptomatic women. The inability of the health care system to significantly decrease the incidence of preterm birth continues to be a challenge. To further complicate the situation, new data shows that infants born between 34 and 37 weeks' gestation who were thought to have minimal long-term effects of preterm birth may be more at risk than previously appreciated. This article reviews evidence-based risk identification, prevention, and management of women experiencing preterm labor and birth.

Smoking among pregnant women in Cantabria (Spain): trend and determinants of smoking cessation

Background

Cantabria (Spain) has one of the highest prevalence of smoking among women of the European Union. The objectives are to assess the trend of smoking during pregnancy in a five-year period and the determinants of smoking cessation during pregnancy in Cantabria.

Methods

A 1/6 random sample of all women delivering at the reference hospital of the region for the period 1998–2002 was drawn, 1559 women. Information was obtained from personal interview, clinical chart, and prenatal care records. In the analysis relative risks and 95% confidence intervals were estimated. Multivariable analysis was carried out using stepwise logistic regression.

Results

Smoking prior to pregnancy decreased from 53.6% in 1998 to 39.4% in 2002. A decrease in smoking cessation among women smoking at the beginning of pregnancy was observed, from 37.3% in 1998 to 20.6% in 2002. The mean number of cigarettes/day (cig/d) before pregnancy remained constant, around 16 cig/d, whereas a slight trend to increase over time was seen, from 7.7 to 8.9 cig/d. In univariate analysis two variables favoured significantly smoking cessation, although they were not included in the stepwise logistic regression analysis, a higher education level and to be married. The logistic regression model included five significant predictors (also significant in univariate analysis): intensity of smoking, number of previous pregnancies, partner's smoking status, calendar year of study period (these four variables favoured smoking continuation), and adequate prenatal care (which increased smoking cessation).

Conclusion

The frequency of smoking among pregnant women is very high in Cantabria. As smoking cessation rate has decreased over time, a change in prenatal care programme on smoking counseling is needed. Several determinants of smoking cessation, such as smoking before pregnancy and partner's smoking, should be also addressed by community programmes.

Possible effects on smokers of cigarette mentholation: a review of the evidence relating to key research questions

Menthol (2-isopropyl-5-methyl-cyclohexan-1-ol) is used in food, pharmaceutical, and tobacco products. Despite its long usage history and GRAS status, scientific literature on effects of cigarette mentholation is limited. Because African-American men have high lung cancer rates and predominantly smoke mentholated cigarettes, and because menthol's cooling effect might affect puffing and smoke inhalation, possible adverse effects of cigarette mentholation have been suggested. We review the evidence on the effects of mentholation on smokers, and we also identify areas for further study. Five large epidemiological studies provide no evidence that cigarette mentholation increases lung cancer risk. Mentholation cannot explain the higher risk for lung cancer in African-American male smokers, who also predominantly smoke mentholated cigarettes. Limited data on other cancers also suggest no risk from mentholation. The scientific literature suggests that cigarette mentholation does not increase puff number or puff volume of smoked cigarettes, and has little or no effect on heart rate, blood pressure, uptake of carbon monoxide, tar intake or retention, or blood cotinine concentration. Mentholation has little effect on other smoke constituents, and no apparent effect on nicotine absorption, airway patency and smoking initiation, dependency or cessation. Any toxicological effects of cigarette mentholation on adult smokers are probably quite limited.

Psychosocial and spiritual factors associated with smoking and substance use during pregnancy in African American and White low-income women

OBJECTIVE

To determine the associations between sociodemographic, psychosocial, and spiritual factors to health risk behaviors during pregnancy in African American and White low-income women.

DESIGN

Descriptive, using prenatal interviews and medical record review as data sources.

SETTING

An urban prenatal clinic in the Midwestern United States.

PARTICIPANTS

One hundred thirty ethnically diverse low-income women.

MAIN OUTCOME MEASURES

Smoking and substance use in pregnancy.

RESULTS

For the total sample, 39% reported smoking and 28% reported substance use in pregnancy. Significant predictors of smoking were White race, less than high school education, abuse, and religiosity. Abuse and depressive symptoms predicted substance use. African American women were significantly less likely to report smoking in pregnancy (28%) than were White women (55%) (p < .05). African American women who smoked during pregnancy were significantly more likely to report lower levels of education (p < .01), less social support from others (p < .01) and total social support (p < .01), higher levels of stress (p < .05), and more frequent substance use (56.5%) than African American women who did not smoke (12%) (p < .001). White women who used substances were significantly more likely to report smoking (p < .01), abuse (p < .05), and a history of delivering a preterm or low-birthweight infant (p < .01) than the White women who did not.

CONCLUSION

Integrating social support and stress-relieving activities in smoking cessation interventions, particularly for African American women, may reduce health risk behaviors, eliminate health disparities, and improve maternal and infant quality of life.

Prediction of Preterm Delivery by Sonographic Estimation of Cervical Length

BACKGROUND

Identification of pregnant women presenting with threatened preterm labor who are destined to deliver prematurely would greatly assist planning their management.

OBJECTIVES

The purpose of the study was to evaluate the ultrasonographic measurement of cervical length as a prognostic factor for predicting preterm birth in cases of threatened preterm labor.

METHODS

The study included 104 women with singleton pregnancies who presented with threatened preterm labor at 24-36 weeks of gestation. Cervical length at presentation was evaluated by transvaginal ultrasonography. Other potential prognostic factors, such as previous history of preterm labor, smoking, parity and administration of tocolytics were assessed. All women were observed for preterm delivery within 7 days of presentation.

RESULTS

The only significant predictor of preterm delivery was cervical length assessed by ultrasound (p<0.000001, odds ratio 93.3, 95% Cl 10.4-837.1).

CONCLUSIONS

Cervical length assessed by transvaginal ultrasonography in women presenting with threatened preterm labor is a powerful predictive tool for progression to preterm delivery.