Influence of smoking and snuff cessation on risk of preterm birth

Impact of Maternal Smoking on Obstetric and Neonatal Outcomes in Twin Pregnancies: A Narrative Review

Maternal smoking, including both traditional cigarettes and electronic ones, is a significant modifiable risk factor associated with adverse perinatal outcomes, especially in twin pregnancies. This narrative review aims to explore the impact of maternal smoking on obstetric and neonatal outcomes in twin pregnancies, which inherently carry a higher risk of complications. A literature search was conducted using the PubMed and EMBASE databases, selecting studies published between January 1994 and October 2024. The findings demonstrate a clear association between smoking and increased risks of preterm birth and fetal growth restriction (FGR) in twin pregnancies. These risks are exacerbated when smoking is combined with other factors, such as preeclampsia and elevated body mass index (BMI). Smoking was also associated with long-term post-natal complications, including respiratory problems like asthma, as well as cognitive and behavioral disorders. However, an association with preeclampsia was not found, and further studies are needed to clarify the relationship in the fields of preterm premature rupture of membranes (PPROM) and fetal death. The adverse effects of smoking are primarily due to reduced oxygen supply to the fetus, caused by nicotine-induced vasoconstriction and carbon monoxide exposure, leading to placental insufficiency and fetal hypoxia. These effects are amplified in twin pregnancies due to the increased physiological demands. The review highlights that smoking cessation interventions during pregnancy are crucial to mitigate these risks and improve maternal and neonatal health outcomes.

The double-edged nature of nicotine: toxicities and therapeutic potentials

Nicotine is the primary addictive component of cigarette smoke and is associated with various smoking-related diseases. However, recent research has revealed its broader cognitive-enhancing and anti-inflammatory properties, suggesting its potential therapeutic applications in several conditions. This review aims to examine the double-edged nature of nicotine, encompassing its positive and negative effects. We provide a concise overview of the physiochemical properties and pharmacology of nicotine, including insights into nicotine receptors. Therefore, the article is divided into two main sections: toxicity and therapeutic potential. We comprehensively explored nicotine-related diseases, focusing on specific signaling pathways and the underlying mechanisms that contribute to its effects. Furthermore, we addressed the current research challenges and future development perspectives. This review aims to inspire future researchers to explore the full medical potential of nicotine, which holds significant promise for the clinical management of specific diseases.

Maternal use of snus as smokeless tobacco in pregnancy and infant lung function

Background

Smoking in pregnancy has detrimental effects on infant respiratory health, while the effects of other nicotine-containing products on infant lung function are unclear. We aimed to explore if smokeless tobacco such as snus used in pregnancy increased the risk of lower lung function in infancy and if the associations differed by sex.

Methods

From the Scandinavian population-based Preventing Atopic Dermatitis and ALLergies in Children birth cohort, we included 1163 infants with available tidal flow-volume measurements at 3 months of age and maternal self-reported use of nicotine-containing products in pregnancy. The risk of a ratio of time to peak tidal expiratory flow to total expiratory time <25th percentile by any nicotine exposure, snus exclusively and cigarette smoking with or without other nicotine-containing products was explored by regression analyses adjusting for maternal age, education and asthma.

Results

Overall 120 out of 1163 (10.3%) infants were exposed to any nicotine in utero, 71 out of 120 by snus exclusively and 49 out of 120 by smoking, with six also exposed to snus. By pregnancy week 6, 85.8% of mothers reported stopping nicotine use. The risk of lower lung function was higher in children exposed in utero to nicotine-containing products with an odds ratio (OR) of 1.63 (95% confidence interval (CI) 1.02-2.59) with a similar tendency for snus exclusively (OR 1.55, 95% CI 0.88-2.71) and smoking (OR 1.79, 0.84-3.84). Effect estimates were similar after adjusting for covariates. No differences of the effect by sex were observed.

Conclusion

Our study suggests that in utero exposure to not only cigarettes, but also snus, may negatively affect infant lung function.

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

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

Use of Swedish smokeless tobacco during pregnancy: A systematic review of pregnancy and early life health risk

BACKGROUND AND AIMS

Smokeless tobacco is a heterogeneous product group with diverse composition and prevalence globally. Tobacco use during pregnancy is concerning due to the risk of adverse pregnancy outcomes and effects on child health. Nicotine may mediate several of these effects. This systematic review measured health outcomes from Swedish smokeless tobacco (snus) use during pregnancy.

METHOD

Literature search was conducted by an information specialist in May 2022. We included human studies of snus use during pregnancy compared with no tobacco use, assessed risk of bias, conducted a meta-analysis and assessed confidence in effect-estimates using Grading of Recommendations, Assessment, Development and Evaluations (GRADE).

RESULTS

We included 18 cohort studies (42 to 1 006 398 participants). Snus use during pregnancy probably (moderate confidence in risk estimates) increase the risk of neonatal apnea, adjusted odds ratio 95% confidence interval [aOR (95% CI)] 1.96 (1.30 to 2.96). Snus use during pregnancy possibly (low confidence in risk estimates) increase the risk of stillbirths aOR 1.43 (1.02 to 1.99), extremely premature births aOR 1.69 (1.17 to 2.45), moderately premature birth aOR 1.26 (1.15 to 1.38), SGA aOR 1.26 (1.09 to 1.46), reduced birth weight mean difference of 72.47 g (110.58 g to 34.35 g reduction) and oral cleft malformations aOR 1.48 (1.00 to 2.21). It is uncertain (low confidence in risk estimates, CI crossing 1) whether snus use during pregnancy affects risk of preeclampsia aOR 1.11 (0.97 to 1.28), antenatal bleeding aOR 1.15 (0.92 to 1.44) and very premature birth aOR 1.26 (0.95 to 1.66). Risk of early neonatal mortality and altered heart rate variability is uncertain, very low confidence. Snus using mothers had increased prevalence of caesarean sections, low confidence.

CONCLUSIONS

This systematic review reveals that use of smokeless tobacco (snus) during pregnancy may adversely impact the developing child.

Polycyclic aromatic hydrocarbons (PAHs) may explain the paradoxical effects of cigarette use on preeclampsia (PE)

Tobacco smoking and use of snus (smokeless tobacco) are associated with adverse effects on pregnancy and neonatal outcomes. Nicotine is considered a key toxicant involved in effects caused by both smoking and snus, while pyrolysis products including polycyclic aromatic hydrocarbons (PAHs) in cigarette smoke represents the constituents most unequally divided between these two groups of tobacco products. The aim of this review was: i) to compare the impact, in terms of relative effect estimates, of cigarette smoking and use of Swedish snus on pregnancy outcomes using similar non-tobacco user controls, and ii) to examine whether exposure to PAHs from smoking could explain possible differences in impact on pregnancy outcomes. We systematically searched MEDLINE, Embase, PsycInfo, Web of Science and the Cochrane Database of Systematic Reviews up to October 2021 and identified studies reporting risks for adverse pregnancy and neonatal outcomes associated with snus use and with smoking relative to pregnant women with no use of tobacco. Both snus use and smoking were associated with increased risk of stillbirth, preterm birth, and oral cleft malformation, with comparable point estimates. These effects were likely due to comparable nicotine exposure. We also found striking differences. While both smoking and snus increased the risk of having small for gestational age (SGA) infants, risk from maternal smoking was markedly higher as was the reduction in birthweight. In contrast, the risk of preeclampsia (PE) was markedly lower in smokers than in controls, while snus use was associated with a slightly increased risk. We suggest that PAHs acting via AhR may explain the stronger effects of tobacco smoking on SGA and also to the apparent protective effect of cigarette smoking on PE. Possible mechanisms involved include: i) disrupted endocrine control of fetal development as well as placental development and function, and ii) stress adaption and immune suppression in placenta and mother.

Perinatal risk factors for mortality in very preterm infants-A nationwide, population-based discriminant analysis

Aim

To assess the strength of associations between interrelated perinatal risk factors and mortality in very preterm infants.

Methods

Information on all live‐born infants delivered in Sweden at 22–31 weeks of gestational age (GA) from 2011 to 2019 was gathered from the Swedish Neonatal Quality Register, excluding infants with major malformations or not resuscitated because of anticipated poor prognosis. Twenty‐seven perinatal risk factors available at birth were exposures and in‐hospital mortality outcome. Orthogonal partial least squares discriminant analysis was applied to assess proximity between individual risk factors and mortality, and receiver operating characteristic (ROC) curves were used to estimate discriminant ability.

Results

In total, 638 of 8,396 (7.6%) infants died. Thirteen risk factors discriminated reduced mortality; the most important were higher Apgar scores at 5 and 10 min, GA and birthweight. Restricting the analysis to preterm infants <28 weeks’ GA (n = 2939, 16.9% mortality) added antenatal corticosteroid therapy as significantly associated with lower mortality. The area under the ROC curve (the C‐statistic) using all risk factors was 0.86, as determined after both internal and external validation.

Conclusion

Apgar scores, gestational age and birthweight show stronger associations with mortality in very preterm infants than several other perinatal risk factors available at birth.

Central Australian Aboriginal women's placental and neonatal outcomes following maternal smokeless tobacco, cigarette or no tobacco use

OBJECTIVE

To describe the placental characteristics and neonatal outcomes of Central Australian Aboriginal women based on maternal self-report of tobacco use.

METHODS

Placental and neonatal variables were collected from a prospective maternal cohort of 19 smokeless tobacco chewers, 23 smokers and 31 no-tobacco users.

RESULTS

Chewers had the lowest placental weight (460 g) while the no-tobacco group had the heaviest placental weight (565 g). Chewers and the no-tobacco group had placental areas of similar size (285 cm2 and 288 cm2 , respectively) while the placentas of smokers were at least 13 cm2 smaller (272 cm2 ). There were two stillbirths in the study and more than one-third (36%) of neonates (newborns) were admitted to the Special Care Nursery, with the chewers' neonates having a higher admission rate compared with smokers' neonates (44% vs. 23%). The cohort mean birthweight (3348 g) was not significantly different between the groups. When stratified for elevated maternal glucose, the chewers' neonates had the lowest mean birthweight (2906 g) compared to the neonates of the no-tobacco group (3242 g) and smokers (3398 g).

CONCLUSIONS

This research is the first to demonstrate that the maternal use of Australian Nicotiana spp. (pituri) as smokeless tobacco may negatively impact placental and neonatal outcomes.

IMPLICATIONS FOR PUBLIC HEALTH

Maternal smokeless tobacco use is a potential source of placental and foetal nicotine exposure. Maternal antenatal screening should be expanded to capture a broader range of tobacco and nicotine products, and appropriate cessation support is required.

Association between environmental tobacco smoke before and during pregnancy and the risk of adverse birth outcomes: a birth cohort study in Wuhan, China

Associations between environmental tobacco smoke (ETS) and the risk of adverse birth outcomes may be confounded. We aimed to clarify the associations of ETS before and during pregnancy with the risk of adverse birth outcomes and determine whether the associations were modified by key potential confounders. A total of 7147 non-smoking mothers from the Tongji Maternal and Child Health Cohort (TMCHC) in Wuhan, China, were included in the final analyses. ETS status was self-reported by pregnant women at their first antenatal care visit before 16 gestational weeks. Information on birth outcomes was extracted from delivery records. Poisson regression was used to identify the association between ETS before and during pregnancy and the risk of adverse birth outcomes. Exposures to ETS before and during pregnancy were reported by 645 (9.0%) and 464 (6.5%) mothers, respectively. Compared with no ETS, continued ETS during pregnancy was associated with an increased risk of preterm birth (PTB) (RR: 1.55, 95% CI: 1.07, 2.25) after adjustment for potential confounders. The association remained consistent in medically indicated PTB and late PTB. The risk of PTB associated with continued ETS during pregnancy was significantly increased in mothers more educated (P for interaction < 0.05). However, the increased risk of low birth weight (LBW) or small for gestational age (SGA) births by ETS during pregnancy was not observed. Exposure to ETS during pregnancy was associated with a higher risk of PTB, but not LBW or SGA births in a Chinese birth cohort.

Maternal smoking and smokeless tobacco use during pregnancy and offspring development: sibling analysis in an intergenerational Swedish cohort

Background

The association between maternal smoking in pregnancy and offspring intellectual disability (ID) is less well understood than that of smoking and fetal growth restriction. As fetal growth and cognitive development may share similar confounding structures, comparison of the two associations may improve understanding of the causal nature of the association with ID. Furthermore, comparisons of smoking with smokeless tobacco use may aid identification of mechanisms of action.

Methods

This was a cohort study of all Swedish births between 1999 and 2012 (n = 1 070 013), with prospectively recorded data. We assessed the association between maternal smoking during pregnancy and offspring outcomes ID and born small for gestational age (SGA). Analyses were repeated for snus use in pregnancy. Using a sibling design, we estimated within-family effects that control for shared sibling characteristics.

Results

Those exposed to maternal smoking in pregnancy had increased odds of ID [odds ratio (OR) = 1.24, 95% confidence interval (CI): 1.16-1.33] and SGA (OR = 2.19, 95% CI: 2.11-2.27) after confounder adjustment. Within-family effects were found for SGA (OR = 1.44, 95% CI: 1.27-1.63) but not ID (OR = 0.92, 95% CI: 0.74-1.14). For snus use, the results for ID were similar to smoking. We found increased odds of offspring SGA among mothers who used snus in pregnancy in sensitivity analyses but not in primary analyses.

Conclusions

Our findings are consistent with a causal effect of maternal smoking in pregnancy on risk of offspring born SGA but not on risk of ID. We found no evidence for a causal effect of snus use in pregnancy on ID and inconclusive evidence for SGA.

The Intricate Interactions between Maternal Smoking and Drinking During Pregnancy and Birthweight Z-Scores of Preterm Births

BACKGROUND

The extent to which smoking and drinking in a local community is associated with nutrition and Z-scores of infants from spontaneous preterm deliveries, is uncertain.

AIM

To investigate associations of different levels of maternal smoking and drinking in spontaneous preterm birth with infant birthweight Z-scores.

METHODS

Information, including gestational age (determined by earliest ultrasound), maternal arm circumference (measured at enrolment), smoking-drinking data (obtained up to 4 occasions), birthweight data (obtained from medical records) and birthweight Z-scores (calculated from INTERGROWTH- 21st study), collected over a period of nine years was used to compare 407 spontaneous preterm births with 3 493 spontaneous term births Analyses of variance, correlations and multiple regression were performed in STATISTICA.

RESULTS

Women with spontaneous preterm birth, had significantly lower gravidity and smaller arm circumference when compared to women with spontaneous birth at term. Women with spontaneous preterm birth drank more and heavier during pregnancy, and more smoked. Gestational age at birth was significantly longer in heavy-smokers-heavy-drinkers compared to heavy-smokers-no-drinkers (7.1 days) and in no-smokers-heavy-drinkers when compared to no-smokers-no-drinkers (11.2 days). Birthweight was significantly lower in low-smokers-heavy-drinkers when compared to low-smokers-no-drinkers (240g) and in heavy-smokers-low-drinkers when compared to no-smokers-low-drinkers (273g). Birthweight Z-scores were significantly lower in low-smokers-heavy-drinkers when compared to low-smokers-low-drinkers and low-smokers-no-drinkers; and, also significantly lower in heavy-smokers-low-drinkers when compared to low-smokers-low-drinkers and no-smokers-low-drinkers.

CONCLUSION

Alcohol aggravates the detrimental effect of smoking on birthweight and birthweight Z-scores but seems to counteract the negative association of smoking with gestational age.

Stressful life events and electronic cigarette use during pregnancy

RATIONALE

Smoking during pregnancy poses a significant health risk for infant well-being. Prior research has linked experiencing stressful life events (SLEs) during pregnancy to prenatal smoking. However, extant research has not assessed whether SLEs experienced during pregnancy are a risk factor for prenatal electronic cigarette use.

OBJECTIVE

This study investigates the association between SLEs and electronic cigarette use during the third trimester of pregnancy.

METHODS

We employ data on 70,626 recent mothers from the 2016-2018 Pregnancy Risk Assessment Monitoring System. Logistic and multinomial logistic regression models were used to examine the association between SLEs and electronic cigarette use during the third-trimester of pregnancy.

RESULTS

The prevalence of electronic cigarette use increased alongside an accumulating history of SLEs (0 SLEs = 0.4%; 1-2 SLEs = 0.9%; 3-5 SLEs = 1.9%; 6+ SLEs = 5.0%). Logistic regression models found 6 or more SLEs were associated with 4.7 times higher odds of electronic cigarette use relative to 0 SLEs after adjusting for demographic and socioeconomic characteristics (AOR = 4.705, 95% CI = 2.960, 7.479). Study findings also showed that women who experienced greater levels of SLEs had a higher prevalence of using any nicotine products (i.e., exclusive electronic cigarette user, exclusive cigarette user, dual user), relative to being a non-smoker. Findings from multinomial logistic regression models revealed that a higher number of SLEs was associated with an increased relative risk of all smoking outcomes. Still, these associations were particularly pronounced in the case of exclusive electronic cigarette user (ARR = 8.485, 95% CI = 4.900, 14.692) and dual-use (ARR = 8.348, 95% CI = 4.113, 16.945) when participants experienced 6 or more SLEs (relative to 0 SLEs).

CONCLUSIONS

Considering the potentially harmful ramifications of electronic cigarette use during pregnancy there is a need for interventions that reduce stressful experiences and decrease smoking during pregnancy.

Smartphone-based financial incentives to promote smoking cessation during pregnancy: A pilot study

Cigarette smoking during pregnancy increases risk for pregnancy complications, growth restriction, and other adverse health outcomes. The most effective intervention for reducing smoking during pregnancy is financial incentives contingent on biochemically-verified smoking abstinence. The present study examined the efficacy of a smartphone-based intervention whereby smoking monitoring and incentive delivery occurred remotely using a mobile app. If efficacious, this remote intervention would allow pregnant women residing in geographically remote areas to benefit from incentives-based cessation interventions. Sixty U.S. pregnant smokers were recruited between May 2018 to May 2019 via obstetrical clinics, Women, Infants, and Children (WIC) offices, and Facebook. Participants were assigned sequentially to one of two treatments: best practices alone (N = 30) or best practices plus financial incentives (N = 30). Outcomes were analyzed using repeated measures analysis based on generalized estimating equations (GEE). Seven-day point prevalence abstinence rates were greater in the incentives versus best practices arms early- (46.7% vs 20.0%, OR = 3.50, 95%CI = 1.11,11.02) and late-antepartum (36.7% vs 13.3%, OR = 3.76, 95%CI = 1.04,13.65), and four- (36.7% vs 10.0%, OR = 5.21, 95%CI = 1.28,21.24) and eight-weeks postpartum (40.0% vs 6.7%, OR = 9.33, 95%CI = 1.87,46.68), although not at the 12- (23.3% vs 10.0%, OR = 2.74, 95%CI = 0.63,11.82) or 24-week (20.0% vs 6.7%, OR = 3.50, 95%CI = 0.65,18.98) postpartum assessments likely due to this pilot study being underpowered for discerning differences at the later assessments, especially 24-weeks postpartum which was three months after treatment completion. These results support the efficacy of this remote, incentives-based intervention for pregnant smokers. Further research evaluating its efficacy and cost-effectiveness in a well-powered, randomized controlled trial appears warranted.

Ion Channel Contributions to Morphological Development: Insights From the Role of Kir2.1 in Bone Development

The role of ion channels in neurons and muscles has been well characterized. However, recent work has demonstrated both the presence and necessity of ion channels in diverse cell types for morphological development. For example, mutations that disrupt ion channels give rise to abnormal structural development in species of flies, frogs, fish, mice, and humans. Furthermore, medications and recreational drugs that target ion channels are associated with higher incidence of birth defects in humans. In this review we establish the effects of several teratogens on development including epilepsy treatment drugs (topiramate, valproate, ethosuximide, phenobarbital, phenytoin, and carbamazepine), nicotine, heat, and cannabinoids. We then propose potential links between these teratogenic agents and ion channels with mechanistic insights from model organisms. Finally, we talk about the role of a particular ion channel, Kir2.1, in the formation and development of bone as an example of how ion channels can be used to uncover important processes in morphogenesis. Because ion channels are common targets of many currently used medications, understanding how ion channels impact morphological development will be important for prevention of birth defects. It is becoming increasingly clear that ion channels have functional roles outside of tissues that have been classically considered excitable.

Attention-deficit/hyperactivity disorder and smoking habits in pregnant women

Background

Attention-deficit/hyperactivity disorder (ADHD) has been associated with an increased risk of tobacco smoking, and more difficulties with smoking cessation compared to non-ADHD individuals. Women with ADHD may therefore show elevated rates of smoking during pregnancy.

Aims

To examine the association between ADHD and smoking habits among pregnant women in Sweden and Norway.

Methods

Women pregnant for the first time were identified in Sweden (n = 622,037), and Norway (n = 293,383), of which 1.2% (n = 7,444), and 1.7% (n = 4,951) were defined as having ADHD, respectively. Data on smoking habits were collected early and late in pregnancy.

Results

In Sweden, ADHD was associated with an increased risk of smoking early in pregnancy, adjusted risk ratio (adjRR) 2.69 (95% confidence interval, 2.58–2.81), and late in pregnancy, adjRR 2.95 (2.80–3.10). Similar findings were observed in the Norwegian data, early in pregnancy, adjRR 2.31 (2.21–2.40), and late in pregnancy, adjRR 2.56 (2.42–2.70). Women with ADHD were more likely to continue smoking during pregnancy, compared to women without ADHD, both in Sweden adjRR 1.13 (1.10–1.17), and in Norway, adjRR 1.16 (1.12–1.20). Having a sibling diagnosed with ADHD was associated with an increased risk of smoking early and late in pregnancy, in both Sweden and Norway.

Conclusions

Women with ADHD are considerably more likely to smoke early and late in (their first) pregnancy and are less likely to stop smoking between the two time points. Smoking, early and late in pregnancy, co-aggregates in families with ADHD. Smoking prevention and intervention programs should be targeted towards women with ADHD, specifically during their childbearing years, to ensure better mother and child outcomes.

Smoking and use of electronic cigarettes (vaping) in relation to preterm birth and small-for-gestational-age in a 2016 U.S. national sample

Women who smoke may be motivated to switch to vaping (use electronic cigarettes, e-cigs) around pregnancy in seeking to alleviate known hazards of smoking. E-cigs typically contain nicotine but either eliminates or greatly reduces exposure to the combustion products of tobacco. We studied a U.S.-wide representative sample of 31,973 live singleton births in 2016. In the three months before pregnancy, 5029 (14%) mothers exclusively smoked tobacco ("sole smokers") and 976 (3%) used both tobacco and e-cigs ("dual-users"). Among pre-pregnancy sole smokers, 44% continued to only smoke while 1% became dual-users in late pregnancy. Logistic regression models were used to assess the adjusted odds ratios (aOR) for preterm and small-for-gestational-age (SGA) by reported smoking or vaping in late pregnancy. Compared to women who used neither product ("non-users"), late-pregnancy sole smokers had increased risks for preterm birth (aOR 1.6, 95% CI 1.2-2.0) and SGA (aOR 2.4, 95% CI 1.8-2.9), after adjusting for their pre-pregnancy smoking or vaping status and other confounders. The adjusted models also showed that late-pregnancy sole vapers had similar risk of preterm birth as non-users (aOR 1.2, 95% CI 0.5-2.7). Late-pregnancy dual-users also had similar risk of preterm birth as non-users (aOR 1.3, 95% CI 0.8-2.3). However, late-pregnancy sole vapers and dual-users had increased risk of SGA compared to non-users (aOR 2.4, 95% CI 1.0-5.7 for sole vapers, and aOR 2.3 95% CI 1.3-4.1 for dual-users). These findings suggest that vapers during pregnancy had similar risk of preterm as non-users but still had elevated risk for restricted fetal growth.

Association of socioeconomic status and clinical and demographic conditions with the prevalence of preterm birth

OBJECTIVE

To examine the effects of socioeconomic and demographic conditions on the prevalence of preterm birth in a local community.

METHODS

Pregnant women (aged ≥16 years) willing to provide informed consent in one of the two languages of the community were recruited in South Africa between August 2007 and January 2015. Specifically designed case report forms collected information and measurements prospectively.

RESULTS

After reviewing the medical records of 5806 women, it was possible to identify those who had spontaneous preterm birth (SPTB), induced preterm birth (IPTB), or spontaneous term birth (STB). Women with IPTB (vs SPTB) were more obese and had higher education levels and household incomes; more had telephones and running water at home. They enrolled earlier and more developed hypertension and pre-eclampsia. Women with SPTB (vs STB) were less obese, shorter, had smaller arm circumferences and higher gravidities and Edinburgh Depression Scores, lower education, fewer telephones, and less running water at home. More women with SPTB used methamphetamine, cigarettes, and were heavier smokers.

CONCLUSION

SPTB and IPTB should not be conflated. Programs to reduce the high prevalence of SPTB should include improving education, lifestyle, and socioeconomic conditions. Addressing hypertension should help reduce preterm inductions.

Individual and Regional Characteristics Associated with Maternal Smoking During Pregnancy in Japan: Healthy Parents and Children 21

Smoking during pregnancy causes various maternal and fetal health problems. Although there are considerable differences in maternal smoking proportions between localities, only a few studies have investigated the effects of regional characteristics on maternal smoking behavior. This study aimed to clarify the association between maternal smoking during pregnancy and individual and regional characteristics. We used data from a large nationwide birth cohort study in Japan that consisted of information on 20,267 women with children aged 3–4 months. The multilevel regression model was used to examine the association between smoking behavior during pregnancy and individual and regional characteristics. On multilevel analysis, late birth order, young age of the mother at birth, low birth weight, low economic status, husband’s smoking during pregnancy, maternal alcohol consumption during pregnancy, absence of a pregnancy counselor, and lack of participation in local events for childrearing were significantly associated with maternal smoking behavior during pregnancy at the individual level. Meanwhile, a high unemployment rate and a high number of nurseries were significantly associated with maternal smoking behavior during pregnancy at the regional level. In conclusion, we showed the relation between maternal smoking during pregnancy and the individual- and regional-level characteristics.

Snus in pregnancy and infant birth size: a mother-child birth cohort study

Rationale

While recent studies show that maternal use of snus during pregnancy is increasing, the potential effects on infant birth size is less investigated, with conflicting results.

Objectives

We aimed to determine if maternal use of snus during pregnancy influences the infant anthropometric and proportional size measures at birth.

Methods

In 2313 mother–child pairs from the population-based, mother–child birth cohort PreventADALL (Preventing Atopic Dermatitis and ALLergies) in Norway and Sweden, we assessed nicotine exposure by electronic questionnaire(s) at 18 and 34 weeks of pregnancy, and anthropometric measurements at birth. Associations between snus exposure and birth size outcomes were analysed by general linear regression.

Results

Birthweight was not significantly different in infants exposed to snus in general, and up to 18 weeks of pregnancy in particular, when adjusting for relevant confounders including maternal age, gestational age at birth, pre-pregnancy body mass index, parity, fetal sex and maternal gestational weight gain up to 18 weeks. We found no significant effect of snus use on the other anthropometric or proportional size measures in multivariable linear regression models. Most women stopped snus use in early pregnancy.

Conclusion

Exposure to snus use in early pregnancy, with most women stopping when knowing about their pregnancy, was not associated with birth size. We were unable to conclude on effects of continued snus use during pregnancy because of lack of exposure in our cohort.

Snus use in pregnancy, reported by 7.1% of 2313 women, was not associated with infant birth size. As most women stopped snus use by 6 weeks gestational age, it was not possible to assess potential birth size effects of persistent use during pregnancy.http://bit.ly/2IG8Vnk

Blood Pressure and Heart Rate Variability in Preschool Children Exposed to Smokeless Tobacco in Fetal Life

Background

Maternal smoking during pregnancy has been associated with higher blood pressure and autonomic imbalance in the offspring. However, it has been difficult to determine the selective prenatal and postnatal contributions as children frequently have been exposed to smoking both before and after birth. The specific role of nicotine is also unclear. We aimed to determine whether exclusive prenatal exposure to nicotine from maternal use of smokeless tobacco (Swedish snus) in pregnancy was associated with blood pressure and autonomic heart rate control in their children.

Methods and Results

We measured oscillometric blood pressures in forty 5‐ to 6‐year‐old children with snus exposure in fetal life (n=21) and in tobacco‐free controls (n=19). Taking the child′s age and height into account, snus‐exposed children had 4.2 (95% CI, 0.2–8.1) mm Hg higher systolic blood pressure than controls (P=0.038). The corresponding sex‐, age‐, and height‐standardized systolic blood pressure centiles were 61 and 46 (95% CI of the difference, 2–28) (P=0.029). Heart rate variability was tested in 30 of the children. The spectral heart rate variability variable low‐frequency/high‐frequency ratio was higher (median, 0.69; interquartile range, 0.45–1.21) in snus‐exposed children than in controls (median, 0.21; interquartile range, 0.32–0.57; P=0.034).

Conclusions

Prenatal snus exposure was associated with higher systolic blood pressure and altered heart rate variability at 6 years of age. These findings may indicate adverse prenatal programming of nicotine, but implications for cardiovascular health in later life remain to be studied. Meanwhile, women should be recommended to abstain from all types of tobacco and nicotine products during pregnancy.

See Editorial Watanabe and Parikh

An intervention in contraceptive counseling increased the knowledge about fertility and awareness of preconception health-a randomized controlled trial

Background: Reproductive life plan counseling (RLPC) is a tool to encourage women and men to reflect upon their reproduction, to avoid unintended pregnancies and negative health behavior that can threaten reproduction. The aim was to evaluate the effect of RLPC among women attending contraceptive counseling. Outcomes were knowledge about fertility and awareness of preconception health, use of contraception, and women's experience of RLPC. Material and methods: Swedish-speaking women, aged 20-40 years, were randomized to intervention group (IG) or control group (CG). Participants (n = 1,946) answered a questionnaire before and two months after (n = 1,198, 62%) the consultation. All women received standard contraceptive counseling, and the IG also received the RLPC, i.e. questions on reproductive intentions, information about fertility, and preconception health. Results: Women in the IG increased their knowledge about fertility: age and fertility, chances of getting pregnant, fecundity of an ovum, and chances of having a child with help of IVF. They also increased their awareness of factors affecting preconception health, such as to stop using tobacco, to refrain from alcohol, to be of normal weight, and to start with folic acid before a pregnancy. The most commonly used contraceptive method was combined oral contraceptives, followed by long-acting reversible contraception. Three out of four women (76%) in the IG stated that the RLPC should be part of the routine in contraceptive counseling. Conclusions: Knowledge about fertility and awareness of preconception health increased after the intervention. The RLPC can be recommended as a tool in contraceptive counseling.

An update on prevalence and risk of snus and nicotine replacement therapy during pregnancy and breastfeeding

AIM

In parallel with falling smoking rates, use of the oral moist tobacco product snus increases among women in reproductive age. We report an update on prevalence and effects of maternal use of snus and nicotine replacement therapy (NRT) during pregnancy and breastfeeding.

METHODS

A literature search of human studies in Medline, PubMed and EMBASE was conducted from September 2016 to May 2018, with stepwise screening of abstracts and subsequent relevant full-text papers for inclusion in Scandinavian and English languages.

RESULTS

Based on three studies, the prevalence of snus use in pregnancy was up to 3.4% in the first trimester and 2.1% in the third trimester. In 12 studies, we found increased risk of several adverse effects, especially preterm delivery, stillbirth and small for gestational age associated with maternal snus use during pregnancy. Knowledge on effects of NRT during pregnancy was conflicting and inconclusive in 10 studies. We did not identify any studies on prevalence or potential health effects of snus or NRT during breastfeeding.

CONCLUSION

Few studies with updated data on the prevalence and adverse health effects of maternal use of snus and NRT during pregnancy were found. No studies during breastfeeding were identified.

Prevention of snus use: Attitudes and activities in the Public Dental Service in the south-eastern part of Norway

Dental health care professionals have the opportunity to play a key role in tobacco prevention and cessation among adolescents. Snus use has increased in Norway, especially in the age group 16-24, whereas there has been a decline in smoking. This study investigated attitudes and activities related to snus prevention among dental health care professionals working in the Public Dental Service (PDS) in south-eastern Norway. A web-based survey with a total of 557 dentists and dental hygienists in seven counties in Norway, with a response rate of 53.5%, was carried out in 2017. Dentists' and dental hygienists' activities regarding preventive snus use intervention were analysed using the chi-square test. Intervention was measured with a score (1-5) based on four questions. Bivariate and multivariate linear regression analyses were used to investigate the associations between the explanatory variables of attitudes/activities and the outcome intervention variable. Approximately 87% of the dentists and 58% of the dental hygienists were not familiar with the "minimum intervention method" for tobacco prevention and cessation. Dental hygienists were most active in informing and supporting their patients in prevention and cessation of snus use. The PDS is an underutilized arena for tobacco prevention and cessation among adolescents, and the intervention potential is particularly high among the dentists.

Qualitative assessment of knowledge transfer regarding preterm birth in Malawi following the implementation of targeted health messages over 3 years

Background

In 2012, we performed a needs assessment and gap analysis to qualitatively assess providers’ and patients’ knowledge and perceptions regarding preterm birth (PTB). During the study, we identified knowledge gaps surrounding methods to reduce the risk of occurrence of PTB and management options if preterm labor/birth occur. We targeted health messages toward these gaps. The objective of the present study was to assess the impact of our community health worker-based patient education program 3 years after it was implemented.

Methods

Fifteen focus groups including 70 participants were included in the study. The groups comprised either patients/patient couples or health providers. A minimum of two facilitators led each group using 22 a priori designed and standardized lead-in prompts for participants with four additional prompts for providers only. A single researcher recorded responses, and transcript notes were reviewed by the facilitators and interpreters immediately following each group discussion to ensure accuracy.

Results

The understanding of term vs preterm gestation was generally accurate. Every participant knew of women who had experienced PTB, and the general perception was that two to three women out of every ten had this experience. The majority of respondents thought that women should present to their local health clinic if they experience preterm contractions; few were aware of the use of antenatal steroids for promoting fetal lung maturity, but many acknowledged that the neonate may be able to receive life-sustaining treatment if born at a higher level of care facility. The majority of participants were aware that PTB could recur in subsequent pregnancies. All respondents were able to list ways that women could potentially reduce the risk of PTB.

Conclusion

After employing targeted health messages, the majority of participants expressed improved understanding of the definition of PTB, methods to prevent risk of PTB, and management options for preterm labor or PTB.

Recommendations for the Appropriate Structure, Communication, and Investigation of Tobacco Harm Reduction Claims. An Official American Thoracic Society Policy Statement

RATIONALE

The tobacco harm reduction literature is replete with vague language, far-reaching claims, and unwarranted certainty. The American Thoracic Society has increasingly recognized the need for a framework for reliably making such claims. Evidence-based standards improving the scientific value and transparency of harm reduction claims are expected to improve their trustworthiness, clarity, and consistency.

METHODS

Experts from relevant American Thoracic Society committees identified key topic areas for discussion. Literature search strategy included English language articles across Medline, Google Scholar, and the Cochrane Collaborative databases, with expanded search terms including tobacco, addiction, smoking, cigarettes, nicotine, and harm reduction. Workgroup members synthesized their evidentiary summaries into a list of candidate topics suitable for inclusion in the final report. Breakout groups developed detailed content maps of each topic area, including points to be considered for suggested recommendations. Successive draft recommendations were modified using an iterative consensus process until unanimous approval was achieved. Patient representatives ensured the document's relevance to the lay public.

RESULTS

Fifteen recommendations were identified, organized into four framework elements dealing with: estimating harm reduction among individuals, making claims on the basis of population impact, appropriately careful use of language, and ethical considerations in harm reduction.

DISCUSSION

This statement clarifies important principles guiding valid direct and inferential harm reduction claims. Ideals for effective communication with the lay public and attention to unique ethical concerns are also delineated. The authors call for formal systems of grading harm reduction evidence and regulatory assurances of longitudinal surveillance systems to document the impact of harm reduction policies.

The toxicity of E-cigarettes and children's respiratory health

Electronic cigarettes (E-cig), also referred to as Electronic Nicotine Delivery System (ENDS), were initially developed in 2003 to reduce the harmful effects of tobacco smoking. Since then, E-cig have become widely available in many countries and are used by many young people who would be unlikely to take up cigarette smoking. However, the adverse effects on child health remain largely unknown. E-cigs are available through regulated sale in many countries, but easily accessible by the internet in others. Adverse effects may be ascribed to the nicotine itself, to the accompanying substances in the aerosol (often referred to as vapour) or to temperature modifications of the content. There is a lack of human studies to assess respiratory effects of nicotine exposure to the unborn or young child. Also assessing the effects of the vaping content apart from nicotine is challenging, with the huge variety of exposure by frequency, duration and content, but experimental studies are on the way that may indicate the level of harm by such products. This article will summarize what is currently known about the use of E-cigs in children and in pregnancy, and discuss adverse effects of direct or in utero exposure to E-cig on the respiratory health of children. We thereby hope to provide a background for discussing potential harms to the respiratory system of children by E-cig exposure in pregnancy and early post-natal life, in a setting where an increasing proportion of adolescent and young adults use E-cigs, marketed to be 95% less harmful than conventional cigarettes.

Joint Effect of Maternal Tobacco Smoking and Pregestational Diabetes on Preterm Births and Congenital Anomalies: A Population-Based Study in Northern Italy

Smoking and pregestational diabetes (PGD) are recognized risk factors for adverse pregnancy outcomes, but to date, no population-based study has investigated their joint effects. Using hospital discharges, we identified all women with PGD delivering in Emilia-Romagna region during 2007-2010 matched 1 : 5 with parturients without diabetes. Our study endpoints were preterm births and congenital anomalies. We measured interaction between PGD and maternal smoking, by calculating excess prevalence and prevalence ratio due to interaction, relative excess risk due to interaction (RERI), attributable proportion (AP), and the synergy index (S). Analyses were performed in the overall study population and in the subgroup whose PGD was validated through diabetes registers. The study included 992 women with PGD (10.5% smokers) and 4788 comparison women (11.9% smokers). The effects of PGD and maternal tobacco smoking were greater than additive for both preterm birth (excess prevalence due to interaction = 11.7%, excess ratio due to interaction = 1.5, RERI = 2.39, AP = 0.51, S = 2.82) and congenital anomalies (excess prevalence due to interaction = 2.2%, excess ratio due to interaction = 1.3, RERI = 1.33, AP = 0.49, S = 5.03). Joint effect on both endpoints was confirmed in the subgroup whose PGD status was validated. In conclusion, we found that maternal tobacco smoking and PGD intensify each other's effect on preterm birth and congenital anomalies.

Associations between lifestyle factors and smoking status during pregnancy in a group of Romanian women

BACKGROUND

There is an estimated birth rate of 9.27 births/1,000 population in Romania each year, with approximately 8.4% born with low birth weight (LBW). Our purpose was to evaluate the relationships between maternal smoking and LBW and preterm birth in Mureș County, Romania.

METHODS

We conducted a cross-sectional survey of 1,278 mothers who had given birth in Mureș County obstetrical wards in 2015, based on a lifestyle questionnaire of 109 items and personal and laboratory data from hospitals records.

RESULTS

The variables associated with smoking during pregnancy taken into account were: Rroma ethnicity, education <8 grades, income lower than 140 dollars (minimum wages in our country), and lack of facilities in their households. In a multivariable model, smoking during pregnancy was correlated with a low level of education (p = .02), coffee and alcohol use (p = .0001), and lack of interest in potential environmental and behavioral risks during pregnancy (including smoking and diet). The newborn baby's weight was associated with smoker status of the mother (OR 1.71, 95%CI 1.09-2.66, p = .01), by the lack of ownership of a household (OR 3.52, 95%CI 2.27-5.47, p = .0001), and by the pregnant woman not receiving proper information regarding a healthy behavior and diet during pregnancy (OR 1.91, 95%CI 1.33-2.74, p = .0005).

CONCLUSION

Our study aimed to emphasize the high rates of maternal smoking during pregnancy and its importance in LBW outcomes in Romanian pregnant women. Moreover, the study highlights disparities in smoking status observed in ethnic minorities and those living in poverty.

Maternal socioeconomic factors and adverse perinatal outcomes in two birth cohorts, 1997/98 and 2010, in São Luís, Brazil

ABSTRACT: Several studies have identified social inequalities in low birth weight (LBW), preterm birth (PTB), and intrauterine growth restriction (IUGR), which, in recent years, have diminished or disappeared in certain locations. Objectives: Estimate the LBW, PTB, and IUGR rates in São Luís, Maranhão, Brazil, in 2010, and check for associations between socioeconomic factors and these indicators. Methods: This study is based on a birth cohort performed in São Luís. It included 5,051 singleton hospital births in 2010. The chi-square test was used for proportion comparisons, while simple and multiple Poisson regression models with robust error variance were used to estimate relative risks. Results: LBW, PTB and IUGR rates were 7.5, 12.2, and 10.3% respectively. LBW was higher in low-income families, while PTB and IUGR were not associated with socioeconomic factors. Conclusion: The absence or weak association of these indicators with social inequality point to improvements in health care and/or in social conditions in São Luís.

Tobacco and nicotine delivery product use in a national sample of pregnant women

Monitoring use of tobacco products among pregnant women is a public health priority, yet few studies in U.S. national samples have been reported on this topic. We examined prevalence and correlates of using cigarettes, e-cigarettes, and other tobacco/nicotine delivery products in a U.S. national sample of pregnant women. Data were obtained from all pregnant women (≥18 years) in the first wave of the Population Assessment of Tobacco and Health (PATH, 2013-2014) Study (N=388). Prevalence of current and prior use of tobacco/nicotine products was examined overall and among current cigarette smokers. Multiple logistic regression was used to examine correlates of use of cigarettes, e-cigarettes, hookah and cigars. Overall prevalence was highest for cigarettes (13.8%), followed by e-cigarettes (4.9%), hookah (2.5%) and cigars (2.3%), and below 1% for all other products. Prevalence of using other tobacco products is much higher among current smokers than the general population, with e-cigarettes (28.5%) most prevalent followed by cigars (14.0%), hookah (12.4%), smokeless (4.7%), snus (4.6%), and pipes (2.1%). Sociodemographic characteristics (poverty, low educational attainment, White race) and past-year externalizing psychiatric symptoms were correlated with current cigarette smoking. In turn, current cigarette smoking and past year illicit drug use were correlated with using e-cigarettes, hookah, and cigars. These results underscore that tobacco/nicotine use during pregnancy extends beyond cigarettes. The results also suggest that use of these other products should be included in routine clinical screening on tobacco use, and the need for more intensive tobacco control and regulatory strategies targeting pregnant women.

Psychosocial interventions for supporting women to stop smoking in pregnancy

BACKGROUND

Tobacco smoking remains one of the few preventable factors associated with complications in pregnancy, and has serious long-term implications for women and babies. Smoking in pregnancy is decreasing in high-income countries, but is strongly associated with poverty and is increasing in low- to middle-income countries.

OBJECTIVES

To assess the effects of smoking cessation interventions during pregnancy on smoking behaviour and perinatal health outcomes.

SEARCH METHODS

In this sixth update, we searched the Cochrane Pregnancy and Childbirth Group's Trials Register (13 November 2015), checked reference lists of retrieved studies and contacted trial authors.

SELECTION CRITERIA

Randomised controlled trials, cluster-randomised trials, and quasi-randomised controlled trials of psychosocial smoking cessation interventions during pregnancy.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and trial quality, and extracted data. Direct comparisons were conducted in RevMan, with meta-regression conducted in STATA 14.

MAIN RESULTS

The overall quality of evidence was moderate to high, with reductions in confidence due to imprecision and heterogeneity for some outcomes. One hundred and two trials with 120 intervention arms (studies) were included, with 88 trials (involving over 28,000 women) providing data on smoking abstinence in late pregnancy. Interventions were categorised as counselling, health education, feedback, incentives, social support, exercise and dissemination.In separate comparisons, there is high-quality evidence that counselling increased smoking cessation in late pregnancy compared with usual care (30 studies; average risk ratio (RR) 1.44, 95% confidence interval (CI) 1.19 to 1.73) and less intensive interventions (18 studies; average RR 1.25, 95% CI 1.07 to 1.47). There was uncertainty whether counselling increased the chance of smoking cessation when provided as one component of a broader maternal health intervention or comparing one type of counselling with another. In studies comparing counselling and usual care (largest comparison), it was unclear whether interventions prevented smoking relapse among women who had stopped smoking spontaneously in early pregnancy. However, a clear effect was seen in smoking abstinence at zero to five months postpartum (11 studies; average RR 1.59, 95% CI 1.26 to 2.01) and 12 to 17 months (two studies, average RR 2.20, 95% CI 1.23 to 3.96), with a borderline effect at six to 11 months (six studies; average RR 1.33, 95% CI 1.00 to 1.77). In other comparisons, the effect was unclear for most secondary outcomes, but sample sizes were small.Evidence suggests a borderline effect of health education compared with usual care (five studies; average RR 1.59, 95% CI 0.99 to 2.55), but the quality was downgraded to moderate as the effect was unclear when compared with less intensive interventions (four studies; average RR 1.20, 95% CI 0.85 to 1.70), alternative interventions (one study; RR 1.88, 95% CI 0.19 to 18.60), or when smoking cessation health education was provided as one component of a broader maternal health intervention.There was evidence feedback increased smoking cessation when compared with usual care and provided in conjunction with other strategies, such as counselling (average RR 4.39, 95% CI 1.89 to 10.21), but the confidence in the quality of evidence was downgraded to moderate as this was based on only two studies and the effect was uncertain when feedback was compared to less intensive interventions (three studies; average RR 1.29, 95% CI 0.75 to 2.20).High-quality evidence suggests incentive-based interventions are effective when compared with an alternative (non-contingent incentive) intervention (four studies; RR 2.36, 95% CI 1.36 to 4.09). However pooled effects were not calculable for comparisons with usual care or less intensive interventions (substantial heterogeneity, I2 = 93%).High-quality evidence suggests the effect is unclear in social support interventions provided by peers (six studies; average RR 1.42, 95% CI 0.98 to 2.07), in a single trial of support provided by partners, or when social support for smoking cessation was provided as part of a broader intervention to improve maternal health.The effect was unclear in single interventions of exercise compared to usual care (RR 1.20, 95% CI 0.72 to 2.01) and dissemination of counselling (RR 1.63, 95% CI 0.62 to 4.32).Importantly, high-quality evidence from pooled results demonstrated that women who received psychosocial interventions had a 17% reduction in infants born with low birthweight, a significantly higher mean birthweight (mean difference (MD) 55.60 g, 95% CI 29.82 to 81.38 g higher) and a 22% reduction in neonatal intensive care admissions. However the difference in preterm births and stillbirths was unclear. There did not appear to be adverse psychological effects from the interventions.The intensity of support women received in both the intervention and comparison groups has increased over time, with higher-intensity interventions more likely to have higher-intensity comparisons, potentially explaining why no clear differences were seen with increasing intervention intensity in meta-regression analyses. Among meta-regression analyses: studies classified as having 'unclear' implementation and unequal baseline characteristics were less effective than other studies. There was no clear difference between trials implemented by researchers (efficacy studies), and those implemented by routine pregnancy staff (effectiveness studies), however there was uncertainty in the effectiveness of counselling in four dissemination trials where the focus on the intervention was at an organisational level. The pooled effects were similar in interventions provided for women classified as having predominantly low socio-economic status, compared to other women. The effect was significant in interventions among women from ethnic minority groups; however not among indigenous women. There were similar effect sizes in trials with biochemically validated smoking abstinence and those with self-reported abstinence. It was unclear whether incorporating use of self-help manuals or telephone support increased the effectiveness of interventions.

AUTHORS' CONCLUSIONS

Psychosocial interventions to support women to stop smoking in pregnancy can increase the proportion of women who stop smoking in late pregnancy and the proportion of infants born low birthweight. Counselling, feedback and incentives appear to be effective, however the characteristics and context of the interventions should be carefully considered. The effect of health education and social support is less clear. New trials have been published during the preparation of this review and will be included in the next update.

Developmental toxicity of nicotine: A transdisciplinary synthesis and implications for emerging tobacco products

While the health risks associated with adult cigarette smoking have been well described, effects of nicotine exposure during periods of developmental vulnerability are often overlooked. Using MEDLINE and PubMed literature searches, books, reports and expert opinion, a transdisciplinary group of scientists reviewed human and animal research on the health effects of exposure to nicotine during pregnancy and adolescence. A synthesis of this research supports that nicotine contributes critically to adverse effects of gestational tobacco exposure, including reduced pulmonary function, auditory processing defects, impaired infant cardiorespiratory function, and may contribute to cognitive and behavioral deficits in later life. Nicotine exposure during adolescence is associated with deficits in working memory, attention, and auditory processing, as well as increased impulsivity and anxiety. Finally, recent animal studies suggest that nicotine has a priming effect that increases addiction liability for other drugs. The evidence that nicotine adversely affects fetal and adolescent development is sufficient to warrant public health measures to protect pregnant women, children, and adolescents from nicotine exposure.

Use of snus and smoking tobacco among pregnant women in the Agder counties

BACKGROUND

The use of snus during pregnancy increases the risk of stillbirths, premature delivery and reduced birthweight. People have been warned against smoking during pregnancy, but less so against the use of snus. We have investigated the use of snus and smoking tobacco among pregnant women in the Agder counties.

MATERIAL AND METHOD

Data on pregnant women and 10 583 births for the years 2012, 2013 and 2014 were retrieved from the electronic birth records of Sørlandet Hospital.

RESULTS

In the three-year period 2012 – 2014, altogether 5  % used snus and 19  % used smoking tobacco before pregnancy and 2  % and 8  % respectively at the end of pregnancy. The use of snus before pregnancy increased from 3.6  % in 2012 to 6.8  % in 2014. The equivalent figures for the first trimester were 1.7  % and 3.4  %, and for the last trimester 1.2  % and 2.1  %. The use of smoking tobacco declined by 2  % over the three-year period. In the age group 16 – 24 years, a total of 12  % used snus before pregnancy and 5  % at the end. Of 522 women who used snus before their pregnancy, altogether 57.5  % had quit during the first trimester and 71.4  % during the third trimester. The corresponding figures for those 2 015 women who used smoking tobacco before their pregnancy were 45.2  % and 58.0  % (p < 0.001).

INTERPRETATION

The use of snus before and during pregnancy doubled over the three-year period 2012 – 2014. The use was especially widespread in the youngest age groups. The proportion of women who quit using snus during their pregnancy was significantly higher than the proportion that quit smoking.

Maternal tobacco use and extremely premature birth - a population-based cohort study

OBJECTIVE

To study the associations of maternal tobacco use (smoking or use of snuff) and risk of extremely preterm birth, and if tobacco cessation before antenatal booking influences this risk. To study the association between tobacco use and spontaneous or medically indicated onset of delivery.

DESIGN

Population-based cohort study.

SETTING

Sweden.

POPULATION

All live singleton births, registered in the Swedish Medical Birth Register, 1999-2012.

METHODS

Odds ratios (OR) with 95% confidence intervals (CI) were calculated using multiple logistic regression analysis.

MAIN OUTCOME MEASURES

Extremely preterm birth (<28 weeks of gestation), very preterm birth (28-31 weeks), moderately preterm birth (32-36 weeks).

RESULTS

Maternal snuff use (OR 1.58; 95% CI: 1.14-2.21) and smoking (OR 1.61; 95% CI: 1.39-1.87 and OR 1.91; 95% CI: 1.53-2.39 for moderate and heavy smoking, respectively) were associated with an increased risk of extremely preterm birth. When cessation of tobacco use was obtained there was no increased risk of preterm birth. Snuff use was associated with a twofold risk increase of medically indicated extremely preterm birth, whereas smoking was associated with increased risks of both medically indicated and spontaneous extremely preterm birth.

CONCLUSIONS

Snuff use and smoking in pregnancy were associated with increased risks of extremely preterm birth. Women who stopped using tobacco before the antenatal booking had no increased risk. These findings indicate that nicotine, the common substance in cigarettes and snuff, is involved in the mechanisms behind preterm birth. The use of nicotine should be minimized in pregnancy.

TWEETABLE ABSTRACT

Tobacco use increases risk of extremely preterm birth. Cessation is preventive. Avoid nicotine in pregnancy.

The effects of nicotine on human fetal development

Maternal smoking during pregnancy continues to represent a major public health concern. Nicotine is extremely harmful to the developing fetus through many different mechanisms, and the harms increase with later gestational age at exposure. Pregnancies complicated by maternal nicotine use are more likely to have significant adverse outcomes. Nicotine-exposed children tend to have several health problems throughout their lives, including impaired function of the endocrine, reproductive, respiratory, cardiovascular, and neurologic systems. Poor academic performance and significant behavioral disruptions are also common, including ADHD, aggressive behaviors, and future substance abuse. To diminish the adverse effects from cigarette smoking, some women are turning to electronic cigarettes, a new trend that is increasing in popularity worldwide. They are largely perceived as being safer to use in pregnancy than traditional cigarettes, although there is not adequate evidence to support this claim. At this time, electronic cigarette use during pregnancy cannot be recommended. Birth Defects Research (Part C) 108:181-192, 2016. © 2016 Wiley Periodicals, Inc.

Hormonal contraception among electronic cigarette users and cardiovascular risk: a systematic review

BACKGROUND

Women who use combined hormonal contraceptives and cigarettes have an increased risk for cardiovascular (CV) events. We reviewed the literature to determine whether women who use hormonal contraceptives (HC) and electronic cigarettes (e-cigarettes) also have an increased risk.

STUDY DESIGN

Systematic review.

METHODS

We searched for articles reporting myocardial infarction (MI), stroke, venous thromboembolism, peripheral arterial disease or changes to CV markers in women using e-cigarettes and HC. We also searched for indirect evidence, such as CV outcomes among e-cigarette users in the general population and among HC users exposed to nicotine, propylene glycol or glycerol.

RESULTS

No articles reported on outcomes among e-cigarette users using HC. Among the general population, 13 articles reported on heart rate or blood pressure after e-cigarette use. These markers generally remained normal, even when significant changes were observed. In three studies, changes were less pronounced after e-cigarette use than cigarette use. One MI was reported among 1012 people exposed to e-cigarettes in these studies. One article on nicotine and HC exposure found both exposures to be significantly associated with acute changes to heart rate, though mean heart rate remained normal. No articles on propylene glycol or glycerol and HC exposure were identified.

CONCLUSION

We identified no evidence on CV outcomes among e-cigarette users using HC. Limited data reporting mostly acute outcomes suggested that CV events are rare among e-cigarette users in the general population and that e-cigarettes may affect heart rate and blood pressure less than conventional cigarettes. There is a need for research assessing joint HC and e-cigarette exposure on clinical CV outcomes.

An Official American Thoracic Society Research Statement: Current Understanding and Future Research Needs in Tobacco Control and Treatment

INTRODUCTION

Since the mid-20th century, the scientific community has substantially improved its understanding of the worldwide tobacco epidemic. Although significant progress has been made, the sheer enormity and scope of the global problem put it on track to take a billion lives this century. Curbing the epidemic will require maximizing the impact of proven tools as well as the development of new, breakthrough methods to help interrupt the spread of nicotine addiction and reduce the downstream morbidity.

METHODS

Members of the Tobacco Action Committee of the American Thoracic Society queried bibliographic databases, including Medline, Embase, and the Cochrane Collaborative, to identify primary sources and reviews relevant to the epidemic. Exploded search terms were used to identify evidence, including tobacco, addiction, smoking, cigarettes, nicotine, and smoking cessation. Evidence was consolidated into three thematic areas: (1) determinants of risk, (2) maternal-fetal exposure, and (3) current tobacco users. Expert panel consensus regarding current gaps in understanding and recommendations for future research priorities was generated through iterative discussion.

RESULTS

Although much has been accomplished, significant gaps in understanding remain. Implementation often lags well behind insight. This report identifies a number of investigative opportunities for significantly reducing the toll of tobacco use, including: (1) the need for novel, nonlinear models of population-based disease control; (2) refinement of "real-world" models of clinical intervention in trial design; and (3) understanding of mechanisms by which intrauterine smoke exposure may lead to persistent, tobacco-related chronic disease.

DISCUSSION

In the coming era of tobacco research, pooled talent from multiple disciplines will be required to further illuminate the complex social, environmental and biological codeterminants of tobacco dependence.

Knowledge and attitudes of adults towards smoking in pregnancy: results from the HealthStyles© 2008 survey

Smoking during pregnancy is causally associated with many adverse health outcomes. Quitting smoking, even late in pregnancy, improves some outcomes. Among adults in general and reproductive-aged women, we sought to understand knowledge and attitudes towards prenatal smoking and its effects on pregnancy outcomes. Using data from the 2008 HealthStyles© survey, we assessed knowledge and attitudes about prenatal smoking and smoking cessation. We classified respondents as having high knowledge if they gave ≥ 5 correct responses to six knowledge questions regarding the health effects of prenatal smoking. We calculated frequencies of correct responses to assess knowledge about prenatal smoking and estimated relative risk to examine knowledge by demographic and lifestyle factors. Only 15 % of all respondents and 23 % of reproductive-aged women had high knowledge of the adverse effects of prenatal smoking on pregnancy outcomes. Preterm birth and low birth weight were most often recognized as adverse outcomes associated with prenatal smoking. Nearly 70 % of reproductive-aged women smokers reported they would quit smoking if they became pregnant without any specific reasons from their doctor. Few respondents recognized the benefits of quitting smoking after the first trimester of pregnancy. Our results suggest that many women lack knowledge regarding the increased risks for adverse outcomes associated with prenatal smoking. Healthcare providers should follow the recommendations provided by the American Congress of Obstetricians and Gynecologists, which include educating women about the health risks of prenatal smoking and the benefits of quitting. Healthcare providers should emphasize quitting smoking even after the first trimester of pregnancy.

Maternal history of childhood sexual abuse and preterm birth: an epidemiologic review

BACKGROUND

History of childhood sexual abuse (CSA) is highly prevalent with as many as one in four American women being victims. Exposure to CSA or other early life traumatic experiences has been associated with adverse reproductive and pregnancy outcomes. However, the effects of CSA on preterm delivery (PTB), a leading cause of neonatal mortality, remain poorly understood. The objectives of this review are (i) to synthesize the available research investigating the relationship between maternal history of childhood sexual abuse (CSA) and preterm delivery (PTB); (ii) to provide suggestions for improving future research on this topic; and (iii) to highlight implications for clinical practice and public health.

METHODS

Relevant articles were identified through searches of four electronic databases (PubMed, CINAHL, Web of Science Core Collection and BIOSIS Online) for studies published before March 2014, as well as through reviewing references of published articles.

RESULTS

A total of six studies published from 1992 to 2010 were included in this review. Overall, findings were inconsistent. Three studies reported statistically significant associations of CSA with PTB (<37 weeks gestation) or shorter mean gestational age at birth. Women with a history of CSA had 2.6 to 4.8-fold increased odds of PTB as compared with women without a history of CSA. Three other studies did not observe statistically significant differences in rates of PTB or mean gestational age at birth in relation to a history of CSA.

CONCLUSIONS

Available evidence on this topic is sparse and inconsistent, and limited by a number of methodological challenges. Given the ubiquity of CSA, as well as the clinical and public health significance of PTB, more rigorously designed epidemiologic studies on the association between CSA and PTB are warranted.

Nicotine and the Developing Human: A Neglected Element in the Electronic Cigarette Debate

The elimination of cigarettes and other combusted tobacco products in the U.S. would prevent tens of millions of tobacco-related deaths. It has been suggested that the introduction of less harmful nicotine delivery devices, such as electronic cigarettes or other electronic nicotine delivery systems, will accelerate progress toward ending combustible cigarette use. However, careful consideration of the potential adverse health effects from nicotine itself is often absent from public health debates. Human and animal data support that nicotine exposure during periods of developmental vulnerability (fetal through adolescent stages) has multiple adverse health consequences, including impaired fetal brain and lung development, and altered development of cerebral cortex and hippocampus in adolescents. Measures to protect the health of pregnant women and children are needed and could include (1) strong prohibitions on marketing that increase youth uptake; (2) youth access laws similar to those in effect for other tobacco products; (3) appropriate health warnings for vulnerable populations; (4) packaging to prevent accidental poisonings; (5) protection of non-users from exposure to secondhand electronic cigarette aerosol; (6) pricing that helps minimize youth initiation and use; (7) regulations to reduce product addiction potential and appeal for youth; and (8) the age of legal sale.

Exploration of preterm birth rates associated with different models of antenatal midwifery care in Scotland: Unmatched retrospective cohort analysis

OBJECTIVES

preterm birth represents a significant personal, clinical, organisational and financial burden. Strategies to reduce the preterm birth rate have had limited success. Limited evidence indicates that certain antenatal care models may offer some protection, although the causal mechanism is not understood. We sought to compare preterm birth rates for mixed-risk pregnant women accessing antenatal care organised at a freestanding midwifery unit (FMU) and mixed-risk pregnant women attending an obstetric unit (OU) with related community-based antenatal care.

METHODS

unmatched retrospective 4-year Scottish cohort analysis (2008-2011) of mixed-risk pregnant women accessing (i) FMU antenatal care (n=1107); (ii) combined community-based and OU antenatal care (n=7567). Data were accessed via the Information and Statistics Division of the NHS in Scotland. Aggregates analysis and binary logistic regression were used to compare the cohorts׳ rates of preterm birth; and of spontaneous labour onset, use of pharmacological analgesia, unassisted vertex birth, and low birth weight. Odds ratios were adjusted for age, parity, deprivation score and smoking status in pregnancy.

FINDINGS

after adjustment the 'mixed risk' FMU cohort had a statistically significantly reduced risk of preterm birth (5.1% [n=57] versus 7.7% [n=583]; AOR 0.73 [95% CI 0.55-0.98]; p=0.034). Differences in these secondary outcome measures were also statistically significant: spontaneous labour onset (FMU 83.9% versus OU 74.6%; AOR 1.74 [95% CI 1.46-2.08]; p<0.001); minimal intrapartum analgesia (FMU 53.7% versus OU 34.4%; AOR 2.17 [95% CI 1.90-2.49]; p<0.001); spontaneous vertex delivery (FMU 71.9% versus OU 63.5%; AOR 1.46 [95% CI 1.32-1.78]; p<0.001). Incidence of low birth weight was not statistically significant after adjustment for other variables. There was no significant difference in the rate of perinatal or neonatal death.

CONCLUSIONS

given this study׳s methodological limitations, we can only claim associations between the care model and or chosen outcomes. Although both cohorts were mixed risk, differences in risk levels could have contributed to these findings. Nevertheless, the significant difference in preterm birth rates in this study resonates with other research, including the recent Cochrane review of midwife-led continuity models. Because of the multiplicity of risk factors for preterm birth we need to explore the salient features of the FMU model which may be contributing to this apparent protective effect. Because a randomised controlled trial would necessarily restrict choice to pregnant women, we feel that this option is problematic in exploring this further. We therefore plan to conduct a prospective matched cohort analysis together with a survey of unit practices and experiences.

Early origins of chronic obstructive lung diseases across the life course

Chronic obstructive lung diseases, like asthma and chronic obstructive pulmonary disease, have high prevalences and are a major public health concern. Chronic obstructive lung diseases have at least part of their origins in early life. Exposure to an adverse environment during critical periods in early life might lead to permanent developmental adaptations which results in impaired lung growth with smaller airways and lower lung volume, altered immunological responses and related inflammation, and subsequently to increased risks of chronic obstructive lung diseases throughout the life course. Various pathways leading from early life factors to respiratory health outcomes in later life have been studied, including fetal and early infant growth patterns, preterm birth, maternal obesity, diet and smoking, children's diet, allergen exposure and respiratory tract infections, and genetic susceptibility. Data on potential adverse factors in the embryonic and preconception period and respiratory health outcomes are scarce. Also, the underlying mechanisms how specific adverse exposures in the fetal and early postnatal period lead to chronic obstructive lung diseases in later life are not yet fully understood. Current studies suggest that interactions between early environmental exposures and genetic factors such as changes in DNA-methylation and RNA expression patterns may explain the early development of chronic obstructive lung diseases. New well-designed epidemiological studies are needed to identify specific critical periods and to elucidate the mechanisms underlying the development of chronic obstructive lung disease throughout the life course.

The Generation R Study: Biobank update 2015

The Generation R Study is a population-based prospective cohort study from fetal life until adulthood. The study is designed to identify early environmental and genetic causes and causal pathways leading to normal and abnormal growth, development and health from fetal life, childhood and young adulthood. In total, 9,778 mothers were enrolled in the study. Data collection in children and their parents include questionnaires, interviews, detailed physical and ultrasound examinations, behavioural observations, Magnetic Resonance Imaging and biological samples. Efforts have been conducted for collecting biological samples including blood, hair, faeces, nasal swabs, saliva and urine samples and generating genomics data on DNA, RNA and microbiome. In this paper, we give an update of the collection, processing and storage of these biological samples and available measures. Together with detailed phenotype measurements, these biological samples provide a unique resource for epidemiological studies focused on environmental exposures, genetic and genomic determinants and their interactions in relation to growth, health and development from fetal life onwards.

Screening practices and attitudes of obstetricians-gynecologists toward new and emerging tobacco products

OBJECTIVE

We examined screening practices and attitudes of obstetricians-gynecologists toward the use of noncombustible tobacco products (chewing tobacco, snuff/snus, electronic cigarettes, and dissolvables) during pregnancy.

STUDY DESIGN

The authors mailed a survey in 2012 to 1024 members of the American College of Obstetricians and Gynecologists, including Collaborative Ambulatory Research Network (CARN) and non-CARN members. Stratified random selection was used to generate CARN and non-CARN samples.

RESULTS

Response rates were 52% and 31% for CARN and non-CARN members, respectively. Of 252 total eligible respondents (those currently providing obstetrics care) 53% reported screening pregnant women at intake for noncombustible tobacco product use all or some of the time, and 40% reported none of the time. Respondents who reported that noncombustible products have adverse health effects during pregnancy, but are safer than cigarettes, ranged from 20.2% (dissolvables) to 29% (electronic cigarettes) and that the health effects are the same as those of cigarettes from 13.5% (electronic cigarettes) to 53.6% (chewing tobacco). Approximately 14% reported that electronic cigarettes have no adverse health effects; <1% reported no health effects for the remaining products. Two-thirds of the respondents wanted to know more about the potential health effects of noncombustible tobacco products; only 5% believed themselves to be fully informed.

CONCLUSION

A large proportion of obstetrician-gynecologists reported never or inconsistently screening their pregnant patients for the use of noncombustible tobacco products. Responses regarding the harms of these products relative to cigarettes were mixed and most respondents wanted more information. Development and dissemination of guidance for providers is needed to improve decision-making regarding noncombustible tobacco products.

Smoking during pregnancy was up to 70% more common in the most deprived municipalities - a multilevel analysis of all singleton births during 2005-2010 in Finland

OBJECTIVE

We investigated whether there was an association between maternal smoking habits during pregnancy and municipality level deprivation defined based on education, income and unemployment after adjustment for individual level covariates, including socioeconomic status (SES), in Finland, a Nordic welfare state.

METHODS

Data were gathered from the Medical Birth Register and comprised all singleton births (n=337,876) during 2005-2010. To account for any correlation of women clustered within a municipality, we fitted generalized estimating equation (GEE) models.

RESULTS

In total, 15.3% of the women with singleton pregnancies smoked during pregnancy. After adjustment for individual level confounders, smoking during pregnancy was 5.4-fold higher among women with the lowest as compared with highest individual SES. Controlling for individual SES, age and year of birth, women living in municipalities defined as intermediately and highly deprived based on education were 53.7% (adjusted odds ratio [aOR] 1.537, 95% confidence interval [CI] 1.493-1.583) and 71.5% (aOR 1.715, 95% CI 1.647-1.785), respectively, more likely to smoke during pregnancy than women in the least deprived municipalities.

CONCLUSIONS

Individual SES is the strongest correlate of smoking during pregnancy but conditional on individual variables; lower municipality aggregate education is associated with up to 70% higher smoking prevalence.

Smokeless tobacco use in pregnancy: an integrative review of the literature

OBJECTIVES

To systematically critique and summarise the available evidence on the outcomes of smokeless tobacco use in pregnancy to inform the public health response.

METHODS

In March 2013, a search was conducted of observational studies where the exposure to smokeless tobacco during pregnancy and maternal, placental and/or neonatal outcomes was assessed. Two reviewers extracted data and completed quality assessment of the literature utilizing the Agency for Healthcare Research and Quality criteria (West et al. 2002).

RESULTS

The search resulted in 211 articles, 21 (10%) of which met the final criteria for integrative review. Ten (10) of the studies are from India, seven (7) from Sweden, two (2) from Alaska and one (1) each from South Africa and Pakistan.

CONCLUSIONS

Many studies lacked sufficient power to estimate precise risks. Most reports were hindered by imprecise measures of exposure and lack of confounding variable control. However, there were indications that maternal smokeless tobacco use increases rates of stillbirth, low birth weight and alters the male:female live birth ratio. Maternal smokeless tobacco use may not be safe for mother or foetus.

Smoking during pregnancy: childbirth and health study in primary care in Iceland

OBJECTIVE

To study the prevalence and possible predictors for smoking during pregnancy in Iceland.

DESIGN

A cross-sectional study.

SETTING

Twenty-six primary health care centres in Iceland 2009-2010. SUBJECTS. Women attending antenatal care in the 11th-16th week of pregnancy were invited to participate by convenient consecutive manner, stratified according to residency. A total of 1111 women provided data in this first phase of the cohort study.

MAIN OUTCOME MEASURES

Smoking habits before and during early pregnancy were assessed with a postal questionnaire, which also included questions about socio-demographic background, physical and emotional well-being, and use of medications.

RESULTS

The prevalence of smoking prior to pregnancy was 20% (223/1111). During early pregnancy, it was 5% (53/1111). In comparison with women who stopped smoking during early pregnancy, those who continued to smoke had on average a significantly lower level of education, had smoked more cigarettes per day before pregnancy, and were more likely to use nicotine replacement therapy in addition to smoking during pregnancy. A higher number of cigarettes consumed per day before pregnancy and a lower level of education were the strongest predictors for continued smoking during pregnancy.

CONCLUSION

The majority of Icelandic women who smoke stop when they become pregnant, and the prevalence of smoking during pregnancy in Iceland is still about 5%. Our results indicate stronger nicotine dependence in women who do not stop smoking during pregnancy. Awareness of this can help general practitioners (GPs) and others providing antenatal care to approach these women with more insight and empathy, which might theoretically help them to quit.