Trends in maternal use of snus and smoking tobacco in pregnancy. A register study in southern Norway

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.

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

OBJECTIVE

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

INTRODUCTION

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

INCLUSION CRITERIA

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

METHODS

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 Unpublished studies were searched in 6 gray literature sources (eg, ProQuest Dissertations and Theses, Google Scholar).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

RESULTS

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

CONCLUSIONS

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

SYSTEMATIC REVIEW REGISTRATION NUMBER

PROSPERO CRD42020178866.

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.

Toxic effects of smokeless tobacco on female reproductive health: A review

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Smokeless tobacco use can lead to impairments of ovarian function, morphology, oocyte quality and hormonal regulation.

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Use of smokeless tobacco during pregnancy has adverse health effects on both the mother and fetus.

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Exposure to smokeless tobacco in utero has long term health consequences on offspring.

The habitual consumption of tobacco in its various form is widespread and a serious public health issue globally. In particular, the use of smokeless tobacco has increased substantially due to its easy availability and misconception that it is relatively harmless compared to smoking. Tobacco use has been well established from numerous studies as a causative agent of devastating illnesses such as cancer, insulin resistance, hypertension, acute respiratory disease, osteoporosis, etc. Limited but growing evidence have also suggested its role in adversely affecting reproductive capabilities and outcomes in women of reproductive age and during pregnancy. This paper provides an updated review on available literature regarding the negative effects of smokeless tobacco use on female reproductive health, during pregnancy and its adverse consequences on the offspring. Existing data suggests the association between chronic smokeless tobacco use and impairment of ovarian morphology and function, oocyte quality, hormonal perturbations, fetal development and long-term health effects on the fetus. Improved understanding of these issues can contribute to better awareness of the dangers of smokeless tobacco products.

Maternal factors associated with smoking during gestation and consequences in newborns: Results of an 18-year study

BACKGROUND

Tobacco use is one of the most important causes of obstetric and perinatal pathologies. Its frequency during pregnancy is high and could be related to various socioeconomic and cultural characteristics of the mothers.

AIM

The aim of this study is to determine the trend and prevalence of smoking in pregnant mothers in our area over the years and the socio-cultural or obstetric factors associated with smoking as well as the repercussions on the newborns related to its consumption.

METHODS

Retrospective study of 18,959 mothers of healthy newborns in the maternity ward of the regional hospital during the years 2002-2019. The variable under study was maternal smoking during pregnancy compared with various maternal, obstetric, and perinatal factors.

RESULTS

A mean percentage of 20.4% of the mothers smoked, with significantly decreasing percentages over the years. There was a significant association between smoking and mothers' age, origin, level of education, the occurrence of previous abortions, parity, type of breastfeeding at discharge, type of delivery, low birth weight, and need for neonatal resuscitation.

CONCLUSIONS

This defines a profile of pregnant smokers on whom it is important to act: young, Spanish, with a low level of education, multiparous, and with previous miscarriages. Its repercussions are also evident with a lower birth weight in newborns. Knowledge of these factors will make it possible to design more effective intervention strategies to reduce smoking during pregnancy.

RELEVANCE FOR PATIENTS

Any effort that reduces smoking habits can improve the health status of mothers and newborns and the first step is to know who are risk pregnants.

Snus and Alcohol: Mutually Rewarding Effects in the Brain? A Matched Controlled Population Study

Background:

The use of moist smokeless tobacco (snus) is increasing in the U.S. and other Western countries, and especially among young people. Snus is associated with several health problems, but the relationship between use of snus and alcohol is scarcely explored. Neuro-cognitive and psychological research suggest an association due to possible mutually rewarding effects in the limbic brain. We investigated this issue in a matched controlled population study.

Methods:

Matched control group design where drinking habits and alcohol consumption in a group of users of snus (n = 1043, mean age = 35.20; n men = 749, n women = 294) were compared to a control group of non-users matched on age and gender (n = 1043, mean age = 35.65; n men = 749, n women = 294). In addition, we registered background variables such as level of education, income, self-perceived general, dental health, mental health, current depressive symptoms, and BMI. In estimation of alcohol consumption, the background variables were used as covariates in factorial analyses of variance (ANCOVA).

Results:

Users of snus had lower level of education, lower income, poorer general, dental, and mental health status than non-users, but there were no differences in BMI. Differences in mental health status were related to drinking habits. Users of snus had a higher frequency of drinking, higher frequency of intoxication, and showed more excess drinking. Controlled for background variables users of snus had a 25.2% higher estimated yearly consumption of alcohol in terms of standard units of alcohol on the weekdays, 26.4% higher on weekends and a 60.2% higher yearly excess consumption.

Conclusion:

Users of snus had an elevated alcohol consumption and another drinking style than non-users. The findings are discussed according to neuro-cognitive and psychopharmacological mechanisms, reward learning and conditioning. The results have implications for prevention, treatment and rehabilitation of alcohol and nicotine dependence.

Impact of nicotine and maternal BMI on fetal birth weight

BACKGROUND

According to the World Health Organization, smoking is the most important risk factor for adverse pregnancy outcomes in industrialized nations. As the individual factors (body mass index - BMI (kg/m2) - and cigarette consumption) have been extensively investigated in pregnancy, we aimed to establish how maternal BMI and nicotine interact with regard to perinatal outcomes and birth weight.

METHODS

Data from 110.047 singleton pregnancies, achieved from the German Perinatal Survey in Schleswig-Holstein and registered between 2010 and 2017 were analyzed in August 2018 concerning maternal BMI and smoking. The BMI was taken from the maternity log. Information concerning the smoking status were self-reported and further subdivided into the following four categories: a) non-smokers; b) 1-7 cigarettes/day; c) 8-14 cigarettes/ day; and d) ≥ 15 cigarettes/ day. Furthermore, we classified women by their BMI into underweight, normal weight, overweight and obese. Comparisons between non-smokers and the respective smoking group, and their relationship with maternal BMI were performed by the t-test (birth weight). A P-value ≤0.05 was considered to indicate statistical significance.

RESULTS

A number of 97.092 women (88.2%) were non-smokers and 12.955 (11.8%) were smokers. Furthermore 10.3% of women of normal weight smoked during pregnancy, but both high and low BMI were associated with a high prevalence of smoking. The proportion of smokers was highest (18.1%) among underweight women (BMI ≤ 18.5 kg/m2). A large number of smokers (15.5%) were registered in the obesity group (BMI ≥ 30 kg/m2). Mean birth weight (≥ 37 + 0 gestational age) increased with increasing maternal BMI, and was reduced by smoking for every BMI category. The differences between smokers and non-smokers were always highly significant (p < 0.001). Mean birth weight varied between 2995 g in underweight frequent smokers and 3607 g in obese non-smokers.

CONCLUSION

Both maternal BMI and smoking during pregnancy influences the birth weight and therefore pregnancy outcome. Smoking during pregnancy was significantly associated with low birth weight. Pregnant women should be advised to cease or at least reduce smoking in order to improve the birth weight of the newborn and to minimize child morbidities.

Evaluation of incomplete maternal smoking data using machine learning algorithms: a study from the Medical Birth Registry of Norway

Background

The Medical Birth Registry of Norway (MBRN) provides national coverage of all births. While retrieval of most of the information in the birth records is mandatory, mothers may refrain to provide information on her smoking status. The proportion of women with unknown smoking status varied greatly over time, between hospitals, and by demographic groups. We investigated if incomplete data on smoking in the MBRN may have contributed to a biased smoking prevalence.

Methods

In a study population of all 904,982 viable and singleton births during 1999–2014, we investigated main predictor variables influencing the unknown smoking status of the mothers’ using linear multivariable regression. Thereafter, we applied machine learning to predict annual smoking prevalence (95% CI) in the same group of unknown smoking status, assuming missing-not-at-random.

Results

Overall, the proportion of women with unknown smoking status was 14.4%. Compared to the Nordic country region of origin, women from Europe outside the Nordic region had 15% (95% CI 12–17%) increased adjusted risk to have unknown smoking status. Correspondingly, the increased risks for women from Asia was 17% (95% CI 15–19%) and Africa 26% (95% CI 23–29%). The most important machine learning prediction variables regarding maternal smoking were education, ethnic background, marital status and birth weight. We estimated a change from the annual observed smoking prevalence among the women with known smoking status in the range of − 5.5 to 1.1% when combining observed and predicted smoking prevalence.

Conclusion

The predicted total smoking prevalence was only marginally modified compared to the observed prevalence in the group with known smoking status. This implies that MBRN-data may be trusted for health surveillance and research.

Supplementary Information

Supplementary information accompanies this paper at 10.1186/s12884-020-03384-y.