Socioeconomic differences in smoking trends among pregnant women at first antenatal visit in Sweden 1982-2001: increasing importance of educational level for the total burden of smoking

Prevalence of smoking during pregnancy and associated social inequalities in developed countries over the 1995-2020 period: A systematic review

BACKGROUND

Smoking during pregnancy (SDP) is an important source of preventable morbidity and mortality for both mother and child.

OBJECTIVES

The aim of this study was to describe changes in the prevalence of SDP over the last 25 years in developed countries (Human Development Index >0.8 in 2020) and associated social inequalities.

DATA SOURCES

A systematic review was conducted based on a search in PubMed, Embase and PsycInfo databases and government sources.

STUDY SELECTION AND DATA EXTRACTION

Published studies between January 1995 and March 2020, for which the primary outcome was to assess the national prevalence of SDP and the secondary outcome was to describe related socio-economic data were included in the analysis. The selected articles had to be written in English, Spanish, French or Italian.

SYNTHESIS

The articles were selected after successive reading of the titles, abstracts and full-length text. An independent double reading with intervention of a third reader in case of disagreement allowed including 35 articles from 14 countries in the analysis.

RESULTS

The prevalence of SDP differed across the countries studied despite comparable levels of development. After 2015, the prevalence of SDP ranged between 4.2% in Sweden and 16.6% in France. It was associated with socio-economic factors. The prevalence of SDP slowly decreased over time, but this overall trend masked inequalities within populations. In Canada, France and the United States, the prevalence decreased more rapidly in women of higher socio-economic status, and inequalities in maternal smoking were more marked in these countries. In the other countries, inequalities tended to decrease but remained significant.

CONCLUSIONS

During pregnancy, that is a period described as a window of opportunity, smoking and social vulnerability factors need to be detected to implement targeted prevention strategies aiming at reducing related social inequalities.

Social Determinants of Cigarette Smoking among American Women during Pregnancy

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

Maternal smoking during pregnancy: Trends and determinants in the conception to community study

BACKGROUND

Despite earlier declines, maternal smoking during pregnancy continues to be a public health problem. We examined trends and factors associated with maternal smoking during and between pregnancy over six years.

METHODS

Participants were 27 532 pregnant women in Tasmanian public hospitals whose smoking status was gathered by midwives during perinatal care between July 2008 and June 2014. Generalized linear modeling was used to examine the trends in prevalence of maternal smoking over time and factors associated with change in smoking status both within and between pregnancies.

RESULTS

Smoking during pregnancy decreased from 25.9% in 2008 to 16.4% in 2014 (57.9% decline). Multivariable regression analysis suggested that maternal alcohol consumption during pregnancy, living in a highly socioeconomically disadvantaged area, and being an Aboriginal or Torres Strait Islander significantly increased the risk of maternal smoking during pregnancy. Being older, married, or in a de facto relationship, and intending to breastfeed were associated with reduced risk of smoking during pregnancy. Between index (first birth recorded in data set) and last pregnancy, 35.1% of smokers quit, but 5.1% of nonsmokers started smoking. Only 8.1% of mothers who smoked during the first half of pregnancy quit by the second half.

CONCLUSIONS

Maternal smoking during pregnancy is decreasing. To sustain the decline, preventive efforts must address the role of social determinants of health (eg, mothers who drink alcohol, live in highly disadvantaged areas, are younger and single) among women who smoke during pregnancy.

Smoking during pregnancy: changes and associated risk factors in Spain, 1980-2016

BACKGROUND

Trends for maternal smoking rates have varied substantially across industrialized countries. The objective was to describe how the prevalence of maternal smoking evolved in Spain during 1980-2016.

METHODS

Data came from the Spanish Collaborative Study of Congenital Malformations. Our sample consisted of 40 934 mothers of newborns with no congenital defects from hospitals all across Spain. We estimated change points in trend and the mean annual change in smoking prevalence using 'joinpoint' regression. Relevant potential factors (age, country of birth, education, parity, planned pregnancy and alcohol consumption) were examined using multivariate logistic regression.

RESULTS

Maternal smoking prevalence in 1980 and 2016 were 14.3% (95% confidence interval [CI]: 11.9-17.0) and 20.4% (95% CI: 15.9-25.8). We identified four periods with distinct trends: a sharp increase during the 80s, a plateau during the 90s, a decrease starting in 2000 and a slowdown of such decrease from 2009 on. Smoking was significantly higher among young women, Spain-born, with low education, unplanned pregnancy, and alcohol consumption.

CONCLUSIONS

Currently in Spain maternal smoking remains very high. Tobacco consumption trend showed an increase during the 80s, a plateau during the 90s, and a reduction in the 2000s. Several sociodemographic and behavioural factors were associated to greater likelihood of smoking.

Acculturation or unequal assimilation? Smoking during pregnancy and duration of residence among migrants in Sweden

A growing corpus of evidence reveals that smoking patterns of migrant women tend to converge with that of the host population over time ('acculturation paradox'). In this paper we aim to adopt a health equity perspective by studying the extent to which this pattern reflects a convergence with the group of natives who are more socioeconomically disadvantaged. Using population-based registers, we study 1,194,296 women who gave birth in Sweden between 1991 and 2012. Using logistic regression, we estimated odds ratios to assess the effect of duration of residence on the association between smoking during pregnancy and women's origin (classified according to inequality-adjusted Human Development Index (iHDI) of the country of birth). Sibling information and multilevel models were used to assess the extent to which our results might be affected by the cross-sectional nature of the data. Smoking during pregnancy increases with duration of residence among migrants from all levels of iHDI to such an extent that they tend to converge or increase in relation to the levels of the Swedish population with low education and low income, leaving behind the native population with high education and income. The results are robust to possible selection bias related to the cross-sectional nature of the data. Our findings indicate the need of a health equity perspective and suggest the use of 'unequal assimilation' rather than 'acculturation paradox' as a more suitable framework to interpret these findings.

Education is the strongest socio-economic predictor of smoking in pregnancy

AIMS

To investigate socio-economic disparities in smoking in pregnancy (SIP) by the mother's education, occupational class and current economic conditions.

DESIGN

Cross-sectional analysis with linked survey and register data.

SETTING

South-western Finland.

PARTICIPANTS

A total of 2667 pregnant women [70% of the original sample (n = 3808)] from FinnBrain, a prospective pregnancy cohort study.

MEASUREMENTS

The outcome was smoking during the first pregnancy trimester, measured from the Finnish Medical Birth Register. Education and occupational class were linked from population registers. Income support recipiency and subjective economic wellbeing were questionnaire-based measures of current economic conditions. These were adjusted for age, partnership status, residential area type, parental separation, parity, childhood socio-economic background, childhood adversities (the Trauma and Distressing Events During Childhood scale) and antenatal stress (Edinburgh Postnatal Depression Scale). Logistic regressions and attributable fractions (AF) were estimated.

FINDINGS

Mother's education was the strongest socio-economic predictor of SIP. Compared with university education, adjusted odds ratios (aORs) of SIP were: 2.2 [95% confidence interval (CI) = 1.2-3.9; P = 0.011] for tertiary vocational education, 4.4 (95% CI = 2.1-9.0; P < 0.001) for combined general and vocational secondary education, 2.9 (95% CI = 1.4-6.1; P = 0.006) for general secondary education, 9.5 (95% CI 5.0-18.2; P < 0.001) for vocational secondary education and 14.4 (95% CI = 6.3-33.0; P < 0.001) for compulsory schooling. The total AF of education was 0.5. Adjusted for the other variables, occupational class and subjective economic wellbeing did not predict SIP. Income support recipiency was associated positively with SIP (aOR = 1.8; 95% CI = 1.1-3.1; P = 0.022). Antenatal stress predicted SIP (aOR = 2.0; 95% CI = 1.4-2.8; P < 0.001), but did not attenuate its socio-economic disparities.

CONCLUSIONS

In Finland, socio-economic disparities in smoking in pregnancy are attributable primarily to differences in the mother's educational level (low versus high) and orientation (vocational versus general).

Secular trends in smoking during pregnancy according to income and ethnic group: four population-based perinatal surveys in a Brazilian city

OBJECTIVES

To assess socioeconomic and ethnic inequalities in smoking during pregnancy over three decades (1982-2011).

SETTING

Population-based study in Pelotas City, Brazil.

PARTICIPANTS

All urban women giving birth in the city hospitals in 1982 (5909), 1993 (5223) and 2004 (4201), plus all urban and rural women delivering from January 2011 to April 2012 (6275).

PRIMARY OUTCOME

Self-reported smoking during pregnancy.

RESULTS

The prevalence of smoking during pregnancy fell from 35.7% in 1982 to 21.0% in 2011. In each survey, prevalence decreased with increasing income (p<0.001). In the poorest quintile, smoking fell by 27.4% in the period studied compared to 67.1% in the wealthiest quintile. In all surveys, prevalence was lower among white women than among those who classified themselves as black or brown (p<0.001). Over time, smoking declined by 50.0% among the former and 30.7% among the latter. Absolute and relative inequalities both increased over time.

CONCLUSIONS

The reduction in smoking during pregnancy was primarily due to a decline among white, high-income women. Further efforts are needed to reduce smoking among all population groups.

Effects of maternal smoking during pregnancy on offspring blood pressure in late adolescence

OBJECTIVES

Previous studies suggest that maternal smoking during pregnancy is associated with elevated offspring blood pressure during childhood. We aimed to investigate whether this association remained in late adolescence and, if so, whether it could be attributed to an intrauterine effect or to familial confounding.

METHODS

We used a national cohort of 87,223 young Swedish men born between 1983 and 1988 with information on both maternal smoking during pregnancy and blood pressure at military conscription. The cohort included 780 full brothers discordant for maternal smoking. Generalized estimation equations were used to estimate regression coefficients (β) with 95% confidence intervals (95% CIs).

RESULTS

We found a small but significant increase in both SBP and DBP for young men whose mothers had been daily smokers during pregnancy compared with sons of nonsmoking mothers: 0.26 (95% CI 0.09 to 0.44) and 0.45 mmHg (95% CI 0.31 to 0.59) for SBP and DBP, respectively. In a within-sibling analysis comparing full brothers discordant for maternal smoking exposure, point estimates were similar but not statistically significant: 0.85 (95% CI -0.19 to 1.90) for DBP and 0.81 (-0.56 to 2.19) for SBP.

CONCLUSION

Maternal smoking during pregnancy is associated with a small but statistically significant increase in offspring blood pressure in late adolescence. Because the association does not appear to be explained by familial confounding, our results support an intrauterine effect of prenatal smoking exposure on blood pressure in late adolescence.

Prenatal exposure to tobacco and future nicotine dependence: population-based cohort study

BACKGROUND

Maternal smoking during pregnancy may increase the risk of nicotine dependence, especially in girls, but data are conflicting and confounding by other familial factors cannot be ruled out.

AIMS

To clarify the relationship between prenatal tobacco exposure and adolescent tobacco uptake and dependence in boys and girls respectively, while taking confounding factors into close consideration.

METHOD

We conducted a prospective longitudinal study, comprising 3020 Swedish youths followed from 11 to 18 years of age. Exposure and outcome information was elicited via self-administered parental and repeated youth questionnaires. Hazard ratios (HRs), odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were calculated as measures of associations.

RESULTS

Girls prenatally exposed to maternal tobacco use had a two- to threefold increased odds of experiencing a high number of withdrawal symptoms (OR = 2.83, 95% CI 1.68-4.87), craving for tobacco (OR = 2.04, 95% CI 1.28-3.32) and heavy tobacco use (five or more cigarettes or snus dips per day) (OR = 1.93, 95% CI 1.30-2.86). These associations were weaker among boys, and did not reach formal statistical significance. Associations between prenatal tobacco exposure and onset of regular tobacco use in both genders appeared to be mostly explained by parents' social position and postnatal smoking behaviour.

CONCLUSIONS

Prenatal exposure to tobacco is linked to an increased risk of nicotine dependence among adolescent girls.

Burden of type 2 diabetes attributed to lower educational levels in Sweden

BACKGROUND

Type 2 diabetes is associated with low socioeconomic position (SEP) in high-income countries. Despite the important role of SEP in the development of many diseases, no socioeconomic indicator was included in the Comparative Risk Assessment (CRA) module of the Global Burden of Disease study. We therefore aimed to illustrate an example by estimating the burden of type 2 diabetes in Sweden attributed to lower educational levels as a measure of SEP using the methods applied in the CRA.

METHODS

To include lower educational levels as a risk factor for type 2 diabetes, we pooled relevant international data from a recent systematic review to measure the association between type 2 diabetes incidence and lower educational levels. We also collected data on the distribution of educational levels in the Swedish population using comparable criteria for educational levels as identified in the international literature. Population attributable fractions (PAF) were estimated and applied to the burden of diabetes estimates from the Swedish burden of disease database for men and women in the separate age groups (30-44, 45-59, 60-69, 70-79, and 80+ years).

RESULTS

The PAF estimates showed that 17.2% of the diabetes burden in men and 20.1% of the burden in women were attributed to lower educational levels in Sweden when combining all age groups. The burden was, however, most pronounced in the older age groups (70-79 and 80+), where lower educational levels contributed to 22.5% to 24.5% of the diabetes burden in men and 27.8% to 32.6% in women.

CONCLUSIONS

There is a considerable burden of type 2 diabetes attributed to lower educational levels in Sweden, and socioeconomic indicators should be considered to be incorporated in the CRA.

Maternal smoking during pregnancy among Aboriginal women in New South Wales is linked to social gradient

OBJECTIVE

Social gradients in Aboriginal health are seldom explored. This study describes social gradients and trends in smoking during pregnancy among Aboriginal mothers in NSW.

METHODS

This was a secondary analysis of the NSW Midwives Data Collection (MDC) 1994-2007, covering all births in NSW. Analyses examined associations between socio-demographic characteristics and smoking during pregnancy.

RESULTS

Data from 1,214,206 pregnant women showed that 17.4% smoked during pregnancy. The rate of smoking during pregnancy among all NSW women declined from 22.3% in 1994 to 12.8% in 2007; the rate among Aboriginal women remained high, declining from 61.4% in 1994 to 50.2% in 2007. Smoking was substantially higher among Aboriginal mothers compared to non-Aboriginal mothers. Socio-economic analyses showed that the smoking rate among low SES Aboriginal mothers was approximately two and a half times that of high SES Aboriginal women, a similar gradient to non-Aboriginal women.

CONCLUSIONS

Indicators of socio-economic position are a consistent, independent correlate of smoking during pregnancy for Aboriginal and non-Aboriginal women.

IMPLICATIONS

There is a need for a social inequalities approach to smoking during pregnancy, specifically targeting more disadvantaged Aboriginal mothers and all teenage mothers for smoking prevention. Strategies to access more disadvantaged mothers should not be missed through broadly focused Aboriginal tobacco control strategies.

Prevalence and predictors of smoking and quitting during pregnancy in Serbia: results of a nationally representative survey

OBJECTIVES

Middle- and low-income countries rarely have national surveillance data on smoking in pregnancy. This nationwide population-representative survey investigated pre- and post-partum smoking and their predictors in Serbia.

METHODS

Using stratified two-stage random cluster sampling, 2,721 women in 66 health care centres were interviewed at 3 and 6 months post-partum.

RESULTS

37.2% of women smoked at some point in pregnancy (average 8.8 cigarettes/per day). Smoking at pregnancy onset and during pregnancy was associated with smoking by others in the home and lower education and family socio-economic status. Almost a quarter of women (23.2%) who quit smoking during pregnancy did not relapse 6 months post-partum. Older women, primiparae, university students and white-collar workers were more likely to successfully quit smoking. More than a half of women were exposed to SHS in their homes (57.6%) and 84.6% allowed smoking in their homes.

CONCLUSION

Smoking during pregnancy in Serbia was two- to threefold higher than in the most affluent western countries. Target groups for action are women with lower education and socio-economic status, as well as health professionals and family members who smoke.

Is income or employment a stronger predictor of smoking than education in economically less developed countries? A cross-sectional study in Hungary

Background

In developed European countries in the last phase of the smoking epidemic, education is a stronger predictor of smoking than income or employment. We examine whether this also applies in economically less developed countries.

Methods

Data from 7218 respondents in the 25-64 age group came from two National Health Interview Surveys conducted in 2000 and 2003 in Hungary. Independent effects of educational level, income and employment status were studied in relation to smoking prevalence, initiation and continuation for all age groups combined and separately for 25-34, 35-49 and 50-64 years old. Absolute levels were evaluated by using age-standardized prevalence rates. Relative differences were assessed by means of logistic regression.

Results

Education and income, but not employment, were associated with equally large differences in smoking prevalence in Hungary in the 25-64 age group. Among men, smoking initiation was related to low educational level, whereas smoking continuation was related to low income. Among women, low education and low income were associated with both high initiation and high continuation rates. Considerable differences were found between the age groups. Inverse social gradients were generally strongest in the youngest age groups. However, smoking continuation among men had the strongest association with low income for the middle-aged group.

Conclusions

Patterns of inequalities in smoking in Hungary can be best understood in relation to two processes: the smoking epidemic, and the additional effects of poverty. Equity orientated tobacco control measures should target the low educated to prevent their smoking initiation, and the poor to improve their cessation rates.

Maternal use of Swedish snuff (snus) and risk of stillbirth

BACKGROUND

Swedish snuff has been discussed internationally as a safer alternative to tobacco smoking. International cigarette manufacturers are promoting new snuff products, and the use of Swedish snuff is increasing, especially among women of childbearing age. The effect of Swedish snuff on pregnancy complications is unknown.

METHODS

In this population-based cohort study, we estimated the risk of stillbirth in snuff users (n = 7629), light smokers (1-9 cigarettes/day; n = 41,488), and heavy smokers (≥10 cigarettes/day; n = 17,014), using nontobacco users (n = 504,531) as reference.

RESULTS

Compared with nontobacco users, snuff users had an increased risk of stillbirth (adjusted odds ratio = 1.6 [95% confidence interval = 1.1-2.3]); the risk was higher for preterm (<37 weeks) stillbirth (2.1 [1.3-3.4]). For light smokers, the adjusted odds ratio of stillbirth was 1.4 (1.2-1.7) and the corresponding risk for heavy smokers was 2.4 (2.0-3.0). When we excluded women with preeclampsia or antenatal bleeding and infants who were small for gestational age, the smoking-related risks of stillbirth was markedly attenuated; the elevated risk for snuff users remained the same level.

CONCLUSIONS

Use of Swedish snuff during pregnancy was associated with a higher risk of stillbirth. The mechanism behind this increased risk seems to differ from the underlying mechanism in smokers. Swedish snuff does not appear to be a safe alternative to cigarette smoking during pregnancy.

Are time-trends of smoking among pregnant immigrant women in Sweden determined by cultural or socioeconomic factors?

Background

The widening socioeconomic gap in smoking during pregnancy remains a challenge to the Swedish antenatal care services. However, the influence of cultural factors in explaining the socioeconomic differences in smoking during pregnancy is not clear among the immigrant women. The aim of this study was to investigate whether the development of smoking prevalence among pregnant immigrant women in Sweden followed the trajectory which could be expected from the stages of the global smoking epidemic model in the women's countries of origin, or not.

Methods

Delivery data on pregnancies in Sweden from 1982 to 2001 was collected from the Swedish Medical Birth Registry. From a total of 2,224,469 pregnant women during this period, all immigrant pregnant women (n = 234,731) were selected to this study. A logistic regression analysis and attributable fraction were used to investigate the association between smoking during pregnancy and the socioeconomic differences among immigrant women.

Results

Overall, the prevalence of smoking among pregnant immigrant women decreased from 30.3% in 1982 to 11.0% in 2001, albeit with remarkable differences between educational levels and country of origin. The greatest decline of absolute prevalence was recorded among low educated women (27,9%) and among other Nordic countries (17,9%). In relative terms, smoking inequalities increased between educational levels regardless of country of origin. The odds ratios for low educational level for women from other Nordic countries increased from 4.9 (95% CI 4.4-5.4) in 1982 to 13.4 (95% CI 11.2-16.2) in 2001, as compared to women with high education in the same group. Further, the total attributable fraction for educational difference increased from 55% in 1982 to 62% in 2001, demonstrating the strong effect of educational attainment.

Conclusions

Our hypothesis that the socioeconomic time trend of smoking based on the stage of the world wide tobacco epidemic model related to country of origin of the immigrant women was not supported by our analyses. Our findings does not support a call for specific "culture sensitive" antismoking policies or interventions in Sweden or similar countries, but reinforce the existing evidence with a focus on women with a low educational level, regardless of cultural background.

Determinants of smoking initiation among women in five European countries: a cross-sectional survey

BACKGROUND

The rate of smoking and lung cancer among women is rising in Europe. The primary aim of this study was to determine why women begin smoking in five different European countries at different stages of the tobacco epidemic and to determine if smoking is associated with certain characteristics and/or beliefs about smoking.

METHODS

A cross-sectional telephone survey on knowledge and beliefs about tobacco was conducted as part of the Women in Europe Against Lung Cancer and Smoking (WELAS) Project. A total of 5,000 adult women from France, Ireland, Italy, Czech Republic, and Sweden were interviewed, with 1,000 from each participating country. All participants were asked questions about demographics, knowledge and beliefs about smoking, and their tobacco use background. Current and former smokers also were asked questions about smoking initiation. Basic statistics on the cross-sectional data was reported with chi-squared and ANOVA p-values. Logistic regression was used to analyze ever versus never smokers. Linear regression analyses were used to analyze age of smoking initiation.

RESULTS

Being older, being divorced, having friends/family who smoke, and having parents who smoke were all significantly associated with ever smoking, though the strength of the associations varied by country. The most frequently reported reason for initiation smoking was friend smoking, with 62.3% of ever smokers reporting friends as one of the reasons why they began smoking. Mean age of smoking initiation was 18.2 years and over 80% of participants started smoking by the age of 20. The highest levels of young initiators were in Sweden with 29.3% of women initiating smoking at age 14-15 and 12.0% initiating smoking younger than age 14. The lowest level of young initiators was in the Czech Republic with 13.7% of women initiating smoking at age 14-15 and 1.4% of women initiating smoking younger than age 14. Women who started smoking because their friends smoked or to look 'cool' were more likely to start smoking at a younger age. Women who started smoking to manage stress or to feel less depressed were more likely to start smoking at an older age.

CONCLUSIONS

In all five participating countries, friends were the primary factor influencing ever smoking, especially among younger women. The majority of participants began smoking in adolescence and the average reported age of smoking initiation was youngest in Sweden and oldest in the Czech Republic.