Cotinine Validation of Self-Reported Smoking During Pregnancy in the Swedish Medical Birth Register

Socioeconomic circumstances, health-related behaviours and paediatric infections: a mediation analysis

OBJECTIVE

To examine how the effect of disadvantaged socioeconomic circumstances on the risk of paediatric infections is mediated by pregnancy smoking, excess weight during pregnancy and breast feeding in children under 5 years of age.

DESIGN

A population-level, retrospective cohort study. The Swedish Medical Birth Register was combined with the National Patient Register, the longitudinal integration database for health insurance and labour market studies, the Cause of Death Register and a local register held by the Child Health Care Unit in Uppsala Region.

SETTING

Uppsala Region, Sweden.

PATIENTS

63 216 term and post-term singletons born to women who resided in Uppsala Region, Sweden between 1997 and 2015.

MAIN OUTCOME MEASURES

Number of hospital admissions for infectious diseases. Secondary outcomes were the number of hospitalisations for respiratory and enteric infections, respectively.

RESULTS

The effect of disadvantaged socioeconomic circumstances, that is, low maternal education on the overall risk of paediatric infections was mediated to a considerable (33%-64%) proportion by pregnancy smoking, excess weight during pregnancy and breast feeding.

CONCLUSIONS

Pregnancy smoking, excess weight during pregnancy and breast feeding mediate a considerable proportion of the association between deprived socioeconomic circumstances and paediatric infectious diseases. Therefore, inequalities in paediatric infectious diseases may be reduced by public health policies addressing these health-related behaviours.

The Swedish medical birth register during five decades: documentation of the content and quality of the register

Pregnancy-related factors are important for short- and long-term health in mothers and offspring. The nationwide population-based Swedish Medical Birth Register (MBR) was established in 1973. The present study describes the content and quality of the MBR, using original MBR data, Swedish-language and international publications based on the MBR.The MBR includes around 98% of all births in Sweden. From 1982 onwards, the MBR is based on prospectively recorded information in standardized antenatal, obstetric, and neonatal records. When the mother and infant are discharged from hospital, this information is forwarded to the MBR, which is updated annually. Maternal data include information from first antenatal visit on self-reported obstetric history, infertility, diseases, medication use, cohabitation status, smoking and snuff use, self-reported height and measured weight, allowing calculation of body mass index. Birth and neonatal data include date and time of birth, mode of delivery, singleton or multiple birth, gestational age, stillbirth, birth weight, birth length, head circumference, infant sex, Apgar scores, and maternal and infant diagnoses/procedures, including neonatal care. The overall quality of the MBR is very high, owing to the semi-automated data extraction from the standardized regional electronic health records, Sweden's universal access to antenatal care, and the possibility to compare mothers and offspring to the Total Population Register in order to identify missing records. Through the unique personal identity numbers of mothers and live-born offspring, the MBR can be linked to other health registers. The Swedish MBR contains high-quality pregnancy-related information on more than 5 million births during five decades.

Maternal smoking during pregnancy and type 1 diabetes in the offspring: a nationwide register-based study with family-based designs

BACKGROUND

Maternal smoking during pregnancy was reported to be associated with a reduced risk of type 1 diabetes in the offspring. We investigated whether this association is consistent with a causal interpretation by accounting for familial (shared genetic and environmental) factors using family-based, quasi-experimental designs.

METHODS

We included 2,995,321 children born in Sweden between 1983 and 2014 and followed them for a diagnosis of type 1 diabetes until 2020 through the National Patient, Diabetes and Prescribed Drug Registers. Apart from conducting a traditional cohort study, we performed a nested case-control study (quasi-experiment) comparing children with type 1 diabetes to their age-matched siblings (or cousins). Information on maternal smoking during pregnancy was retrieved from the Swedish Medical Birth Register. Multivariable adjusted Cox proportional hazards regression and conditional logistic regression were used.

RESULTS

A total of 18,617 children developed type 1 diabetes, with a median age at diagnosis of 9.4 years. The sibling and cousin comparison design included 14,284 and 7988 of these children, respectively. Maternal smoking during pregnancy was associated with a 22% lower risk of offspring type 1 diabetes in the full cohort (hazard ratio 0.78, 95% confidence interval [CI] 0.75-0.82). The corresponding odds ratio was 0.78 (95% CI 0.69-0.88) in the sibling and 0.72 (95% CI 0.66-0.79) in the cousin comparison analysis.

CONCLUSIONS

This nationwide, family-based study provides support for a protective effect of maternal smoking on offspring type 1 diabetes. Mechanistic studies are needed to elucidate the underlying pathways behind this link.

Fetal exposure to maternal cigarette smoking and male reproductive function in young adulthood

Maternal smoking during pregnancy constitutes a potential, major risk factor for adult male reproductive function. In the hitherto largest longitudinal cohort, we examined biomarkers of reproductive function according to maternal smoking during the first trimester and investigated whether associations were mitigated by smoking cessation prior to the fetal masculinization programming window. Associations between exposure to maternal smoking and semen characteristics, testicular volume and reproductive hormones were assessed among 984 young men from the Fetal Programming of Semen Quality (FEPOS) cohort. Maternal smoking was assessed through interview data and measured plasma cotinine levels during pregnancy. We applied negative binomial, logistic and linear regression models to estimate differences in outcomes according to levels of maternal smoking. Sons of light smokers (≤ 10 cigarettes/day) had a 19% (95% CI - 29%, - 6%) lower sperm concentration and a 24% (95% CI - 35%, - 11%) lower total sperm count than sons of non-smokers. These estimates were 38% (95% CI - 52%, - 22%) and 33% (95% CI - 51%, - 8%), respectively, for sons of heavy smokers (> 10 cigarettes/day). The latter group also had a 25% (95% CI 1%, 54%) higher follitropin level. Similarly, sons exposed to maternal cotinine levels of  > 10 ng/mL had lower sperm concentration and total sperm count. Smoking cessation prior to gestational week seven was not associated with a higher reproductive capacity. We observed substantial and consistent exposure-response associations, providing strong support for the hypothesis that maternal smoking impairs male reproductive function. This association persisted regardless of smoking cessation in early pregnancy.

Perinatal factors and hospitalisations for severe childhood infections: a population-based cohort study in Sweden

OBJECTIVE

To examine the association between perinatal factors and hospitalisations for sepsis and bacterial meningitis in early childhood (from 28 days to 2 years of age).

DESIGN

A population-based cohort study. The Swedish Medical Birth Register was combined with the National Inpatient Register, the Cause of Death Register, the Total Population Register and the Longitudinal integration database for health insurance and labour market studies. Associations between perinatal factors and hospitalisations were examined using negative binomial regression models.

SETTING

Sweden.

PARTICIPANTS

1 406 547 children born in Sweden between 1997 and 2013.

MAIN OUTCOME MEASURES

Hospital admissions for sepsis and bacterial meningitis recorded between 28 days and 2 years of life.

RESULTS

Gestational age was inversely associated with severe infections, that is, extreme prematurity was strongly associated with an increased risk of sepsis, adjusted incidence rate ratio (aIRR) 10.37 (95% CI 6.78 to 15.86) and meningitis aIRR 6.22 (95% CI 2.28 to 16.94). The presence of congenital malformation was associated with sepsis aIRR 3.89 (95% CI 3.17 to 4.77) and meningitis aIRR 1.69 (95% CI 1.09 to 2.62). Moreover, children born small or large for gestational age were more likely to be hospitalised for sepsis and children exposed to maternal smoking were more likely to be hospitalised for meningitis.

CONCLUSIONS

Prematurity and several other perinatal factors were associated with an increased risk of severe infections in young children. Therefore, clinical guidelines for risk assessment of infections in young children should consider perinatal factors.

Lifestyle Habits among Pregnant Women in Denmark during the First COVID-19 Lockdown Compared with a Historical Period-A Hospital-Based Cross-Sectional Study

The first national lockdown in Denmark due to the COVID-19 pandemic was declared on 11 March 2020. From this date, national restrictions were imposed. We aimed to assess the potential influence of this first nationwide lockdown on exercise, alcohol consumption, and smoking in early pregnancy. Using a cross-sectional study based on routinely collected patient-reported data, we compared the lifestyle habits of women who were pregnant during the first phase of the pandemic (COVID-19 group) (n = 685) with those of women who were pregnant the year before (Historical group) (n = 787). We found a reduction in any exercise (PR = 0.91, 95% CI (0.84 to 0.99), in adherence to national recommendations of exercise (PR = 0.89, 95% CI (0.80 to 0.99), in cycling (15% vs. 28%, p < 0.0001), and swimming (0.3% vs. 3%, p = 0.0002) in the COVID-19 group compared with the Historical group. The prevalence of binge drinking was reduced in the COVID-19 group compared with the Historical group (PR = 0.80, 95% CI (0.68 to 0.93). In contrast, the prevalence of any weekly alcohol consumption and smoking cessation during pregnancy was similar between groups. Our findings indicate that national restrictions due to the COVID-19 pandemic influenced the lifestyle habits of pregnant women and should be addressed in antenatal counseling.

Central Australian Aboriginal women's pregnancy, labour and birth outcomes following maternal smokeless tobacco (pituri) use, cigarette use or no-tobacco use: a prospective cohort study

BACKGROUND

Outcomes related to maternal smoked tobacco (cigarette) use have been substantially examined over the past 50 years with resultant public health education targeted towards the reduction of use during pregnancy. However, worldwide the effects of maternal smokeless tobacco use have been less well explored and in Australia, there has been no examination of maternal outcomes in relation to the use of Australian Nicotiana spp. (tobacco plant) as a smokeless tobacco, colloquially known as pituri. The aim of this study is to describe the maternal outcomes of a group of central Australian Aboriginal women in relation to their self-reported tobacco use.

METHODS

Eligible participants were > 18 years of age, with a singleton pregnancy, > 28 weeks gestation, and who planned to birth at the Alice Springs Hospital (the major regional hospital for central Australia, in the Northern Territory, Australia). The sample consisted of 73 conveniently recruited women categorized by tobacco-use status as no-tobacco users (n = 31), pituri chewers (n = 19), and smokers (n = 23).

RESULTS

There were differences in the groups in relation to teenage pregnancies; 35% of no-tobacco users, compared with 5% of pituri users, and 13% of smokers were <  20 years of age. The chewers had a higher rate (48%) of combined pre-existing and pregnancy-related elevated glucose concentrations compared with smokers (22%) and no-tobacco users (16%).The pituri chewers had the lowest rate (14%) of clinically significant post-partum hemorrhage (> 1000 ml) compared with 22% of smokers and 36% of the no-tobacco users.

CONCLUSIONS

This is the first research to examine pituri use in pregnancy and the findings indicate possible associations with a range of adverse maternal outcomes. The use of smokeless tobacco needs to be considered in maternal healthcare assessment to inform antenatal, intrapartum and postpartum care planning.

IMPLICATIONS FOR PUBLIC HEALTH

Female smokeless tobacco use is a global phenomenon and is particularly prevalent in low and middle income countries and in Indigenous populations. The findings contribute to the developing knowledge around maternal smokeless tobacco use and maternal outcomes. Maternal screening for a broader range of tobacco and nicotine products is required.

NOTE TO READERS

In this research, the central Australian Aboriginal women chose the term 'Aboriginal' to refer to themselves, and 'Indigenous' to refer to the broader First Peoples. That choice has been maintained in the reporting of the research findings.

Smoking During Pregnancy Among Immigrant Women With Same-Origin and Swedish-Born Partners

Introduction

Although ethnically mixed couples are on the rise in industrialized countries, their health behaviors are poorly understood. We examined the associations between partner’s birthplace, age at immigration, and smoking during pregnancy among foreign-born women.

Methods

Population-based register study including all pregnancies resulting in a livebirth or stillbirth in Sweden (1991–2012) with complete information on smoking and parental country of birth. We compared the prevalence of smoking during pregnancy between women in dual same-origin foreign-born unions (n = 213 111) and in mixed couples (immigrant women with a Swedish-born partner) (n = 111 866) using logistic regression. Swedish-born couples were used as a benchmark.

Results

The crude smoking rate among Swedish women whose partners were Swedish was 11%. Smoking rates of women in dual same-origin foreign-born unions varied substantially by birthplace, from 1.3% among women from Asian countries to 23.2% among those from other Nordic countries. Among immigrant groups with prevalences of pregnancy smoking higher than that of women in dual Swedish-born unions, having a Swedish-born partner was associated with lower odds of smoking (adjusted odds ratios: 0.72–0.87) but with higher odds among immigrant groups with lower prevalence (adjusted odds ratios: 1.17–5.88). These associations were stronger among women immigrating in adulthood, whose smoking rates were the lowest.

Conclusions

Swedish-born partners “pull” smoking rates of immigrant women toward the level of smoking of Swedish-born women, particularly among women arrived during adulthood. Consideration of a woman’s and her partner’s ethnic background and life stage at migration may help understand smoking patterns of immigrant women.

Implications

We found that having a Swedish-born partner is associated with higher rates of smoking during pregnancy among immigrants from regions where women smoke less than Swedish women, but with lower smoking rates among immigrants from regions where women smoke more. This implies that prevention efforts should concentrate on newly arrived single women from low prevalence regions, such as Africa and Asia, whereas cessation efforts may target women from high prevalence regions, such as other European countries. These findings suggest that pregnancy smoking prevention or cessation interventions may benefit from including partners and approaches culturally tailored to mixed unions.

Exposure to psychosocial work strain and changes in smoking behavior during pregnancy - a longitudinal study within the Danish National Birth Cohort

Objective:

Knowledge of the relationship between psychosocial strain in the work environment and smoking during pregnancy is scarce. This study aimed to examine the association between psychosocial job strain and change in smoking behavior during pregnancy.

Methods:

The cohort included 65 645 pregnancies from the Danish National Birth Cohort (1996–2002), where pregnant women were interviewed on job factors and lifestyle during the first and third trimesters. Smoking was categorized into non-, non-daily, and daily smoking at each interview. Psychosocial job strain was categorized into four groups based on the concept of Karasek’s demand–control model: low strain (reference), passive, active and high strain. Associations between psychosocial strain and change in smoking status between the first and second interviews were analyzed by multinomial logistic regression, separately for each smoking category at first interview.

Results:

Non-smoking women exposed to high strain work were more likely to become daily smokers [adjusted odds ratio (OR_adj) 1.41, (95% confidence interval (CI) 1.08–1.83)] compared to non-smoking women exposed to low strain work. Non-smoking women exposed to passive work were more likely to become both non-daily and daily smokers [OR_adj 1.59 (95% CI 1.21–2.08) and OR_adj 1.32 (95% CI 1.03–1.70), respectively]. Daily smoking women exposed to high strain work were less likely to decrease their smoking [OR_adj 0.57 (95% CI 0.32–0.99)] compared to daily smoking women exposed to low strain work.

Conclusions:

Psychosocial strain influenced the women’s smoking behavior during pregnancy, especially in job types with low control.

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.

The importance of socioeconomic position in smoking, cessation and environmental tobacco smoke exposure during pregnancy

Tobacco is still a leading cause of premature death and morbidity. Particular attention has been given to pregnant women due to the scientific evidence on the importance of early life exposures for disease onset later in life. The purpose of this study was to assess smoking prevalence, smoking cessation rate and environmental tobacco smoke (ETS) exposure, and the role of socioeconomic position (SEP) on these behaviors among pregnant women. Cross-sectional data of 619 pregnant women, aged between 18 and 46 years, from Porto Metropolitan Area, Portugal, on current smoking, ETS exposure and SEP indicators was collected, face-to-face, using a questionnaire filled in during a personal interview at the postpartum hospital stay. The smoking prevalence, and ETS exposure among non-smokers before pregnancy was 27.6% and 57.4%, respectively. 4.1% of the participants reported to have stopped smoking before pregnancy, whereas about 41% quitted along pregnancy, resulting in a smoking prevalence at birth of 14.6%. Exposure to ETS also decreased throughout pregnancy to 49.8% at birth. Lower educational level was significantly associated with both higher smoking prevalence and exposure to ETS and lower smoking cessation. This study demonstrates that smoking and ETS exposure during pregnancy remains high, and that there are still significant socioeconomic inequalities in smoking; thus tobacco-focused preventive interventions need to be reinforced.

Changes in parental smoking during pregnancy and risks of adverse birth outcomes and childhood overweight in Europe and North America: An individual participant data meta-analysis of 229,000 singleton births

BACKGROUND

Fetal smoke exposure is a common and key avoidable risk factor for birth complications and seems to influence later risk of overweight. It is unclear whether this increased risk is also present if mothers smoke during the first trimester only or reduce the number of cigarettes during pregnancy, or when only fathers smoke. We aimed to assess the associations of parental smoking during pregnancy, specifically of quitting or reducing smoking and maternal and paternal smoking combined, with preterm birth, small size for gestational age, and childhood overweight.

METHODS AND FINDINGS

We performed an individual participant data meta-analysis among 229,158 families from 28 pregnancy/birth cohorts from Europe and North America. All 28 cohorts had information on maternal smoking, and 16 also had information on paternal smoking. In total, 22 cohorts were population-based, with birth years ranging from 1991 to 2015. The mothers' median age was 30.0 years, and most mothers were medium or highly educated. We used multilevel binary logistic regression models adjusted for maternal and paternal sociodemographic and lifestyle-related characteristics. Compared with nonsmoking mothers, maternal first trimester smoking only was not associated with adverse birth outcomes but was associated with a higher risk of childhood overweight (odds ratio [OR] 1.17 [95% CI 1.02-1.35], P value = 0.030). Children from mothers who continued smoking during pregnancy had higher risks of preterm birth (OR 1.08 [95% CI 1.02-1.15], P value = 0.012), small size for gestational age (OR 2.15 [95% CI 2.07-2.23], P value < 0.001), and childhood overweight (OR 1.42 [95% CI 1.35-1.48], P value < 0.001). Mothers who reduced the number of cigarettes between the first and third trimester, without quitting, still had a higher risk of small size for gestational age. However, the corresponding risk estimates were smaller than for women who continued the same amount of cigarettes throughout pregnancy (OR 1.89 [95% CI 1.52-2.34] instead of OR 2.20 [95% CI 2.02-2.42] when reducing from 5-9 to ≤4 cigarettes/day; OR 2.79 [95% CI 2.39-3.25] and OR 1.93 [95% CI 1.46-2.57] instead of OR 2.95 [95% CI 2.75-3.15] when reducing from ≥10 to 5-9 and ≤4 cigarettes/day, respectively [P values < 0.001]). Reducing the number of cigarettes during pregnancy did not affect the risks of preterm birth and childhood overweight. Among nonsmoking mothers, paternal smoking was associated with childhood overweight (OR 1.21 [95% CI 1.16-1.27], P value < 0.001) but not with adverse birth outcomes. Limitations of this study include the self-report of parental smoking information and the possibility of residual confounding. As this study only included participants from Europe and North America, results need to be carefully interpreted regarding other populations.

CONCLUSIONS

We observed that as compared to nonsmoking during pregnancy, quitting smoking in the first trimester is associated with the same risk of preterm birth and small size for gestational age, but with a higher risk of childhood overweight. Reducing the number of cigarettes, without quitting, has limited beneficial effects. Paternal smoking seems to be associated, independently of maternal smoking, with the risk of childhood overweight. Population strategies should focus on parental smoking prevention before or at the start, rather than during, pregnancy.

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.

Effect of maternal smoking during pregnancy on childhood type 1 diabetes: a whole-of-population study

AIMS/HYPOTHESIS

Evidence of an association between maternal smoking during pregnancy (prenatal smoking) and childhood type 1 diabetes is mixed. Previous studies have been small and potentially biased due to unmeasured confounding. The objectives of this study were to estimate the association between prenatal smoking and childhood type 1 diabetes, assess residual confounding with a negative control design and an E-value analysis, and summarise published effect estimates from a meta-analysis.

METHODS

This whole-of-population study (births from 1999 to 2013, participants aged ≤15 years) used de-identified linked administrative data from the South Australian Early Childhood Data Project. Type 1 diabetes was diagnosed in 557 children (ICD, tenth edition, Australian Modification [ICD-10-AM] codes: E10, E101-E109) during hospitalisation (2001-2014). Families not given financial assistance for school fees was a negative control outcome. Adjusted Cox proportional HRs were calculated. Analyses were conducted on complete-case (n = 264,542, type 1 diabetes = 442) and imputed (n = 286,058, type 1 diabetes = 557) data. A random-effects meta-analysis was used to summarise the effects of prenatal smoking on type 1 diabetes.

RESULTS

Compared with non-smokers, children exposed to maternal smoking only in the first or second half of pregnancy had a 6% higher type 1 diabetes incidence (adjusted HR 1.06 [95% CI 0.73, 1.55]). Type 1 diabetes incidence was 24% lower (adjusted HR 0.76 [95% CI 0.58, 0.99]) among children exposed to consistent prenatal smoking, and 16% lower for exposure to any maternal smoking in pregnancy (adjusted HR 0.84 [95% CI 0.67, 1.08]), compared with the unexposed group. Meta-analytic estimates showed 28-29% lower risk of type 1 diabetes among children exposed to prenatal smoking compared with those not exposed. The negative control outcome analysis indicated residual confounding in the prenatal smoking and type 1 diabetes association. E-value analysis indicated that unmeasured confounding associated with prenatal smoking and childhood type 1 diabetes, with a HR of 1.67, could negate the observed effect.

CONCLUSIONS/INTERPRETATION

Our best estimate from the study is that maternal smoking in pregnancy was associated with 16% lower childhood type 1 diabetes incidence, and some of this effect was due to residual confounding.

Associations of perinatal characteristics with endometriosis: a nationwide birth cohort study

BACKGROUND

Perinatal characteristics are associated with subsequent risk of several chronic diseases. Previous studies regarding endometriosis were based on small samples and retrospective data and were limited by unmeasured confounding bias, leading to conflicting and inconclusive findings. We investigated the associations of maternal and birth characteristics with risk of endometriosis among Swedish women of reproductive age.

METHODS

This total-population register-based cohort study consisted of 628 312 singleton women born in Sweden between 1973 and 1987, who were followed for diagnosed endometriosis from age 15 years until the end of 2012. Multivariable Cox regression was applied to examine associations with perinatal characteristics. Residual unmeasured confounding was assessed through within-family and E-value analyses.

RESULTS

During follow-up, 8262 women received an endometriosis diagnosis. There were clear dose-response/linear associations of endometriosis with lower maternal education, endometriosis in the mother [adjusted hazard ratio (aHR): 2.24, 95% confidence interval (CI): 2.04-2.46], maternal smoking during pregnancy (aHR: 1.18, 95% CI: 1.04-1.33 for moderate smoker and aHR: 1.36, 95% CI: 1.18-1.57 for heavy smoker vs non-smoker), lower birthweight, and lower birthweight-for-gestational age (aHR: 0.93 per standard deviation increase, 95% CI: 0.91-0.95). Within-family and E-value analyses suggested that these perinatal characteristics are robust predictors of the incidence of endometriosis. We also found that an estimated 26% of the association between maternal smoking and early-onset endometriosis could be explained by birthweight-for-gestational age.

CONCLUSION

This study finds support for fetal origins of endometriosis, in that exposure to adverse environment or restricted development during the perinatal period may increase the risk. Further research is needed to provide an understanding of the underlying mechanisms.

Maternal smoking during pregnancy and fractures in offspring: national register based sibling comparison study

OBJECTIVE

To study the impact of maternal smoking during pregnancy on fractures in offspring during different developmental stages of life.

DESIGN

National register based birth cohort study with a sibling comparison design.

SETTING

Sweden.

PARTICIPANTS

1 680 307 people born in Sweden between 1983 and 2000 to women who smoked (n=377 367, 22.5%) and did not smoke (n=1 302 940) in early pregnancy. Follow-up was until 31 December 2014.

MAIN OUTCOME MEASURE

Fractures by attained age up to 32 years.

RESULTS

During a median follow-up of 21.1 years, 377 970 fractures were observed (the overall incidence rate for fracture standardised by calendar year of birth was 11.8 per 1000 person years). The association between maternal smoking during pregnancy and risk of fracture in offspring differed by attained age. Maternal smoking was associated with a higher rate of fractures in offspring before 1 year of age in the entire cohort (birth year standardised fracture rates in those exposed and unexposed to maternal smoking were 1.59 and 1.28 per 1000 person years, respectively). After adjustment for potential confounders the hazard ratio for maternal smoking compared with no smoking was 1.27 (95% confidence interval 1.12 to 1.45). This association followed a dose dependent pattern (compared with no smoking, hazard ratios for 1-9 cigarettes/day and ≥10 cigarettes/day were 1.20 (95% confidence interval 1.03 to 1.39) and 1.41 (1.18 to 1.69), respectively) and persisted in within-sibship comparisons although with wider confidence intervals (compared with no smoking, 1.58 (1.01 to 2.46)). Maternal smoking during pregnancy was also associated with an increased fracture incidence in offspring from age 5 to 32 years in whole cohort analyses, but these associations did not follow a dose dependent gradient. In within-sibship analyses, which controls for confounding by measured and unmeasured shared familial factors, corresponding point estimates were all close to null. Maternal smoking was not associated with risk of fracture in offspring between the ages of 1 and 5 years in any of the models.

CONCLUSION

Prenatal exposure to maternal smoking is associated with an increased rate of fracture during the first year of life but does not seem to have a long lasting biological influence on fractures later in childhood and up to early adulthood.

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

BACKGROUND

The use of tobacco products including Swedish snus (moist snuff) in pregnancy may cause adverse health outcomes. While smoking prevalence has decreased among fertile women in Norway, snus use has increased during the last years. We investigated whether these trends were reflected also during pregnancy in a population of women in Southern Norway.

METHODS

Data on smoking tobacco and snus use at three time points before and during pregnancy for 20,844 women were retrieved from the electronic birth record for the years 2012-2017. The results for the three-year period 2015-2017 were compared with a previously studied period 2012-2014. Prevalence and quit rates of tobacco use within groups of age, parity and education were reported. Within the same groups adjusted quit rates were analyzed using logistic regression. Mean birthweight and Apgar score of offspring were calculated for tobacco-users and non-users.

RESULTS

There was an increase of snus use before pregnancy from the period 2012-2014 to the period 2015-2017 from 5.1% (CI; 4.6 to 5.5) to 8.4% (CI; 7.8 to 8.9). Despite this, the use of snus during pregnancy did not increase from the first to the second period, but stabilized at 2.8% (CI; 2.5 to 3.2) in first trimester and 2.0% (CI; 1.7 to 2.2) in third trimester. Cigarette smoking decreased significantly both before and during pregnancy. Snus use and smoking during pregnancy were associated with a reduction in average birthweight, but no significant effects on Apgar scores. Odds ratios for quitting both snus and smoking tobacco during pregnancy were higher for women aged 25-34 years, for the primiparas and for those with a high level of education. Pregnant women were more likely to have quit tobacco use in the last time period compared to the first.

CONCLUSIONS

While smoking during pregnancy was decreasing, the use of snus remained constant, levelling off to around 3% in first trimester and 2% in third trimester. Approximately 25% of those that used snus, and 40% that smoked before pregnancy, continued use to the third trimester. This calls for a continuous watch on the use of snus and other nicotine products during pregnancy.

Prevalence and predictors of maternal smoking prior to and during pregnancy in a regional Danish population: a cross-sectional study

BACKGROUND

Maternal smoking is still a major public health problem posing the risk of several negative health outcomes for both the pregnant woman and her offspring. The prevalence of maternal smoking in Denmark and other high-income countries has decreased continuously since the 1980s, and a prevalence below 10% of women who continue to smoke during pregnancy has been reported in studies after 2010. Previous studies have shown that low socioeconomic status is associated with maternal smoking. Information from the Danish Birth Register about maternal smoking shows that the prevalence of women who report to smoke in pregnancy has decreased continuously with 23.3% who reported ever smoking in pregnancy in 2000, 12.9% in 2010 and 9.0% in 2017. The aim of this study was to estimate the prevalence of maternal smoking at the time of conception and at 20 weeks of gestation in a regional Danish population, to describe differences in maternal characteristics among smokers, quitters and never-smokers, and to estimate predictors of smoking at the time of conception.

METHODS

A cross-sectional study was conducted among pregnant women receiving antenatal care at the Department of Obstetrics, Zealand University Hospital, Denmark from August 2015 to March 2016 (n = 566). The main outcome was smoking at the time of conception and at 20 weeks of gestation. The questionnaire also collected information about maternal, health-related and sociodemographic characteristics. Descriptive analysis was conducted, and multivariate logistic regression analysis was used to assess the potential associated predictors (adjusted odds ratio).

RESULTS

The prevalence of self-reported smoking at the time of conception was 16% (n = 90) and 6% smoked at 20 weeks of gestation (n = 35), as 61% of smokers quit smoking during early pregnancy. Multiple logistic regression analysis showed that significant predictors for smoking at conception were the socioeconomic factors; ≤12 years of education, shift work and being unemployed.

CONCLUSION

The prevalence of self-reported maternal smoking in this regional Danish population of pregnant women is lower than seen in previous studies. However, predictors for smoking at the time of conception remain to be factors of low socioeconomic status confirming a social inequality in maternal smoking. Women at risk of smoking during pregnancy must be identified in early pregnancy or even before pregnancy and be offered interventions to help them quit 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.

Stopping when knowing: use of snus and nicotine during pregnancy in Scandinavia

The risk of adverse health effects in offspring due to maternal tobacco smoking during pregnancy is well documented [1], including epigenetic changes persisting in the offspring after prenatal exposure [2]. The effects of fetal exposure to nicotine from non-combustible tobacco products, such as snus or nicotine-replacement therapies (NRTs), are less clear. Use of snus leads to systemic absorption of nicotine into the maternal circulatory system, with subsequent exposure of the foetus through the placenta [3].

In young women, the use of snus increases in parallel with decreasing smoking rates but the  use in pregnancy is unclear. Our aims were to determine the prevalence of snus use, smoking and other nicotine-containing product use during pregnancy, and to identify predictors for snus use in pregnancy.

Prevalence was determined for 2528 women in Norway and Sweden based on the Preventing Atopic Dermatitis and ALLergies (PreventADALL) study, a population-based, mother–child birth cohort. Electronic questionnaires were completed in pregnancy week 18 and/or week 34, and potential predictors of snus use were analysed using logistic regression models.

Ever use of any snus, tobacco or nicotine-containing products was reported by 35.7% of women, with similar rates of snus use (22.5%) and smoking (22.6%). Overall, 11.3% of women reported any use of nicotine-containing products in pregnancy up to 34 weeks, most often snus alone (6.5%). Most women (87.2%) stopped using snus by week 6 of pregnancy.

Snus use in pregnancy was inversely associated with age and positively associated with urban living and personal or maternal history of smoking. While 11.3% of women used snus or other nicotine-containing products at some time, most stopped when recognising their pregnancy. Younger, urban living, previously smoking women were more likely to use snus in pregnancy.

Of the 11.3% of women using any nicotine products in pregnancy (most often snus (6.5%)), the majority stop within pregnancy week 6. Snus use is associated with urban living, previous smoking, in utero smoking exposure of the index woman and lower age.http://ow.ly/Gyg230nmxIo

Agreement of offspring-reported parental smoking status: the RHINESSA generation study

BACKGROUND

With increasing interest in exposure effects across generations, it is crucial to assess the validity of information given on behalf of others.

AIMS

To compare adult's report of their parent's smoking status against parent's own report and examine predictors for discrepant answers.

METHODS

We studied 7185 offspring (18-51 years) and one of their parents, n = 5307 (27-67 years) participating in the Respiratory Health in Northern Europe, Spain and Australia (RHINESSA) generation study. Information about parent's smoking status during offspring's childhood and mother's smoking status during pregnancy was obtained by questionnaires from parents and their offspring. We calculated sensitivity, specificity and Cohen's Kappa [κ] for agreement using parent's own report as the gold standard. We performed logistic regression to examine if offspring's sex, age, educational level, asthma status, own smoking status or parental status, as well as the parent's sex and amount of smoking during childhood predicted disagreement.

RESULTS

The sensitivity for offspring's correct report of parent's smoking status during childhood (0-10 years) was 0.82 (95% CI 0.81-0.84), specificity was 0.95 (95% CI 0.95-0.96) and a good agreement was observed, κ = 0.79 (95% CI 0.78-0.80). Offspring's report of mothers' smoking status during pregnancy showed a lower sensitivity, 0.66 (95% CI 0.60-0.71), a slightly lower specificity, 0.92 (95% CI 0.90-0.95) and a good agreement, κ = 0.61 (95% CI 0.55-0.67). In multivariate logistic regression analysis, offspring not having children was a predictor for discrepant answers (odds ratio [OR] 2.11 [95% CI 1.21-3.69]). Low amount of parents' tobacco consumption, < 10 cigarettes/day (OR 2.72 [95% CI 1.71-4.31]) also predicted disagreement compared to ≥10 cigarettes per day, and so did offspring's reports of fathers' smoking status (OR 1.73 [95% CI 1.09-2.74]) compared to mothers' smoking status. Offspring's sex, asthma status, educational level, smoking status or age was not related to discrepant answers.

CONCLUSIONS

Adults report their parent's smoking status during their childhood, as well as their mother' smoking status when pregnant with them, quite accurately. In the absence of parents' direct report, offspring's reports could be valuable.

Maternal weight and infections in early childhood: a cohort study

OBJECTIVE

The aim of this study was to examine this association between maternal weight during pregnancy and the incidence of hospitalisations for infectious diseases during early childhood.

DESIGN

A population-based cohort study.

SETTING

A national cohort was created by combining data from the Swedish Medical Birth Register, the National Inpatient Register, the Cause of Death Register, the Total Population Register and the Longitudinal integration database for health insurance and labour market studies.

PATIENTS

693 007 children born in Sweden between 1998 and 2006.

MAIN OUTCOME MEASURES

Number of hospitalisations for infectious diseases during the first 5 years of life, overall and for categories of infectious diseases (lower respiratory, enteric, upper respiratory, genitourinary, perinatal, skin and soft tissue, neurological and eye, digestive tract, bloodstream and other infections).

RESULTS

Overweight (body mass index (BMI) 25.0-29.9) and obesity (BMI≥30) during pregnancy were associated with a higher overall incidence of hospitalisations for infectious diseases, adjusted incidence rate ratio (IRR) 1.05 (95% CI 1.03 to 1.06) and adjusted IRR 1.18 (95% CI 1.16 to 1.21). Overweight and obesity during pregnancy were strongly associated with perinatal infections, adjusted IRR 1.34 (95% CI 1.25 to 1.44) and adjusted IRR 1.72 (95% CI 1.57 to 1.88). In contrast, we found no association between maternal weight during pregnancy and infections of skin and soft tissue, the nervous system, the digestive tract or the bloodstream.

CONCLUSIONS

We observed an association between overweight and obesity during pregnancy, and hospitalisations for infectious diseases during early childhood.

Association between paternal smoking at the time of pregnancy and the semen quality in sons

BACKGROUND

Maternal smoking during pregnancy has repeatedly been associated with decreased sperm counts in sons. Nevertheless, our team recently detected a lower total sperm count in the sons of smoking fathers as compared to sons of non-smoking fathers. Since paternal and maternal tobacco smoking often coincide, it is difficult to discriminate whether effects are mediated paternally or maternally when using questionnaire- or register-based studies. Therefore, getting an objective measure of the maternal nicotine exposure level during pregnancy might help disentangling the impact of paternally and maternally derived exposure.

OBJECTIVES

Our aim was to study how paternal smoking at the time of the pregnancy was associated with semen quality in the sons after adjusting for the maternal levels of nicotine exposure during pregnancy.

METHODS

We recruited 104 men (17-20 years old) from the general Swedish population. The participants answered a questionnaire about paternal smoking. Associations between smoking and semen volume, total sperm count, sperm concentration, morphology and motility were adjusted for levels of the nicotine metabolite cotinine in stored maternal serum samples obtained from rubella screening between the 6th and 35th week of pregnancy. We additionally adjusted for the estimated socioeconomic status.

RESULTS

After adjusting for the maternal cotinine, the men of smoking fathers had 41% lower sperm concentration and 51% lower total sperm count than the men of non-smoking fathers (p = 0.02 and 0.003, respectively). This was robust to the additional adjustment.

CONCLUSIONS

Our results suggest a negative association between paternal smoking and sperm counts in the sons, independent of the level maternal nicotine exposure during the pregnancy.

The Effect of Cigarette Smoking during Pregnancy on Endocrine Pancreatic Function and Fetal Growth: A Pilot Study

Introduction

Cigarette smoking in pregnancy is a common cause of fetal growth restriction. We aimed to investigate endocrine pancreatic function of mother–infant dyads in relation to cigarette smoking, as a possible mechanism for the poor fetal growth.

Methods

Prospective study of smoking mothers (10 cigarettes or more per day, self-reported to the midwife) and non-smoker control mothers during their first pregnancy. Insulin, glucose, C-peptide, HbA1C, fructosamine, prolactin, serotonin, and cortisol were measured in maternal blood at 24–26 weeks and in umbilical cord blood at birth. Cotinine was also measured in cord blood.

Results

Of 37 smokers and 36 non-smokers recruited, cord blood was obtainable from 38 babies (19 in each group). In utero cigarette exposure was associated with lower birthweight (3,035 ± 490 versus 3,405 ± 598 g, p = 0.005), with linear modeling of the smoking cohort showing a 41 g reduction for every increase of one cigarette smoked per day (95% CI −71 to −11 g, p = 0.010). There were no differences between groups in indices of maternal or perinatal endocrine pancreatic dysfunction. Heavier smoking independently correlated with higher maternal fasting levels of glucose (p = 0.044) and C-peptide (p = 0.011). We did not observe any significant associations between the daily number of cigarettes and any of the cord blood parameters. We also looked for differences between cohorts based on infant gender. Serotonin levels were higher in smoking mothers with male fetuses (p = 0.01 to p = 0.004).

Conclusion

Endocrine pancreatic dysfunction does not appear to be a major contributing factor to nicotine-associated fetal growth restriction. The higher serotonin levels in smoking mothers carrying male infants is of uncertain significance but could be a manifestation of gender differences in susceptibility to the long-term effects of cigarette smoking.

Changes in Smoking Rates Among Pregnant Women and the General Female Population in Australia, Finland, Norway, and Sweden

Introduction:

Smoking rates have dropped substantially in most developed countries in recent decades. This general trend has, however, not always been evident among women—particularly younger women. Smoking habits do, however, often change in connection with pregnancy and the aim of this study is to determine whether smoking during pregnancy follows general trends in smoking rates in the general female population in four countries with active anti-tobacco policies and decreasing population smoking rates.

Methods:

Changes in rates of persistent smoking, that is, smoking in late pregnancy or daily smoking among all women of childbearing age were described according to age groups. Data were retrieved from the Australian Household Drug Surveys during 2000–2013 and from registries and surveys in Finland, Norway, and Sweden between 1995 and 2014.

Results:

In general, persistent smoking has decreased and late-pregnancy smoking rates are lower than daily smoking rates among all women. However, younger women are more likely to be persistent smokers regardless of pregnancy status. In Norway and Finland, persistent smoking was most common among young pregnant women and in Sweden there was an increased polarization between age groups. In Australia, a steady decrease in smoking rates appears to have stalled in younger pregnant women.

Conclusion:

Although smoking has declined substantially in recent decades, there are groups lagging behind this general trend. Young pregnant women are of particular concern in this respect. The possibility that these findings reflect the changing characteristics of younger pregnant women is discussed.

Implications:

This study puts recent trends in maternal smoking into a broader context by relating developments to changes in smoking rates among women in general. By using similar data from four countries we were able to follow changes in smoking rates “within” groups of women within the four countries without being limited by methodological problems related to cross-country or inter-group comparisons. We were above all able to show that aggregate data disclose the strong age gradient in maternal smoking habits.

Perinatal Biochemical Confirmation of Smoking Status by Trimester

Introduction:

Tobacco use during pregnancy is the most modifiable risk factor associated with poor pregnancy outcomes. Self-reported tobacco use has been demonstrated to have high misclassification rates. The aims were to examine misclassification rates of perinatal tobacco use during each trimester of pregnancy and 8 weeks postpartum, and to evaluate characteristics associated with misclassification of tobacco use status.

Methods:

This is secondary analysis of a prospective, multicenter trial of pregnant women, and it includes participants who were biochemically identified as tobacco users during their first trimester (N = 103). Each trimester and once postpartum, tobacco use was assessed via self-report and validated using a cutoff of 100 ng/mL for urine cotinine via NicAlert test strips to indicate current use. Those who self-reported as nonusers but were identified as users via urine cotinine were considered misclassified; misclassification rates were determined for each time period. Logistic regression assessed maternal factors associated with misclassification status.

Results:

Misclassification rates declined from 35.0% at first trimester to 31.9% and 26.6% at the second and third; the postpartum rate was 30.4%. These rates did not differ significantly from each other at the 0.05 level. Race/ethnicity was associated with misclassification status; white/non-Hispanic women were 87% less likely to be misclassified (p < .001).

Conclusion:

Misclassification of prenatal smoking status decreases as pregnancy progresses, though the observed rate change was not significant. Minority women may be at particular risk for non-disclosure of tobacco use. Biochemical validation should be considered when assessing perinatal tobacco use via self-report, given high misclassification rates throughout the perinatal period.

Implications:

These results demonstrate that regardless of trimester, more than one-quarter of tobacco-using pregnant women may not disclose tobacco use throughout pregnancy and early postpartum. Although the rate of misclassification decreased from first to third trimester and then increased in the immediate postpartum, these changes in misclassification rates were not significant. Minority groups may be at particular risk of misclassification compared with white/non-Hispanic women. Biochemical validation is warranted throughout pregnancy to encourage cessation as tobacco use is one of the most easily-modified risk factors for poor birth outcomes.

Parental smoking, maternal alcohol, coffee and tea consumption and the risk of childhood brain tumours: the ESTELLE and ESCALE studies (SFCE, France)

PURPOSE

To investigate whether parental smoking around the time of pregnancy or maternal consumption of beverages (alcohol, coffee, or tea) during pregnancy were associated with the risk of CBT.

METHODS

We pooled data from two French national population-based case-control studies with similar designs conducted in 2003-2004 and 2010-2011. The mothers of 510 CBT cases (directly recruited from the national childhood cancer register) and 3,102 controls aged under 15 years, frequency matched by age and gender, were interviewed through telephone, which included questions about prenatal parental smoking and maternal consumption of alcohol, coffee and tea. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using unconditional logistic regression, adjusted for age, sex and study of origin.

RESULTS

No association was seen between CBT and the mother smoking or drinking alcohol, coffee, or tea during the index pregnancy. The OR between CBT and paternal smoking in the year before birth (as reported by the mother) was 1.25 (95% CI 1.03, 1.52) with an OR of 1.09 (0.99, 1.19) for every 10 cigarettes per day (CPD) smoked. The association between paternal smoking and CBT appeared to be stronger in children diagnosed before the age of five years (OR 1.52, 95% CI 1.14, 2.02) and for astrocytoma (OR 1.86, 95% CI 1.26, 2.74).

CONCLUSION

We found some evidence of a weak association between paternal smoking in the year before the child's birth and CBT, especially astrocytomas. These findings need to be replicated in other samples, using similar classifications of tumour subtypes.

The Role of Maternal Adverse Childhood Experiences and Race in Intergenerational High-Risk Smoking Behaviors

INTRODUCTION

A history of adversity in childhood is associated with cigarette smoking in adulthood, but there is less evidence for prenatal and next-generation offspring smoking. We investigated the association between maternal history of childhood adversity, pregnancy smoking, and early initiation of smoking in offspring, overall and by maternal race/ethnicity.

METHODS

Data on maternal childhood exposure to physical abuse, household alcohol abuse, and household mental illness, prenatal smoking behaviors, and offspring age of smoking initiation were analyzed from the US National Longitudinal Survey of Youth 1979 (NLSY79, n = 2999 mothers) and the NLSY79 Children and Young Adults Survey (NLSYCYA, n = 6596 children). Adjusted risk ratios were estimated using log-linear regression models. We assessed multiplicative interaction by race/ethnicity for all associations and a three-way interaction by maternal exposure to adversity and race/ethnicity for the association between prenatal and child smoking.

RESULTS

Maternal exposure to childhood physical abuse was significantly associated with 39% and 20% increased risks of prenatal smoking and child smoking, respectively. Household alcohol abuse was associated with significantly increased risks of 20% for prenatal smoking and 17% for child smoking. The prenatal smoking-child smoking relationship was modified by maternal exposure to household alcohol abuse and race. There were increased risks for Hispanic and white/other mothers as compared to the lowest risk group: black mothers who did not experience childhood household alcohol abuse.

CONCLUSIONS

Mothers in this national sample who experienced adversity in childhood are more likely to smoke during pregnancy and their offspring are more likely to initiate smoking before age 18. Findings varied by type of adversity and race/ethnicity.

IMPLICATIONS

These findings support the importance of a life-course approach to understanding prenatal and intergenerational smoking, and suggest that maternal early-life history is a potentially important risk factor that could be targeted with screening and interventions to reduce smoking in pregnant women and their children.

A population study of first and subsequent pregnancy smoking behaviors in Ohio

OBJECTIVE

The objective of this study is to identify maternal characteristics associated with non-smoking during a subsequent pregnancy after first pregnancy smoking.

STUDY DESIGN

We conducted a retrospective population-based analysis of Ohio vital birth records from 2007 to 2013. We used logistic regression to calculate adjusted odds ratios with 95% confidence intervals for detection of characteristics associated with non-smoking during a subsequent pregnancy after first pregnancy smoking.

RESULTS

Among 75 190 mothers, 75.6% were non-smokers and 13.7% were smokers during both pregnancies. During their first pregnancy, 49.7% of 15 075 smokers quit. Of them, 50.1% remained non-smokers during their subsequent pregnancy. Women who reduced, but continued smoking during their first pregnancy, were more than five times as likely to smoke during their subsequent pregnancy than women who quit (odds ratio (95% confidence interval): 2.85 (2.43 to 3.35) vs 0.55 (0.45 to 0.67)).

CONCLUSION

Interventions targeting complete cessation, rather than reduction in smoking among first-time mothers, may be the most effective at optimizing long-term health benefits.

Social Disparities in Maternal Smoking during Pregnancy: Comparison of Two Birth Cohorts (1996-2002 and 2003-2012) Based on Data from the German KiGGS Study

Background: Maternal smoking during pregnancy represents a significant developmental risk for the unborn child. This study investigated social differences in maternal smoking behavior during pregnancy in mothers living in Germany. The study focused on maternal age at delivery, social status and migration background. Method: The evaluation of data was based on two surveys carried out as part of the German Health Interview and Examination Survey for Children and Adolescents (KiGGS) carried out in 2003-2006 and in 2009-2012. The study compared the information given by parents of children aged between 0 and 6 years who were born either in the period from 1996 to  2002 (KiGGS baseline study, n = 4818) or in the period from 2003 to 2012 (KiGGS Wave 1, n = 4434). Determination of social status was based on parental educational levels, occupational position and income. Children classified as having a two-sided migration background either had parents, both of whom had immigrated to Germany, or were born abroad and had one parent who had immigrated to Germany; children classified as having a one-sided migration background had been born in Germany but had one parent who had immigrated to Germany. Results: The percentage of children whose mothers had smoked during pregnancy was 19.9 % for the older birth cohort and 12.1 % for the younger birth cohort. In both birth cohorts, the probability of being exposed to tobacco smoke was twice as high for children whose mothers were aged < 25 years at delivery compared to the children of older mothers. Children from socially deprived families were most affected by smoking behavior, and the relative social differences were found to have even increased over time (KiGGS baseline study: OR = 6.34; 95 % CI = 4.53-8.86; KiGGS Wave 1: OR = 13.88; 95 % CI = 6.85-28.13). A two-sided migration background was associated with a lower risk of exposure to smoking. Conclusions: The KiGGS results are in accordance with the results of other national and international studies which have shown that the percentage of mothers who smoke during pregnancy is declining. Because of a change in the method how data are collected for the KiGGS survey (written questionnaire vs. telephone interview) the trend results must be interpreted with caution. Measures aimed at preventing smoking and weaning women off smoking should focus particularly on younger and socially deprived mothers.

Metabolomics reveals effects of maternal smoking on endogenous metabolites from lipid metabolism in cord blood of newborns

INTRODUCTION

A general detrimental effect of smoking during pregnancy on the health of newborn children is well-documented, but the detailed mechanisms remain elusive.

OBJECTIVES

Beside the specific influence of environmental tobacco smoke derived toxicants on developmental regulation the impact on the metabolism of newborn children is of particular interest, first as a general marker of foetal development and second due to its potential predictive value for the later occurrence of metabolic diseases.

METHODS

Tobacco smoke exposure information from a questionnaire was confirmed by measuring the smoking related metabolites S-Phenyl mercapturic acid, S-Benzyl mercapturic acid and cotinine in maternal urine by LC-MS/MS. The impact of smoking on maternal endogenous serum metabolome and children's cord blood metabolome was assessed in a targeted analysis of 163 metabolites by an LC-MS/MS based assay. The anti-oxidative status of maternal serum samples was analysed by chemoluminiscence based method.

RESULTS

Here we present for the first time results of a metabolomic assessment of the cordblood of 40 children and their mothers. Several analytes from the group of phosphatidylcholines, namely PCaaC28:1, PCaaC32:3, PCaeC30:1, PCaeC32:2, PCaeC40:1, and sphingomyelin SM C26:0, differed significantly in mothers and children's sera depending on smoking status. In serum of smoking mothers the antioxidative capacity of water soluble compounds was not significantly changed while there was a significant decrease in the lipid fraction.

CONCLUSION

Our data give evidence that smoking during pregnancy alters both the maternal and children's metabolome. Whether the different pattern found in adults compared to newborn children could be related to different disease outcomes should be in the focus of future studies.

Maternal Smoking during Pregnancy and Daughters' Preeclampsia Risk

Background

An obstetrical paradox is that maternal smoking is protective for the development of preeclampsia. However, there are no prior studies investigating the risk of preeclampsia in women who were exposed to tobacco smoking during their own fetal period. We aimed to study the subsequent risk of preeclampsia in women who were exposed to tobacco smoke in utero, using a national population-based register.

Methods

Data were obtained from the Medical Birth Register of Sweden for women who were born in 1982 (smoking data first recorded) or after, who had given birth to at least one child; 153 885 pregnancies were included.

Results

The associations between intrauterine smoking exposure (three categories: non-smokers, 1–9 cigarettes/day [moderate exposure], and >9 cigarettes/day [heavy exposure]) and subsequent preeclampsia (n = 5721) were assessed using logistic regressions. In models adjusted for maternal age, parity and own smoking, the odds ratios (OR) for preeclampsia were 1.06 [95% CI: 0.99,1.13 for moderate intrauterine exposure, and 1.18, [95% CI: 1.10,1.27] for heavy exposure. Estimates were slightly strengthened in non-smoking women who experienced heavy intrauterine exposure (adjusted OR 1.24 [95% CI: 1.14,1.34]). Results were no longer statistically significant after adjustment for the woman’s own BMI, gestational age and birthweight Z-scores.

Conclusion

These data revealed some evidence of a possible weak positive association between intrauterine smoking exposure and the risk of subsequent preeclampsia, however, results were not significant over all manifestations of preeclampsia and confounder adjustment. The increased risk might be mediated through exposed women’s own BMI or birthweight.

Establishment of the MethyLight Assay for Assessing Aging, Cigarette Smoking, and Alcohol Consumption

The environmental factors such as aging, smoking, and alcohol consumption have been reported to influence DNA methylation (DNAm). However, the versatility of DNAm measurement by DNAm array systems is low in clinical use. Thus, we developed the MethyLight assay as a simple method to measure DNAm. In the present study, we isolated peripheral blood DNA from 33 healthy volunteers and selected cg25809905, cg02228185, and cg17861230 as aging, cg23576855 as smoking, and cg02583484 as alcohol consumption biomarkers. The predicted age by methylation rates of cg25809905 and cg17861230 significantly correlated with chronological age. In immortalized B-cells, DNAm rates of two sites showed a younger status than the chronological age of donor. On the other hand, the predicted age of the patients with myocardial infarction (MI) was not accelerated. The methylation rate of cg23576855 was able to discriminate the groups based on the smoking status. The DNAm rate of cg02583484 was reduced in subjects with habitual alcohol consumption compared to that of subjects without habitual alcohol consumption. In conclusion, our MethyLight assay system reconfirms that aging, smoking, and alcohol consumption influenced DNAm in peripheral blood in the Japanese. This MethyLight system will facilitate DNAm measurement in epidemiological and clinical studies.