Maternal Smoking: A Life Course Blood Pressure Determinant?

Association of secondhand smoke exposure during pregnancy with left ventricle structure and function in offspring at 4 years old: a prospective birth cohort study

BACKGROUND

The association of secondhand smoke exposure during pregnancy with childhood cardiac alterations remains insufficiently elucidated. This study aims to explore the correlation between maternal passive smoking during gestation with cardiac structure and function of offspring.

METHODS

1089 mother-offspring pairs from the Shanghai Birth Cohort were included. Information on secondhand smoke exposure during each trimester of pregnancy and baseline characteristics was documented during pregnancy via structured questionnaire. Subsequent follow-up assessments, encompassing anthropometric information and echocardiographic evaluation, were conducted from 2018 to 2021, when the children were 4 years old. Multiple linear regressions models were used to explore the association of secondhand smoke exposure during pregnancy with left ventricular measurements in early childhood.

RESULTS

Secondhand smoke exposure during pregnancy was correlated with increased left ventricle (LV) internal diameter in diastole [LVIDd; β = 0.38, 95%CI: (0.06, 0.70)] and in systole [LVIDs; β = 0.28, 95%CI: (0.02, 0.54)] adjusted for maternal and child characteristics. Specifically, maternal passive smoking in early pregnancy (≤ 12 weeks of gestation) showed a positive association with LV internal diameter in diastole [LVIDd; β = 0.46, 95%CI: (0.14, 0.79)], in systole [LVIDs; β = 0.35, 95%CI: (0.09, 0.60)], end diastolic volume [LVEDV; β = 1.45, 95%CI: (0.26, 2.63)] and end systolic volume [LVESV; β = 0.68, 95%CI: (0.18, 1.19)]. No significant association was observed between secondhand smoke exposure during pregnancy and LV function of offspring.

CONCLUSION

Secondhand smoke exposure during pregnancy was correlated with subclinical alterations in LV dimensions of offspring, especially during the early stage of pregnancy. Further research is necessary to confirm our findings and to explore the long-term effect of these cardiac changes on later cardiovascular risks.

Prevalence and factors associated with hypertension among children attending pre-schools in Dar es Salaam, Tanzania

BACKGROUND

Childhood hypertension has become a public health problem due to its increasing prevalence and complications; the high prevalence is noted to mirror an increase in obesity among children. Hypertension in children is frequently undiagnosed due to challenges in getting appropriate cuff sizes and interpretation of the readings. Several studies have been carried out among children however; most of available information is focused on hypertension among older children and adolescents.

METHODS

A cross sectional study was conducted in 2 districts of Dar es Salaam region namely Ilala and Kinondoni from October to November 2020. Children aged 2-5 years attending pre-schools in these districts meeting the inclusion criteria and whose parent/guardian signed informed consent were included. Questionnaires were used to collect socio-demographic characteristics; anthropometric and three oscillometric single- occasion blood pressure measurements were taken. The average blood pressure was compared to the standard charts for age and sex provided by the American Academy of Pediatrics 2017 to determine the blood pressure category of the child.

RESULTS

A total of 1083 children fulfilled the eligibility criteria and were enrolled into the study, 51.3% (556/1083) of participants were males and the median age was 4 years (IQR 3-5). Blood pressures for 252 (23.3%) participants were in the high blood pressure range (19.8% with elevated blood pressure and 3.5% with hypertension). No significant gender difference was observed among those with high blood pressure. Factors that were noted to be significantly associated with elevated blood pressure included low birth weight (p = 0.036), increasing age (p = 0.032) and body mass index (p < 0.001).

CONCLUSION

High prevalence of elevated blood pressure in this population of pre-school aged children is alarming. Low birth weight, increasing age and body mass index were significantly associated with elevated blood pressure.

Polygenic Interactions With Environmental Exposures in Blood Pressure Regulation: The HUNT Study

BACKGROUND

The essential hypertension phenotype results from an interplay between genetic and environmental factors. The influence of lifestyle exposures such as excess adiposity, alcohol consumption, tobacco use, diet, and activity patterns on blood pressure (BP) is well established. Additionally, polygenic risk scores for BP traits are associated with clinically significant phenotypic variation. However, interactions between genetic and environmental risk factors in hypertension morbidity and mortality are poorly characterized.

METHODS AND RESULTS

We used genotype and phenotype data from up to 49 234 participants from the HUNT (Trøndelag Health Study) to model gene-environment interactions between genome-wide polygenic risk scores for systolic BP and diastolic BP and 125 environmental exposures. Among the 125 environmental exposures assessed, 108 and 100 were independently associated with SBP and DBP, respectively. Of these, 12 interactions were identified for genome-wide PRSs for systolic BP and 4 for genome-wide polygenic risk scores for diastolic BP, 2 of which were overlapping (P < 2 × 10-4). We found evidence for gene-dependent influence of lifestyle factors such as cardiorespiratory fitness, dietary patterns, and tobacco exposure, as well as biomarkers such as serum cholesterol, creatinine, and alkaline phosphatase on BP.

CONCLUSIONS

Individuals that are genetically susceptible to high BP may be more vulnerable to common acquired risk factors for hypertension, but these effects appear to be modifiable. The gene-dependent influence of several common acquired risk factors indicates the potential of genetic data combined with lifestyle assessments in risk stratification, and gene-environment-informed risk modeling in the prevention and management of hypertension.

Impact of Maternal Smoking, Offspring Smoking, and Genetic Susceptibility on Crohn's Disease and Ulcerative Colitis

BACKGROUND AND AIMS

The long-term impact of maternal smoking during pregnancy [MSDP] on the risk of Crohn's disease [CD] and ulcerative colitis [UC] in adult offspring remains uncertain. The present study aimed to investigate the individual and combined effects of early life exposure [MSDP], offspring personal behaviour [smoking], and genetic risk on the development of CD and UC in adult offspring.

METHODS

We conducted a prospective cohort study using UK Biobank data, including 334 083 participants recruited between 2006 and 2010, with follow-up until December 31, 2021. Multivariable Cox regression models were used to evaluate the associations of genetic factors, maternal and personal smoking, and their combination with CD and UC.

RESULTS

Participants exposed to MSDP had an 18% increased risk of CD compared to those without MSDP (hazard ratio [HR] = 1.18, 95% confidence interval [CI] = 1.01-1.39). However, no significant association was found between MSDP and UC risk [HR = 1.03, 95% CI = 0.92-1.16]. Personal smoking increased the risk of CD and UC, and had a numerically amplified effect with MSDP. Participants with high genetic risk and MSDP had a 2.01-fold [95% CI = 1.53-2.65] and a 2.45-fold [95% CI = 2.00-2.99] increased risk of CD and UC, respectively, compared to participants without MSDP and with low genetic risk.

CONCLUSIONS

Our prospective cohort study provides evidence that MSDP increases the risk of CD in adult offspring, whereas no evidence supports their causal association. Additionally, smoking and genetic susceptibility had a numerically amplified effect with MSDP on CD and UC, but the interaction lacked statistical significance.

Associations of maternal and personal smoking with all-cause and cause-specific mortality risk and life expectancy: a prospective cohort study

OBJECTIVES

The aim of this study was to evaluate the individual and combined effects of maternal smoking during pregnancy (MSDP) and personal smoking on mortality and life expectancy.

STUDY DESIGN

A prospective cohort study based on the UK Biobank, with a median follow-up of 12.47 years.

METHODS

This study employed multivariate Cox regression to determine the relative risks of mortality from all causes and specific diseases according to maternal and/or personal smoking status and pack-years of smoking (0, 1-20, 21-30, >30). Additionally, this study estimated the additive interaction between the two exposures. Life table analyses were performed using the estimated age-specific mortality rates to forecast life expectancy.

RESULTS

Results indicated that MSDP elevated the risk of all-cause mortality (HR = 1.12, 95% CI: 1.09-1.15) and mortality due to neoplasms (HR = 1.10, 95% CI: 1.06-1.12), circulatory (HR = 1.13, 95% CI: 1.06-1.19), respiratory (HR = 1.27, 95% CI: 1.16-1.40) and digestive system diseases (HR = 1.22, 95% CI: 1.08-1.38). Notably, both multiplicative and additive interactions were observed between maternal and personal smoking, with Relative Excess Risk due to Interaction (RERI) values for mortality from all causes, neoplasms, circulatory, and respiratory diseases being 0.21, 0.22, 0.16, and 0.76, respectively. This study also found a trend towards shorter gained life expectancy when maternal smoking and increasing pack-years of personal smoking were combined.

CONCLUSIONS

In this cohort study of UK Biobank, MSDP was associated with an increased risk of all-cause mortality and reduced life expectancy, suggesting that quitting smoking during pregnancy might have health and longevity benefits for both generations.

Maternal smoking during pregnancy links to childhood blood pressure through birth weight and body mass index: NHANES 1999-2018

Maternal smoking during pregnancy (MSDP) is associated with lower birth weight, childhood obesity, and elevated blood pressure (BP) in offspring. We aimed to examine whether birth weight and body mass index (BMI) mediate the effect of MSDP on BP in children. The study included 14,713 children aged 8 to 15 years from the National Health and Nutrition Examination Surveys from 1999 to 2018. General third-variable models were used to examine the mediating effects of birth weight and BMI on the association of MSDP with BP. A total of 1928 (13.1%) children were exposed to MSDP. MSDP was associated with reduced birth weight (p < 0.001), increased BMI (p < 0.001), and elevated systolic BP (p = 0.005). MSDP was not associated with systolic BP after adjustment for birth weight and BMI z-score (p = 0.875), with 95.0% of the effect of MSDP on BP mediated by birth weight (39.1%) and BMI (55.9%). In conclusion, lower birth weight and increased obesity measures mediate the adverse effects of MSDP on BP in children. These findings provide novel mechanistic insight into the adverse effect of MSDP on BP in children and have implications for preventing hypertension in later life.

Neonatal AVPR1a Methylation and In-Utero Exposure to Maternal Smoking

(1) Introduction: Epigenetic changes have been proposed as a biologic link between in-utero exposure to maternal smoking and health outcomes. Therefore, we examined if in-utero exposure to maternal smoking was associated with infant DNA methylation (DNAm) of cytosine-phosphate-guanine dinucleotides (CpG sites) in the arginine vasopressin receptor 1A AVPR1a gene. The AVPR1a gene encodes a receptor that interacts with the arginine vasopressin hormone and may influence physiological stress regulation, blood pressure, and child development. (2) Methods: Fifty-two infants were included in this cohort study. Multivariable linear models were used to examine the effect of in-utero exposure to maternal smoking on the mean DNAm of CpG sites located at AVPR1a. (3) Results: After adjusting the model for substance use, infants with in-utero exposure to maternal smoking had a reduction in DNAm at AVPR1a CpG sites by -0.02 (95% CI -0.03, -0.01) at one month of age. In conclusion, in-utero exposure to tobacco smoke can lead to differential patterns of DNAm of AVPR1a among infants. Conclusions: Future studies are needed to identify how gene expression in response to early environmental exposures contributes to health outcomes.

Effect of maternal smoking during pregnancy on child blood pressure in a European cohort

Hypertension is a public health issue that can have its origin in the early phases of development. Maternal smoking during pregnancy (MSDP) could play a role in offspring's cardio-metabolic programming. To assess the relationship between MSDP and later blood pressure (BP) in children we conducted a secondary analysis of a randomized dietary intervention trial (EU-Childhood Obesity Project). Healthy term infants with normal birth weight were recruited during the first 8 weeks of life in 5 European countries and followed until 11 years of age. Data on MSDP was collected at recruitment. BP and anthropometry were assessed at 11 years of age. Children were classified according to AAP guidelines as normal BP: BP < 90th percentile; high BP: ≥ 90th percentile with the subset of children having BP > 95th percentile categorized as hypertensive. Out of 572 children, 20% were exposed to MSDP. At 11 years, 26.8% had BP over the 90th centile. MSDP beyond 12 weeks of gestation was associated with higher systolic BP percentile (adjusted B 6.935; 95% CI 0.454, 13.429; p = 0.036) and over twofold increase likelihood of hypertension (OR 2.195; 95% CI 1.089, 4.423; p = 0.028) in children at 11 years. MSDP was significantly associated with later BP in children.

Prepregnancy BMI, gestational weight gain and offspring caries experience: Avon longitudinal study of parents and children

Pre-existing maternal overweight/obesity and pregnancy weight gain are associated with adverse birth outcomes such as low birth weight and prematurity, which may increase the risk of developmental tooth defects and early childhood caries. We sought to investigate the association between prepregnancy BMI, gestational weight gain (GWG) and the risk of early childhood caries. Data from 1,429 mother-offspring participants of the 1991/1992 Avon Longitudinal Study of Parents and Children were analyzed. The exposures were prepregnancy BMI (under/normal weight vs. overweight/obese), and gestational weight gain (GWG) based on the Institute of Medicine’s recommended levels. The main outcome measured was offspring caries experience determined by clinical oral examinations at three time points. Log binomial regression estimated risk ratios and 95% confidence intervals. Seventy six percent (76%) of the mothers were under/normal weight prepregnancy, 39% and 26% respectively gained less and more than the recommended weight for their prepregnancy BMI during pregnancy. Being overweight/obese prepregnancy was associated with unadjusted RR (95% CI) of offspring caries of 1.16 (0.90, 1.51) at 31-months, 1.20 (0.96, 1.49) at 43-months and 1.09 (0.91, 1.30) at 61-months. GWG less than recommended was associated with higher unadjusted offspring caries experience of 1.13 (0.86, 1.48), 1.17 (0.92, 1.48) and 1.04 (0.87, 1.25) at 31-months, 43-months and 61-months respectively. There was insufficient evidence to indicate an association between prepregnancy BMI and gestational weight gain on offspring caries experience risk.

Anthropometric measures and blood pressure of Greenlandic preschool children

The study aims to describe anthropometric data of Greenlandic preschool children, blood pressure (BP) measures and effects of maternal smoking during pregnancy in a follow-up of the ACCEPT birth cohort. The study included 102 children (55 boys and 47 girls) aged 3.5-5.5 years. Anthropometric measures included weight, height, head circumference (HC), body mass index (BMI), waist and hip circumference, ratio for height/weight, waist/height, waist/hip and BP measurements. Overweight and obesity-prevalence was determined using the international obesity task force BMI references for children. Significant increases in anthropometrics from 3.5 to 5.5 years included weight, height, HC and hip circumference, whereas ratio for height/weight, waist/hip and waist/height decreased. Boys had significantly larger HC than girls. The prevalence of overweight and obesity was similar (35.1%) between genders. Mean systolic and diastolic BP were 104 and 68 mmHg, respectively. Children of mothers smoking during pregnancy had higher hip circumference, lower waist/hip ratio and higher diastolic BP. The study present updated anthropometric data and BP of Greenlandic preschool children and effects of maternal smoking during pregnancy. The prevalence of overweight and obesity was higher than previously reported and maternal smoking during pregnancy affected the child data.Abbreviations ACCEPT: Adaptation to Climate Change, Environmental Pollution and dietary Transition; BMI: Body Mass Index; BP: Blood Pressure; Circ: Circumference; DBP: Diastolic Blood Pressure; FFH: Fisher-Freeman-Halton exact test; HC: Head Circumference; H: Height; HDL: high-density lipoprotein; HiC: Hip Circumference; IOTF International Obesity Task Force, Max: maximum, Min: minimum, P25: 25th percentile, P75: 75th percentile, SBP: Systolic Blood Pressure, SD: Standard Deviation; VDLD: very-low-density lipoprotein; WaC: Waist Circumference, W: Weight, WHO: World Health Organization.

Prenatal nicotine exposure was associated with long-term impact on the cardiovascular system and regulation-Review

AIM

The aim of this structured review was to discuss knowledge of nicotine use during pregnancy and long-term effects on children's cardiovascular function.

METHODS

PubMed and MEDLINE were searched for original papers that covered various forms of nicotine exposure during pregnancy and this identified 314 papers published in English from inception of the databases to 1 March 2021. The research focus was prenatal exposure that had long-term effects on the cardiovascular system. The search was expanded from the reference list of the selected papers, which identified another 17 papers.

RESULTS

The 34 original papers that were included covered 172,696 subjects from foetuses to 19 years of age. Cardiovascular autonomic dysfunction was discussed in 12 of the papers and 16 studies reported on blood pressure. The remaining studies covered structural or functional changes in arterial wall or heart. There were convincing data on autonomic dysfunction and increased blood pressure. Some data were conflicting and problems with misclassification of exposure were evident.

CONCLUSION

Prenatal nicotine exposure was associated with long-term developmental changes in the cardiovascular system and regulation. There were no safe periods, doses or nicotine products during pregnancy and women should abstain when planning a pregnancy.

Does Prenatal Exposure to CNS Stimulants Increase the Risk of Cardiovascular Disease in Adult Offspring?

Prenatal exposure to an adverse uterine environment can have long lasting effects on adult offspring through DNA methylation, histone acetylation, and other epigenetic effects that alter gene expression and physiology. It is well-known that consumption of CNS stimulants such as caffeine, nicotine, amphetamines, and cocaine during pregnancy can adversely impact the offspring. However, most work in this area has focused on neurological and behavioral outcomes and has been limited to assessments in young offspring. The impact of prenatal exposure to these agents on the adult cardiovascular system has received relatively little attention. Evidence from both animal and human studies indicate that exposure to CNS stimulants during the gestational period can negatively impact the adult heart and vasculature, potentially leading to cardiovascular diseases later in life. This review discusses our current understanding of the impact of prenatal exposure to cocaine, methamphetamine, nicotine, and caffeine on the adult cardiovascular system.

Factors Associated with Primary Hypertension in Pediatric Patients: An Up-to-Date

BACKGROUND

Arterial hypertension in children is considered a common alteration nowadays, mainly because obesity is a growing worldwide problem closely related to increased blood pressure. Childhood hypertension can be classified as primary or secondary, depending on the etiology. Primary or essential hypertension still has its pathophysiology not fully elucidated, and there is no consensus in the literature on most underlying mechanisms. In this review, genetic and environmental factors, including sodium and potassium intake, socioeconomic status, ethnicity, family structure, obesity, sedentary lifestyle, prematurity and low birth weight, prenatal and postnatal exposures are highlighted.

OBJECTIVE

The present study aimed to perform an update on primary hypertension in childhood, providing clinicians and researchers an overview of the current state of the literature regarding the influence of genetic and environmental factors.

METHODS

This integrative review searched for articles on genetic and environmental factors related to primary hypertension in pediatric patients. The databases evaluated were PubMed and Scopus.

RESULTS

The studies have provided insights regarding many genetic and environmental factors, in addition to their association with the pathophysiology of primary hypertension in childhood. Findings corroborated the idea that primary hypertension is a multifactorial disease. Further studies in the pediatric population are needed to elucidate the underlying mechanisms.

CONCLUSION

The study of primary hypertension in pediatrics has utmost importance for the adoption of preventive measures and the development of more efficient treatments, therefore reducing childhood morbidity and the incidence of cardiovascular diseases and other health consequences later in life.

Early Determinants of Childhood Blood Pressure at the Age of 6 Years: The GECKO Drenthe and ABCD Study Birth Cohorts

Background

There is still uncertainty about the nature and relative impact of early determinants on childhood blood pressure. This study explored determinants of blood pressure at the age of 6 years in 2 Dutch birth cohorts.

Methods and Results

Results of hierarchical multiple linear regression analyses in GECKO (Groningen Expert Center for Kids With Obesity) Drenthe study (n=1613) were replicated in ABCD (Amsterdam Born Children and Their Development) study (n=2052). All analyses were adjusted for child's age, sex, height, and body mass index (BMI), and maternal education and subsequently performed in the combined sample. No associations were found between maternal smoking during pregnancy and childhood blood pressure. In the total sample, maternal prepregnancy BMI was positively associated with systolic blood pressure (SBP) (β [95% CI], 0.09 [0.02–0.16] mm Hg) and diastolic blood pressure (β [95% CI], 0.11 [0.04–0.17] mm Hg). Children of women with hypertension had higher SBP (β [95% CI], 0.98 [0.17–1.79] mm Hg). Birth weight standardized for gestational age was inversely associated with SBP (β [95% CI], −6.93 [−9.25 to −4.61] mm Hg) and diastolic blood pressure (β [95% CI], −3.65 [−5.70 to −1.61] mm Hg). Longer gestational age was associated with lower SBP (β [95% CI] per week, −0.25 [−0.42 to −0.08] mm Hg). Breastfeeding for 1 to 3 months was associated with lower SBP (β [95% CI], −0.96 [−1.82 to −0.09] mm Hg) compared with no or <1 month of breastfeeding. Early BMI gain from the age of 2 to 6 years was positively associated with SBP (β [95% CI], 0.41 [0.08–0.74] mm Hg) and diastolic blood pressure (β [95% CI], 0.37 [0.07–0.66] mm Hg), but no effect modification by birth weight was found.

Conclusions

Higher maternal prepregnancy BMI, maternal hypertension, a relatively lower birth weight for gestational age, shorter gestational age, limited duration of breastfeeding, and more rapid early BMI gain contribute to higher childhood blood pressure at the age of 6 years.

Early Life Exposure to Nicotine: Postnatal Metabolic, Neurobehavioral and Respiratory Outcomes and the Development of Childhood Cancers

Cigarette smoking during pregnancy is associated with numerous obstetrical, fetal, and developmental complications, as well as an increased risk of adverse health consequences in the adult offspring. Nicotine replacement therapy and electronic nicotine delivery systems (e-cigarettes) have been developed as a pharmacotherapy for smoking cessation and are considered safer alternatives for women to smoke during pregnancy. The safety of nicotine replacement therapy use during pregnancy has been evaluated in a limited number of short-term human trials, but there is currently no information on the long-term effects of developmental nicotine exposure in humans. However, animal studies suggest that nicotine alone may be a key chemical responsible for many of the long-term effects associated with maternal cigarette smoking on the offspring and increases the risk of adverse neurobehavioral outcomes, dysmetabolism, respiratory illness, and cancer. This review will examine the long-term effects of fetal and neonatal nicotine exposure on postnatal health.

Prenatal smoking and the risk of early childhood caries: A prospective cohort study

Introduction

Dental caries is a chronic complex disease of multifactorial etiology that affects a quarter of U.S. children. This study evaluated the association between prenatal smoking and offspring caries experience and used a negative control exposure analysis to assess if the association is causal.

Methods

Data from 1429 mother-offspring participants of the 1991/92 Avon Longitudinal Study of Parents and Children conducted in Bristol, England were analyzed. Prenatal smoking (yes v. no) and quantity smoked (none, <half pack, ≥half pack) were self-reported while offspring caries experience was determined by clinical oral examinations at 3 time points. Discrete time hazards regression estimated hazard odds of first occurrence of offspring caries, and substituted partner smoking for prenatal smoking in a negative control exposure analysis.

Results

Overall, 22% smoked during pregnancy while 36% of partners smoked. The adjusted hazard odds of first occurrence of caries experience in the offsprings of prenatal smokers compared to the offsprings of non-smokers was 1.42 (95% CI: 1.08, 1.86). Relative to non-smoking, smoking <half pack/day and ≥half pack/day during pregnancy were associated with higher adjusted hazard odds of offspring caries experience: 1.10 (95% CI: 0.79, 1.54) and 1.38 (0.98, 1.95) respectively. Partner smoking was associated with 33% (95% CI: 1.07, 1.65) higher adjusted hazard odds of first offspring caries experience occurrence.

Conclusions

Prenatal and partner smoking appear associated with greater offspring caries experience. The positive association with partner smoking suggests either a shared genetic predisposition or unmeasured common environmental factors with the mother as opposed to a direct biological effect of the intrauterine environment.

Critical review of nutrition, blood pressure and risk of hypertension through the lifecycle: do B vitamins play a role?

Hypertension is the leading cause of preventable mortality worldwide, contributing to over 9 million deaths per annum, predominantly owing to cardiovascular disease. The association of obesity, physical inactivity and alcohol with elevated blood pressure (BP) is firmly established. Weight loss or other dietary strategies, such as the Dietary Approaches to Stop Hypertension (DASH) diet, have been shown to be effective in lowering BP. Additionally, specific nutrients are recognised to contribute to BP, with higher sodium intake linked with an increased risk of hypertension, while potassium is associated with a reduced risk of hypertension. Of note, emerging evidence has identified a novel role for one-carbon metabolism and the related B vitamins, particularly riboflavin, in BP. Specifically in adults genetically at risk of developing hypertension, owing to the common C677T polymorphism in MTHFR, supplemental riboflavin (co-factor for MTHFR) was shown in randomised trials to lower systolic BP by up to 13 mmHg. A BP response to intervention of this magnitude could have important clinical impacts, given that a reduction in systolic BP of 10 mmHg is estimated to decrease stroke risk by 40%. This review aims to explore the factors contributing to hypertension across the lifecycle and to critically evaluate the evidence supporting a role for nutrition, particularly folate-related B vitamins, in BP and risk of hypertension. In addition, gaps in our current knowledge that warrant future research in this area, will be identified.

Maternal Use of Snus in Pregnancy and Early Childhood Blood Pressure: A Warning for e-Cigarettes?

See Article Nordenstam et al

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

Background

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

Methods and Results

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

Conclusions

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

See Editorial Watanabe and Parikh

The burden of adverse obstetric and perinatal outcomes from maternal smoking in an Australian cohort

BACKGROUND

Maternal smoking is associated with a number of adverse outcomes with a dose-dependent increase in risk. The aim of this study was to evaluate the obstetric and perinatal outcomes in women who smoked during pregnancy.

METHODS

This was a retrospective cohort study of women who smoked during pregnancy and birthed at a major perinatal centre in Australia between January 2000 and April 2017. The study cohort was compared to a cohort of women who did not smoke in pregnancy. Smoking status was ascertained on history and included all types of smoking. Demographic characteristics and obstetric, intrapartum and perinatal outcomes were compared between the two groups.

RESULTS

The study cohort included 20 477 (14.6%) women who smoked during pregnancy and 119 396 controls. Women who smoked tended to be younger, of higher body mass index (BMI), Caucasian and Indigenous ethnicity. Smokers were less likely to be nulliparous, but more likely to be hypertensive and have a lower socioeconomic status compared to non-smokers. Women who smoked were more likely to have a caesarean section for non-reassuring fetal status (adjusted odds ratio (aOR) 1.16, 95%CI 1.07-1.26, P < 0.001). The infants of women who smoked were more likely to be born preterm, have a lower median birth weight and birth weights <10th (aOR 1.76, 95%CI 1.66-1.86, P < 0.001) and <5th centile (aOR 2.00, 95%CI 1.86-2.16, P < 0.001). Neonatal outcomes in the smoking cohort were worse with an increase in neonatal intensive care unit admission (aOR 1.34, 95%CI 1.27-1.43, P < 0.001), severe acidosis (aOR 1.41, 95%CI 1.27-1.43, P < 0.001) and a composite of severe neonatal outcomes (18.0% vs 12.0%, aOR 1.35, 95%CI 1.28-1.43, P < 0.001).

CONCLUSION

Women who smoke in pregnancy have worse obstetric and perinatal outcomes compared to controls and should be managed as high risk.