Parental Smoking and Vascular Damage in Young Adult Offspring: Is Early Life Exposure Critical?

Fetal Growth and Preterm Birth Influence Cardiovascular Risk Factors and Arterial Health in Young Adults

Objective—

Impaired fetal growth is associated with cardiovascular disease in adulthood. The mechanisms of this association remain poorly described. We aimed to determine the associations of impaired fetal growth and preterm birth with cardiovascular risk factors and arterial health in a large cohort of young adults.

Methods and Results—

Carotid intima-media thickness, brachial flow-mediated dilatation and cardiovascular risk factors were compared between young adults (24–45 years) born at term with impaired fetal growth (birth weight <10th percentile; n=207), born preterm (<37 weeks' gestation; n=253), and a control group born at term with normal fetal growth (birth weight 50–90th percentile; n=835), in the Cardiovascular Risk in Young Finns study. Compared with controls, those with impaired fetal growth had elevated triglycerides ( P =0.006), C-reactive protein ( P =0.004), low-density lipoprotein cholesterol, systolic blood pressure (both P =0.06), and intima-media thickness and impaired flow-mediated dilatation (both P =0.02), the latter partially mediated by systolic blood pressure, C-reactive protein, and triglycerides. Those born preterm had higher intima-media thickness ( P =0.005) and lower flow-mediated dilatation ( P =0.03) compared with controls, although this was restricted to those with concurrent fetal growth restriction.

Conclusion—

Impaired fetal growth is associated with impaired endothelial function and elevated preclinical atherosclerosis in young adults, partly mediated by inflammation, blood pressure, and triglycerides. This association is most marked for those also born preterm.

Secondhand smoke exposure and coronary artery calcification among nonsmoking participants of a population-based cohort

BACKGROUND

Secondhand smoke (SHS) consists of fine particulate matter, carcinogens, and various toxins that affect large parts of the population. SHS increases the risk for acute cardiovascular events and may contribute to the development of atherosclerosis.

OBJECTIVES

We investigated the association of SHS with coronary artery calcification (CAC).

METHODS

In this cross-sectional analysis, we used baseline data (2000-2003) from 1,766 never-smokers without clinically manifested coronary heart disease, 45-75 years of age, from the Heinz Nixdorf Recall Study, an ongoing, prospective, population-based cohort study in Germany. Self-reported frequent SHS at home, at work, and in other places was assessed by questionnaire. CAC scores were derived based on electron-beam computed tomography. We conducted multiple linear regression analysis using exposure to SHS as the explanatory variable and ln(CAC+1) as the response variable. We conducted logistic regression to estimate the odds ratio (OR) for presence of any CAC.

RESULTS

Frequent exposure to SHS was reported by 21.5% of participants. After adjustment for age, sex, and socioeconomic status, CAC + 1 was 21.1% [95% confidence interval (CI): -5.5%, 55.2%] higher in exposed than in unexposed participants. After adjusting for other cardiovascular risk factors, the association was attenuated (15.4%; 95% CI: -9.6%, 47.2%). SHS exposure was also associated with a CAC score > 0 (fully adjusted OR = 1.38; 95% CI: 1.03, 1.84).

CONCLUSIONS

Self-reported frequent exposure to SHS was associated with subclinical coronary atherosclerosis in our cross-sectional study population. Considering the widespread exposure and the clinical relevance of coronary atherosclerosis, this result, if confirmed, is of public health importance.

Cardiovascular and metabolic influences of fetal smoke exposure

Many epidemiological studies showed associations of low birth weight with cardiovascular disease, type 2 diabetes and obesity. The associations seem to be consistent and stronger among subjects with a postnatal catch up growth. It has been suggested that developmental changes in response to adverse fetal exposures might lead to changes in the fetal anatomy and physiology. These adaptations may be beneficial for short term, but may lead to common diseases in adulthood. Maternal smoking during pregnancy is one of the most important adverse fetal exposures in Western countries, and is known to be associated with a 150-200 g lower birth weight. An accumulating body of evidence suggests that maternal smoking during pregnancy might be involved in pathways leading to both low birth weight and common diseases, including cardiovascular disease, type 2 diabetes and obesity, in adulthood. In this review, we discuss epidemiological studies focused on the associations of maternal smoking with fetal growth and development and cardiovascular and metabolic disease in later life. We also discuss potential biological mechanisms, and challenges for future epidemiological studies.

Cardiovascular and metabolic influences of fetal smoke exposure

Many epidemiological studies showed associations of low birth weight with cardiovascular disease, type 2 diabetes and obesity. The associations seem to be consistent and stronger among subjects with a postnatal catch up growth. It has been suggested that developmental changes in response to adverse fetal exposures might lead to changes in the fetal anatomy and physiology. These adaptations may be beneficial for short term, but may lead to common diseases in adulthood. Maternal smoking during pregnancy is one of the most important adverse fetal exposures in Western countries, and is known to be associated with a 150–200 g lower birth weight. An accumulating body of evidence suggests that maternal smoking during pregnancy might be involved in pathways leading to both low birth weight and common diseases, including cardiovascular disease, type 2 diabetes and obesity, in adulthood. In this review, we discuss epidemiological studies focused on the associations of maternal smoking with fetal growth and development and cardiovascular and metabolic disease in later life. We also discuss potential biological mechanisms, and challenges for future epidemiological studies.

Carotid intima–media thickness: a suitable alternative for cardiovascular risk as outcome?

BACKGROUND

Surrogate markers for cardiovascular disease might be of great value in observational research, clinical trials, and clinical practice. Carotid intima-media thickness (CIMT) is probably the most commonly used marker for atherosclerotic disease as an alternative for cardiovascular morbidity and mortality. A suitable marker for atherosclerosis, however, should meet several criteria before it can be validly used.

METHODS AND RESULTS

We reviewed the literature following a set of criteria for a surrogate marker. These include a comparison with a 'gold standard'; adequate reproducibility; cross-sectional relations with established risk factors and prevalent disease; relations with severity of atherosclerosis elsewhere in the arterial system; relations with the occurrence with future events; ability for a biomarker to change over time; ability to be affected by interventions over time; and relations between change over time in biomarker level and change in risk. A large number of studies from a variety of populations provide evidence for the validity of CIMT as a suitable measure of atherosclerotic disease. Data on the relation between change in CIMT and change in risk, however, is much sparser.

CONCLUSION

CIMT progression meets the criteria of a surrogate for cardiovascular disease endpoints and may be considered as a valid alternative for cardiovascular events as outcome. Further studies should examine the association between changes in CIMT and changes in risk for future events.

Maternal cigarette smoking is associated with reduced high-density lipoprotein cholesterol in healthy 8-year-old children

AIMS

Smoking in pregnancy is common. Its effects on lipoprotein levels and arterial structure in childhood are not well characterized. We aimed to determine the effects of maternal smoking in pregnancy on lipoprotein levels and arterial wall thickness in healthy pre-pubertal children.

METHODS AND RESULTS

A community-based longitudinal study with prospective ascertainment of exposure to smoking in pregnancy and environmental tobacco smoke (ETS) since birth and then lipoprotein and arterial measurements at age 8 years. In 616 newborn infants (gestation >36 weeks and birth weight >2.5 kg) data were collected prospectively by questionnaire on smoking in pregnancy and ETS exposure in childhood. At age 8-years, 405 of the children had measurements of lipoproteins, blood pressure (BP) and carotid intima-media thickness. Children born to mothers who smoked in pregnancy had lower HDL cholesterol [1.32 vs. 1.50 mmol/L, 95% confidence interval (CI) for difference -0.28 to -0.08, P = 0.0005], higher triglycerides (1.36 vs. 1.20 mmol/L, 95% CI for ratio 1.01-1.30, P = 0.04) and higher systolic BP (102.1 vs. 99.9 mmHg, 95% CI for difference 0.6-3.8, P = 0.006). After adjustment for maternal passive smoking, post-natal ETS exposure, gender, breast feeding duration, physical inactivity, and adiposity, smoking in pregnancy remained significantly associated with lower HDL cholesterol (difference = -0.22 mmol/L, 95% CI -0.36 to -0.08, P = 0.003) but not with higher systolic BP. Neither smoking in pregnancy nor post-natal ETS exposure was associated with alterations of carotid artery wall thickness.

CONCLUSION

Smoking in pregnancy is independently associated with significantly lower HDL cholesterol in healthy 8-year-old children.

The association between breastfeeding and the cardiovascular system in early childhood

BACKGROUND

Breastfeeding is suggested to have beneficial effects on children's health and future health status. However, its cardiovascular effects in childhood and possibly later in life remain largely unclear.

OBJECTIVE

The aim of the present study was to determine the cardiovascular effects of exclusive breastfeeding in early childhood.

DESIGN

We used the ongoing WHeezing Illnesses STudy LEidsche Rijn (WHISTLER) birth cohort to obtain data on infant feeding. In the first 306 children who were 5 y of age, ultrasonographic measurements of the carotid artery were performed to obtain carotid intima-media thickness (CIMT), distensibility, and elastic modulus.

RESULTS

At 5 y of age, children who had been exclusively breastfed in infancy for 3 to 6 mo had a CIMT that was 21.1 μm greater than that of exclusively formula-fed children (95% CI: 5.0, 37.2 μm; P = 0.01, adjusted for confounders). CIMT was not significantly different between children exclusively breastfed for either <3 or >6 mo and formula-fed children. In addition, no significant differences in carotid stiffness were observed between groups.

CONCLUSIONS

The duration of exclusive breastfeeding in infancy is related to properties of the carotid arterial wall at the age of 5 y, as shown by the greater CIMT in children who were exclusively breastfed for 3 to 6 mo. This relation was independent of early growth in infancy and current cardiovascular disease risk factors. The choice of infant feeding appears to have an effect on the vascular system already in early childhood.

Second hand smoke exposure in children: environmental factors, physiological effects, and interventions within pediatrics

BACKGROUND

Second hand smoke (SHS) exposure has long been correlated with many adverse disease processes, particularly in children. For children growing up with socioeconomic disadvantages and increased exposure to SHS, exposure can have far-reaching consequences.

OBJECTIVE

The purpose of this review was to examine the literature assessing the effects of SHS exposure in children, as well as the perspectives of both parents and providers regarding current practices in cessation counseling. The review also sought out recommendations on ways to increase the influence of pediatricians on parental smoking.

STUDY GROUP

Children under the age of 18 years.

METHODS

PubMed and MEDLINE were searched systematically. A narrative approach was used because the studies differed in methods and data.

RESULTS

The studies showed correlations between SHS exposure and sudden infant death syndrome (SIDS), asthma, altered respiratory function, infection, cardiovascular effects, behavior problems, sleep difficulties, increased cancer risk, and a higher likelihood of smoking initiation. Questionnaires of both parents and pediatricians showed that pediatricians are not consistently carrying out the recommended smoking cessation interventions, with lack of training as a primary barrier. Nevertheless, interventions targeting improved cessation training for both residents and practicing pediatricians have been studied and show promising results.

CONCLUSIONS

SHS exposure has many detrimental effects on children's health, particularly for those in low socioeconomic circumstances, for which factors in the built environment accentuated a higher baseline risk. By counseling parents, expanding residency education, and continuing advocacy work, pediatricians can have a significant positive impact on children's health as related to SHS exposure.

In utero exposure to maternal smoking and women's risk of fetal loss in the Norwegian Mother and Child Cohort (MoBa)

BACKGROUND

Whether in utero exposure to tobacco smoke increases a woman's risk of fetal loss later in life is unknown, though data on childhood exposure suggest an association may exist. This study evaluated the association between in utero exposure to tobacco smoke and fetal loss in the Norwegian Mother and Child Cohort Study (MoBa), which enrolled ∼40% of the pregnant women in Norway from 1999 to 2008.

METHODS

Information on exposure to tobacco smoke in utero, the woman's own smoking behavior during pregnancy and other factors was obtained by a questionnaire completed at ∼17 weeks of gestation. Subsequent late miscarriage (fetal death <20 weeks) and stillbirth (fetal death ≥ 20 weeks) were ascertained from the Norwegian Medical Birth Registry. This analysis included 76 357 pregnancies (MoBa data set version 4.301) delivered by the end of 2008; 59 late miscarriages and 270 stillbirths occurred. Cox proportional hazards models were fit for each outcome and for all fetal deaths combined.

RESULTS

The adjusted hazard ratio (HR) of late miscarriage was 1.23 [95% confidence interval (CI), 0.72-2.12] in women with exposure to maternal tobacco smoke in utero when compared with non-exposed women. The corresponding adjusted HR for stillbirths was 1.11 (95% CI, 0.85-1.44) and for all fetal deaths combined, it was 1.12 (95% CI, 0.89-1.43).

CONCLUSIONS

The relatively wide CI around the HR for miscarriage reflected the limited power to detect an association, due to enrollment around 17 weeks of gestation. However, for in utero exposure to tobacco smoke and risk of stillbirth later in life, where the study power was adequate, our data provided little support for an association.

Maternal smoking in pregnancy, adult adiposity and other risk factors for cardiovascular disease

OBJECTIVE

To establish whether maternal smoking in pregnancy is associated with risk factors for cardiovascular disease (CVD) in mid-adulthood and whether associations are explained by postnatal influences.

METHODS

Participants were 8815 men and women in the 1958 British birth cohort, with data on CVD risk factors measured at 45 y. Maternal smoking was recorded at birth.

RESULTS

Offspring of smokers had a higher adult BMI, waist circumference, blood pressure, HbA1c and triglycerides on average than offspring of non-smokers; females had lower HDL cholesterol levels. Total cholesterol was unrelated to maternal smoking. Associations were abolished after adjustment for postnatal influences across life, except for BMI and waist circumference: offspring of smokers had a BMI greater by 0.83 kg/m(2) on average than offspring of non-smokers and a 1.8 cm larger waist circumference. Mean BMI and waist circumference increased with number of cigarettes that the mother smoked, but were not elevated in offspring whose mother had quit smoking before or early in pregnancy.

CONCLUSIONS

Adults exposed to tobacco in utero had a more adverse CVD risk profile in mid-adulthood which appeared to reflect a lifetime accumulation of postnatal influences; whereas their higher BMI and central adiposity may be due in part to intrauterine mechanisms.

Prenatal allergen and diesel exhaust exposure and their effects on allergy in adult offspring mice

Background

Multiple studies have suggested that prenatal exposure to either allergens or air pollution may increase the risk for the development of allergic immune responses in young offspring. However, the effects of prenatal environmental exposures on adult offspring have not been well-studied. We hypothesized that combined prenatal exposure to Aspergillus fumigatus (A. fumigatus) allergen and diesel exhaust particles will be associated with altered IgE production, airway inflammation, airway hyperreactivity (AHR), and airway remodeling of adult offspring.

Methods

Following sensitization via the airway route to A. fumigatus and mating, pregnant BALB/c mice were exposed to additional A. fumigatus and/or diesel exhaust particles. At age 9-10 weeks, their offspring were sensitized and challenged with A. fumigatus.

Results

We found that adult offspring from mice that were exposed to A. fumigatus or diesel exhaust particles during pregnancy experienced decreases in IgE production. Adult offspring of mice that were exposed to both A. fumigatus and diesel exhaust particles during pregnancy experienced decreases in airway eosinophilia.

Conclusion

These results suggest that, in this model, allergen and/or diesel administration during pregnancy may be associated with protection from developing systemic and airway allergic immune responses in the adult offspring.

Identifying patterns of immune-related disease: use in disease prevention and management

BACKGROUND

Childhood susceptibility to diseases linked with immune dysfunction affects over a quarter of the pediatric population in some countries. While this alone is a significant health issue, the actual impact of immune-related diseases extends over a lifetime and involves additional secondary conditions. Some comorbidities are well known (e.g., allergic rhinitis and asthma). However, no systematic approach has been used to identify life-long patterns of immune-based disease where the primary condition arises in childhood. Such information is useful for both disease prevention and treatment approaches.

DATA SOURCES

Recent primary research papers as well as review articles were obtained from PubMed, Chem Abstracts, Biosis and from the personal files of the authors. Search words used were: the diseases and conditions shown Figs. 1 and 2 in conjunction with comorbid, comorbidities, pediatric, childhood, adult, immune, immune dysfunction, allergy, autoimmune, inflammatory, infectious, health risks, environment, risk factors.

RESULTS

Childhood diseases such as asthma, type-1 diabetes, inflammatory bowel disease, respiratory infections /rhinitis, recurrent otitis media, pediatric celiac, juvenile arthritis and Kawasaki disease are examples of significant childhood health problems where immune dysfunction plays a significant role. Each of these pediatric diseases is associated with increased risk of several secondary conditions, many of which appear only later in life. To illustrate, four prototypes of immune-related disease patterns (i.e., allergy, autoimmunity, inflammation and infectious disease) are shown as tools for: 1) enhanced disease prevention; 2) improved management of immune-based pediatric diseases; and 3) better recognition of underlying pediatric immune dysfunction.

CONCLUSIONS

Identification of immune-related disease patterns beginning in childhood provides the framework for examining the underlying immune dysfunctions that can contribute to additional diseases in later life. Many pediatric diseases associated with dysfunctional immune responses have been linked with an elevated risk of other diseases or conditions as the child ages. Diseases within a pattern may be interlinked based on underlying immune dysfunctions and/or current therapeutic approaches for managing the entryway diseases. It may be beneficial to consider treatment options for the earliest presenting diseases that will concomitantly reduce the risk of immune-linked secondary conditions. Additionally, improved disease prevention is possible with more relevant and age-specific immune safety testing.

Arterial intima-media thickness, endothelial function, and apolipoproteins in adolescents frequently exposed to tobacco smoke

BACKGROUND

Exposure to tobacco smoke is associated with markers of preclinical atherosclerosis in adults, but its effect on arterial structure in adolescents is unknown.

METHODS AND RESULTS

Healthy 13-year-old adolescents from the atherosclerosis prevention trial STRIP were studied. Maximum carotid and aortic intima-media thickness and brachial artery flow-mediated dilation were measured in 494 adolescents using high-resolution ultrasound. Serum lipid, lipoprotein, and apolipoprotein (Apo) A-I and B concentrations were determined using standard methods. Exposure to tobacco smoke was measured annually between ages 8 and 13 years using serum cotinine concentrations, analyzed with gas chromatography. To define longitudinal exposure, cotinine values of children having serum cotinine measured 2 to 6 times during follow-up were averaged and divided into tertiles (exposure groups): low (n=160), intermediate (n=171), and high (n=163). Adolescents with higher longitudinal exposure to tobacco smoke had increased carotid intima-media thickness (exposure groups [mean+/-SD]: low, 0.502+/-0.079 mm; intermediate, 0.525+/-0.070 mm; high, 0.535+/-0.066 mm; P<0.001) and increased aortic intima-media thickness (exposure groups: low, 0.527+/-0.113 mm; intermediate, 0.563+/-0.139 mm; high, 0.567+/-0.126 mm; P=0.008). The flow-mediated dilation decreased when cotinine level increased (exposure groups: low, 10.43+/-4.34%; intermediate, 9.78+/-4.38%; high, 8.82+/-4.14%; P=0.004). Moreover, ApoB (P=0.014) and ApoB/ApoA-I ratio (P=0.045) increased with increase in cotinine level. The associations between tobacco smoke exposure and ultrasound variables were unchanged after adjusting for traditional atherosclerosis risk factors and for ApoB.

CONCLUSIONS

Frequent exposure to tobacco smoke is independently associated with arterial changes of preclinical atherosclerosis and increased ApoB levels among healthy adolescents. Clinical Trial Registration- clinicaltrials.gov. Identifier: NCT00223600.