Incidence of atrial fibrillation in relation to birth weight and preterm birth

Preterm Birth, Small for Gestational Age, and Large for Gestational Age and the Risk of Atrial Fibrillation Up to Middle Age

Importance

Adverse birth outcomes, including preterm birth, small for gestational age (SGA), and large for gestational age (LGA) are associated with increased risks of hypertension, ischemic heart disease, stroke, and heart failure, but knowledge regarding their associations with atrial fibrillation (AF) is limited and inconsistent.

Objective

To investigate whether preterm birth, SGA, or LGA are associated with increased risks of AF later in life.

Design, Setting, and Participants

This multinational cohort study included Danish, Swedish, and Finnish national health registries. Live singleton births in Denmark from 1978 through 2016, in Sweden from 1973 through 2014, and in Finland from 1987 through 2014, who were followed up until December 31, 2016, in Denmark, December 31, 2021, in Sweden, and December 31, 2014, in Finland were included. Data analyses were performed between January 2021 and August 2022.

Exposures

Preterm birth (less than 37 gestational weeks), SGA (less than 10th percentile birth weight for gestational age), and LGA (more than 90th percentile birth weight for gestational age) identified from medical birth registers.

Main Outcomes and Measures

Diagnosis of AF obtained from nationwide inpatient and outpatient registers. The study team ran multivariable Cox proportional hazard models and flexible parametric survival models to estimate hazard ratios (HRs) and 95% CIs for AF according to preterm birth, SGA, and LGA. Sibling analyses were conducted to control for unmeasured familial factors.

Results

The cohort included 8 012 433 study participants (maximum age, 49 years; median age, 21 years; male, 51.3%). In 174.4 million person-years of follow-up, 11 464 participants had a diagnosis of AF (0.14%; median age, 29.3 years). Preterm birth and LGA were associated with increased AF risk in both the full population cohort and in the sibling analyses; the multivariate HRs from the cohort analyses were 1.30 (95% CI, 1.18-1.42) and 1.55 (95% CI, 1.46-1.63), respectively. Preterm birth was more strongly associated with AF in childhood than in adulthood. Children born SGA had an increased risk of AF in the first 18 years of life but not afterwards.

Conclusions and Relevance

Preterm births and LGA births were associated with increased risks of AF up to middle age independently of familial confounding factors. Individuals born SGA had an increased AF risk only during childhood.

The association of gestational age and birthweight with blood pressure, cardiac structure, and function in 4 years old: a prospective birth cohort study

BACKGROUND

Current evidence relating birthweight and gestational age to cardiovascular risk is conflicting. Whether these factors have independent or interactive impacts on cardiovascular parameters during early childhood remains unclear. The goal of this study was to explore whether there were any independent and interactive effects of gestational age and birthweight on blood pressure, left ventricle (LV) structure, and function in 4 years old.

METHODS

This study included 1194 children in the Shanghai Birth Cohort from 2013 to 2016. Information about the mothers and children was recorded at time of birth using a questionnaire. Follow-up measurements, including anthropometric, blood pressure, and echocardiography, were taken between 2018 and 2021, when the children were 4 years old. Multiple linear or logistic regressions and restricted cubic spline were used to explore the association of birthweight and gestational age with cardiovascular measurements.

RESULTS

Gestational age had a significant negative correlation with both systolic blood pressure [β =  - 0.41, 95% CI: (- 0.76, - 0.07)] and mean arterial pressure [β =  - 0.36, 95%CI: (- 0.66, - 0.07)]. The risk of prehypertension decreased with increased gestational age [OR = 0.54, 95% CI: (0.32, 0.93)]. The relationship between birthweight with blood pressure was U-shape (P for non-linear < 0.001). The wall thickness, volume, mass, and cardiac output of LV increased with birthweight, though the ejection fraction [β =  - 1.02, 95% CI: (- 1.76, - 0.27)] and shorten fraction [β = 0.72, 95% CI: (- 1.31, - 0.14)] decreased with birthweight. The risk of LV hypertrophy was not associated with birthweight [OR = 1.59, 95% CI: (0.68, 3.73)].

CONCLUSIONS

In this study, we found different associations of birthweight and gestational age with cardiovascular measurements in the offspring at 4 years old. Gestational age influenced blood pressure independent of birthweight. Heart size and function at 4 years old was influenced mostly by birthweight and not by gestational age.

A Mixture of Endocrine Disrupting Chemicals Associated with Lower Birth Weight in Children Induces Adipogenesis and DNA Methylation Changes in Human Mesenchymal Stem Cells

Endocrine Disrupting Chemicals (EDCs) are man-made compounds that alter functions of the endocrine system. Environmental mixtures of EDCs might have adverse effects on human health, even though their individual concentrations are below regulatory levels of concerns. However, studies identifying and experimentally testing adverse effects of real-life mixtures are scarce. In this study, we aimed at evaluating an epidemiologically identified EDC mixture in an experimental setting to delineate its cellular and epigenetic effects. The mixture was established using data from the Swedish Environmental Longitudinal Mother and child Asthma and allergy (SELMA) study where it was associated with lower birth weight, an early marker for prenatal metabolic programming. This mixture was then tested for its ability to change metabolic programming of human mesenchymal stem cells. In these cells, we assessed if the mixture induced adipogenesis and genome-wide DNA methylation changes. The mixture increased lipid droplet accumulation already at concentrations corresponding to levels measured in the pregnant women of the SELMA study. Furthermore, we identified differentially methylated regions in genes important for adipogenesis and thermogenesis. This study shows that a mixture reflecting human real-life exposure can induce molecular and cellular changes during development that could underlie adverse outcomes.

The Risk of Atrial Fibrillation Increases with Earlier Onset of Obesity: A Mendelian Randomization Study

Background: Obesity is a well-established risk factor for atrial fibrillation (AF). Previous epidemiological research on obesity and AF often focused on adult populations and now broadened to earlier in life. Therefore, this study aimed to determine the relationships between obesity at different periods of life and the risk of AF. Methods: A two-sample Mendelian randomization (MR) study design using summarised data from 6 genome-wide association studies (GWASs) was employed in this study. Single nucleotide polymorphisms (SNPs) associated with adult obesity, childhood obesity, childhood body mass index (BMI), waist-to-hip ratio adjusted for BMI (WHRadjBMI), birth weight and AF were independently retrieved from large-scale GWASs. For SNP identification, the genome-wide significance threshold was set at p <5.00×10^-8. To obtain causal estimates, MR analysis was conducted using the inverse variance-weighted (IVW) method. The weighted median, MR-Egger methods and MR-robust adjusted profile score (MR-RAPS) were used to evaluate the robustness of MR analysis. Results: A total of 204 SNPs were identified as the genetic instrumental variables (5 SNPs for childhood obesity, 13 SNPs for childhood BMI, 137 SNPs for birth weight, 35 SNPs for adult WHRadjBMI, and 14 SNPs for adult obesity). The results of MR analysis demonstrated that the genetically predicted adult obesity, childhood BMI, and birth weight were associated with AF risk. Notably, a 1 unit standard deviation (1-SD) increase in adult obesity was related to a 13% increased risk of AF [p=6.51×10^-7, OR, 1.13 (95% CI, 1.08-1.19)], a 1-SD increase in childhood BMI was related to a 18% increased risk of AF [p=1.77×10^-4, OR, 1.18 (95% CI, 1.08-1.29)], and a 1-SD increase in birth weight was related to a 26% increased risk of AF [p=1.27×10^-7, OR, 1.26 (95% CI, 1.16-1.37)]. There was no evidence of pleiotropy or heterogeneity between the MR estimates obtained from multiple SNPs. Conclusion: Our study reveals the association of genetic susceptibility to obesity with a higher risk of AF. Moreover, an earlier age at obesity was associated with an increased risk of AF. Therefore, public awareness of the dangers of obesity and active early weight control may prevent the development of AF.

Association between birth weight and risk of cardiovascular disease: Evidence from UK Biobank

BACKGROUND AND AIMS

Birth weight has been linked to cardiovascular disease (CVD) risk in adulthood, but no consensus has emerged on the threshold of birth weight for the lowest CVD risk and few studies have examined potential interaction between birth weight and adult adiposity.

METHODS AND RESULTS

A total of 256,787 participants, who had birth weight data and were free of CVD at baseline, were included from UK Biobank. Multivariate restricted cubic splines and Cox regression models were used to assess the association between birth weight and CVD. We observed nonlinear inverse associations of birth weight with the risk of coronary heart disease (CHD), stroke, and heart failure. Participants with the first quintile of birth weight (≤2.85 kg) had higher risks for CHD (hazard ratio [HR] = 1.23, 95% confidence interval [CI]: 1.15-1.32), stroke (HR = 1.19, 95% CI: 1.03-1.37), and heart failure (HR = 1.28, 95% CI: 1.11-1.48), as compared to the fourth quintile (3.41-3.79 kg). There was a significant interaction between birth weight and adult body mass index (BMI) on CHD and heart failure (both P for interaction <0.001), showing the highest risk for those who had birth weight ≤2.85 kg and BMI ≥30 kg/m² (HR = 1.96, 95% CI: 1.70-2.25 and HR = 2.39, 95% CI: 1.77-3.22, respectively).

CONCLUSIONS

Our findings indicate nonlinear inverse associations between birth weight and CVD risk, with a threshold of 3.41-3.79 kg for the lowest risk. Moreover, low birth weight may interact with adult obesity to increase the risk of CHD and heart failure.

Genetic Determinants of Increased Body Mass Index Partially Mediate the Effect of Elevated Birth Weight on the Increased Risk of Atrial Fibrillation

Background: Although several observational studies have shown an association between birth weight (BW) and atrial fibrillation (AF), controversy remains. In this study, we aimed to explore the role of elevated BW on the etiology of AF.

Methods: A two-sample Mendelian randomization (MR) study was designed to infer the causality. The genetic data on the associations of single-nucleotide polymorphisms (SNPs) with BW and AF were separately obtained from two large-scale genome-wide association studies with up to 321,223 and 1,030,836 individuals, respectively. SNPs were identified at a genome-wide significant level (p <5 × 10⁻⁸). The inverse variance-weighted (IVW) method was employed to obtain causal estimates as our primary analysis. Sensitivity analyses with various statistical methods were applied to evaluate the robustness of the results, and multivariable MR analysis was conducted to determine whether this association was mediated by the body mass index (BMI).

Results: In total, 144 SNPs were identified as the genetic instrumental variables. MR analysis revealed a causal effect of elevated BW on AF (OR = 1.27, 95% CI = 1.14–1.40, p = 5.70 × 10⁻⁶). All the results in sensitivity analyses were consistent with the primary result. The effect of BW on AF was attenuated when adjusted for BMI (OR = 1.16, 95% CI = 1.01–1.33, p = 0.04).

Conclusions: This study indicated that elevated BW was significantly associated with increased lifelong risk of AF, which may be partially mediated by BMI.

Childhood Risk Factors and Adulthood Cardiovascular Disease: A Systematic Review

OBJECTIVE

To conduct a comprehensive review of the literature on childhood risk factors and their associations with adulthood subclinical and clinical cardiovascular disease (CVD).

STUDY DESIGN

A systematic search was performed using the MEDLINE, EMBASE, PsycINFO, CINAHL, and Web of Science databases to identify English-language articles published through June 2018. Articles were included if they were longitudinal studies in community-based populations, the primary exposure occurred during childhood, and the primary outcome was either a measure of subclinical CVD or a clinical CVD event occurring in adulthood. Two independent reviewers screened determined whether eligibility criteria were met.

RESULTS

There were 210 articles that met the predefined criteria. The greatest number of publications examined associations of clinical risk factors, including childhood adiposity, blood pressure, and cholesterol, with the development of adult CVD. Few studies examined childhood lifestyle factors including diet quality, physical activity, and tobacco exposure. Domains of risk beyond "traditional" cardiovascular risk factors, such as childhood psychosocial adversity, seemed to have strong published associations with the development of CVD.

CONCLUSIONS

Although the evidence was fairly consistent in direction and magnitude for exposures such as childhood adiposity, hypertension, and hyperlipidemia, significant gaps remain in the understanding of how childhood health and behaviors translate to the risk of adulthood CVD, particularly in lesser studied exposures like glycemic indicators, physical activity, diet quality, very early life course exposure, and population subgroups.

Impact of Maternal Food Restriction on Heart Proteome in Appropriately Grown and Growth-Restricted Wistar-Rat Offspring

Objective: Fetal growth restriction is associated with increased postnatal cardiovascular morbidity. The alterations in heart physiology and structure caused by in utero nutrient deprivation have not been extensively studied. We aim to investigate the impact of maternal food restriction on the cardiac proteome of newborn rats with normal (non-fetal growth-restricted (FGR)) and reduced (FGR) birth weight. Methods: On day 14 of gestation, 10 timed pregnant rats were randomized into two nutritional groups: (a) Standard laboratory diet and (b) 50% global food restriction. Pups born to food-restricted mothers were subdivided, based on birthweight, into fetal growth-restricted (FGR) and non-FGR, while pups born from normally nourished mothers were considered controls. Rat neonates were euthanized immediately after birth and the hearts of 11 randomly selected male offspring (n = 4 FGR, n = 4 non-FGR, n = 3 control group) were analyzed using quantitative proteomics. Results: In total, 7422 proteins were quantified (q < 0.05). Of these, 1175 were differentially expressed in FGR and 231 in non-FGR offspring vs. control with 151 common differentially expressed proteins (DEPs) between the two groups. Bioinformatics analysis of DEPs in FGR vs. control showed decreased integrin and apelin cardiac fibroblast signaling, decreased muscle contraction and glycolysis, and over-representation of a protein network related to embryonic development, and cell death and survival. Conclusion: Our study illustrates the distinct proteomic profile of FGR and non-FGR offspring of food-restricted dams underlying the importance of both prenatal adversities and birth weight in cardiac physiology and development.

The Association Between High Birth Weight and Long-Term Outcomes-Implications for Assisted Reproductive Technologies: A Systematic Review and Meta-Analysis

Background: Studies have shown that the prevalence of children born with high birth weight or large for gestational age (LGA) is increasing. This is true for spontaneous pregnancies; however, children born after frozen embryo transfer (FET) as part of assisted reproductive technology (ART) also have an elevated risk. In recent years, the practice of FET has increased rapidly and while the perinatal and obstetric risks are well-studied, less is known about the long-term health consequences. Objective: The aim of this systematic review was to describe the association between high birth weight and LGA on long-term child outcomes. Data Sources: PubMed, Scopus, and Web of Science were searched up to January 2021. Exposure included high birth weight and LGA. Long-term outcome variables included malignancies, psychiatric disorders, cardiovascular disease, and diabetes. Study Selection: Original studies published in English or Scandinavian languages were included. Studies with a control group were included while studies published as abstracts and case reports were excluded. Data Extraction: The methodological quality, in terms of risk of bias, was assessed by pairs of reviewers. Robins-I (www.methods.cochrane.org) was used for risk of bias assessment in original articles. For systematic reviews, AMSTAR (www.amstar.ca) was used. For certainty of evidence, we used the GRADE system. The systematic review followed PRISMA guidelines. When possible, meta-analyses were performed. Results: The search included 11,767 articles out of which 173 met the inclusion criteria and were included in the qualitative analysis, while 63 were included in quantitative synthesis (meta-analyses). High birth weight and/or LGA was associated with low to moderately elevated risks for certain malignancies in childhood, breast cancer, several psychiatric disorders, hypertension in childhood, and type 1 and 2 diabetes. Conclusions: Although the increased risks for adverse outcome in offspring associated with high birth weight and LGA represent serious health effects in childhood and in adulthood, the size of these effects seems moderate. The identified risk association should, however, be taken into account in decisions concerning fresh and frozen ART cycles and is of general importance in view of the increasing prevalence in high birthweight babies.

Association Between Preterm Birth and Arrested Cardiac Growth in Adolescents and Young Adults

Importance

Premature birth is associated with substantially higher lifetime risk for cardiovascular disease, including arrhythmia, ischemic disease, and heart failure, although the underlying mechanisms are poorly understood.

Objective

To characterize cardiac structure and function in adolescents and young adults born preterm using cardiac magnetic resonance imaging (MRI).

Design, Setting, and Participants

This cross-sectional cohort study at an academic medical center included adolescents and young adults born moderately to extremely premature (20 in the adolescent cohort born from 2003 to 2004 and 38 in the young adult cohort born in the 1980s and 1990s) and 52 age-matched participants who were born at term and underwent cardiac MRI. The dates of analysis were February 2016 to October 2019.

Exposures

Premature birth (gestational age ≤32 weeks) or birth weight less than 1500 g.

Main Outcomes and Measures

Main study outcomes included MRI measures of biventricular volume, mass, and strain.

Results

Of 40 adolescents (24 [60%] girls), the mean (SD) age of participants in the term and preterm groups was 13.3 (0.7) years and 13.0 (0.7) years, respectively. Of 70 adults (43 [61%] women), the mean (SD) age of participants in the term and preterm groups was 25.4 (2.9) years and 26.5 (3.5) years, respectively. Participants from both age cohorts who were born prematurely had statistically significantly smaller biventricular cardiac chamber size compared with participants in the term group: the mean (SD) left ventricular end-diastolic volume index was 72 (7) vs 80 (9) and 80 (10) vs 92 (15) mL/m2 for adolescents and adults in the preterm group compared with age-matched participants in the term group, respectively (P < .001), and the mean (SD) left ventricular end-systolic volume index was 30 (4) vs 34 (6) and 32 (7) vs 38 (8) mL/m2, respectively (P < .001). Stroke volume index was also reduced in adolescent vs adult participants in the preterm group vs age-matched participants in the term group, with a mean (SD) of 42 (7) vs 46 (7) and 48 (7) vs 54 (9) mL/m2, respectively (P < .001), although biventricular ejection fractions were preserved. Biventricular mass was statistically significantly lower in adolescents and adults born preterm: the mean (SD) left ventricular mass index was 39.6 (5.9) vs 44.4 (7.5) and 40.7 (7.3) vs 49.8 (14.0), respectively (P < .001). Cardiac strain analyses demonstrated a hypercontractile heart, primarily in the right ventricle, in adults born prematurely.

Conclusions and Relevance

In this cross-sectional study, adolescents and young adults born prematurely had statistically significantly smaller biventricular cardiac chamber size and decreased cardiac mass. Although function was preserved in both age groups, these morphologic differences may be associated with elevated lifetime cardiovascular disease risk after premature birth.

Genetically Determined Birthweight Associates With Atrial Fibrillation: A Mendelian Randomization Study

BACKGROUND

Atrial fibrillation is a common cardiovascular disorder, characterized by irregular electrical activity in the upper chambers of the heart. Both chronic cardiometabolic risk factors and genetics have been shown to contribute to the development of atrial fibrillation. Birthweight has also been associated with risk of atrial fibrillation.

METHODS

In the current study, we utilized a genetic approach to study the effect of birthweight on atrial fibrillation. We used 2-sample Mendelian randomization to consider the impact of birthweight on incident atrial fibrillation using summary data from the Early Growth Genetics Consortium GWAS of birthweight and a large biobank-based GWAS of atrial fibrillation.

RESULTS

Using the framework of 2-sample Mendelian randomization, we found that a 1-SD genetic elevation of birthweight was associated with increased risk of atrial fibrillation (odds ratio, 1.27 [95% CI, 1.14-1.41]; P=1×10^-5) with sensitivity analyses demonstrating robustness of this result.

CONCLUSIONS

Our findings clarify the directionality of the relationship between birthweight and atrial fibrillation, supporting the growing body of evidence that intrauterine growth has a lifelong impact on cardiovascular health.

Birth weight and cardiac function assessed by echocardiography in adolescence: Avon Longitudinal Study of Parents and Children

OBJECTIVE

Maternal hemodynamics in pregnancy is associated with fetal growth and birth weight, which in turn are associated with offspring cardiovascular disease later in life. The aim of this study was to quantify the extent to which birth weight is associated with cardiac structure and function in adolescence.

METHODS

A subset of offspring (n = 1964; 55% female) of the Avon Longitudinal Study of Parents and Children were examined with echocardiography at a mean age of 17.7 (SD, 0.3) years. The associations of birth-weight Z-score for sex and gestational age with cardiac structure (assessed by relative wall thickness, left ventricular mass index (LVMI) and left atrial diameter index), systolic function (assessed by ejection fraction and left ventricular wall velocity) and diastolic function (assessed by early/late mitral inflow velocity (E/A) and early mitral inflow velocity/mitral annular early diastolic velocity (E/e')) were evaluated. Linear regression models were adjusted for several potential confounders, including maternal prepregnancy body mass index, age, level of education and smoking during pregnancy.

RESULTS

Higher birth-weight Z-score was associated with lower E/A (mean difference, -0.024; 95% CI, -0.043 to -0.005) and E/e' (mean difference, -0.05; 95% CI, -0.10 to -0.001) and higher LVMI (mean difference, 0.38 g/m2.7 ; 95% CI, 0.09 to 0.67). There was no or inconsistent evidence of associations of birth-weight Z-score with relative wall thickness, left atrial diameter and measurements of systolic function. Further analyses suggested that the association between birth-weight Z-score and LVMI was driven mainly by an association observed in participants born small-for-gestational age and it did not persist when risk factors in adolescence were accounted for.

CONCLUSIONS

Higher birth weight adjusted for sex and gestational age was associated with differences in measures of diastolic function in adolescence, but the observed associations were small. It remains to be determined the extent to which these associations translate into increased susceptibility to cardiovascular disease later in life. © 2018 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

Preterm Birth Is a Novel, Independent Risk Factor for Altered Cardiac Remodeling and Early Heart Failure: Is it Time for a New Cardiomyopathy?

PURPOSE OF REVIEW

Around 10% of the global population is born preterm (< 37 weeks' gestation). Preterm birth is associated with an increased risk of cardiovascular events, with preterm-born individuals demonstrating a distinct cardiac phenotype. This review aims to summarize the main phenotypic features of the preterm heart and directions for future research to develop novel intervention strategies.

RECENT FINDINGS

Being born between 28 and 31 weeks' gestation results in a 4-fold higher risk of heart failure in childhood and adolescence and 17-fold increased risk when born less than 28 weeks' gestation. In support of this being due to a reduction in myocardial functional reserve, preterm-born young adults have an impaired left ventricular cardiac systolic response to moderate and high intensity physiological stress, despite having a preserved resting left ventricular ejection fraction. Similar impairments under physiological stress were also recently reported regarding the right ventricle in young adults born preterm. Preterm birth relates to a unique cardiac phenotype with an impaired response to stress conditions. These data, combined with the work in animal models, suggest that being born preterm may lead to a novel form of cardiomyopathy. Understanding the driving mechanisms leading to this unique cardiac phenotype is important to reduce risk of future heart failure and cardiovascular events.

Early Life Risk Factors for Incident Atrial Fibrillation in the Helsinki Birth Cohort Study

Background

Early life risk factors are associated with cardiometabolic disease, but have not been fully studied in atrial fibrillation (AF). There are discordant results from existing studies of birth weight and AF, and the impact of maternal body size, gestational age, placental size, and birth length is unknown.

Methods and Results

The Helsinki Birth Cohort Study includes 13 345 people born as singletons in Helsinki in the years 1934–1944. Follow‐up was through national registries, and ended on December 31, 2013, with 907 incident cases. Cox regression analyses stratified on year of birth were constructed for perinatal variables and incident AF, adjusting for offspring sex, gestational age, and socioeconomic status at birth. There was a significant U‐shaped association between birth weight and AF (P for quadratic term=0.01). The lowest risk of AF was found among those with a birth weight of 3.4 kg (3.8 kg for women [85th percentile] and 3.0 kg for men [17th percentile]). High maternal body mass index (≥30 kg/m²) predicted offspring AF; hazard ratio 1.36 (95% CI 1.07–1.74, P=0.01) compared with normal body mass index (<25 kg/m²). Maternal height was associated with early‐onset AF (<65.3 years), hazard ratio 1.47 (95% CI 1.24–1.74, P<0.0001), but not with later onset AF. Results were independent of incident coronary artery disease, hypertension, or diabetes mellitus.

Conclusions

High maternal body mass index during pregnancy and maternal height are previously undescribed predictors of offspring AF. Efforts to prevent maternal obesity might reduce later AF in offspring. Birth weight has a U‐shaped relation to incident AF independent of other perinatal variables.

Exposure to multiple chemicals in a cohort of reproductive-aged Danish women

BACKGROUND

Current exposure assessment research does not sufficiently address multi-pollutant exposure and their correlations in human media. Understanding the extent of chemical exposure in reproductive-aged women is of particular concern due to the potential for in utero exposure and fetal susceptibility.

OBJECTIVES

The objectives of this study were to characterize concentrations of chemical biomarkers during preconception and examine correlations between and within chemical classes.

METHODS

We examined concentrations of 135 biomarkers from 16 chemical classes in blood and urine from 73 women aged 18-40 enrolled in Snart Foraeldre/Milieu, a prospective cohort study of pregnancy planners in Denmark (2011-2014). We compared biomarker concentrations with United States similarly-aged, non-pregnant women who participated in the National Health and Nutrition Environmental Survey (NHANES) and with other international biomonitoring studies. We performed principal component analysis to examine biomarker correlations.

RESULTS

The mean number of biomarkers detected in the population was 92 (range: 60-108). The most commonly detected chemical classes were phthalates, metals, phytoestrogens and polycyclic aromatic hydrocarbons. Except blood mercury, urinary barium and enterolactone, geometric means were higher in women from NHANES. Chemical classes measured in urine generally did not load on a single component, suggesting high between-class correlation among urinary biomarkers, while there is high within-class correlation for biomarkers measured in serum and blood.

CONCLUSIONS

We identified ubiquitous exposure to multiple chemical classes in reproductive-aged Danish women, supporting the need for more research on chemical mixtures during preconception and early pregnancy. Inter- and intra-class correlation between measured biomarkers may reflect common exposure sources, specific lifestyle factors or shared metabolism pathways.

Parametric modeling of quantile regression coefficient functions with censored and truncated data

Quantile regression coefficient functions describe how the coefficients of a quantile regression model depend on the order of the quantile. A method for parametric modeling of quantile regression coefficient functions was discussed in a recent article. The aim of the present work is to extend the existing framework to censored and truncated data. We propose an estimator and derive its asymptotic properties. We discuss goodness-of-fit measures, present simulation results, and analyze the data that motivated this article. The described estimator has been implemented in the R package qrcm.

Clinical significance of nutritional status in patients with atrial fibrillation: An overview of current evidence

BACKGROUND

Obesity is a well-known atherosclerosis risk factor; however, its role and the importance of undernutrition in atrial fibrillation (AF) pathogenesis are still not well understood. The aim of this study was to present the current state of knowledge on this issue in different groups of patients.

METHODS

Systematic review of papers published between 1980 and 2016.

RESULTS

The literature shows contradicting views regarding the impact of nutritional status on the risk, course, and complications of AF. On the one hand, it has been revealed that overweight, obesity, and high birth mass increase the risk of AF, and that their reduction is linked to an improved course of AF and reduced all-cause and cardiovascular mortality. On the other hand, a so-called obesity paradox has been found, which shows lower all-cause mortality in overweight patients with AF compared to those of normal weight or who are underweight. It has also been shown, although based on a small number of studies, that the relationship between nutritional status and risk of AF and its complication may be U-shaped, which means that not only patients with obesity, but also individuals with underweight, cachexia, and low birth weight may have an increased risk and poor outcome of AF.

CONCLUSIONS

The relationship between patients' nutritional status and the course of AF has become clearer but it requires further studies examining the importance of weight reduction on AF course.