Environmental Exposures and Pediatric Cardiology: A Scientific Statement From the American Heart Association.

Environmental toxicants and pollutants are causes of adverse health consequences, including well-established associations between environmental exposures and cardiovascular diseases. Environmental degradation is widely prevalent and has a long latency period between exposure and health outcome, potentially placing a large number of individuals at risk of these health consequences. Emerging evidence suggests that environmental exposures in early life may be key risk factors for cardiovascular conditions across the life span. Children are a particularly sensitive population for the detrimental effects of environmental toxicants and pollutants given the long-term cumulative effects of early-life exposures on health outcomes, including congenital heart disease, acquired cardiac diseases, and accumulation of cardiovascular disease risk factors. This scientific statement highlights representative examples for each of these cardiovascular disease subtypes and their determinants, focusing specifically on the associations between climate change and congenital heart disease, airborne particulate matter and Kawasaki disease, blood lead levels and blood pressure, and endocrine-disrupting chemicals with cardiometabolic risk factors. Because children are particularly dependent on their caregivers to address their health concerns, this scientific statement highlights the need for clinicians, research scientists, and policymakers to focus more on the linkages of environmental exposures with cardiovascular conditions in children and adolescents.

Prevalence and correlates of diagnosed and probable polycystic ovary syndrome (PCOS) in a cohort of parous women.

OBJECTIVES: To assess correlates of diagnosed and probable polycystic ovary syndrome (PCOS) among parous women. METHODS: This study includes 557 women recruited from multi-specialty clinics in eastern Massachusetts. We categorized women as "diagnosed PCOS" based on medical records and self-reported clinician-diagnoses. Next, we constructed a category of "probable PCOS" for women without a diagnosis but with ≥2 of the following: ovulatory dysfunction (cycle length<21 or ≥35 days), hyperandrogenism (free testosterone>75th percentile), or elevated anti-Müllerian hormone (>75th percentile). We classified the remaining as "no PCOS," and compared characteristics across groups. RESULTS: 9.7% had diagnosed and 9.2% had probable PCOS. The frequency of irregular cycles was similar for diagnosed and probable PCOS. Free testosterone and AMH were higher for probable than diagnosed PCOS. Frequency of irregular cycles and both hormones were higher for the two PCOS groups vs. the no PCOS group. Obesity prevalence for diagnosed PCOS was twice that of probable PCOS (43.9% vs. 19.6%), yet the two groups had similar HbA1c and adiponectin. CONCLUSIONS: Women with probable PCOS are leaner but have comparable glycemic traits to those with a formal diagnosis, highlighting the importance of assessing biochemical profiles among women with irregular cycles, even in the absence of overweight/obesity.

Breastfeeding Duration and Cardiometabolic Health during Adolescence: A Longitudinal Analysis.

OBJECTIVE: To investigate the longitudinal association between breastfeeding duration and cardiometabolic health, using repeated measures study design among children and adolescents. STUDY DESIGN: This study included 634 offsprings aged 10 to 21 years (52% female) from the Early Life Exposure in Mexico to Environmental Toxicants birth cohort followed up to four time points during adolescence. Breastfeeding duration was prospectively quantified using questionnaires during early childhood. Cardiometabolic risk factors, body composition, and weight-related biomarkers were assessed as outcomes during adolescent follow-up visits. Sex-stratified linear mixed-effects models were used to model the association between quartiles of breastfeeding duration and outcomes, adjusting for age and additional covariates. RESULTS: Median breastfeeding duration was 7 months (minimum = 0, maximum = 36). Boys in the second quartile (median breastfeeding = 5 months) had lower total fat mass % (ß (SE) -3.2 (1.5) P = .037), and higher lean mass % (3.1 (1.6) P = .049) and skeletal muscle mass % (1.8 (0.8) P = .031) compared with the reference group (median breastfeeding = 2 months). A positive linear trend between breastfeeding duration and trunk lean mass % (0.1 (0.04) P = .035) was found among girls. No association was found with other cardiometabolic indicators. CONCLUSION: Despite sex-specific associations of breastfeeding duration with body composition, there was a lack of substantial evidence for the protective effects of breastfeeding against impaired cardiometabolic health during adolescence among Mexican youth. Further longitudinal studies with a robust assessment of breastfeeding are recommended.

Metabolomic signatures for blood pressure from early to late adolescence: findings from a U.S. cohort.

INTRODUCTION: Metabolite signatures for blood pressure (BP) may reveal biomarkers, elucidate pathogenesis, and provide prevention targets for high BP. Knowledge regarding metabolites associated with BP in adolescence remains limited. OBJECTIVES: Investigate the associations between metabolites and adolescent BP, both cross-sectionally (in early and late adolescence) and prospectively (from early to late adolescence). METHODS: Participants are from the Project Viva prospective cohort. During the early (median: 12.8 years; N = 556) and late (median: 17.4 years; N = 501) adolescence visits, we conducted untargeted plasma metabolomic profiling and measured systolic (SBP) and diastolic BP (DBP). We used linear regression to identify metabolites cross-sectionally associated with BP at each time point, and to assess prospective associations of changes in metabolite levels from early to late adolescence with late adolescence BP. We used Weighted Gene Correlation Network Analysis and Spearman's partial correlation to identify metabolite clusters associated with BP at each time point. RESULTS: In the linear models, higher androgenic steroid levels were consistently associated with higher SBP and DBP in early and late adolescence. A cluster of 59 metabolites, mainly composed of androgenic steroids, correlated with higher SBP and DBP in early adolescence. A cluster primarily composed of fatty acid lipids was marginally associated with higher SBP in females in late adolescence. Multiple metabolites, including those in the creatine and purine metabolism sub-pathways, were associated with higher SBP and DBP both cross-sectionally and prospectively. CONCLUSION: Our results shed light on the potential metabolic processes and pathophysiology underlying high BP in adolescents.

Metabolomic data presents challenges for epidemiological meta-analysis: a case study of childhood body mass index from the ECHO consortium.

INTRODUCTION: Meta-analyses across diverse independent studies provide improved confidence in results. However, within the context of metabolomic epidemiology, meta-analysis investigations are complicated by differences in study design, data acquisition, and other factors that may impact reproducibility. OBJECTIVE: The objective of this study was to identify maternal blood metabolites during pregnancy (> 24 gestational weeks) related to offspring body mass index (BMI) at age two years through a meta-analysis framework. METHODS: We used adjusted linear regression summary statistics from three cohorts (total N = 1012 mother-child pairs) participating in the NIH Environmental influences on Child Health Outcomes (ECHO) Program. We applied a random-effects meta-analysis framework to regression results and adjusted by false discovery rate (FDR) using the Benjamini-Hochberg procedure. RESULTS: Only 20 metabolites were detected in all three cohorts, with an additional 127 metabolites detected in two of three cohorts. Of these 147, 6 maternal metabolites were nominally associated (P < 0.05) with offspring BMI z-scores at age 2 years in a meta-analytic framework including at least two studies: arabinose (Coefmeta = 0.40 [95% CI 0.10,0.70], Pmeta = 9.7 × 10-3), guanidinoacetate (Coefmeta = - 0.28 [- 0.54, - 0.02], Pmeta = 0.033), 3-ureidopropionate (Coefmeta = 0.22 [0.017,0.41], Pmeta = 0.033), 1-methylhistidine (Coefmeta = - 0.18 [- 0.33, - 0.04], Pmeta = 0.011), serine (Coefmeta = - 0.18 [- 0.36, - 0.01], Pmeta = 0.034), and lysine (Coefmeta = - 0.16 [- 0.32, - 0.01], Pmeta = 0.044). No associations were robust to multiple testing correction. CONCLUSIONS: Despite including three cohorts with large sample sizes (N > 100), we failed to identify significant metabolite associations after FDR correction. Our investigation demonstrates difficulties in applying epidemiological meta-analysis to clinical metabolomics, emphasizes challenges to reproducibility, and highlights the need for standardized best practices in metabolomic epidemiology.

Maternal educational attainment in pregnancy and epigenome-wide DNA methylation changes in the offspring from birth until adolescence.

Maternal educational attainment (MEA) shapes offspring health through multiple potential pathways. Differential DNA methylation may provide a mechanistic understanding of these long-term associations. We aimed to quantify the associations of MEA with offspring DNA methylation levels at birth, in childhood and in adolescence. Using 37 studies from high-income countries, we performed meta-analysis of epigenome-wide association studies (EWAS) to quantify the associations of completed years of MEA at the time of pregnancy with offspring DNA methylation levels at birth (n = 9 881), in childhood (n = 2 017), and adolescence (n = 2 740), adjusting for relevant covariates. MEA was found to be associated with DNA methylation at 473 cytosine-phosphate-guanine sites at birth, one in childhood, and four in adolescence. We observed enrichment for findings from previous EWAS on maternal folate, vitamin-B12 concentrations, maternal smoking, and pre-pregnancy BMI. The associations were directionally consistent with MEA being inversely associated with behaviours including smoking and BMI. Our findings form a bridge between socio-economic factors and biology and highlight potential pathways underlying effects of maternal education. The results broaden our understanding of bio-social associations linked to differential DNA methylation in multiple early stages of life. The data generated also offers an important resource to help a more precise understanding of the social determinants of health.

Growth Velocities Across Distinct Early Life Windows and Child Cognition: Insights from a Contemporary US Cohort.

OBJECTIVE: To evaluate the relative importance of overall and period-specific postnatal growth and their interaction with fetal growth on cognition in a generally well-nourished population. STUDY DESIGN: We included 1052 children from Project Viva, a prospective cohort in Boston, Massachusetts. Using linear spline mixed-effects models, we modeled length/height and body mass index (BMI) trajectories from birth to 7 years and estimated standardized overall (0-7 years) and period-specific growth velocities ie, early infancy (0-4 months), late infancy (4-15 months), toddlerhood (15-37 months), and early childhood (37-84 months). We investigated associations of growth velocities as well as their interactions with birthweight-for-gestational age on mid-childhood (mean age: 7.9 years) IQ, visual memory and learning, and visual motor ability. RESULTS: Greater overall height velocity was associated with modestly higher design memory score, (adjusted ß [95% CI] 0.19 [-0.01,0.38] P = .057])points per SD increase but lower verbal IQ (-0.88 [-1.76,0.00] P = .051). Greater early infancy height velocity was associated with higher visual motor score (1.92 [0.67,3.18]). Greater overall BMI velocity was associated with lower verbal IQ (-0.71 [-1.52,0.11] P = .090). Greater late infancy BMI velocity was associated with lower verbal IQ (-1.21 [-2.07,-0.34]), design memory score (-0.22 [-0.42,-0.03)], but higher picture memory score (0.22 [0.01,0.43]). Greater early infancy height velocity (-1.5 SD vs 1.5 SD) was associated with higher nonverbal IQ (margins [95% CI] 102.6 [98.9106.3] vs 108.2 [104.9111.6]) among small-for-gestational age infants (P-interaction = 0.04). CONCLUSIONS: Among generally well-nourished children, there might not be clear cognitive gains with faster linear growth except for those with lower birthweight-for-gestational age, revealing the potential importance of early infancy compensatory growth.

Maternal Diet Quality During Pregnancy and Offspring Hepatic Fat in Early Childhood: The Healthy Start Study.

BACKGROUND: Overnutrition in utero may increase offspring risk of nonalcoholic fatty liver disease (NAFLD), but the specific contribution of maternal diet quality during pregnancy to this association remains understudied in humans. OBJECTIVES: This study aimed to examine the associations of maternal diet quality during pregnancy with offspring hepatic fat in early childhood (median: 5 y old, range: 4-8 y old). METHODS: Data were from 278 mother-child pairs in the longitudinal, Colorado-based Healthy Start Study. Multiple 24-h recalls were collected from mothers during pregnancy on a monthly basis (median: 3 recalls, range: 1-8 recalls starting after enrollment), and used to estimate maternal usual nutrient intakes and dietary pattern scores [Healthy Eating Index-2010 (HEI-2010), Dietary Inflammatory Index (DII), and Relative Mediterranean Diet Score (rMED)]. Offspring hepatic fat was measured in early childhood by MRI. Associations of maternal dietary predictors during pregnancy with offspring log-transformed hepatic fat were assessed using linear regression models adjusted for offspring demographics, maternal/perinatal confounders, and maternal total energy intake. RESULTS: Higher maternal fiber intake and rMED scores during pregnancy were associated with lower offspring hepatic fat in early childhood in fully adjusted models [Back-transformed ß (95% CI): 0.82 (0.72, 0.94) per 5 g/1000 kcal fiber; 0.93 (0.88, 0.99) per 1 SD for rMED]. In contrast, higher maternal total sugar and added sugar intakes, and DII scores were associated with higher offspring hepatic fat [Back-transformed ß (95% CI): 1.18 (1.05, 1.32) per 5% kcal/d added sugar; 1.08 (0.99, 1.18) per 1 SD for DII]. Analyses of dietary pattern subcomponents also revealed that lower maternal intakes of green vegetables and legumes and higher intake of "empty calories" were associated with higher offspring hepatic fat in early childhood. CONCLUSIONS: Poorer maternal diet quality during pregnancy was associated with greater offspring susceptibility to hepatic fat in early childhood. Our findings provide insights into potential perinatal targets for the primordial prevention of pediatric NAFLD.

Maternal Diet Quality Is Associated with Placental Proteins in the Placental Insulin/Growth Factor, Environmental Stress, Inflammation, and mTOR Signaling Pathways: The Healthy Start ECHO Cohort.

BACKGROUND: Maternal nutritional status affects placental function, which may underlie the intrauterine origins of obesity and diabetes. The extent to which diet quality is associated with placental signaling and which specific pathways are impacted is unknown. OBJECTIVES: To examine sex-specific associations of maternal diet quality according to the Healthy Eating Index (HEI)-developed to align with recommendations from the Dietary Guidelines for Americans-with placental proteins involved in metabolism and mediators of environmental stress, inflammation, and growth factors. METHODS: Among 108 women from the Healthy Start cohort with a mean ± SD age of 29.0 ± 6.1 y and a prepregnancy BMI (in kg/m2) of 24.8 ± 5.3, we conducted multivariable linear regression analysis stratified by offspring sex. We adjusted for maternal race or ethnicity, age, education, prenatal smoking habits, and physical activity and tested for an association of maternal HEI >57 compared with ≤57 and the abundance and phosphorylation of key proteins involved in insulin/growth factor signaling; mediators of environmental stress, inflammation, and growth factors; mechanistic target of rapamycin signaling proteins; and energy sensing in placental villus samples. HEI >57 was chosen given its prior relevance among Healthy Start mother-child dyads. RESULTS: In adjusted models, HEI >57 was associated with greater abundance of insulin receptor ß (0.80; 95% CI: 0.11, 1.49) in placentas of females. In males, maternal HEI >57 was associated with greater activation and abundance of select placental nutrient-sensing proteins and environmental stress, inflammation, and growth factor proteins (S6K1Thr389/S6K1: 0.81; 95% CI: 0.21, 1.41; JNK1Thr183/Tyr185/JNK1: 0.82; 95% CI: 0.27, 1.37; JNK2Thr183/Tyr185/JNK2: 0.57; 95% CI: 0.02, 1.11). CONCLUSIONS: Higher-quality diet had sex-specific associations with placental protein abundance/phosphorylation. Given that these proteins have been correlated with neonatal anthropometry, our findings provide insight into modifiable factors and placental pathways that should be examined in future studies as potential links between maternal diet and offspring metabolic health. This trial was registered at clinicaltrials.gov as NCT02273297.

Applications of conceptual models from lifecourse epidemiology in ecology and evolutionary biology.

In ecology and evolutionary biology (EEB), the study of developmental plasticity seeks to understand ontogenetic processes underlying the phenotypes upon which natural selection acts. A central challenge to this inquiry is ascertaining a causal effect of the exposure on the manifestation of later-life phenotype due to the time elapsed between the two events. The exposure is a potential cause of the outcome-i.e. an environmental stimulus or experience. The later phenotype might be a behaviour, physiological condition, morphology or life-history trait. The latency period between the exposure and outcome complicates causal inference due to the inevitable occurrence of additional events that may affect the relationship of interest. Here, we describe six distinct but non-mutually exclusive conceptual models from the field of lifecourse epidemiology and discuss their applications to EEB research. The models include Critical Period with No Later Modifiers, Critical Period with Later Modifiers, Accumulation of Risk with Independent Risk Exposures, Accumulation of Risk with Risk Clustering, Accumulation of Risk with Chains of Risk and Accumulation of Risk with Trigger Effect. These models, which have been widely used to test causal hypotheses regarding the early origins of adult-onset disease in humans, are directly relevant to research on developmental plasticity in EEB.

Menstrual cycle length and adverse pregnancy outcomes among women in Project Viva.

BACKGROUND: Retrospective studies suggest that menstrual cycle length may be a risk marker of adverse pregnancy outcomes, but this evidence is susceptible to recall bias. OBJECTIVE: To evaluate the prospective association between menstrual cycle length and the risk of adverse pregnancy outcomes. METHODS: Secondary analysis of 2046 women enrolled in Project Viva at ~10 weeks of gestation and followed through delivery. The exposure was menstrual cycle length. The outcomes included gestational glucose tolerance (gestational diabetes/impaired glucose tolerance [GDM/IGT] and isolated hyperglycaemia), hypertensive disorders of pregnancy (gestational hypertension/preeclampsia), gestational weight gain, birthweight-for-gestational age z-scores (BWZ) categorised in tertiles, preterm birth and birth outcome (live birth and pregnancy loss). We used modified Poisson and multinomial logistic regression adjusted for age, race/ethnicity, parity, age at menarche and pre-pregnancy body mass index. RESULTS: Mean (SD) age at enrolment was 32.1 (4.9) years. Most women (74.3%) had a cycle length of 26-34 days (reference group), 16.2% reported short cycles (≤25 days), and 9.5% reported long/irregular cycles (≥35 days/too irregular to estimate). Compared with the reference group, women with short cycles had lower odds of GDM/IGT (odds ratio [OR] 0.50, 95% confidence interval [CI] 0.28, 0.89), whereas women with long/irregular cycles had higher odds (OR 1.72, 95% CI 1.04, 2.83). Additionally, women with short cycles had higher odds of having a newborn in the lowest tertile of BWZ (OR 1.45, 95% CI 1.06, 1.98). There was a U-shaped relation between cycle length and preterm birth with both short (relative risk [RR] 1.49, 95% CI 0.98, 2.27) and long/irregular (RR 2.04, 95% CI 1.30, 3.20) cycles, associated with a higher risk. CONCLUSIONS: Variation in menstrual cycle length may be a risk marker of GDM/IGT, lower birth size and preterm birth and flag women who may benefit from targeted monitoring and care before and during pregnancy.

History of infertility and pregnancy outcomes in Project Viva: a prospective study.

BACKGROUND: Infertility has been associated with the risk of adverse pregnancy outcomes. It is not clear whether infertility and underlying causes of infertility or the use of medically assisted reproduction (MAR) therapies are responsible for the observed associations. In this study, we aimed to evaluate the association of history of infertility with pregnancy outcomes and identify whether the associations, if present, differed by subgroups defined by the use of MAR. METHODS: Prospective study of 2201 pregnant women from the Boston-area Project Viva cohort. The exposure was history of infertility based on self-reported time to pregnancy ≥12 mo (or ≥ 6 mo if ≥35 y) or use of MAR; a diagnosis of infertility or claims for infertility treatments from medical records. The outcomes included: gestational glucose tolerance (gestational diabetes, impaired glucose tolerance, isolated hyperglycemia vs. normoglycemia), hypertensive disorders (gestational hypertension/preeclampsia vs. normotension), gestational weight gain (inadequate/excessive vs. adequate), systolic (SBP) and diastolic blood pressure, birthweight-for-gestational age z-score (tertile 2 and 3 vs. 1), preterm birth (<37 vs. ≥37 weeks at delivery), and birth outcome (pregnancy loss vs. live birth). We performed linear and logistic/multinomial regression analyses adjusted for age, race/ethnicity, age at menarche, pre-pregnancy BMI, and prenatal smoking. RESULTS: Mean (SD) age was 32.0 (5.0) years, and 18.8% of women had history of infertility, 32.6% of whom used MAR. SBP across pregnancy was 0.72 mmHg higher in women with vs. without infertility (95% CI 0.02, 1.42). The associations were stronger among women who used MAR (ß 1.32 mmHg, 95% CI 0.21, 2.44), especially among those who used gonadotropins or gonadotropin-releasing hormone [GnRH] agonists (ß 1.91 mmHg, 95% CI 0.48, 3.35). Other outcomes were not associated with history of infertility. CONCLUSIONS: A history of infertility was associated with higher SBP during pregnancy, with stronger associations among those who used gonadotropins or GnRH agonists. Future studies are needed to confirm these findings and determine their clinical implications.

Association of total lifetime breastfeeding duration with midlife handgrip strength: findings from Project Viva.

BACKGROUND: Lactation has long term effects on maternal health, but the relationship between lactation and long-term handgrip strength, a marker of musculoskeletal function and healthy aging, has not been explored. OBJECTIVE: Examine the relationship between total lifetime breastfeeding duration (BFD) and midlife handgrip strength. METHODS: We measured handgrip strength as a marker of overall strength among 631 women in the Project Viva cohort. At the same visit, women reported their BFD for each birth, and we derived total lifetime BFD. We used multivariable linear regression models to estimate associations of lifetime BFD in months with midlife handgrip strength in kilograms, adjusted for race/ethnicity, education, marital status, household income, age at first pregnancy and age at handgrip strength assessment. RESULTS: Mean (standard deviation) age was 50.7 (5.1) years, lifetime BFD was 21.6 (19.5) months, and handgrip strength was 28.0 kg (6.0) in the dominant and 26.0 kg (5.6) in the non-dominant hand. In fully adjusted models, each 3-month increment in lifetime BFD was associated with 0.10 kg (95% CI 0.02, 0.18) higher handgrip strength for the dominant hand and 0.10 kg (95% CI 0.03, 0.18) for the nondominant hand. Results were similar in models examining mean BFD per pregnancy rather than total BFD. There was no evidence of effect modification by race/ethnicity. CONCLUSIONS: Our study suggests that there is a small beneficial effect of lifetime BFD on handgrip strength. Future studies can explore mechanisms by which BFD affects body composition and associations with other outcomes related to lean mass such as sarcopenia.

Maternal carbohydrate intake during pregnancy is associated with child peripubertal markers of metabolic health but not adiposity.

OBJECTIVE: To examine the associations of trimester-specific maternal prenatal carbohydrate (CHO) intake with offspring adiposity and metabolic health during peripuberty. DESIGN: Prospective cohort study in which maternal dietary intake was collected via validated FFQ during each trimester. Offspring adiposity and metabolic biomarkers were evaluated at age 8-14 years. We used multivariable linear regression to examine associations between total energy-adjusted maternal CHO intake and offspring BMI z-score, skinfold thickness and metabolic syndrome risk z-score calculated as the average of waist circumference, fasting glucose, fasting C-peptide, TAG:HDL and systolic blood pressure + diastolic blood pressure/2. SETTING: Mexico City, Mexico. PARTICIPANTS: 237 mother-child pairs in the Early Life Exposure in Mexico to Environmental Toxicants cohort. RESULTS: We found non-linear associations of maternal CHO intake during pregnancy with offspring metabolic health during peripuberty. After adjusting for maternal age, and child age, sex and pubertal status, children whose mothers were in the fourth v. first quartile of total CHO intake during the third trimester had 0·42 (95 % CI -0·01, 0·08) ng/ml lower C-peptide and 0·10 (95 % CI -0·02, 0·22) units lower C-peptide insulin resistance (CP-IR). We found similar magnitude and direction of association with respect to net CHO intake during the first trimester and offspring C-peptide and CP-IR. Maternal CHO intake during pregnancy was not associated with offspring adiposity. CONCLUSIONS: In this study of mother-child pairs in Mexico City, children born to women in the highest quartile of CHO intake during pregnancy had lowest C-peptide and CP-IR during peripuberty. Additional research is warranted to replicate and identify mechanisms.

How does exposure to overnutrition in utero lead to childhood adiposity? Testing the insulin hypersecretion hypothesis in the EPOCH cohort.

AIMS/HYPOTHESIS: Our aim was to explore metabolic pathways linking overnutrition in utero to development of adiposity in normal-weight children. METHODS: We included 312 normal-weight youth exposed or unexposed to overnutrition in utero (maternal BMI ≥25 kg/m2 or gestational diabetes). Fasting insulin, glucose and body composition were measured at age ~10 years (baseline) and ~16 years (follow-up). We examined associations of overnutrition in utero with baseline fasting insulin, followed by associations of baseline fasting insulin with adiposity (BMI z score [BMIZ], subcutaneous adipose tissue [SAT], visceral adipose tissue [VAT]), insulin resistance (HOMA-IR) and fasting glucose during follow-up. RESULTS: >All participants were normal weight at baseline (BMIZ -0.32 ± 0.88), with no difference in BMIZ for exposed vs unexposed youth (p = 0.14). Of the study population, 47.8% were female sex and 47.4% were of white ethnicity. Overnutrition in utero corresponded with 14% higher baseline fasting insulin (geometric mean ratio 1.14 [95% CI 1.01, 1.29]), even after controlling for VAT/SAT ratio. Higher baseline fasting insulin corresponded with higher BMIZ (0.41 [95% CI 0.26, 0.55]), SAT (13.9 [95% CI 2.4, 25.4] mm2), VAT (2.0 [95% CI 0.1, 3.8] mm2), HOMA-IR (0.87 [95% CI 0.68, 1.07]) and fasting glucose (0.23 [95% CI 0.09, 0.38] SD). CONCLUSIONS/INTERPRETATION: Overnutrition in utero may result in hyperinsulinaemia during childhood, preceding development of adiposity. However, our study started at age 10 years, so earlier metabolic changes in response to overnutrition were not taken into account. Longitudinal studies in normal-weight youth starting earlier in life, and with repeated measurements of body weight, fat distribution, insulin sensitivity, beta cell function and blood glucose levels, are needed to clarify the sequence of metabolic changes linking early-life exposures to adiposity and dysglycaemia.

Maternal diet quality during pregnancy is associated with biomarkers of metabolic risk among male offspring.

AIMS/HYPOTHESIS: Limited data exist on the association between maternal diet quality during pregnancy and metabolic traits in offspring during early childhood, which is a sensitive period for risk of obesity-related disorders later in life. We aimed to examine the association of maternal diet quality, as indicated by the Healthy Eating Index-2010 (HEI), in pregnancy with offspring metabolic biomarkers and body composition at age 4-7 years. METHODS: We used data from 761 mother-offspring pairs from the Healthy Start study to examine sex-specific associations of HEI >57 vs ≤57 with offspring fasting glucose, leptin, cholesterol, HDL, LDL, percentage fat mass, BMI z score and log-transformed insulin, 1/insulin, HOMA-IR, adiponectin, triacylglycerols, triacylglycerols:HDL, fat mass, and sum of skinfolds. Multivariable linear regression models accounted for maternal race/ethnicity, age, education, smoking habits during pregnancy and physical activity, and child's age. RESULTS: During pregnancy, mean (SD) HEI score was 55.0 (13.3), and 43.0% had an HEI score >57. Among boys, there was an inverse association of maternal HEI with offspring glucose, insulin, HOMA-IR and adiponectin. For instance, maternal HEI >57 was associated with lower fasting glucose (-0.11; 95% CI -0.20, -0.02 mmol/l), and lower concentrations of: insulin by 15.3% (95% CI -24.6, -5.0), HOMA-IR by 16.3% (95% CI -25.7, -5.6) and adiponectin by 9.3% (95% CI -16.1, -2.0). Among girls, there was an inverse association of maternal HEI with insulin and a positive association with LDL. However, following covariate adjustment, all estimates among girls were attenuated to the null. CONCLUSIONS/INTERPRETATION: Greater compliance with the USA Dietary Guidelines via the HEI may improve the maternal-fetal milieu and decrease susceptibility for poor metabolic health among offspring, particularly boys. Future studies are warranted to confirm these associations and determine the underlying mechanisms.

Maternal blood glucose level and offspring glucose-insulin homeostasis: what is the role of offspring adiposity?

AIMS/HYPOTHESIS: The aim of this work was to investigate the association of maternal HbA1c during mid-pregnancy with biomarkers of glucose-insulin homeostasis during early childhood (4-7 years of age) and to assess whether and how offspring adiposity at birth and at age 4-7 years mediates this relationship among 345 mother-child pairs in the Healthy Start Study. METHODS: The exposure was maternal HbA1c (mmol/mol) measured at 20-34 gestational weeks and categorised into tertiles. The outcomes were offspring fasting glucose, 1/insulin, HOMA2-IR, and HOMA2-B at age 4-7 years. The mediators were per cent fat mass (%FM) at birth, %FM at age 4-7 years, and the sum of the two as a metric of cumulative adiposity. Mediation analyses were conducted via a counterfactual-based approach. All models accounted for maternal race/ethnicity, offspring age and sex. RESULTS: There was a significant total effect of maternal HbA1c on offspring glucose and 1/insulin. Specifically, we observed a positive trend across tertiles of HbA1c and offspring glucose (p trend <0.001), and an inverse trend across tertiles of HbA1c and offspring 1/insulin (p trend = 0.04). For instance, compared with offspring of women in the lowest tertile of HbA1c, those whose mothers were in the second and third tertiles had 0.04 mmol/l (95% CI -0.05, 0.13) and 0.17 mmol/l (95% CI 0.08, 0.26) higher fasting glucose concentrations at age 4-7 years, respectively. Adjustment for pre-pregnancy BMI did not appreciably change the results. We found no evidence of mediation by offspring adiposity at any life stage. CONCLUSIONS/INTERPRETATION: Offspring of women with higher HbA1c during pregnancy had higher fasting glucose and lower insulin sensitivity by early childhood. These relationships were largely unaffected by the child's own adiposity. Graphical abstract.

A biologist's guide to model selection and causal inference.

A goal of many research programmes in biology is to extract meaningful insights from large, complex datasets. Researchers in ecology, evolution and behavior (EEB) often grapple with long-term, observational datasets from which they construct models to test causal hypotheses about biological processes. Similarly, epidemiologists analyse large, complex observational datasets to understand the distribution and determinants of human health. A key difference in the analytical workflows for these two distinct areas of biology is the delineation of data analysis tasks and explicit use of causal directed acyclic graphs (DAGs), widely adopted by epidemiologists. Here, we review the most recent causal inference literature and describe an analytical workflow that has direct applications for EEB. We start this commentary by defining four distinct analytical tasks (description, prediction, association, causal inference). The remainder of the text is dedicated to causal inference, specifically focusing on the use of DAGs to inform the modelling strategy. Given the increasing interest in causal inference and misperceptions regarding this task, we seek to facilitate an exchange of ideas between disciplinary silos and provide an analytical framework that is particularly relevant for making causal inference from observational data.

Pre- and Perinatal Correlates of Ideal Cardiovascular Health during Early Childhood: A Prospective Analysis in the Healthy Start Study.

OBJECTIVES: To characterize prevalence of ideal cardiovascular health (ICVH) during early childhood (4-7 years of age), and to identify pre- and perinatal biological, sociodemographic, metabolic, and behavioral correlates of ICVH. STUDY DESIGN: Among 350 mother-child pairs in the Healthy Start Study, we defined ICVH as no exposure to second hand smoke; ≥1 hour/day of moderate-to-vigorous physical activity; body mass index ≤85th percentile; systolic and diastolic blood pressure <90th percentile; cholesterol <170 mg/dL, fasting glucose <100 mg/dL; and healthy diet, per the American Heart Association. Pre- and perinatal characteristics were obtained from questionnaires, medical records, and in-person visits. Because of low prevalence of ICVH, we focused on prevalence of meeting ≥6 metrics in the analysis. We examined bivariate associations of each characteristic with % meeting ≥6 metrics and included those that were significant (P < .05) in a multivariable logistic regression model. RESULTS: ICVH prevalence at mean ± SD age 4.7±0.6 years was 6.9%; boys had twice the prevalence as girls (9% vs 4.4%). Most (>85%) children met criteria for second hand smoke, body mass index, blood pressure, cholesterol, and glucose, and only one-third met criteria for physical activity (31.4%) and diet (35.1%). In multivariable analyses, key correlates of ICVH were maternal weight status (ORoverweight/obese vs nonoverweight/obese = 0.41 [0.23, 0.73]) and offspring sex (ORmale vs female = 2.14 [1.22, 3.65]). CONCLUSIONS: At age 4-7 years, ICVH prevalence is already low, with diet and adequate physical activity being the limiting factors. Healthy maternal weight prior to pregnancy and male sex are potential determinants of childhood ICVH. Additional work is required to explore associations of early-life ICVH with future health outcomes.

Associations of Nutrient Intake Changes During Childhood with Adolescent Hepatic Fat: The Exploring Perinatal Outcomes Among CHildren Study.

OBJECTIVE: To examine associations of dietary changes from childhood to adolescence with adolescent hepatic fat and whether the PNPLA3 rs738409 risk allele, a strong genetic risk factor for hepatic fat, modifies associations. STUDY DESIGN: Data were from 358 participants in the Exploring Perinatal Outcomes among CHildren (EPOCH) study, a longitudinal cohort in Colorado. Diet was assessed by food frequency questionnaire in childhood (approximately 10 years of age) and adolescence (approximately 16 years of age) and converted to nutrient densities. Hepatic fat was assessed in adolescence by magnetic resonance imaging. Linear regression was used to test associations of dietary changes from childhood to adolescence with adolescent hepatic fat. RESULTS: Increases in fiber, vegetable protein, and polyunsaturated fat intake from childhood to adolescence were associated with lower adolescent hepatic fat, and increases in animal protein were associated with higher hepatic fat (ß per 5-unit increase on log-hepatic fat: -0.12 [95% CI, -0.21 to -0.02] for ▵fiber; -0.26 [95% CI, -0.45 to -0.07] for ▵vegetable protein; -0.18 [95% CI, -0.35 to -0.02] for ▵polyunsaturated fat; 0.13 [95% CI, 0.04-0.22] for ▵animal protein). There was evidence of effect modification by PNPLA3 variant, whereby inverse associations of ▵fiber and ▵vegetable protein and positive associations of ▵saturated fat with adolescent hepatic fat were stronger in risk allele carriers. Most conclusions were similar after adjusting for obesity in adolescence, but associations of ▵saturated fat with hepatic fat were attenuated toward the null. CONCLUSIONS: Our results suggest that nutrient intake changes between childhood and adolescence, particularly decreases in fiber and vegetable protein and increases in saturated fat intake, interact with the PNPLA3 variant to predict higher hepatic fat in adolescence, and may be targets for reducing hepatic fat in high-risk youth.