Introduction The case-crossover design is a widely applicable design for observational studies. Its major advantages include robustness against unmeasured time-invariant and slowly varying confounders, as well as high statistical efficiency, both attributable to its self-controlled nature. Methods In this tutorial, we illustrate applications of the case-crossover design not only for assessing associations with short-term exposures, for which it was originally developed, but also for intermediate- and long-term exposures, using examples from our published studies. We further discuss key methodological considerations for its practical implementation. Results We presented two subtypes of the case-crossover design, time-stratified and symmetric bidirectional, illustrated through examples of published studies evaluating the associations between air pollution exposures and the risk of hypertension hospitalization. As the exposure time frame extends from short to long term, the ability of the case-crossover design to inherently adjust for slowly varying confounders through self-matching diminishes. Consequently, additional confounders should be included in the regression model. Several considerations are important when using the case-crossover design: first, analyses are restricted to discordant individuals whose exposures differ between the case and control periods; second, there should be no underlying time trend in exposure within the time scheme of case and control periods. Conclusions Despite these limitations, the case-crossover design remains an attractive method for observational studies as it inherently adjusts for unmeasured time invariant and slowly varying confounders, such as genetics. While the examples focus on air pollution, the broad applicability of the case-crossover design makes it a valuable approach in various fields, including clinical research.

Exposure to neurotoxic metals early in life can disrupt brain development and increase risk of later mental health problems, but vulnerable periods and underlying mechanisms remain unclear. We examined how early life exposures to mixtures of metals affect children's brain and behavior using naturally shed "baby" teeth as a biomarker of direct exposure. We studied 489 children aged 8 to 14 years and reconstructed weekly concentrations of nine metals from 20 weeks before birth to 40 weeks after birth. We assessed behavior using standardized questionnaires and measured brain structure and function with magnetic resonance imaging. Using lagged weighted quantile sum regression, we identified sensitive developmental windows during which higher exposure to metal mixtures was linked to more behavioral problems, smaller brain volume, reduced brain global efficiency, and weaker white matter integrity. Findings suggest that the developing brain is especially vulnerable to metals in early life, with lasting effects into adolescence.

The relationships between chronic exposure to wildfire smoke PM2.5 (particulate matter with aerodynamic diameter of ≤2.5 μm) and mortality remain poorly understood, with causal evidence being particularly scarce. In this ecological study, we used a doubly robust method, incorporating flexible generalized propensity score estimation that captured potential nonlinearity and interactions among confounders and relaxed the distribution form assumption for exposure, to estimate the effects of annual exposure to wildfire smoke PM2.5 on all-cause and cause-specific mortality in the contiguous United States from 2006 to 2020. We found that wildfire smoke PM2.5 was associated with increased mortality rate for all studied outcomes, except for deaths from transport accidents or falls, which served as negative outcome controls. Wildfire smoke PM2.5 was responsible for ~24,100 all-cause deaths per year in the contiguous United States. The exposure-response curve for all-cause mortality increased monotonically, with no evidence of a "safe" threshold. Among the six cause-specific outcomes, mortality from neurological disease showed the greatest increase per 0.1 μg/m3 increase in smoke PM2.5 exposure. Our study provided robust evidence for the chronic effect of wildfire smoke PM2.5 on mortality, underscoring the urgent need for targeted measures to mitigate the substantial and escalating burden of wildfires.

Copper (Cu) is an essential metal involved in neurobiological processes including energy metabolism and neurotransmission, yet dysregulated Cu levels may adversely affect brain health and olfactory performance. Although olfactory dysfunction has primarily been studied in older adults and neurodegenerative disease, adolescence is a critical period of brain maturation during which the olfactory system may be particularly vulnerable. This cross-sectional study examined associations between Cu exposure, olfactory bulb (OB) volume, and olfactory performance in 200 adolescents and young adults (64% female; ages 13-25) from the Public Health Impact of Metals Exposure cohort. Cu concentrations in blood, urine, hair, and saliva were measured using inductively coupled plasma mass spectrometry. T2-weighted magnetic resonance imaging scans estimated left, right, and total OB volumes using a three-stage deep learning pipeline. Olfactory performance was assessed using the Sniffin' Sticks test. Weighted quantile sum regression evaluated associations between a Cu mixture index and OB outcomes, while standard linear regression models assessed individual Cu biomarkers. Models were adjusted for age and sex. A higher Cu index was associated with reduced left (β = -0.72, 95% CI [-1.42, -0.02]), right (β = -0.79, 95% CI [-1.43, -0.15]), and total OB volume (β = -1.55, 95% CI [-2.85, -0.25]), as well as lower odor threshold scores (β = -0.23, 95% CI [-0.42, -0.03]). Individual biomarkers were not independently associated with outcomes. These findings suggest that Cu exposure may adversely affect olfactory neurodevelopment during adolescence and highlight the importance of studying environmental exposures relevant to long-term neurological health.

Lead exposure is neurotoxic during pregnancy and early childhood. Quantifying the expected effects of potential lead reductions on neurologic outcomes is valuable for decision makers. We estimated associations between integrated lead levels during pregnancy and early childhood on children's intellectual performance framed as hypothetical interventions to decrease lead levels. Our data source was the Programming Research in Obesity, Growth, Environment, and Social Stressors (PROGRESS) longitudinal birth cohort in Mexico City. Data included information on multiple biomarkers in the pre-and postnatal periods. We assessed the child's intellectual functioning at 48 months of age with McCarthy Scales of Children's Abilities including specific domains and the composite of these scales called the General Cognitive Index (GCI). We generated multi-media biomarkers (MMBs) combining lead biomarkers across biologic matrix and developmental period, using Weighted Quantile Sum Regression (WQS), and g-computation to estimate mean differences in cognitive scores (95%CIs) under hypothetical lead-reduction interventions. We estimated a mean difference of 0.60 points [95%CI: -0.25, 1.46] for the GCI and 0.77 [95%CI: 0.24, 1.30] for the perceptual scale following a 40% hypothetical reduction. When examined separately, prenatal exposure showed the strongest association with the perceptual domain and postnatal exposure with the quantitative domain. A sensitivity analysis using principal component analysis, agnostic to exposure directionality, yielded mostly null but directionally inconsistent results. Our results suggest that potentially 40% reductions of lead levels during pregnancy and early childhood in Mexico City may be associated with modest improvements in specific cognitive domains, although results were sensitive to the method used to construct MMBs.

Background:The role of adipokines in childhood glycemia is poorly understood. We investigate the longitudinal association between adipokines and glycemia in a cohort of children in Mexico City. Methods:Children from the Programming Research in Obesity, Growth, Environment, and Social Stressors (PROGRESS) cohort (948 children, 52% male) were followed longitudinally from birth. Leptin, adiponectin, glucose, and HbA 1c were measured at four, six, and eight years, and fasting insulin at eight years. Adiponectin to leptin ratio (ALR) and HOMA2 indices were computed. Longitudinal associations were examined by linear mixed models and cross-sectional associations were examined by multivariable linear regression. All models were adjusted for maternal and child covariates. Findings:Between ages four and eight years, average levels of leptin increased from 3·2 to 10·8 ug/mL; adiponectin dropped from 15·7 to 13·7 ng/mL; and ALR dropped from 9·1 to 3·1 ug/ng. Longitudinally, across timepoints four, six, and eight years after birth, there was no association between adipokines and glycemia. However, the cross-sectional analysis at age 8 years found an association between leptin and insulin (1·0, 95% CI: 1·0; 1·1), HOMA2-B (1·0, 95% CI: 1·0; 1·0), HOMA2-IR (1·0, 95% CI: 1·0; 1·1), and HOMA2-S (0·9, 95% CI: 0·9; 0·9). Interpretation:Further investigation is needed to understand the role of adipokines in the development of T2DM in children and the factors that may alter adipokine metabolism.

Background Prenatal exposure to pesticides and psychosocial factors often co-occurs, particularly in low- and middle-income settings, yet their joint effects on epigenetic age acceleration (EAA) in early life remain unknown. We investigated the joint associations of prenatal pesticides metabolites and psychosocial factors on EAA in the first five years of life in the South African Drakenstein Child Health Study. Methods In 643 mothers, we measured 11 urinary pesticide metabolites and seven psychosocial factors during the second trimester of pregnancy. Child DNA methylation was measured in whole blood at ages 1, 3, and 5 years. EAA was estimated using the Horvath, Skin & Blood Horvath (skinHorvath), and Wu epigenetic clocks. Longitudinal associations were estimated using generalized estimating equations, adjusted for confounders. Joint mixture associations were evaluated using weighted quantile sum regression (WQS) and quantile g-computation (QGCOMP). Results The joint prenatal exposure mixture was positively associated with Wu (β per one quintile increase in the mixture [95% CI]: 0.41 years [0.15, 0.80]), skinHorvath (0.11 years [0.06, 0.16]), and Horvath EAA (0.31 years [0.20, 0.46]) over time using WQS. Psychosocial factors, particularly food insecurity, physical interpersonal violence, and stress biomarkers, contributed most to the total mixture effect for all clocks. Pyrethroid metabolites PBA and TDCCA were top pesticide contributors to Wu EAA. Pathway enrichment analyses of clock-specific CpGs revealed distinct biological architectures, with the Wu clock enriched for neurodevelopmental and immune pathways, and metabolic pathways for the Horvath clock. Discussion Joint prenatal exposure to pesticides and psychosocial factors was associated with increased EAA across early childhood, with psychosocial factors contributing the most to the total effect. These findings highlight the importance of assessing chemical and non-chemical stressors jointly and clock-specific biological interpretation in epigenetic aging research.

There is limited knowledge about the sexually dimorphic effects of manganese (Mn) on children’s temporal cognition (i.e., time perception), an important component of executive function, and whether impacts differ by sex. We proposed that the effects of prenatal Mn exposure on children’s ability to perceive time could be best assessed using a multi-media biomarker (MMB) to estimate cumulative exposure. Children aged 6–7 from Mexico City were administered a temporal response differentiation task, an operant test in which a reward is provided if they correctly hold a lever down between 10 and 14 s (s). Short (< 10s) and long holds (> 14s) were incorrect and not rewarded. Blood and urinary Mn levels were assessed from mothers in the 2nd and 3rd trimesters. A covariate-adjusted generalized weighted quantile sum (WQS) regression estimated the effect of a Mn MMB index (combining blood and urine biomarkers into a single metric) on temporal cognitive performance. Sex-stratified models were also assessed. Higher prenatal Mn MMB index, representing higher exposure levels, was significantly associated with impaired performance across multiple cognitive timing measures. When examining Mn exposure in sex-stratified analyses, girls exhibited significantly poorer performance than boys. Among girls, higher prenatal Mn MMB index was associated with fewer timing holds (β = -2.14; 95%CI: -3.57, -0.72), fewer total holds (β = -2.11; 95%CI: -4.18, -0.04), and lower timing accuracy, reflected in total holds excluding durations of 2s or less (β = -1.29; 95%CI: -1.49, -1.09), and greater variability in lever hold durations for total holds (β = 0.67; 95%CI: 0.09, 1.24). High Mn exposure impacts temporal assessment pathways with greater impacts in girls. Our results also highlight the necessity of assessing sex as a biological factor in prenatal Mn exposure, as the sex specificity of results was clear in the stratified models. Results may reflect sex-specific susceptibility via dopamine signaling, neurodevelopmental timing, and/or hormonal influences, warranting further research on these mechanisms.

Whether fetal lung development may be vulnerable to gestational exposure to metals is unknown. We analyzed mother-child pairs in Project Viva, a prospective prebirth cohort in eastern Massachusetts, USA. Concentrations of 11 essential and nonessential metals were measured in maternal first-trimester erythrocytes (~10 weeks). Measures of lung function were obtained by spirometry, and asthma status by recall, at the mid-childhood visit (~8 years). We fit both Bayesian hierarchical models with weakly informative priors and conventional multivariable linear and logistic regressions (MLRs) to estimate associations of the metals with lung function and asthma. The analytic sample included 804 mother-child pairs (76.0% non-Hispanic White; 16.7% of children had current asthma). Each standard deviation increase in magnesium was associated with higher forced vital capacity (mean difference: 26 mL, 95% credible interval (CrI); 5, 47), higher forced expiratory volume in 1 second (FEV1) (25 mL, 95% CrI: 6, 44), and lower odds of current asthma (odds ratio: 0.88, 95% CrI: 0.71, 1.1). BHMs provided more modest and precise estimates than MLRs. Our results suggest early pregnancy intake of magnesium may enhance fetal lung development and may confer a modest reduction in the risk of asthma.

Abstract Importance Fine particulate matter (PM2.5) is a key risk factor of lung cancer incidence and mortality. However, the specific effect of PM2.5 originating from wildfire smoke, an increasingly important contributor to total PM2.5 in the US driven by climate change, on mortality of patients with lung cancer remain unclear. Objective To explore the effect of long-term exposure to wildfire smoke versus non-smoke PM2.5 on all-cause mortality of older lung cancer patients. Design, Setting, and Participants This cohort study included patients ≥65 years with primary diagnosis of lung cancer from the SEER-Medicare database from 2006 to 2019 linked with estimates of exposure to wildfire smoke and non-smoke PM2.5 based on patients’ residential zip codes. Exposures Three-year moving average exposures to wildfire smoke and non-smoke PM2.5. Main Outcomes and Measures The study outcome was all-cause mortality after primary lung cancer diagnosis. A time-varying Cox proportional hazards model was applied to estimate hazard ratios (HRs) for mortality risk. Results Among 503,409 patients with 1,542,491 person-years of follow up, each 1-μg/m3 increase in wildfire smoke PM2.5 was associated with a 9.3% increased mortality risk (HR: 1.09, 95% CI: 1.08-1.11), substantially greater than that of non-smoke PM2.5 (HR: 1.020, 95% CI: 1.018-1.022). The number of smoke days and of smoke waves, reflecting duration and frequency of wildfire smoke PM2.5 exposure, were also positively associated with mortality risk. Larger effect of wildfire smoke PM2.5 was observed among women, patients with lung cancer other than non-small cell lung cancer, patients with comorbidities, and those not receiving first course treatment after diagnosis. Conclusions Wildfire smoke posed a substantially larger risk in older lung cancer patients than non-smoke PM2.5. Under a changing climate, strengthening wildfire management and reducing wildfire smoke exposure in clinical care could improve survival of older lung cancer patients. Citation Format: Min Zhang, Juan P. Wisnivesky, Minghao Qiu, Mahdieh Danesh Yazdi, Rosalind J. Wright, Joel D. Schwartz, Christine C. Ekenga, Robert O. Wright, Yaguang Wei. Long-term exposure to wildfire smoke PM2.5 and survival of older lung cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 6251.

Ambient fine particulate matter (PM2.5) is a proven human lung carcinogen associated with lung cancer incidence. However, the relative toxicity of the various chemical components of PM2.5 and their joint association with all-cause mortality following lung cancer diagnosis remain unclear. We conducted a cohort study of 528,127 adults aged ≥65 years with lung cancer diagnosed between 2000 and 2019, derived from the SEER-Medicare database. Patients were followed annually from diagnosis until death, loss to follow-up, or end of the study in 2019. Two-year moving average exposures to 15 p.m.2.5 chemical components were estimated using high-resolution spatiotemporal models and linked to each patient based on residential ZIP code in each year. We used generalized weighted quantile sum regression with random holdouts to estimate both the joint association of PM2.5 component mixtures with all-cause mortality and the relative contribution of each component, adjusted for demographics, histological type, stage, first-course treatments, comorbidities, and neighborhood-level covariates. We found that joint exposure to PM2.5 component mixtures was associated with increased mortality, with relative risk of 1.011 (95% confidence interval [CI]: 1.010, 1.013) per decile increase in all components. Although differences in contributions were modest, silicon, nitrate, vanadium, zinc, and iron appeared to be more influential contributors, suggesting that controlling related sources, such as road dust, traffic emissions, fossil fuel combustion, and heavy fuel oil combustion, may obtain greater potential benefits. Exploratory subgroup analyses suggested that the joint association may be stronger among patients with non-small cell lung cancer, those with later-stage disease, and female patients.

Objective:To estimate the associations between gestational weight gain and maternal immediate perinatal and postpartum outcomes by pooling data from low and middle income countries. Design:Individual participant data meta-analyses. Data sources:PubMed, Embase, Web of Science, and Cochrane Library, based on three searches (Search 1: all prospective studies published from January 2000 to May 2021; Search 2: randomized controlled trials of balanced energy and protein supplementation published until June 2021; Search 3: randomized controlled trials of anti-infectious agents published until August 2021). Eligibility criteria for selecting studies:Prospective studies (randomised controlled trials or observational cohort studies) with measured maternal weight during pregnancy and data available on maternal height, based in populations from low and middle income countries with no underlying conditions. Results:The analyses included 156 300 women from 61 studies and 23 countries, with most participants based in South Asia (n=78 454, 50.2%) and sub-Saharan Africa (n=36 327, 23.2%). Compared with women with adequate (90-125%) gestational weight gain, women with excessive (>125%) gestational weight gain had a higher risk of caesarean delivery (risk ratio 1.10, 95% confidence interval 1.06 to 1.13, τ2=0.000) and emergency caesarean delivery (risk ratio 1.22, 1.03 to 1.43, τ2=0.000). Women with moderately (70% to <90%) or severely inadequate (<70%) versus adequate gestational weight gain had lower risks for caesarean delivery (risk ratio in women with moderately inadequate gestational weight gain 0.88, 95% confidence interval 0.84 to 0.92, τ2=0.004; risk ratio in women with severely inadequate gestational weight gain 0.82, 0.77 to 0.88, τ2=0.010) and emergency caesarean delivery (risk ratio in moderately inadequate gestational weight gain 0.82, 0.71 to 0.95, τ2=0.004; risk ratio in severely inadequate gestational weight gain 0.73, 0.56 to 0.96, τ2=0.103). Excessive versus adequate gestational weight gain was associated with higher postpartum weight retained at any time point (mean difference 2.00 kg, 95% confidence interval 1.49 to 2.50, τ2=1.317), whereas moderately and severely inadequate gestational weight gain were associated with lower retained weight compared with adequate gestational weight gain. Similar trends were found for postpartum body mass index. Severely inadequate gestational weight gain was associated with lower systolic and diastolic blood pressure at any time point post partum than adequate gestational weight gain. No associations were observed for other outcomes including postpartum depressive symptoms or breastfeeding. Evidence indicating an interaction between gestational weight gain and body mass index before pregnancy was found when examining the risk of caesarean delivery and postpartum weight retention, body mass index, and systolic blood pressure as outcomes. Conclusions:These findings support the association between suboptimal gestational weight gain and adverse maternal outcomes in the immediate perinatal and postpartum periods. Further research examining the consequences of suboptimal gestational weight gain in low and middle income countries would be valuable to inform potential strategies to improve long term maternal health. Review registration:PROSPERO CRD42023432836.

Background: The mesolimbic dopamine system is a critical component of the brain’s reward pathways encompassing motivation, reward processing, reinforcement learning, and goal-directed behaviors. Early execution of reward-seeking neurobehaviors may influence later childhood adiposity. We investigated performance on a reward-based operant conditioning paradigm in relation to adiposity in later childhood.Methods: Children aged 6–7 years completed five Operant Testing Battery tasks that used nickels as rewards with higher scores reflecting greater reward sensitivity and heightened responsiveness to reinforcement. Repeated BMI (body mass index) and percentage (%) body fat were assessed from ages 8 to 10. A covariate-adjusted generalized weighted quantile sum (WQS) regression was used to derive an integrated neurobehavioral index across five tasks to estimate joint association with later adiposity measures. Stratified analyses assessed male- and female-dimorphic differences.Results: The neurobehavioral index was positively associated with BMI at ages 8 and 10 (β=0.40kg/m²; 95%CI:0.12–0.68; p =0.005 and β=0.43kg/m²; 95%CI:0.14–0.72; p =0.003, respectively) and %body fat at ages 8 and 10 (β=1.09%; 95%CI:0.14–2.03; p=0.025 and β=1.45%; 95%CI:0.60–2.29; p=0.001, respectively). Among males, higher index scores were associated with greater BMI at age 8 (β=0.48kg/m²; 95%CI:0.12–0.84; p=0.01), BMI at age 10 (β=0.52kg/m²; 95%CI:0.14–0.90; p=0.007), and %body fat at age 10 (β=1.72%; 95%CI:0.61–2.84; p=0.003) and among females was positively associated with %body fat at age 8 (β=1.58%; 95%CI: 0.35–2.82; p=0.013). Temporal processing and learning behavior contributed to the highest mixture weights in most models.Conclusion: Emerging reward-driven response patterns, as captured through laboratory-based operant conditioning tasks, may contribute to adiposity later in childhood.

The objective of this study was to estimate the association between gestational phthalate metabolite concentrations and mixtures and pediatric antibody response at 4-years of age to common childhood vaccines, while also exploring sexually dimorphic effects. This study utilized data from the Programming, Research, Obesity, and Social Stressors (PROGRESS) Study, an ongoing, longitudinal cohort of mother-child pairs residing in Mexico City. Fifteen phthalate metabolites were measured in spot urine samples collected from mothers during their second and third trimesters. Children have been regularly followed, with data collection on lifestyle, clinical, socio-economic, and demographic factors, and archived biologic specimen. IgG-specific antibody serum levels to measles, mumps, rubella, diphtheria, tetanus, and pertussis were quantified from children at the mean 4.7 years of age. Linear regression models, with log2 transformation of both the outcome and exposure variables, estimated the association between individual phthalate metabolites and antibody concentrations. Phthalate mixtures were analyzed using the Quantile G-Computational approach and Bayesian Kernel Machine regression. All analyses were also sex-stratified to investigate sexually dimorphic effects. The present analysis included 362 mother-child pairs. During the second trimester of pregnancy, a doubling increase of mono-2-ethyl-5-carboxypentyl terephthalate (MECPTP) concentrations was associated with a 6.98% decrease (95% CI: - 11.68%, - 2.04%) in diphtheria and a 2.57% decrease (95% CI: - 4.74%, - 0.35%) in mumps antibody levels, respectively. No statistically significant sex-differences were observed. Mixtures analyses did not reach statistical significance but observed similar associations with MECPTP. Concentrations of MECPTP, a replacement phthalate, were negatively associated with anti-diphtheria antibody levels in Hispanic children indicating a potential detrimental effect of newer alternative phthalates on pediatric health.

Purpose: This study evaluated associations among breastfeeding duration and combined breast/formula feeding on childhood dental caries. Methods: This was a cross-sectional study of 3- to 6-year-old children (n =1,256) in the National Health and Nutrition Examination Survey, 2015-2018. Duration of breastfeeding and breast/formula feeding were assessed through structured interviews. Caries experience was assessed as having at least 1 decayed and filled tooth. Survey-weighted logistic regression adjusted for confounders evaluated associations. Results: The average maternal age at delivery was 28 years (standard error=0.28). About half (49.7%) of the children were girls. Thirty-eight percent of the children were breastfed for no more than 6 months, 20% for more than 6 to 12 months, and approximately 9% were breastfed for more than 12 to 18 months and over 18 months, while 24% were exclusively formula-fed. Relative to children breastfed for no more than 6 months, those breastfed for longer than 18 months had a nonsignificant covariate-adjusted caries experience odds (odds ratio [OR]=1.55, 95 percent confidence interval [95% CI]=0.80 to 3.01). Relative to children who were exclusively breastfed, those who were nonconcurrently breastfed/formula-fed (ie, there was no overlap in breastfeeding and formula feeding) had higher covariate-adjusted caries experience odds (OR=3.01, 95% CI=1.18 to 7.67). Conclusions: Nonconcurrent breast/formula feeding was associated with increased dental caries prevalence. Additional studies are needed to confirm these results and evaluate underlying mechanisms.

BACKGROUND:Hepatocellular carcinoma (HCC) is the most common primary liver cancer and often arises in cirrhosis cases. Current surveillance methods, including ultrasonography and α-fetoprotein, have limited sensitivity for early detection. Blood metabolomics may improve HCC risk prediction. We aimed to identify pre-diagnostic plasma metabolites associated with HCC risk and evaluate whether cirrhosis-related metabolites enhance prediction beyond established risk factors in a multiethnic population. METHODS:We analyzed data from a nested case-control study with pre-diagnostic blood samples in the Multiethnic Cohort, including 240 HCC cases, 151 cirrhosis cases, and individually matched controls. Metabolome-wide association studies and pathway enrichment analyses were performed, followed by feature selection in the cirrhosis samples to construct HCC prediction models. RESULTS:Of 294 metabolites analyzed, 53 were significantly associated with HCC after false discovery rate correction (odds ratios: 0.25-3.93). Pathway analyses highlighted perturbations in lipid and amino acid metabolism. Two cirrhosis-associated metabolites, glutamate and glycochenodeoxycholate, were consistently selected and improved HCC prediction. Adding these metabolites to known risk factors (age, sex, race/ethnicity, study area, BMI, smoking, alcohol consumption, and diabetes) increased the AUC from 0.64 to 0.73 (P < 0.001). CONCLUSIONS:Pre-diagnostic metabolomic profiling revealed metabolic alterations linked to HCC risk, emphasizing dysregulated amino acid and bile acid pathways within the cirrhosis context. IMPACT:Glutamate and glycochenodeoxycholate improved HCC risk prediction beyond established factors, supporting biologically plausible links between hepatic metabolic dysfunction and hepatocarcinogenesis. These findings highlight the potential of metabolomic biomarkers to enhance surveillance and risk stratification among patients with cirrhosis.

ObjectiveTo assess the associations between serum stress-related hormones (cortisol and cortisone) at one month postpartum and AMH levels at 4- and 10-year follow-ups. MethodsIn a subset of 107 postpartum mothers enrolled in the PROGRESS cohort (at a mean age of 29.5 years), we measured serum cortisol and cortisone at one month postpartum via untargeted metabolomics. At 4- and 10-year follow-ups, we measured serum AMH levels. Serum cortisol, cortisone, and the cortisol-to-cortisone (F/E) ratio were analyzed both as continuous variables and as tertiles. The association between serum stress hormones and log2-transformed AMH levels was assessed using multivariable linear regression. ResultsThe serum cortisol and F/E ratio showed a weak and inverse association with AMH concentration at the 4-year follow-up. However, at the 10-year follow-up, each unit increase in the F/E ratio was associated with a 45% reduction in AMH levels (β = −0.60, 95% CI: −1.13; −0.07). In addition, when repeated time points were considered in the model, each unit increase in the F/E ratio was associated with a 32% reduction in AMH levels (β = −0.38, 95% CI: −0.75; −0.01). The analysis by tertiles of serum cortisone showed a dose–response relationship with AMH levels at the 10-year follow-up, while the F/E ratio was only associated in the highest tertile at the 4- and 10-year follow-ups, including when considering the model with repeated time points. ConclusionOur findings suggest that a higher F/E ratio is associated with a lower AMH level, especially in mothers in the highest tertile of serum stress hormone levels. Our results support the role of stress hormone imbalance in ovarian aging.

BACKGROUND & AIMS:Early life exposures shape intestinal and immune development and later risk of inflammatory bowel disease. Per- and polyfluoroalkyl substances, or forever chemicals, are associated with intestinal inflammation and inflammatory bowel disease. However, the impact of early life per- and polyfluoroalkyl substances exposure on later intestinal inflammation is not known. METHODS:We conducted untargeted per- and polyfluoroalkyl substances analyses in early life samples from mother-offspring dyads across 3 cohorts. These included dried blood spots from offspring (n = 84) and cord blood (n = 93) from 2 prospective birth cohorts of mothers with and without inflammatory bowel disease in New York, New York, and maternal serum during pregnancy (n = 14) from a birth cohort in Mexico City, Mexico. Fecal calprotectin, a biomarker of intestinal inflammation, was measured longitudinally in offspring stool. Covariate-adjusted weighted quantile sum regression models were used to estimate associations between per- and polyfluoroalkyl substances and fecal calprotectin. RESULTS:Per- and polyfluoroalkyl substances metabolites were detected across all sample types. Higher levels of per- and polyfluoroalkyl substances mixtures were associated with higher fecal calprotectin between 1 and 6 years of age in both dried blood spot and cord blood analyses (covariate-adjusted β estimates for change in log-transformed fecal calprotectin at age 6 years per decile increase in the per- and polyfluoroalkyl substances mixture was 0.44 [95% confidence interval, 0.18-0.70] and 0.69 [95% confidence interval, 0.53-0.85], respectively) Similarly, higher levels of per- and polyfluoroalkyl substances mixtures in maternal serum were associated with higher fecal calprotectin in late childhood (β, 0.19; 95% confidence interval, 0.05-0.33). Compared with mother-offspring dyads without maternal inflammatory bowel disease, those with maternal inflammatory bowel disease were more likely to have higher perfluoro-1-octane sulfonamide acetic acid and 3-perfluorohexyl-2-hydroxypropyl acrylate levels in dried blood spots and cord blood, respectively; these per- and polyfluoroalkyl substances metabolites were also the top contributors to offspring fecal calprotectin. CONCLUSIONS:Per- and polyfluoroalkyl substances chemicals are detectable in early life samples, indicating exposure during this period of vulnerability, and are associated with higher fecal calprotectin in childhood across 3 birth cohorts.