Caffeinated Beverage Intake and Serum Caffeine Metabolites and Risk of Pregnancy Loss (OR17-04-19)

Ambient air pollution during developmental windows of spermatogenesis and semen quality among an infertility treatment seeking population

Russo LM et al., 2025 · Ecotoxicol Environ Saf · Free full text on PubMed Central

Prior studies have observed impacts of air pollution on semen quality, but timing of exposure during developmental windows of spermatogenesis and impacts of low-to-moderate air pollution is less well understood. We examined the relation between air pollution and semen quality in the Folic Acid and Zinc Supplementation Trial (2013-2018), which enrolled male partners of couples seeking infertility treatment in the Salt Lake City, Utah region (n = 2015). Semen quality parameters were assessed at baseline, 2-, 4-, and 6-months follow-up. Measures of daily air pollutants at each participant's residence were abstracted from Community Multiscale Air Quality models (fine particulate matter: PM2.5, sulfur dioxide, nitrogen dioxide, and ozone: O3), linked to participants' residential addresses, and averaged across the 74-day spermatogenesis window prior to the sample collection date for each study visit, and across four developmental windows of spermatogenesis (mitosis, meiosis I-II, spermiogenesis, and spermiation). Generalized linear mixed models considered four repeated semen sample measures per participant and adjusted for co-pollutants, age, season, and income. In multi-pollutant models, O3 during early-to-mid spermatogenesis (meiosis I+II and spermiogenesis) was related to lower percent normal morphology (% difference -6.73, 95 % CI -9.82, -3.54 and % difference -3.83, 95 % CI -7.51, 0.00, respectively). Additionally, PM2.5 and O3 during late spermatogenesis (spermiation) were associated with lower count and concentration, and PM2.5 with lower progressive motility. These findings suggest that exposure to low-to-moderate levels of air pollution may negatively impact semen quality and indicate that exposure to O3 during meiosis and spermiogenesis may particularly affect normal sperm morphological development.

Child Opportunity Index at birth and asthma with recurrent exacerbations in the US ECHO program

Miller RL et al., 2025 · Journal of Allergy and Clinical Immunology · Free full text on PubMed Central

The association of prenatal dietary factors with child autism diagnosis and autism-related traits using a mixtures approach: Results from the ECHO Cohort

Bragg MG et al., 2025 · J Nutr · Free full text on PubMed Central

Previous research on the role of maternal diet in relation to autism has focused on examining individual nutrient associations. Few studies have examined associations with multiple nutrients using mixtures approaches, which may better reflect true exposure scenarios. To examine associations of nutrient mixtures with children's autism diagnosis and traits scores within a large, diverse population. Participants were drawn from the US Environmental influences on Child Health Outcomes (ECHO) consortium. Maternal prenatal diet was reported via validated food frequency questionnaires. Children's autism-related traits were measured using the Social Responsiveness Scale (SRS) and autism diagnoses were from parent report of physician diagnosis. Bayesian kernel machine regression (BKMR) was used to examine the overall mixture effect and interactions between a set of 5 primary nutrients (folate, vitamin D, omega 3 and omega 6 fatty acids, and iron), adjusted for potential confounders, in relationship to child outcomes. Secondary analyses were conducted in a subset of cohorts with an expanded set of 14 nutrients. Traditional linear and logistic regression models were also run for comparison of results to mixture models. 2,614 participants drawn from 7 ECHO cohorts were included in primary analysis. Mixture analyses suggested that increasing the overall 5-nutrient mixture was associated with lower SRS scores. Individual U-shaped associations and bivariate interactions between folate and omega 3 fatty acids were suggested. In the subset included in the secondary analyses of the 14-nutrient mixture, a modest inverse trend remained, but individual nutrient associations were altered, with vitamin D demonstrating higher relative importance than other nutrients. Strong associations with autism diagnosis were not observed. In this large sample, we found evidence for combined nutrient effects with broader autism-related traits. Because results for individual nutrients were sensitive to mixture components, replication of combined associations between nutrients and autism-related outcomes is needed.

Prospectively assessed perceived stress associated with early pregnancy losses among women with history of pregnancy loss

Schliep KC et al., 2022 · Hum Reprod · Free full text on PubMed Central

What is the association between perceived stress during peri-conception and early pregnancy and pregnancy loss among women who have experienced a prior pregnancy loss? Daily perceived stress above the median is associated with over a 2-fold risk of early pregnancy loss among women who have experienced a prior loss. WHAT IS KNOWN ALREADY? Women who have experienced a pregnancy loss may be more vulnerable to stress while trying to become pregnant again. While prior research has indicated a link between psychological stress and clinically confirmed miscarriages, research is lacking among a pre-conceptional cohort followed prospectively for the effects of perceived stress during early critical windows of pregnancy establishment on risk of both hCG-detected pregnancy losses and confirmed losses, while considering important time-varying confounders. STUDY DESIGN, SIZE, Secondary data analysis of the EAGeR trial (2007-2011) among women with an hCG-detected pregnancy (n = 797 women). PARTICIPANTS/MATERIALS, SETTING, Women from four US clinical centers enrolled pre-conceptionally and were followed ≤6 cycles while attempting pregnancy and, as applicable, throughout pregnancy. Perceived stress was captured via daily diaries and end-of-month questionnaires. Main outcome measures include hCG-detected and clinically recognized pregnancy losses. MAIN Among women who had an hCG-confirmed pregnancy, 188 pregnancies (23.6%) ended in loss. Women with high (>50th percentile) versus low (≤50th percentile) peri-implantation or early pregnancy weekly perceived stress had an elevated risk of experiencing any pregnancy loss (hazard ratio (HR): 1.69, 95% CI: 1.13, 2.54) or clinical loss (HR: 1.58, 95% CI: 0.96, 2.60), with higher risks observed for women experiencing an hCG-detected loss (HR: 2.16, 95% CI: 1.04, 4.46). Models accounted for women's age, BMI, employment, marital status, income, education, race, parity, prior losses, exercise and time-varying nausea/vomiting, caffeine, alcohol and smoking. LIMITATIONS, We were limited in our ability to clearly identify the mechanisms of stress on pregnancy loss due to our sole reliance on self-reported perceived stress, and the lack of biomarkers of different pathways of stress. This study provides new insight on early pregnancy perceived stress and risk of pregnancy loss, most notably hCG-detected losses, among women with a history of a prior loss. Our study is an improvement over past studies in its ability to account for time-varying early pregnancy symptoms, such as nausea/vomiting, and lifestyle factors, such as caffeine, alcohol and smoking, which are also risk factors for psychological stress and pregnancy loss. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland (Contract numbers: HHSN267200603423, HHSN267200603424, HHSN267200603426, HHSN275201300023I). Additionally, K.C.S. was supported by the National Institute on Aging of the National Institutes of Health under Award Number K01AG058781. The authors have no conflicts of interest to disclose. #NCT00467363.

Caffeinated beverage intake and serum caffeine metabolites and risk of pregnancy loss

Purdue‐Smithe A et al., 2019 · Current Developments in Nutrition

The association between caffeine and pregnancy loss remains controversial due to limitations of prior studies such as relying on self-reported intake only, exposure measurement after clinical confirmation of pregnancy, and potential time-varying confounding by nausea/vomiting and lifestyle factors, which may be affected by prior caffeine exposure. Thus, our aim was to evaluate associations of preconception and early pregnancy serum caffeine, paraxanthine, and theobromine, self-reported intake of caffeinated beverages, and risk of pregnancy loss among 1228 reproductive-age women attempting pregnancy in the EAGeR trial during 2007–2011. We estimated HRs and 95% CIs for any pregnancy loss, hCG loss (prior to ultrasound confirmation), and clinical loss (after ultrasound confirmation) according to caffeinated beverage intake and caffeine biomarkers measured at preconception and the 8(th) week of gestation using weighted adjusted Cox proportional hazards models. At preconception, 67%, 28%, and 9% of women reported any intake of caffeinated sodas, coffee, and tea, respectively. Preconception total caffeinated beverage intake of ≥3 vs. 0 cups/day was associated with 85% (95% CI: 1.18, 2.94) higher risk of any pregnancy loss, driven primarily by associations for hCG loss (HR: 2.88 (95% CI: 1.20, 6.91)). Caffeinated soda intake was associated with hCG loss (≥2 vs. 0.2 vs. ≤0.2 ng/mL) at preconception was strongly associated with hCG loss (HR: 4.51 (95% CI: 1.36, 14.91)). Serum caffeine, paraxanthine, and theobromine measured at the 8th week of gestation were not associated with risk of loss. Collectively, these data suggest that caffeine intake prior to pregnancy may increase risk of pregnancy loss, particularly in early gestation. Funding Sources: Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD.

Preconception caffeine metabolites, caffeinated beverage intake, and fecundability

Purdue-Smithe AC et al., 2022 · Am J Clin Nutr · Free full text on PubMed Central

Caffeine is the most frequently used psychoactive substance in the United States and >90% of reproductive-age women report some amount of intake daily. Despite biological plausibility, previous studies on caffeine and fecundability report conflicting results. Importantly, prior studies measured caffeine exposure exclusively by self-report, which is subject to measurement error and does not account for factors that influence caffeine metabolism. Our objective was to examine associations between preconception serum caffeine metabolites, caffeinated beverage intake, and fecundability. Participants included 1228 women aged 18-40 y with a history of 1-2 pregnancy losses in the EAGeR (Effects of Aspirin in Gestation and Reproduction) trial. We prospectively evaluated associations of preconception caffeine metabolites (i.e., caffeine, paraxanthine, and theobromine) measured from 1191 serum samples untimed to a specific time of day, self-reported usual caffeinated beverage intakes at baseline, and time-varying cycle-average caffeinated beverage intake, with fecundability. Using Cox proportional hazards models, we estimated fecundability odds ratios (FORs) and 95% CIs according to each metabolite. Follow-up was complete for 89% (n = 1088) of participants. At baseline, 85%, 73%, and 91% of women had detectable serum caffeine, paraxanthine, and theobromine, respectively. A total of 797 women became pregnant during ≤6 cycles of preconception follow-up. After adjusting for potential confounders, neither serum caffeine [tertile (T)3 compared with T1 For: 0.87; 95% CI: 0.71, 1.08], paraxanthine (T3 compared with T1 For: 0.92; 95% CI: 0.75, 1.14), nor theobromine (T3 compared with T1 For: 1.15; 95% CI: 0.95, 1.40) were associated with fecundability. Baseline intake of total caffeinated beverages was not associated with fecundability (>3 compared with 0 servings/d adjusted For: 0.99; 95% CI: 0.74, 1.34), nor was caffeinated coffee (>2 compared with 0 servings/d adjusted For: 0.93; 95% CI: 0.45, 1.92) or caffeinated soda (>2 servings/d adjusted For: 0.92; 95% CI: 0.71, 1.20). Our findings are reassuring that caffeine exposure from usual low to moderate caffeinated beverage intake likely does not influence fecundability.This trial was registered at clinicaltrials.gov as NCT00467363.

Serum caffeine and paraxanthine concentrations and menstrual cycle function: correlations with beverage intakes and associations with race, reproductive hormones, and anovulation in the BioCycle Study

Schliep KC et al., 2016 · Am J Clin Nutr · Free full text on PubMed Central

Clinicians often recommend limiting caffeine intake while attempting to conceive; however, few studies have evaluated the associations between caffeine exposure and menstrual cycle function, and we are aware of no previous studies assessing biological dose via well-timed serum measurements. We assessed the relation between caffeine and its metabolites and reproductive hormones in a healthy premenopausal cohort and evaluated potential effect modification by race. Participants (n = 259) were followed for ≤2 menstrual cycles and provided fasting blood specimens ≤8 times/cycle. Linear mixed models were used to estimate associations between serum caffeine biomarkers and geometric mean reproductive hormones, whereas Poisson regression was used to assess risk of sporadic anovulation. The highest compared with the lowest serum caffeine tertile was associated with lower total testosterone [27.9 ng/dL (95% CI: 26.7, 29.0 ng/dL) compared with 29.1 ng/dL (95% CI: 27.9, 30.3 ng/dL), respectively] and free testosterone [0.178 ng/mL (95% CI: 0.171, 0.185 ng/dL) compared with 0.186 ng/mL (95% CI: 0.179, 0.194 ng/dL), respectively] after adjustment for age, race, percentage of body fat, daily vigorous exercise, perceived stress, depression, dietary factors, and alcohol intake. The highest tertiles compared with the lowest tertiles of caffeine and paraxanthine were also associated with reduced risk of anovulation [adjusted RRs (aRRs): 0.39 (95% CI: 0.18, 0.87) and 0.40 (95% CI: 0.18, 0.87), respectively]. Additional adjustment for self-reported coffee intake did not alter the reproductive hormone findings and only slightly attenuated the results for serum caffeine and paraxanthine and anovulation. Although reductions in the concentrations of total testosterone and free testosterone and decreased risk of anovulation were greatest in Asian women, there was no indication of effect modification by race. Caffeine intake, irrespective of the beverage source, may be associated with reduced testosterone and improved menstrual cycle function in healthy premenopausal women.

Clinical, metabolomic, and proteomic profiles associated with reproductive outcomes in unexplained recurrent pregnancy loss

Song Z et al., 2026 · Frontiers in endocrinology · Free full text on PubMed Central

To identify preconception clinical and multi-omics factors associated with conception and early pregnancy loss in women with unexplained recurrent pregnancy loss (URPL). In this prospective cohort study, 149 women with URPL selected from 420 outpatients based on guideline-recommended criteria were enrolled between November 2024 and May 2025 and followed-up for 12 months. Preconception fasting plasma was analyzed for clinical biomarkers, untargeted metabolomics, and data-independent acquisition proteomics. Outcomes included conception, ongoing pregnancy beyond 12 weeks and early pregnancy loss before 12 weeks. Multivariable logistic regression was used to evaluate the associations of clinical and multi-omics factors with reproductive outcomes, adjusting for maternal age, body mass index, number of prior losses, and use of assisted reproductive technology. Of 149 women, 99 conceived (66.4%) during the follow-up. By 12 weeks of gestation, 67 (67.7%) had ongoing pregnancies and 32 (32.3%) experienced early pregnancy loss. Higher testosterone was associated with lower probability of conception (adjusted odds ratio [aOR] 0.50, 95% confidence interval [CI] 0.28-0.89, p = 0.019). Women who conceived showed higher levels of progesterone-related metabolites, including 17-hydroxyprogesterone (fold change, FC = 3.89), pregnanediol 3-O-glucuronide (FC = 2.37), and pregnanetriol 3α-O-β-D-glucuronide (FC = 2.39). Among women who conceived, higher prolactin was associated with higher odds of early pregnancy loss (aOR 1.09, 95% CI 1.01-1.18, p = 0.036), and anti-phosphatidylserine/prothrombin showed a borderline association (aOR 1.07, 95% CI 1.00-1.14, p = 0.052). Early pregnancy loss was characterized by lower bile acid-related metabolites and higher caffeine and methylxanthine metabolites. Proteomic analysis showed enrichment of bile acid biosynthetic process. After adjustment, higher 7α,12α-dihydroxy-3-oxocholest-4-en-27-oic acid was associated with lower odds of early pregnancy loss (aOR 0.64, 95% CI 0.44-0.95, p = 0.025). Higher testosterone was associated with lower odds of conception. Among women who conceived, early pregnancy loss was associated with higher prolactin, borderline higher anti-PS/PT, lower bile acid-related metabolites, and higher caffeine-related metabolites, with 7α,12α-dihydroxy-3-oxocholest-4-en-27-oic acid identified as an exploratory metabolomic candidate. These findings suggest that potential androgen-related biology, prolactin, non-criteria antiphospholipid antibodies, and bile acid metabolism may be associated with reproductive outcomes in URPL, warranting validation in independent cohorts.