Urinary phenol concentrations and fecundability and early pregnancy loss

Untargeted metabolomics and machine learning unveil the exposome and metabolism linked with the risk of early pregnancy loss

Early pregnancy loss (EPL) may result from exposure to emerging contaminants (ECs), although the underlying mechanisms remain poorly understood. This case-control study measured over 2000 serum features, including 37 ECs, 6 biochemicals, and 2057 endogenous metabolites, in serum samples collected from 48 EPL patients and healthy pregnant women. The median total concentration of targeted EC in the EPL group (65.9 ng/mL) was significantly higher than in controls (43.0 ng/mL; p < 0.05). Four machine learning algorithms were employed to identify key molecular features and develop EPL risk prediction models. A random forest model based on chemical data achieved a predictive accuracy of 95 %, suggesting a potential association between EPL and chemical exposure, with phthalic acid esters identified as significant contributors. Ninety-five potential metabolite biomarkers were selected, which were predominantly enriched in pathways related to spermidine and spermine biosynthesis, ubiquinone biosynthesis, and pantothenate and coenzyme A biosynthesis. C17-sphinganine was identified as a leading biomarker with an area under the curve of 0.93. Furthermore, exposure to bis(2-ethylhexyl)phthalate was linked to an increased risk of EPL by disrupting lipid metabolism. These findings indicate that combining untargeted metabolomics with machine learning approaches offers novel insights into the mechanisms of EPL related to EC exposure.

Interpretable machine learning-based insights into early-life endocrine disruptor exposure and small vulnerable newborns

Early-life exposure to endocrine-disrupting chemicals (EDCs) may contribute to small vulnerable newborns, including conditions such as being small for gestational age (SGA) and preterm birth (PTB), yet evidence remains limited. This study, which is based on 739 mother-infant pairs in the Chinese Jiashan Birth Cohort (2016-2018), including 39 SGA and 38 PTB cases, employed interpretable machine learning to elucidate the isolated effects of 34 EDCs on SGA and PTB risk and sex interactions in a multi-substance exposure context. Extra Trees and CatBoost classifiers performed best for SGA and PTB, respectively, achieving sensitivities of 0.60 and 0.73 and specificities of 0.82 and 0.97. For SGA, key predictors included bisphenol A (2,3-dihydroxypropyl) glycidyl ether (BADGE-H2O), benzophenone (bZp), bisphenol A bis(2,3-dihydroxypropyl) ether (BADGE-2H2O), propyl paraben (PrP), and 2-methylthio-benzothiazole (2-Me-S-BTH). Lower exposures to BADGE-H2O, bZp, and BADGE-2H2O (concentrations below 0.21, 4.22, and 0.93 μg·g-1 creatinine, respectively) and higher exposure to 2-Me-S-BTH (above 0.15 μg·g-1 creatinine) were both associated with increased SGA risk. Notably, BADGE-H2O, BADGE-2H2O, and PrP showed significant interactions with fetal sex. For PTB, key predictors included ethyl paraben (EtP), methyl paraben (MeP), bZp, BADGE-H2O, and 1H-benzotriazole (1-H-BTR). Lower BADGE-H2O and higher EtP and bZp exposures increased PTB risk (< 0.10 and > 0.01 and 0.60 μg·g-1 creatinine, respectively). Male fetuses appeared more susceptible to EtP and MeP, and female fetuses were more susceptible to 1-H-BTR. Bayesian kernel machine regression was performed to compare the results. This study demonstrated the potential of interpretable machine learning in environmental epidemiology.

Adding short-duration gonadotropin-releasing hormone antagonist and gonadotropin to natural cycle frozen embryo transfer allowed scheduling of transfer day without compromising live birth

OBJECTIVE

To determine whether there is an association between the type of natural cycle frozen embryo transfer (FET) (scheduled vs. traditional) and live birth outcomes.

DESIGN

Retrospective cohort of all natural cycle FETs across a single network of fertility clinics in the United States.

SUBJECTS

All natural cycle FETs performed in ovulatory patients between January 2019 and April 2022.

EXPOSURE

Scheduled natural cycle FET cycles that received a short-duration of gonadotropin-releasing hormone antagonist (1 ampule/d) with low-dose gonadotropins (75 IU/d) to delay ovulation to enable more flexible scheduling of the FET were compared with cycles without delay.

MAIN OUTCOME MEASURES

Live birth.

RESULTS

There were a total of 1,087 natural cycle FETs that met the inclusion criteria. The scheduled natural cycle FET protocol was used in 114 (10.5%) of these cycles. The mean age was 35 (interquartile range, 33-38) years. Preimplantation genetic testing for aneuploidy was used in 76.3% (n = 87) of scheduled natural cycle FET cycles and 68.9% (n = 670) of natural cycle FET cycles. The scheduled natural cycle FET group had a significantly higher estradiol level (318 vs. 249 pg/mL) and a lower luteinizing hormone level (5.7 vs. 13.4 mIU/mL) at ovulatory trigger but a comparable peak endometrial thickness (9.4 vs. 9.7 mm) compared with the natural cycle FET group. Overall, there was a significant increase in the rates of positive human chorionic gonadotropin (scheduled natural cycle, 81.6%, vs. natural cycle, 64.3%; relative risk [RR], 1.26 [95% confidence interval {CI}, 1.15-1.38]) and clinical pregnancy (scheduled natural cycle, 68.4%, vs. natural cycle, 57.1%; RR, 1.21 [95% CI, 1.06-1.38]) in the scheduled natural cycle group. There were a higher proportion of live births in the scheduled natural cycle group; however, this did not reach statistical significance (scheduled natural cycle, 57.0%, vs. natural cycle, 49.4%; RR, 1.15 [95% CI, 0.97-1.36]). A subanalysis of preimplantation genetic testing for aneuploidy cycles yielded similar results.

CONCLUSION

A scheduled natural cycle FET protocol using a short duration of gonadotropin-releasing hormone antagonist along with low-dose gonadotropin add-back did not reduce live birth compared with traditional natural cycle FET cycles. These results suggest that this is an alternative FET protocol that may serve as a viable strategy to provide flexibility in scheduling the day of FET while still allowing a patient to undergo a natural cycle protocol. This protocol modification may enable more clinics to offer natural cycle FET.

The ENDOMIX perspective: how everyday chemical mixtures impact human health and reproduction by targeting the immune system†

Endocrine-disrupting chemicals are natural and synthetic compounds found ubiquitously in the environment that interfere with the hormonal-immune axis, potentially impacting human health and reproduction. Exposure to endocrine-disrupting chemicals has been associated with numerous health risks, such as neurodevelopmental disorders, metabolic syndrome, thyroid dysfunction, infertility, and cancers. Nevertheless, the current approach to establishing causality between these substances and disease outcomes has limitations. Epidemiological and experimental research on endocrine-disrupting chemicals faces challenges in accurately assessing chemical exposure and interpreting non-monotonic dose response curves. In addition, most studies have focused on single chemicals or simple mixtures, overlooking complex real-life exposures and mechanistic insights, in particular regarding endocrine-disrupting chemicals' impact on the immune system. The ENDOMIX project, funded by the EU's Horizon Health Program, addresses these challenges by integrating epidemiological, risk assessment, and immunotoxicology methodologies. This systemic approach comprises the triangulation of human cohort, in vitro, and in vivo data to determine the combined effects of chemical mixtures. The present review presents and discusses current literature regarding human reproduction in the context of immunotolerance and chemical disruption mode of action. It further underscores the ENDOMIX perspective to elucidate the impact of endocrine-disrupting chemicals on immune-reproductive health.

Environmental phenol exposures in 6- to 12-week-old infants: The Infant Feeding and Early Development (IFED) study

BACKGROUND

Exposure to phenols, endocrine-disrupting chemicals used in personal care and consumer products, is widespread. Data on infant exposures are limited despite heightened sensitivity to endocrine disruption during this developmental period. We aimed to describe distributions and predictors of urinary phenol concentrations among U.S. infants ages 6-12 weeks.

METHODS

The Infant Feeding and Early Development (IFED) study is a prospective cohort study of healthy term infants enrolled during 2010-2013 in the Philadelphia region. We measured concentrations of seven phenols in 352 urine samples collected during the 6- or 8- and/or 12-week study visits from 199 infants. We used linear mixed models to estimate associations of maternal, sociodemographic, infant, and sample characteristics with natural-log transformed, creatinine-standardized phenol concentrations and present results as mean percent change from the reference level.

RESULTS

Median concentrations (μg/L) were 311 for methylparaben, 10.3 for propylparaben, 3.6 for benzophenone-3, 2.1 for triclosan, 1.0 for 2,5-dichlorophenol, 0.7 for BPA, and 0.3 for 2,4-dichlorophenol. Geometric mean methylparaben concentrations were approximately 10 times higher than published estimates for U.S. children ages 3-5 and 6-11 years, while propylparaben concentrations were 3-4 times higher. Infants of Black mothers had higher concentrations of BPA (83%), methylparaben (121%), propylparaben (218%), and 2,5-dichorophenol (287%) and lower concentrations of benzophenone-3 (-77%) and triclosan (-53%) than infants of White mothers. Triclosan concentrations were higher in breastfed infants (176%) and lower in infants whose mothers had a high school education or less (-62%). Phenol concentrations were generally higher in summer samples.

CONCLUSIONS

Widespread exposure to select environmental phenols among this cohort of healthy U.S. infants, including much higher paraben concentrations compared to those reported for U.S. children, supports the importance of expanding population-based biomonitoring programs to infants and toddlers. Future investigation of exposure sources is warranted to identify opportunities to minimize exposures during these sensitive periods of development.

Associations of dichlorophenols, trichlorophenols, and ortho-phenylphenol with the risk and prognosis of diabetes and prediabetes: A population-based study

2,4-dichlorophenol (2,4-DCP), 2,5-DCP, 2,4,5-trichlorophenol (2,4,5-TCP), 2,4,6-TCP, and ortho-phenylphenol (OPP) are widely present in the environment. However, their associations with risk and prognosis of diabetes and prediabetes remains unclear. We investigated the associations of these five phenols with the risk of diabetes and prediabetes, and with all-cause and cardiovascular disease (CVD) mortality, in adults with diabetes or prediabetes (n=6419). Information on diabetes and prediabetes indicators, and mortality data was collected from the National Health and Nutrition Examination Survey. Logistic and Cox regression models were used to explore the associations of the five phenols with risk and prognosis of diabetes and prediabetes. Participants in the highest urinary 2,4-DCP and 2,5-DCP tertiles had higher odds of diabetes [adjusted odds ratio (aOR), 1.34, 95 % confidence interval (CI): 1.10, 1.62; aOR, 1.29, 95 % CI: 1.07, 1.56, respectively] than those in the lowest tertiles. Participants with urinary OPP concentrations above the limit of detection (LOD), but below median had an aOR of 1.25 (95 % CI: 1.08, 1.46) for prediabetes compared to those with concentrations below the LOD. In adults with diabetes, the highest 2,4-DCP and 2,5-DCP tertiles were associated with all-cause mortality [adjusted hazard ratio (aHR), 1.49; 95 % CI: 1.08, 2.06; aHR, 1.49; 95 % CI: 1.08, 2.05, respectively] and CVD mortality (aHR, 2.58; 95 % CI: 1.33, 4.97; aHR, 1.96; 95 % CI: 1.06, 3.60, respectively) compared with the lowest tertiles. Compared with 2,4,5-TCP concentrations below the LOD, those above median were associated with all-cause mortality (aHR: 1.75; 95 % CI: 1.24, 2.48) and CVD mortality (aHR: 2.34; 95 % CI: 1.19, 4.63) in adults with prediabetes. Furthermore, the associations between these phenols and mortality were strengthened in some subgroups. Environmental exposure to 2,4-DCP, 2,5-DCP, 2,4,5-TCP, and OPP increases the risk or adverse prognosis of diabetes or prediabetes in adults in the US. Further studies are required to confirm these findings.

Influence of maternal endocrine disrupting chemicals exposure on adverse pregnancy outcomes: A systematic review and meta-analysis

Maternal endocrine disrupting chemicals (EDCs) exposure, the common environmental pollutants, was capable of involving in adverse pregnancy outcomes. However, the evidence of their connection is not consistent. Our goal was to comprehensively explore the risk of EDCs related to adverse pregnancy outcomes. One hundred and one studies were included from two databases before 2023 to explore the association between EDCs and adverse pregnancy outcomes including miscarriage, small for gestational age (SGA), low birth weight (LBW) and preterm birth (PTB). We found that maternal PFASs exposure was positively correlated with PTB (OR:1.13, 95% CI:1.04-1.23), SGA (OR:1.10, 95% CI:1.04-1.16) and miscarriage (OR:1.09, 95% CI:1.00-1.19). The pooled estimates also showed maternal PAEs exposure was linked with PTB (OR:1.16, 95% CI:1.11-1.21), SGA (OR:1.20, 95% CI:1.07-1.35) and miscarriage (OR:1.55, 95% CI:1.33-1.81). In addition, maternal exposure to some specific class of EDCs including PFOS, MBP, MEHP, DEHP, and BPA was associated with PTB. Maternal exposure to PFOS, PFOA, PFHpA was associated with SGA. Maternal exposure to BPA was associated with LBW. Maternal exposure to MMP, MEHP, MEHHP, MEOHP, BPA was associated with miscarriage. Maternal PFASs, PAEs and BPA exposure may increase adverse pregnancy outcomes risk according to our study. However, the limited number of studies on dose-response hampered further explanation for causal association.