Maternal urine phthalate metabolite exposure and miscarriage risk: a nested case-control study of the Zunyi Birth Cohort

Impact of Endocrine-Disrupting Chemicals, Climate, and Air Pollution on Pregnancy Outcomes: A Scoping Review

Environmental pollutants, including endocrine-disrupting chemicals (EDCs), air pollution, and climate change, are increasingly recognized for their potential impact on pregnancy outcomes. EDCs, found in pesticides, industrial chemicals, and personal care products, are associated with preterm birth and fetal growth restriction, primarily through hormonal interference. Air pollution, notably PM2.5, NO2, and O3, has been linked to increased rates of preterm birth, low birth weight, and stillbirth. Climate factors, such as extreme heat, elevate risks of pregnancy loss and preterm birth, with significant impacts on vulnerable populations across diverse socioeconomic and geographic regions. These exposures contribute to adverse pregnancy outcomes through mechanisms involving oxidative stress, inflammation, and endocrine disruption. The interplay among these environmental factors underscores the need for integrated, longitudinal studies to understand their combined effects on pregnancy outcomes better. Future research should focus on region-specific impacts, cumulative exposure, and policy-driven interventions to mitigate these environmental risks, especially in vulnerable populations disproportionately affected by these hazards. This scoping review synthesizes recent findings from 2019 to 2024 to highlight these associations and identify research gaps.

Maternal Thyroid Hormones as Mediators between Phthalate Exposure and Neonatal Birth Weight: A Cross-Sectional Study from the Zunyi Birth Cohort

Studies have shown that exposure to phthalates can affect neonatal birth weight. However, epidemiological evidence on the mediating role of maternal thyroid hormones is limited. Therefore, this study, based on the Compliance Birth Cohort, aimed to reveal the potential mediating function of maternal thyroid hormones during pregnancy between phthalic acid ester (PAE) exposure and neonatal birth weight. The study included 1274 mother-infant pairs. Linear regression analysis revealed a negative association between MIBP and neonatal birth weight (β = -62.236; 95% CI: -118.842, -5.631). Bayesian kernel-machine regression (BKMR) indicated a nonlinear negative association between PAE metabolites (PAEs) and birth weight. Linear regression analysis revealed a positive association between neonatal birth weight and FT3 (β = 41.605; 95% CI: 2.631, 80.380). The BKMR model also found a positive association between thyroid hormones and birth weight but in a nonlinear manner. Additionally, linear regression analyses showed that TSH, TT3, TT4, FT3, and FT4 were associated with PAEs. The BKMR model revealed an inverted U-shaped association of PAEs with TT3 and FT3 and a nonlinear association with TSH, TT4, and FT4. Structural equation modeling revealed that MMP, MIBP, MBP, MEHP, MOP, MBZP, and MEOHP contributed to a net reduction in neonatal birth weight of 32 g through the TT3, FT3, TT4, and FT4 pathways. The findings suggest that exposure to PAEs during pregnancy leads to a reduction in neonatal birth weight, possibly due to the involvement of maternal thyroid hormones as mediators. Controlling maternal thyroid hormone levels during pregnancy may be a viable method to reduce the harmful effects of phthalate exposure on the developing fetus.

Seasonal variation in urinary PAH metabolite levels and associations with neonatal birth outcomes

Previous studies have demonstrated that exposure to polycyclic aromatic hydrocarbons (PAHs) can affect maternal and infant health. However, the conclusions regarding the effects of seasonal PAH exposure on maternal and infant health have been inconsistent. To further elucidate this issue, this study included data from 2282 mother-infant pairs in the Zuni birth cohort. The objective was to investigate the association between maternal late-pregnancy urinary PAH metabolite concentrations and neonatal birth outcomes during the heating and non-heating seasons. The results demonstrated that PAH exposure in Zunyi was primarily dominated by 2-OHNAP and 1-OHNAP and that the concentrations of PAH metabolites were significantly higher during the heating season. Furthermore, PAH metabolite exposure was found to affect neonatal birth weight, birth length, and parity index with seasonal differences. Further dose-effect analyses revealed nonlinear relationships and seasonal differences between PAH metabolites and neonatal birth weight, birth length, and parity index. Bayesian kernel mechanism regression modeling demonstrated that the inverted U-shaped relationship between PAH metabolites and neonatal birth weight and parity index was exclusive to the heating season. Consequently, it can be posited that maternal exposure to PAH metabolites during late pregnancy exerts a detrimental influence on neonatal growth and development, which is further compounded by the use of heating fuels. This highlights the necessity to either control or alter the use of heating fuels during pregnancy.

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.

Determination of Polycyclic Aromatic Hydrocarbons (PAHs) and Phthalates in Human Placenta by Mixed Hexane/Ether Extraction and Gas Chromatography-Mass Spectrometry/Mass Spectrometry (GC-MS/MS)

In this study, we evaluated the extraction effect of three different extractants, namely hexane + ether (v/v = 3:1), acetonitrile and ethyl acetate, on polycyclic aromatic hydrocarbons (PAHs) and phthalic acid esters (PAEs) in placenta detected and analysed by triple quadrupole gas chromatography-mass spectrometry (GC-MS/MS). The results showed that n-hexane + ether (v/v = 3:1) had the highest extraction efficiency. Under the optimal conditions, the limits of detection (LOD) for the 10 PAHs were 0.003-0.0167 μg/L with relative standard deviations (RSD) of 1.4-5.48% and detection rates of 68.19-107.05%, and the correlation coefficients were (R2, 0.9982-0.9999). The LODs for the nine PAEs were 0.0015-3.5714 μg/L and the correlation coefficients were (R2, 0.9982-0.9999). The limits of detection (S/N = 3) for the nine PAHs were 0.0015-0.5714 μg/L with relative standard deviations (RSD) of 3.15-8.37%, and the detection rates were 80.45-112.59% with correlations of (R2, 0.9972-0.9998). The method was applied to the analysis of PAHs and phthalates in placenta samples from pregnant women. The method's accuracy and applicability were demonstrated. In comparison with other methods for the detection of PAEs and PAHs, the method proposed in this paper has a wider linear range, lower minimum detection limit and comparable recovery with good correlation. This paper is dedicated to providing another method for improving the performance of extracting solid tissues.