Microplastic abundance in placental chorionic villi detected by pyrolysis-gas chromatography/mass spectrometry in cases of spontaneous miscarriage during early pregnancy.

Abstract

Background: There is widespread concern regarding the effect of microplastics (MPs) on human reproductive health. The accumulation of MPs and their potential effect on adverse pregnancy outcomes must be determined, particularly from the perspective of the maternal-foetal interface during early gestation, because abnormal composition and metabolism of chorionic villi are closely related to early embryonic development. This study aimed to identify and quantify the mean mass concentrations and polymer types of MPs in human chorionic villi, and investigate the potential association between the abundance of MPs and spontaneous miscarriage.

Methods: Chorionic villi were collected from 31 participants in their first trimester, including normal carriage terminated for social factors (NC, n = 13) and unexplained spontaneous miscarriage (SM, n = 18). Qualitative and quantitative detection of 11 types of MPs was performed by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Differences in the abundance of specific MPs between the two groups were analysed by t-tests. Individual clinical characteristics and lifestyle information were collected to identify the primary sources and factors that may impact MPs in chorionic villi. Statistical analyses, including a correlation analysis and the binary logistic regression model, were used to assess the effect of MP accumulation on early pregnancy outcomes.

Findings: MPs were detected in all samples and four main types were identified, namely polyethylene (PE), polyvinyl chloride (PVC), polystyrene (PS), and polypropylene (PP). PVC was the most abundant. The total abundance of MPs in patients with SM was significantly higher than that in controls (273.08 ± 50.89 μg/g vs 226.37 ± 42.35 μg/g, p = 0.011). The accumulation of total MPs (r = 0.5947, p < 0.01) and PVC (r = 0.5649, p < 0.05) in patients with SM was positively correlated with age but not body mass index. Participants who regularly consumed bottled water generally showed significantly elevated levels of PE and total MPs in their villi, while frequent seafood consumption had a significant effect on PE, PVC, PS, and PP concentrations.

Interpretation: We identified the presence of MPs in chorionic villi during the first trimester and established an association between the abundance of MPs and unexplained SM. These findings suggest that accumulation of MPs at the maternal-foetal interface during the first trimester are related to an increased risk of miscarriage and that these cross-generational effects during early gestation represent potential reproductive toxicity of MPs. Further research is warranted to elucidate the underlying mechanisms, and larger sample sizes are required to validate the observed trends.

Funding: This study was supported by grants from the "Pioneer" and "Leading Goose" R&D Program of Zhejiang (2024C03242) and the Medical Science Projects of Zhejiang Province (No. 2023KY013).