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Background Per- and polyfuoroalkyl substances (PFAS) are categorized as persistent organic pollutants and commonly detected in humans, and their toxicity has attracted widespread attention. However, few studies have reported comparison of PFAS levels and potential factors between women pregnant using assisted reproduction technology (ART) and women pregnant naturally. Objective To analyze and compare serum concentrations and sociodemographic determinants of PFAS in pregnant women conceiving through ART and conceiving naturally from Shanghai. Methods Based on the China National Birth Cohort (CNBC) in Shanghai from 2017 to 2019, 333 pregnant women conceiving through ART and 689 pregnant women conceiving naturally were recruited during the same period as study subjects. The concentrations of 32 PFAS were measured in early-pregnancy serum of all pregnant women, and four PFAS with the highest co-exposure levels in both groups were included in the subsequent analysis. Multiple linear regression models were performed to evaluate the associations of sociodemographic factors with serum PFAS concentrations in the two groups respectively. Beta coefficients and 95% confidence intervals (CI) were exponentiated to calculate the ratio of the geometric mean (GM) of PFAS concentrations after each unit change in the independent variable. Results Perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), 6∶2 chlorinated polyfluoroethersulfonic acid (6∶2 Cl-PFESA), and perfluorohexanesulfonic acid (PFHxS) were four major PFAS in serum of pregnant women conceiving through ART and conceiving naturally, and the concentrations of PFOA, PFOS, and 6∶2 Cl-PFESA were higher in pregnant women conceiving through ART than in pregnant women conceiving naturally (P <0.05). The results of multiple linear regression analysis showed that age at pregnancy and household income were associated with serum PFAS levels in both groups. The serum concentrations of PFOS were higher in pregnant women aged ≥35 years old who conceiving through ART (GM ratio=1.26, 95%CI: 1.04, 1.54) and conceiving naturally (GM ratio=1.24, 95%CI: 1.08, 1.42) than pregnant women aged <30 years old respectively. Pregnant women conceiving through ART and conceiving naturally whose household annual income >300000 CNY had lower serum concentrations of PFOA [GM ratio (95%CI): 0.82 (0.72, 0.95) and 0.89 (0.81, 0.97), respectively] and PFHxS [GM ratio (95%CI): 0.66 (0.51, 0.86) and 0.77 (0.66, 0.90), respectively] than those women whose household annual income <200000 CNY. Additionally, pregnant women conceiving naturally with a graduate education or above had lower serum 6∶2 Cl-PFESA concentrations than women with an education below college (GM ratio: 0.81), and multiparous pregnant women conceiving naturally had higher serum concentrations of PFOS, 6∶2 Cl-PFESA, and PFHxS than primiparous pregnant women (GM ratio: 1.14, 1.25, and 1.27 respectively). Conclusion Although differences in serum PFAS levels are found between pregnant women conceiving through ART and women conceiving naturally in this study, maternal age and household income are common determinants of PFAS exposure levels in both populations. We find no special sociodemographic factors to affect PFAS concentrations of pregnant women conceiving through ART compared to pregnant women conceiving naturally. Further research is required to explore other potential factors.
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Per-and polyfluoroalkylated substances (PFASs) are a group of persistent organic pollutants that are widespread in the environment and organisms. Given their unique hydrophobicity, oil-repellence, and chemical stability, PFASs are widely used in various industrial and commercial products. PFASs can accumulate and be biomagnified through the food chain, and its toxic effects have posed a certain threat to human health. The response of the immune system to PFASs exposure is one of the most sensitive human health effects, and has attracted remarkable attention from related scientists and organizations. We summarized international and domestic epidemiological studies on the associations between exposure to PFASs and immune system, including immunosuppression and immunoenhancement. We also reviewed experimental evidence of PFASs on immune system from perspectives of immune organs, immune cells, and cytokines. Furthermore, the possible mechanisms of peroxisome proliferator-activated receptor-α (PPAR-α)-dependent, nuclear factor-κB (NF-κB)-activated, and mitochondrial apoptosis pathways were summarized. While the relationships between PFASs and immune-related diseases in human are not yet conclusive, accumulative epidemiological studies provide evidence for associations between PFASs and reduced immune response to vaccination in children. In addition, previous studies mainly focus on the immunotoxicity of traditional PFASs, and our understanding of the molecular mechanism of the effects of PFASs on immune system is still in its infancy. Therefore, it is necessary to further explore the immunotoxicity of new PFASs and associated mechanism.
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Background Exercise during pregnancy is closely related to maternal and infant health. Previous studies in developed countries have linked maternal exercise during pregnancy with newborn body weight as well as subcutaneous fat thickness. However, the relevant studies in China are limited, and the conclusions remain inconsistent. Objective To investigate the effects of maternal exercise during pregnancy on neonatal weight and subcutaneous fat thickness. Methods Based on the Shanghai Birth Cohort, 959 maternal-infant pairs were included in this study. The International Physical Activity Questionnaire was used to collect average weekly frequency and daily minutes of walking in the first and second trimesters, and entropy weight method was used to calculate the cumulative exercise index in the two trimesters. Birth weight was measured using a calibrated weigh scale. Subcutaneous fat thickness was measured at abdomen, scapula, and triceps with a Harpenden skinfold caliper for all newborns and the sum of the thickness for the three sites was then calculated. A multiple linear regression model was employed to estimate the relationships of cumulative exercise index during pregnancy with neonatal body weight and subcutaneous fat thickness. Subgroup analyses stratified by pre-pregnancy body mass index (BMI) and sex of newborns were also performed. Results The mean age of pregnant women was (28.5±3.8) years, and the pre-pregnancy BMI was (21.4±3.0) kg·m−2. Newborn boys were slightly more than newborn girls (54.3% vs 45.7%), and the neonatal weight was (3374.0±427.5) g. The means of newborns' abdominal, scapular, and triceps subcutaneous fat thickness were (4.4±1.3), (5.4±1.4), and (6.0±1.5) mm, respectively, and the sum of subcutaneous fat thickness was (15.8±3.9) mm. In the first and second trimesters, 77.3% and 88.7% of pregnant women walked 4 d per week and more, respectively; the daily minutes of walking was (36.9±27.2) min and (43.3±26.3) min, respectively; the cumulative exercise index was 25.6±17.7 and 35.9±21.1, respectively. The results of multiple linear regression analysis showed that the cumulative exercise index in the second trimester was negatively associated with newborns' abdominal (b=−0.006, 95%CI: −0.010-−0.003), scapular (b=−0.005, 95%CI: −0.009-−0.002), triceps (b=−0.006, 95%CI: −0.010-−0.002), and their sum of (b=−0.018, 95%CI: −0.028-−0.007) subcutaneous fat thickness (P<0.05); in the first and second trimesters, however, the relationship between maternal cumulative exercise and newborns' body weight was not significant. The results of stratified analyses showed that the negative associations between maternal cumulative exercise index and newborns' subcutaneous fat thickness for the second trimester remained significant in the subgroups of boys and neonates whose mothers had normal pre-pregnancy BMI (P<0.05). Conclusion Cumulative exercise index in the second trimester is negatively correlated with the neonatal thickness of subcutaneous fat, and the association may be altered by neonatal sexes and maternal pre-pregnancy BMI levels.