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The relationship between maternal mercury (Hg) intake and the risk of spontaneous preterm birth (SPB) remains unclear. We conducted a nested case-control study from a prospective cohort in Shanxi Province, China, to explore their associations. In total, 126 pregnant women with SPB (cases) and 348 controls with term delivery were included. We measured the Hg concentrations in their serum (Hg s ) and blood cell (Hg c ) fractions and calculated the concentration ratio of Hg in serum to Hg in blood cells (Hg s/c ). We found that only the Hg s/c in the case group was slightly higher than that in control group. The OR of Hg s/c associated with SPB risk was 1.57 [95%CI: 0.99-2.46] with adjusting confounders. After stratification by sampling time, the association above was only statistically significant in the first trimester. High Hg s/c may increase the risk of SPB in the first trimester among women with relatively low Hg exposure., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Titanium (Ti) is commonly used in additives in the form of titanium dioxide (TiO 2 ). However, our understanding of the effect of Ti on reproductive health remains limited. This nested case-control study, performed in a Ti mining exposure field, investigated the association between maternal blood Ti concentration and the risk of low birth weight (LBW), as well as the potential biological mechanism. A total of 45 women who delivered LBW infants (cases) and 352 women with normal birth weight infants (controls) were included. We collected maternal peripheral blood samples in the first or early second trimester to measure Ti concentration in serum (Ti sr ) and blood cells (Ti bc ), as well as inflammatory, lipid, and oxidative stress biomarkers thereof. The demographic characteristics of the women included in the study were also obtained. The results showed that the median total blood Ti concentration (Ti tb ) in the case group was significantly higher than that in the control group (134 vs. 129 ng/mL, P = 0.039). A higher Ti tb level was associated with a greater risk of LBW [odds ratio = 2.62; 95% confidence interval (CI): 1.16-5.90], but no such association was observed for Ti sr or Ti bc after adjusting for potential confounders. The serum lipid biomarkers TC, TG, and total lipids (TL) were all negatively associated with Ti sr and Ti tb . Serum 8-OHdG was positively associated with Ti bc . We concluded that a high Ti tb during early pregnancy may increase the risk of LBW. Lipid metabolism and oxidative stress may play an important role in the adverse health effects associated with Ti exposure. Thus, our results merit more attention to the probable adverse effects of titanium exposure during pregnancy., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Numerous animal studies have shown that high arsenic exposure can induce neural tube defect (NTD) formation. However, epidemiological evidence related to this finding is scarce. The key objective of our study is to evaluate whether maternal arsenic exposure is associated with NTD risk in Northern China. Our case-control study was conducted in 11 countries or cities in Shanxi and Hebei provinces during 2003-2007. A total of 774 mothers were included as participants: 511 controls and 263 cases (including 123 with anencephaly, 115 with spina bifida, 18 with encephalocele, and 7 with other NTD subtypes). The arsenic concentration was measured in a specific section of hair that grew from 3 months before to 3 months after conception. We found a higher hair arsenic concentration in the NTD cases with median (inter-quartile range) of 0.093 (0.025-0.387) μg/g hair than that in the controls with a value of 0.082 (0.030-0.414) μg/g hair. Maternal hair arsenic concentration above its median of the controls was associated with an increased risk of the total NTDs with an adjusted odds ratio (OR) of 1.32 [95% confidence interval (CI): (0.91-1.92)], which was not statistically significant (p = 0.14), although the crude OR without adjusting for the confounders of 1.68 (95% CI: 1.24-2.27; p < 0.001) suggested that hair arsenic is a risk factor of NTDs. There was no dose-response relationship between maternal hair arsenic concentration and the risk of total NTDs. Similar phenomena were found for anencephaly and spina bifida, respectively. Overall, our findings showed that maternal periconceptional arsenic exposure may not significantly contribute to the risk of NTD development in Northern China; other risk factors need to be further examined in future studies., (Copyright © 2019 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Few studies from western countries have linked prenatal exposure to ambient particulate matter <2.5 μm (PM 2.5 ) with increased risk of congenital anomalies. However, the results are mixed. Particularly, evidence is limited for Chinese pregnant women., Methods: In this retrospective cohort study, we matched the data of all pregnant women laboured in public hospitals during 2015-2016 in Yinchuan, a capital city of northwest China and the data of daily average PM 2.5 , nitrogen dioxide (NO 2 ), sulphur dioxide (SO 2 ) and ozone (O 3 ) concentrations of the nearest monitor station. We calculated a time-dependent exposure over the entire pregnancy for each woman. We used a time varying Cox proportional hazards model to explore the association between PM 2.5 exposure and the risk of congenital anomalies, after adjusting for individual confounders and other pollutants., Results: A total of 39,386 singleton live births were included in the study, and 530 (1.35%) were with congenital anomalies. An increase of 10 μg/m 3 in PM 2.5 exposure over the entire pregnancy was significantly associated with increased risk of congenital anomalies, with hazard ratio (HR) of 1.35 [95% confidence interval (95%CI): 1.16, 1.58]. For subtype analyses, PM 2.5 exposure exhibited a significant association with cardiac anomalies and other unclassifiable anomalies, with HRs of 1.60 (95%CI: 1.24, 2.08) and 1.42 (95%CI: 1.07, 1.89), respectively. The impacts of PM 2.5 exposure on orofacial anomalies and musculoskeletal anomalies were not significant., Conclusion: Our results indicate high concentration of PM 2.5 could increase the risk of congenital anomalies among Chinese, especially for cardiac anomalies. Self-protective measures involving reducing PM 2.5 pollution exposure during pregnancy as well as environmental policies aiming to restrict PM 2.5 emission could be helpful to reduce the burden of cognitional anomalies., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Background: The effect of maternal copper (Cu) level on the risk of spontaneous preterm birth (SPB) remains debate. Therefore, we conducted a prospective nested case-control study in Shanxi Province to investigate the relationship between maternal serum Cu concentration and SPB risk, as well as the potential mediation effect of lipid metabolism., Method: From an overall cohort of 4229 women, 147 women affected by SPB at 20-36 gestational weeks (cases) and 381 women who delivered at ≥37 gestational weeks (controls) were included in our nested case-control study. Maternal blood samples were collected during 4-22 gestational weeks, and the concentrations of Cu, total cholesterol (TC), and triglycerides (TG) were measured. Information on maternal social demographic characteristics were collected using questionnaires. Unconditional logistic regression models were used to estimate the associations of Cu, TC or TG levels with SPB risk. Linear regressions were used to assess the relationships between concentrations of Cu and TC or TG., Results: Serum Cu concentrations in the case group (median: 184 μg/dL) were significantly higher than those in the control group (median: 166 μg/dL, p < 0.0001). Compared to the lowest serum Cu levels, the odds ratios associated with SPB increased to 2.02 (95% confidence interval [CI]: 1.07, 3.82), 3.10 (1.54, 6.22) and 4.18 (2.11, 8.27) in the second, third and fourth quartile respectively, after adjusting for sampling time, maternal age, pre-pregnancy BMI, education, occupation, parity, spontaneous abortion history, folic acid use, medication use, pre-pregnancy passive smoking status, child gender and fasting status. Plasma concentrations of TC and TG were positively associated with SPB risk in a dose-dependent manner. However, when stratified by sampling time, the above-mentioned relationships were significant in the first trimester but not in the second. In addition, plasma concentrations of TC and TG were positively correlated with serum Cu concentrations., Conclusions: High maternal Cu level in the first trimester may increase the risk of SPB, by potentially increasing plasma concentrations of TC and TG., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Background: Thorium is ubiquitous in the environment and its relationship with birth defects is still under discussion. This study aimed to investigate the associations of maternal exposure to thorium with risk of neural tube defects (NTDs) by using a case–control study, as well as the relationship between thorium exposure and the indoor air pollution from coal combustion. Methods: This study was conducted in 11 local healthcare hospitals during 2003–2007 in Shanxi and Hebei provinces, China. A total of 774 mothers were included as participants who delivering 263 fetuses with NTDs including 123 with anencephaly, 115 with spina bifida, 18 with encephalocele, and 7 other NTD subtypes (cases), and 511 health fetuses without NTDs (controls). Their hair samples were collected as close as to the occipital posterior scalp, of which those grew from 3 months before to 3 months after conception was cut to measure the thorium concentration by inductively coupled plasma-mass spectrometry. Results: We found a higher hair thorium concentration in the total NTD cases with 0.901 (0.588–1.382) ng/g hair [median (inter-quartile range)] than that in the controls with a value of 0.621 (0.334–1.058) ng/g hair. Similar results were found for the three concerned NTD subtypes. Maternal hair thorium concentration above its median of the controls was associated with an increased risk of the total NTDs with an adjusted odds ratio of 1.80 [95% confidence interval (CI), 1.23–2.63)] by adjusting for all confounders. There was obvious dose-response relationship between maternal hair thorium concentration and the risk of total NTDs, as well as their two subtypes (i.e. anencephaly and spina bifida). Maternal hair thorium concentration was positive associated with their exposure level to indoor air pollution from coal combustion during cooking. Conclusions: Overall, our findings revealed that maternal periconceptional thorium exposure was associated with the risk of NTDs in North China. Reducing the coal usage in the household cooking activities may decrease maternal thorium exposure level. [ABSTRACT FROM AUTHOR]