Trace Minerals, Heavy Metals, and Preeclampsia: Findings from the Boston Birth Cohort

Pregnancy Metal Mixtures and Blood Pressure and Hypertension in Mid-Life: A Prospective U.S. Cohort Study

BACKGROUND

The long-term associations between metal mixtures in pregnancy and women's mid-life blood pressure (BP) and hypertension remain unclear.

METHODS

In Project Viva (enrolled 1999-2002), we measured nonessential (arsenic, barium, cadmium, cesium, mercury, lead) and essential metals (copper, magnesium, manganese, selenium, zinc) in red blood cells, along with folate and vitamin B12 in plasma, collected during pregnancy. We measured mid-life BP from 2017 to 2021 (median age, 51.2 years). We examined associations of individual metals with BP using linear regression and with hypertension (≥130/80 mm Hg or use of antihypertensive medication) using modified Poisson regression. We used Bayesian kernel machine regression to examine the mixture effects of metals and micronutrients.

RESULTS

The median follow-up time of the 493 women was 18.1 years (interquartile range, 17.8-18.6 years). After adjustment, a doubling of copper and manganese was associated with 0.75 (95% CI, 0.57-0.99) and 0.80 (95% CI, 0.71-0.91) times the risk of hypertension, respectively. Although higher cesium and selenium levels were associated with a slightly increased risk of hypertension, the 95% CIs were wide and crossed the null. A doubling of vitamin B12 was associated with a 3.64 (95% CI, 1.23-6.04) mm Hg lower systolic BP and a 2.52 (95% CI, 0.72-4.32) mm Hg lower diastolic BP. Bayesian kernel machine regression showed linear associations with no metal-metal or metal-micronutrient interactions. The essential metal mixture was monotonically associated with lower BP, while its association with hypertension showed threshold effects.

CONCLUSIONS

Optimizing essential metal levels during pregnancy, particularly copper and manganese, along with vitamin B12, may protect against higher BP and hypertension in mid-life women.

Cadmium levels in maternal blood, placenta, and cord blood in relation to preeclampsia and fetal growth: a case-control study in China

This study aims to delineate the levels of Cd exposure in maternal blood, placenta, and cord blood, and to explore the association between Cd levels and the risk of preeclampsia (PE), as well as its potential impact on fetal growth among affected individuals. A case-control study was performed at the First Hospital of Shanxi Medical University, involving 373 pregnant women diagnosed with PE and 485 controls. Cd was measured in maternal blood, placenta, and cord blood using ICP-MS. The association between Cd and birth weight z-score was analyzed by multivariate linear regression. Logistic regression analysis was used to investigate the relationships between Cd and the risk of PE, and Cd and the risk of fetal growth. The concentration of Cd in the placenta was higher than that in maternal blood and cord blood. The highest tertile of placental Cd was identified as a risk factor for PE (OR = 2.704, 95% CI: 1.865, 3.921). Among pregnant women with PE, higher levels of Cd exposure in the placenta were negatively associated with birth weight z-scores (per doubling: β = -0.134, 95% CI: -0.264, -0.004), and the highest tertile of placental Cd was associated with an elevated risk of SGA (OR = 2.103, 95% CI: 1.164, 3.801). Furthermore, an interaction between Cd and PE was identified. In conclusion, Cd can accumulate in the placenta of pregnant women, and high placental Cd exposure not only increases the risk of PE but also exacerbates the risk of SGA outcome in PE pregnant women.

Mercury and cadmium-induced inflammatory cytokines activation and its effect on the risk of preeclampsia: a review

During the last decade, there has been an increase in exposure to heavy metals that can affect human health and the environment, especially mercury (Hg) and cadmium (Cd). These exposures can pollute the rivers or oceans, then contaminating marine organisms. Humans as the last consumer of this food chain cycle can be a place for the bioaccumulation of Hg and Cd, especially for people living in coastal areas, including pregnant women. Exposure to heavy metals Hg and Cd can have a high risk of triggering blood vessel disorders, penetrating the blood-brain barrier (BBB) and the placental barrier, one of which can increase the risk of preeclampsia. Several immunological biomarkers such as some cytokines associated with Hg and Cd exposure are also involved in the pathophysiology of preeclampsia, which are the placental implantation process and endothelial dysfunction in pregnant women. Therefore, countries that have a high incidence of preeclampsia should be aware of the environmental factors, especially heavy metal pollution such as Hg and Cd.

Gestational arsenite exposure alters maternal postpartum heart size and induces Ca2+-handling dysregulation in cardiomyocytes

Cardiovascular disease is the leading cause of mortality in the United States. Studies suggest a role for environmental exposures in the etiology of cardiovascular disease, including exposure to arsenic through drinking water. Arsenic exposure during pregnancy has been shown to have effects on offspring, but few studies have examined impacts on maternal cardiovascular health. Although our prior work documented the detrimental effect of arsenic on the maternal heart during pregnancy, our current study examines the effect of gestational arsenic exposure on the maternal heart postpartum. Timed-pregnant wild-type (C57BL/6J) mice were exposed to 0, 100, or 1,000 µg/L sodium arsenite (NaAsO2) via drinking water from embryonic day 2.5 until parturition. Postpartum heart structure and function was assessed via transthoracic echocardiography and gravimetric measurement. Hypertrophic markers were probed via qRT-PCR and Western blot. Isolated cardiomyocyte Ca2+-handling and contraction were also assessed, along with the expression of with Ca2+-handling and contractile proteins. Interestingly, we found that exposure to either 100 or 1,000 µg/L sodium arsenite increased postpartum heart size at postpartum day 12 vs. nonexposed postpartum controls. At the cellular level, we found altered cardiomyocyte Ca2+-handling and contraction, along with expression changes of key contractile proteins, including α-actin and cardiac myosin binding protein C (cMyBP-c). Together, these findings suggest that gestational arsenic exposure impacts the postpartum maternal heart, possibly inducing long-term cardiovascular changes. Furthermore, these findings highlight the importance of reducing arsenic exposure during pregnancy, and the need for more research on the impact of arsenic on maternal heart health and adverse pregnancy events.NEW & NOTEWORTHY Gestational exposure to sodium arsenite at environmentally relevant doses (100 and 1,000 µg/L) increases postpartum heart size, and induces dysregulated Ca2+ homeostasis and impaired shortening in isolated cardiomyocytes. This is the first study to demonstrate that gestational arsenic exposure impacts postpartum heart structure and function beyond the exposure period.

Re-thinking the link between exposure to mercury and blood pressure

Hypertension or high blood pressure (BP) is a prevalent and manageable chronic condition which is a significant contributor to the total global disease burden. Environmental chemicals, including mercury (Hg), may contribute to hypertension onset and development. Hg is a global health concern, listed by the World Health Organization (WHO) as a top ten chemical of public health concern. Most people are exposed to some level of Hg, with vulnerable groups, including Indigenous peoples and small-scale gold miners, at a higher risk for exposure. We published a systematic review and meta-analysis in 2018 showing a dose-response relationship between Hg exposure and hypertension. This critical review summarizes the biological effects of Hg (both organic and inorganic form) on the underlying mechanisms that may facilitate the onset and development of hypertension and related health outcomes and updates the association between Hg exposure (total Hg concentrations in hair) and BP outcomes. We also evaluated the weight of evidence using the Bradford Hill criteria. There is a strong dose-response relationship between Hg (both organic and inorganic) exposure and BP in animal studies and convincing evidence that Hg contributes to hypertension by causing structural and functional changes, vascular reactivity, vasoconstriction, atherosclerosis, dyslipidemia, and thrombosis. The underlying mechanisms are vast and include impairments in antioxidant defense mechanisms, increased ROS production, endothelial dysfunction, and alteration of the renin-angiotensin system. We found additional 16 recent epidemiological studies that have reported the relationship between Hg exposure and hypertension in the last 5 years. Strong evidence from epidemiological studies shows a positive association between Hg exposure and the risk of hypertension and elevated BP. The association is mixed at lower exposure levels but suggests that Hg can affect BP even at low doses when co-exposed with other metals. Further research is needed to develop robust conversion factors among different biomarkers and standardized measures of Hg exposure. Regulatory agencies should consider adopting a 2 µg/g hair Hg level as a cut-off for public health regulation, especially for adults older than child-bearing age.

Manganese exposure and perinatal health: a systematic review of literature

Manganese is essential for adequate feto-maternal health; however, an inverted U-shaped relation has been found between maternal manganese status and pregnancy complications. This systematic review summarizes the effect of maternal manganese exposure and perinatal health. We adopted a systematic approach to retrieve the recent literature. After applying the inclusion/exclusion criterion, a total of 20 studies were included in this review. Results found a non-significant relationship between maternal manganese exposure and risk of gestational diabetes mellitus (GDM), while only three studies reported the association between higher manganese levels and risk of preterm birth. Also, inconsistent results were found regarding higher manganese status and risk of low birth weight. This review reported no association between higher maternal manganese status andrisk of GDM. Nevertheless, the paucity of literature related to small for gestational age and pre-eclampsia prohibits a conclusion. Further studies are required for evaluation of environmental manganese exposure and maternal manganese status.

Exposure to organophosphate ester flame retardants and plasticizers and associations with preeclampsia and blood pressure in pregnancy

BACKGROUND

Organophosphate esters (OPEs), flame retardants and plasticizers found widely in consumer products, may impact vascularization processes in pregnancy. Yet, the association between maternal exposure to OPEs and both preeclampsia and blood pressure during pregnancy remains understudied.

METHODS

Within the LIFECODES Fetal Growth Study (N = 900), we quantified 8 OPE metabolites from maternal urine collected at up to 3 time points during pregnancy and created within-subject geometric means. Outcomes included diagnosis of preeclampsia and longitudinal systolic (SBP) and diastolic (DBP) blood pressure measurements (mean = 14 per participant). Cox proportional hazards models were used to estimate associations between OPE metabolites and preeclampsia. Associations between average OPE metabolite concentrations and repeated blood pressure measurements were estimated using generalized estimating equations.

RESULTS

Five OPE metabolites were detected in at least 60% of samples; 3 metabolites detected less frequently (5-39%) were examined in an exploratory analysis as ever vs. never detectable in pregnancy. There were 46 cases of preeclampsia in our study population. Associations between OPE metabolites and preeclampsia were null. We noted several divergent associations between OPE metabolites and longitudinal blood pressure measurements. An interquartile range (IQR) difference in average bis(2-chloroethyl) phosphate concentrations was associated with a decrease in SBP (-0.81 mmHg, 95% confidence interval [CI]: -1.62, 0.00), and, conversely, bis(1-chloro-2-propyl) phosphate was associated with a slight increase in SBP (0.94 mmHg, 95% CI: 0.28, 1.61). We also noted a decrease in SBP in association with several metabolites with low detection frequency.

CONCLUSIONS

We observed null associations between OPE metabolites and preeclampsia, but some positive and some inverse associations with blood pressure in pregnancy. While our study was well-designed to assess associations with blood pressure, future studies with a larger number of preeclampsia cases may be better poised to investigate the association between OPE metabolites and phenotypes of this heterogenous hypertensive disorder of pregnancy.

A study on the mediating role of serum hormones in the effects of heavy metals on preeclampsia

Exposure to environmental heavy metals may pose a risk factor for developing preeclampsia (PE) modified through intervention. This case-control study aimed to investigate the association between serum heavy metal concentrations and PE in pregnant women and whether hormones served as mediating factors in the impact of heavy metals on PE. From October 2020 to 2022, 160 patients with PE and 160 pregnant women with normal deliveries were recruited at Dongguan Songshan Lake Central Hospital. Serum concentrations of manganese (Mn), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), lead (Pb), β-human chorionic gonadotropin (β-hCG), progesterone (P), estradiol (E2), testosterone (T), cortisol (Cort), and cortisone (Cor) were measured. Logistic, restricted cubic splines, weighted quantile sum and multivariate linear regression models were employed to account for different aspects and explore the relationships among heavy metals, hormones, and PE. Mediation model analysis was performed to assess the role of hormones in mediation. The median concentrations of Mn, E2, and Cort were lower in the PE group than in the control group. The median concentrations of Cu, Zn, β-hCG, and T were higher in the PE than in the control. Mn, E2, and Cort showed negative associations with PE, while Cu, Zn, β-hCG, and T demonstrated positive associations, as determined through logistic regression. Mn, Cu, and Zn displayed linear dose-response relationships with PE. Zn and Cu had high weights in the positive association model of mixed heavy metal exposure with PE. The mediation analysis revealed that serum E2, P, T, Cort, and Cort/Cor might be potential mediators of the association between heavy metals (Mn, Cu, and Zn) and PE.

Gestational arsenite exposure alters maternal postpartum heart size and induces Ca 2+ handling dysregulation in cardiomyocytes

Cardiovascular disease is the leading cause of mortality in the US. Studies suggest a role for environmental exposures in the etiology of cardiovascular disease, including exposure to arsenic through drinking water. Arsenic exposure during pregnancy has been shown to have effects on offspring, but few studies have examined impacts on maternal cardiovascular health. While our prior work documented the detrimental effect of arsenic on the maternal heart during pregnancy, our current study examines the effect of gestational arsenic exposure on the maternal heart postpartum. Timed-pregnant wild-type (C57BL/6J) mice were exposed to 0, 100 or 1000 µg/L sodium arsenite (NaAsO2) via drinking water from embryonic day 2.5 (E2.5) until parturition. Postpartum heart structure and function was assessed via transthoracic echocardiography and gravimetric measurement. Hypertrophic markers were probed via qRT-PCR and western blot. Isolated cardiomyocyte Ca 2+ -handling and contraction were also assessed, and expression of proteins associated with Ca 2+ handling and contraction. Interestingly, we found that exposure to either 100 or 1000 µg/L sodium arsenite increased postpartum heart size at P12 vs. non-exposed postpartum controls. At the cellular level, we found altered cardiomyocyte Ca 2+ -handling and contraction. We also found altered expression of key contractile proteins, including α-Actin and cardiac myosin binding protein C (cMyBP-c). Together, these findings suggest that gestational arsenic exposure impacts the postpartum maternal heart, possibly inducing long-term cardiovascular changes. Furthermore, these findings highlight the importance of reducing arsenic exposure during pregnancy, and the need for more research on the impact of arsenic and other environmental exposures on maternal heart health and adverse pregnancy events.

New & Noteworthy

Gestational exposure to sodium arsenite at environmentally relevant doses (100 and 1000 µg/L) increases postpartum heart size, and induces dysregulated Ca 2+ homeostasis and impaired shortening in isolated cardiomyocytes. This is the first study to demonstrate that gestational arsenic exposure impacts postpartum heart structure and function beyond the exposure period.

Environmental exposure to metal(loid)s and hypertensive disorders of pregnancy: A systematic review

BACKGROUND

Environmental exposure to metal(loid)s has been associated with adverse effects on human health, but the systemic repercussion of these elements on the development of hypertensive disorders of pregnancy (HDP) is still poorly understood.

OBJECTIVE

To summarize evidence published about the influence of environmental exposure to aluminum, arsenic, barium, cadmium, lead, strontium and mercury on the development of HDP.

METHODS

We conducted a systematic literature review according to the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. The search strategy was validated by the Peer Review of Electronic Search Strategies. We searched for articles published up to February 2023 in seven databases without language restriction. Two researchers conducted the steps for selection, data extraction and evaluation of the methodological quality of the instruments for epidemiological studies of the Joanna Briggs Institute. Any disagreements were resolved by a third researcher.

RESULTS

We obtained 5076 records, of which 37 articles met the inclusion criteria moderate to high methodological quality. Single exposure to metal(loid)s was predominant, and the leading biological matrix analyzed to detect the concentrations from exposure was maternal blood. Lead was the metal investigated the most, and had the largest number of studies showing positive association with HDP. In relation to the other metal(loid)s, higher levels were found in women with HDP in comparison with healthy women, but the finding of a cause-effect relationship was inconsistent.

CONCLUSIONS

Although we found evidence of harmful effects of the metal(loid)s studied on human health, the results were inconclusive with regard to HDP. Longitudinal studies that consider prospective investigation, adjustment of confounding factors and the interference of other contaminants in the exacerbation of oxidative stress in women from the preconception phase to the puerperal period should be encouraged.

Cadmium Associated Preeclampsia: A Systematic Literature Review of Pregnancy and Birth Outcomes

Preeclampsia (PE), caused by multiple factors, is one of the most serious complications of pregnancy. Cadmium (Cd) is a heavy metal environmental pollutant, reproductive toxicant, and endocrine disruptor, which can increase the risk of PE. Cd toxicity due to occupational, diet, and environmental factors has worsened the risk. Studies showed elevated Cd concentration in maternal blood and placenta of PE women. However, the implicit association between Cd associated PE is still not highlighted. We systematically reviewed Cd-associated PE and its effect on pregnancy and birth outcomes. Based on "Preferred reporting items for systematic reviews and meta-analyses (PRISMA)" guidelines, eighty-six studies were identified by PubMed, Web of Science (WOS), and Scopus databases. Publications were included until October 2023 and articles screened based on our inclusion criteria. Our study identified that the exposure of controlled and uncontrolled Cd induces PE, which negatively affects pregnancy and birth outcomes. Given the serious nature of this finding, Cd is a potential adverse agent that impacts pregnancy and future neonatal health. Further comprehensive studies covering the whole trimesters of pregnancy and neonatal developments are warranted. Data on the molecular mechanisms behind Cd-induced PE is also essential for potential preventive, diagnostic, or therapeutic targets.

The Relationship Between Heavy Metals and Missed Abortion: Using Mediation of Serum Hormones

Accumulating evidence suggests that heavy metal exposure may have adverse effects on the fetal development. Furthermore, disruption of serum hormone homeostasis can result in the adverse pregnancy outcomes. Therefore, this study aimed to investigate the potential association between heavy metals and missed abortion, with a focus on whether serum hormones mediate this relationship. The concentrations of heavy metals and hormones in serum were measured in this case-control study. Statistical models including, logistic regression model, principal component analysis (PCA), and weighted quantile sum (WQS) regression model were employed to examine the relationship between heavy metals, serum hormones, and missed abortion. Furthermore, the mediation analysis was performed to assess the role of serum hormones as potential mediators in this relationship. This study revealed significant associations between heavy metal exposure and missed abortion. Notable, the WQS index weight, which was mainly influenced by copper (Cu) and zine (Zn), is associated with missed abortion. Moreover, heavy metals including manganese (Mn), nickel (Ni), Zn, arsenic (As), Cu, cadmium (Cd), and lead (Pb) were found to be associated with serum levels of β-human chorionic gonadotropin (β-hCG), progesterone (P), estradiol (E2), and lactogen (HPL). In addition, the mediation analysis indicated that β-hCG explained a portion of the association (ranging from 18.77 to 43.51%) of between Mn, Ni, Zn, and As exposure and missed abortion. Serum P levels explained 17.93 to 51.70% of the association between Ni, Cu, and As exposure and missed abortion. Serum E2 levels played a significant mediating role, explaining a portion of the association (ranging from 22.14 to 73.60%) between Mn, Ni, Cu, As, Cd, and Pb exposure and missed abortion. Our results suggested that β-hCG, P, and E2 are one of the potential mediators in the complex relationship between heavy metals exposure and missed abortion. These results highlight the importance of considering both heavy metal exposure and serum hormone levels in understanding the etiology of missed abortion.

First trimester prenatal metal mixtures, vitamins, and hypertensive disorders of pregnancy in the project viva cohort

BACKGROUND

Hypertensive disorders of pregnancy (HDP) such as preeclampsia and gestational hypertension are major contributors to maternal and child morbidity and mortality. Previous studies have reported associations with selected metals and vitamins but are limited in sample size and non-prospective study designs. We evaluated prospective associations of metal mixtures with HDP and tested interactions by vitamins.

STUDY DESIGN

We measured first trimester (median = 10.1 weeks) concentrations of essential (copper, magnesium, manganese, selenium, zinc) and nonessential (arsenic, barium, cadmium, cesium, mercury, lead) metals in red blood cells (n = 1,386) and vitamins (B12 and folate) in plasma (n = 924) in Project Viva, a pre-birth US cohort. We collected diagnosis of HDP by reviewing medical records. We used multinomial logistic regression and Bayesian Kernel Machine Regression to estimate individual and joint associations of metals with HDP and interactions by vitamins, after adjusting for key covariates.

RESULTS

The majority of participants were non-Hispanic white (72.5 %), never smokers (68.5 %) with a mean (SD) age of 32.3 (4.6) years. Fifty-two (3.8 %) developed preeclampsia and 94 (6.8 %) gestational hypertension. A doubling in first trimester erythrocyte copper was associated with 78 % lower odds of preeclampsia (OR=0.22, 95 % confidence interval: 0.08, 0.60). We also observed significant associations between higher erythrocyte total arsenic and lower odds of preeclampsia (OR=0.80, 95 % CI: 0.66, 0.97) and higher vitamin B12 and increased odds of gestational hypertension (OR=1.79, 95 % CI: 1.09, 2.96), but associations were attenuated after adjustment for dietary factors. Lower levels of the overall metal mixture and essential metal mixture were associated with higher odds of preeclampsia. We found no evidence of interactions by prenatal vitamins or between metals.

CONCLUSION

Lower levels of a first-trimester essential metal mixture were associated with an increased risk of preeclampsia, primarily driven by copper. No associations were observed between other metals and HDP after adjustment for confounders and diet.

Cadmium exposure activates mitophagy through downregulating thyroid hormone receptor/PGC1α signal in preeclampsia

Gestational cadmium exposure increases the risk of preeclampsia. Placenta mitophagy was activated in preeclampsia. The aim of present study was to explore the mechanism of cadmium-induced mitophagy activation and its association with preeclampsia. Mitophagy markers expression levels were detected by quantitative real-time PCR, Western blot, immunofluorescence and immunochemistry in preeclampsia placenta. JEG3 cells were treated with CdCl2, iopanoic acid (IOP), 3-methyladenine and PGC1α SiRNA to verify mechanism of cadmium-induced mitophagy. Mitophagy marker LC3BII/I and P62 expression were increased and mitochondrial membrane receptor protein TOM20 and FUNDC1 expression were decreased in preeclampsia placenta as compared with that in normotension control. Mitophagy marker LC3BII/I and P62 expression were increased and TOM20 and FUNDC1 expression was decreased in CdCl2-treated JEG3 cells. Meanwhile, mitochondrial biogenesis regulator, PGC1α expression was decreased in preeclampsia and CdCl2-treated JEG3 cells. The expressions of LC3B and P62 were increased and the expressions of TOM20, FUNDC1 and PGC1α were decreased in IOP-treated cell. PGC1α SiRNA transfection led to increased expression of LC3BII/I and P62 and decreased expression of TOM20 and FUNDC1. The expression of sFlt1 was increased in preeclampsia placenta, CdCl2-treated cells, in IOP-treated cells and in PGC1α SiRNA transfected cells. 3-methyladenine treatment protected the increased expression of sFlt1 in CdCl2-treated cells, in IOP-treated cells and in PGC1α SiRNA transfected cells. Meanwhile, co-treatment of cadmium and IOP or PGC1αSiRNA led to a reduce expressions of OPA1, MFN1, MFN2 and FUNDC1 as compared to cadmium-treated, IOP-treated and PGC1α SiRNA-treated cells. These results elucidated that maternal cadmium exposure activated placenta mitophagy through downregulation of thyroid hormone receptor signal mediated decreased expression of PGC1α and was associated with the occurrence of preeclampsia.

Association of Blood Manganese and Preeclampsia: A Systematic Review and Meta-analysis

A systematic review and meta-analysis was performed to comprehensively evaluate the association between manganese (Mn) level and preeclampsia (PE) during pregnancy. Relevant observational studies were retrieved by searching Medline, Web of Science, Embase, and Cochrane Library from database inception to May 25, 2023. Pooling results was performed using a random-effects model incorporating heterogeneity. This meta-analysis incorporated 18 observational studies, which included 1113 women with PE and 5480 normotensive pregnant women. Pooled results showed that compared to normotensive control, women with PE had significantly lower blood Mn concentration (standardized mean difference: -0.36, 95% confidence interval: -0.50 to -0.22, p < 0.001; I2 = 67%). Subgroup analysis showed that the results were not significantly affected by study country (African, Asian, or Western), timing of blood sampling (before, at, or after the diagnosis of PE), mean blood Mn level of controls, or numbers of confounding factors adjusted (p for subgroup analysis all > 0.05), while methods for measuring blood Mn levels might affect the results (p for subgroup difference < 0.001). Finally, pooled results of three studies showed that a high level of blood Mn was related to a low risk of PE with blood Mn analyzed in continuous (risk ratio [RR]: 0.71, 95% CI: 0.59 to 0.85, p < 0.001; I2 = 0%) and categorized variables (RR: 0.50, 95% CI: 0.30 to 0.82, p = 0.006; I2 = 32%). In conclusion, a low blood level of Mn may be associated with PE in pregnant women.

An integrative data-centric approach to derivation and characterization of an adverse outcome pathway network for cadmium-induced toxicity

Cadmium is a prominent toxic heavy metal that contaminates both terrestrial and aquatic environments. Owing to its high biological half-life and low excretion rates, cadmium causes a variety of adverse biological outcomes. Adverse outcome pathway (AOP) networks were envisioned to systematically capture toxicological information to enable risk assessment and chemical regulation. Here, we leveraged AOP-Wiki and integrated heterogeneous data from four other exposome-relevant resources to build the first AOP network relevant for inorganic cadmium-induced toxicity. From AOP-Wiki, we filtered 309 high confidence AOPs, identified 312 key events (KEs) associated with inorganic cadmium from five exposome-relevant databases using a data-centric approach, and thereafter, curated 30 cadmium relevant AOPs (cadmium-AOPs). By constructing the undirected AOP network, we identified a large connected component of 18 cadmium-AOPs. Further, we analyzed the directed network of 59 KEs and 82 key event relationships (KERs) in the largest component using graph-theoretic approaches. Subsequently, we mined published literature using artificial intelligence-based tools to provide auxiliary evidence of cadmium association for all KEs in the largest component. Finally, we performed case studies to verify the rationality of cadmium-induced toxicity in humans and aquatic species. Overall, cadmium-AOP network constructed in this study will aid ongoing research in systems toxicology and chemical exposome.

An exploratory study on the association of multiple metals in serum with preeclampsia

Background

Individual metal levels are potential risk factors for the development of preeclampsia (PE). However, understanding of relationship between multiple metals and PE remains elusive.

Purpose

The purpose of this study was to explore whether eight metals [zinc (Zn), manganese (Mn), copper (Cu), nickel (Ni), lead (Pb), arsenic (As), cadmium (Cd), and mercury (Hg)] in serum had a certain relationship with PE.

Methods

A study was conducted in Dongguan, China. The concentrations of metals in maternal serum were assessed using inductively coupled plasma mass spectrometry (ICP-MS). Data on various factors were collected through a face-to-face interview and hospital electronic medical records. The unconditional logistic regression model, principal component analysis (PCA) and Bayesian Kernel Machine Regression (BKMR) were applied in our study.

Results

The logistic regression model revealed that the elevated levels of Cu, Pb, and Hg were associated with an increased risk of PE. According to PCA, principal component 1 (PC1) was predominated by Hg, Pb, Mn, Ni, Cu, and As, and PC1 was associated with an increased risk of PE, while PC2 was predominated by Cd and Zn. The results of BKMR indicated a significant positive cumulative effect of serum metals on PE risk, with Ni and Cu exhibiting a significant positive effect. Moreover, BKMR results also revealed the nonlinear effects of Ni and Cd.

Conclusion

The investigation suggests a potential positive cumulative impact of serum metals on the occurrence of PE, with a particular emphasis on Cu as a potential risk factor for the onset and exacerbation of PE. These findings offer valuable insights for guiding future studies on this concern.

The relationship between cadmium exposure and preeclampsia: a systematic review and meta-analysis

Background

Cadmium (Cd) is a heavy metal associated with several human disorders. Preeclampsia is a major cause of maternal mortality worldwide. The association between maternal Cd exposure and preeclampsia remains elusive.

Methods

To better understand this relationship, we conducted a systematic review and meta-analysis of eligible studies from five databases (PubMed, Embase, Web of Science, Scopus, and CNKI) from their inception to September 10, 2022. The quality of these studies was evaluated using the Newcastle-Ottawa quality assessment scale (NOS). We use random-effects models to calculate overall standardized mean differences (SMDs) and 95% confidence intervals (CIs). Sensitivity analyses were performed to assess the robustness of our results. We also evaluated publication bias using Egger's and Begg's tests. Additionally, we conducted meta-regression and sub-group analyses to identify potential sources of heterogeneity between studies.

Results

Our analysis included a total of 17 studies with 10,373 participants. We found a significant association between maternal cadmium exposure and the risk of preeclampsia (SMD 0.27, 95% CI 0.09-0.44, p < 0.01). No significant publication bias was detected in Begg's or Egger's tests. Meta-regression suggested that geographical location, year of publication, cadmium samples, sample size, and measurement methods did not contribute to heterogeneity between studies.

Conclusion

Our findings suggest that maternal blood cadmium levels are associated with an increased risk of preeclampsia. In contrast, the pregnant women's urine or placental levels of cadmium may not suggest preeclamptic risk during pregnancy. Further high-quality clinical studies and animal experiments are needed to understand this association better.

Systematic review registration

PROSPERO, https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=361291, identifier: CRD42022361291.

Perinatal health effects of herbicides exposures in the United States: the Heartland Study, a Midwestern birth cohort study

BACKGROUND

The objective of the Heartland Study is to address major knowledge gaps concerning the health effects of herbicides on maternal and infant health. To achieve this goal, a two-phased, prospective longitudinal cohort study is being conducted. Phase 1 is designed to evaluate associations between biomarkers of herbicide concentration and pregnancy/childbirth outcomes. Phase 2 is designed to evaluate potential associations between herbicide biomarkers and early childhood neurological development.

METHODS

People (target enrollment of 2,000) who are seeking prenatal care, are ages 18 or older, and are ≤ 20 + 6 weeks gestation will be eligible for recruitment. The Heartland Study will utilize a combination of questionnaire data and biospecimen collections to meet the study objectives. One prenatal urine and buccal sample will be collected per trimester to assess the impact of herbicide concentration levels on pregnancy outcomes. Infant buccal specimens will be collected post-delivery. All questionnaires will be collected by trained study staff and clinic staff will remain blinded to all individual level research data. All data will be stored in a secure REDCap database. Hospitals in the agriculturally intensive states in the Midwestern region will be recruited as study sites. Currently participating clinical sites include Indiana University School of Medicine- affiliated Hospitals in Indianapolis, Indiana; Franciscan Health Center in Indianapolis, Indiana; Gundersen Lutheran Medical Center in La Crosse, Wisconsin, and University of Iowa in Iowa City, Iowa. An anticipated 30% of the total enrollment will be recruited from rural areas to evaluate herbicide concentrations among those pregnant people residing in the rural Midwest. Perinatal outcomes (e.g. birth outcomes, preterm birth, preeclampsia, etc.) will be extracted by trained study teams and analyzed for their relationship to herbicide concentration levels using appropriate multivariable models.

DISCUSSION

Though decades of study have shown that environmental chemicals may have important impacts on the health of parents and infants, there is a paucity of prospective longitudinal data on reproductive impacts of herbicides. The recent, rapid increases in herbicide use across agricultural regions of the United States necessitate further research into the human health effects of these chemicals, particularly in pregnant people. The Heartland Study provides an invaluable opportunity to evaluate health impacts of herbicides during pregnancy and beyond.

TRIAL REGISTRATION

The study is registered at clinicaltrials.gov, NCT05492708 with initial registration and release 05 August, 2022.

Associations between the chemical exposome and pregnancy induced hypertension

Exposure to environmental chemicals has been linked to an increased risk of pregnancy-induced hypertension (PIH). This prospective cohort study examined the associations between PIH and maternal chemical exposure to four classes of chemicals (i.e., phthalates, bisphenols, perfluoroalkyl acids, non-essential metals and trace minerals). Participants included 420 pregnant women from the Alberta Pregnancy Outcomes and Nutrition (APrON) cohort who had data available on diagnosed PIH and environmental chemical exposure. Twelve phthalate metabolites, two bisphenols, eight perfluoroalkyl acids and eleven non-essential metals or trace minerals were quantified in maternal urine or blood samples collected in the second trimester of pregnancy. Associations between the urinary and blood concentrations of these chemicals and PIH were assessed using multiple logistic and LASSO regression analyses in single- and multi-chemical exposure models, respectively. Thirty-five (8.3%) participants were diagnosed with PIH. In single chemical exposure models, two phthalate metabolites, mono-methyl phthalate (MMP) and monoethyl phthalate (MEP), three perfluoroalkyl acids, perfluoroheptanoic acid (PFHpA), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA), and one metal, manganese, were associated with increased odds of PIH. The metabolites of di (2-ethylhexyl) phthalate (DEHP) and the molar sum of these metabolites, as well as antimony, displayed trend associations (p < 0.10). In multi-chemical exposure models using LASSO penalized regressions and double-LASSO regressions, MEP (AOR: 1.43, 95% CI: 1.09-1.88, p = 0.009) and PFNA (AOR: 2.03, 95% CI: 1.01-4.07, p = 0.04) were selected as the chemicals most highly associated with PIH. These findings suggest that maternal levels of phthalates and perfluoroalkyl acids may be associated with the diagnosis on PIH. Future research should consider both individual and multi-chemical exposures when examining predictors of PIH and other maternal cardiometabolic health disorders, such as preeclampsia, eclampsia, HELLP syndrome, and gestational diabetes.

Maternal antioxidant micronutrient deficiencies among pre-eclamptic women in Enugu, Nigeria: a cross-sectional analytical study

OBJECTIVES

To determine the prevalence of antioxidant micronutrient deficiencies in pregnant women with pre-eclampsia and healthy pregnant women, and to assess the relationships between trace element deficiency in pregnancy and the severity of pre-eclampsia in Enugu, Nigeria.

METHODS

We performed a secondary analysis of a cross-sectional analytical study of serum concentrations of copper, selenium, zinc, magnesium, and manganese in 81 pregnant women with pre-eclampsia and healthy pregnant women (controls) who were matched for age, gestational age, body mass index, and parity. This study was performed at the University of Nigeria Teaching Hospital, Ituku-Ozalla, Enugu. Participants' sera were analyzed with an atomic absorption spectrophotometer.

RESULTS

Trace element deficiencies were common and similar between women with pre-eclampsia and controls. However, women with pre-eclampsia were more likely to be deficient in manganese than controls (odds ratio = 2.28, 95% confidence interval: 1.90-2.75). Among the micronutrients studied, only manganese concentrations were significantly lower in women without severe symptoms of pre-eclampsia than in those with severe symptoms of pre-eclampsia.

CONCLUSIONS

Micronutrient deficiency is common in pregnant women with pre-eclampsia and in healthy pregnant women in Enugu, Nigeria. Only manganese deficiency is higher in women with pre-eclampsia than in healthy pregnant women.

The association between dietary mineral intake and the risk of preeclampsia in Chinese pregnant women: a matched case-control study

Previous studies on the relationship between dietary minerals and preeclampsia (PE) have given inconsistent results. The aim of this study was to further clarify the relationship between dietary minerals intake and PE in Chinese pregnant women. In this study, 440 pairs of hospital-based preeclamptic and healthy women were matched 1:1. Dietary intake was obtained through a 78-item semi-quantitative food frequency questionnaire. Multivariate conditional logistic regression was used to estimate the odds ratios (ORs) and 95% confidence intervals (CIs). Restricted cubic splines were plotted to evaluate the dose-response relationship between dietary minerals intake and PE. This study found significant inverse associations for dietary intake of calcium, magnesium, phosphorus, iron, copper, manganese and zinc and the risk of PE in both univariate and multivariate models (all P- trend < 0.05). After adjusting for possible confounders, compared with the lowest quartile, the odds ratio of the highest quartile was 0.74 (95% CI 0.56-0.98) for calcium, 0.63 (95% CI 0.42-0.93) for magnesium, 0.45 (95% CI 0.31-0.65) for phosphorus, 0.44 (95% CI 0.30-0.65) for iron, 0.72 (95% CI 0.53-0.97) for copper, 0.66 (95% CI 0.48-0.91) for manganese and 0.38 (95% CI 0.25-0.57) for zinc. In addition, a reverse J-shaped relationship between dietary minerals intake and PE risk was observed (P-overall association < 0.05). In Chinese pregnant women, a higher intake of dietary minerals, including calcium, magnesium, phosphorus, copper, iron, manganese, and zinc was associated with a lower odds of PE.

In Utero Exposure to Metals and Birth Outcomes in an Artisanal and Small-Scale Gold Mining Birth Cohort in Madre de Dios, Peru

BACKGROUND

Few birth cohorts in South America evaluate the joint effect of minerals and toxic metals on neonatal health. In Madre de Dios, Peru, mercury exposure is prevalent owing to artisanal gold mining, yet its effect on neonatal health is unknown.

OBJECTIVES

We aimed to determine whether toxic metals are associated with lower birth weight and shorter gestational age independently of antenatal care and other maternal well-being factors.

METHODS

Data are from the COhorte de NAcimiento de MAdre de Dios (CONAMAD) birth cohort, which enrolled pregnant women in Madre de Dios prior to their third trimester and obtained maternal and cord blood samples at birth. We use structural equation models (SEMs) to construct latent variables for the maternal metals environment (ME) and the fetal environment (FE) using concentrations of calcium, iron, selenium, zinc, magnesium, mercury, lead, and arsenic measured in maternal and cord blood, respectively. We then assessed the relationship between the latent variables ME and FE, toxic metals, prenatal visits, hypertension, and their effect on gestational age and birth weight.

RESULTS

Among 198 mothers successfully enrolled and followed at birth, 29% had blood mercury levels that exceeded the U.S. Centers for Disease Control and Prevention threshold of 5.8 μ g / L and 2 mothers surpassed the former 5 - μ g / dL threshold for blood lead. The current threshold value is 3.5 μ g / dL . Minerals and toxic metals loaded onto ME and FE latent variables. ME was associated with FE (β = 0.24; 95% CI: 0.05, 0.45). FE was associated with longer gestational age (β = 2.31; 95% CI: - 0.3 , 4.51) and heavier birth weight. Mercury exposure was not directly associated with health outcomes. A 1% increase in maternal blood lead shortened gestational age by 0.05 d (β = - 0.75 ; 95% CI: - 1.51 , - 0.13 ), which at the 5 - μ g / dL threshold resulted in a loss of 3.6 gestational days and 76.5 g in birth weight for newborns. Prenatal care visits were associated with improved birth outcomes, with a doubling of visits from 6 to 12 associated with 5.5 more gestational days (95% CI: 1.6, 9.4) and 319 g of birth weight (95% CI: 287.6, 350.7).

DISCUSSION

Maternal lead, even at low exposures, was associated with shorter gestation and lower birth weight. Studies that focus only on harmful exposures or nutrition may mischaracterize the dynamic maternal ME and FE. SEMs provide a framework to evaluate these complex relationships during pregnancy and reduce overcontrolling that can occur with linear regression. https://doi.org/10.1289/EHP10557.

Effects of Xenobiotic Compounds on Preeclampsia and Potential Mechanisms

Preeclampsia (PE) refers to a disease with new hypertension and albuminuria or other end-organ damage after 20 weeks of pregnancy. As a major complication of pregnancy, PE can increase the morbidity and mortality of pregnant women and fetuses and cause serious social burden. Recently, it has been found that exposure to xenobiotic compounds, especially endocrine disruptors in the environment, may contribute to the development of PE. However, the underlying mechanism is still unclear. It is generally believed that PE is related to placental dysplasia, spiral artery remodelling failure, oxidative stress, etc. Therefore, in order to better prevent the occurrence of PE and reduce the damage and impact on mother and fetus, this paper reviews the role and potential mechanism of PE induced by exogenous chemicals and provides an outlook on the environmental etiology of PE.

Association of Selenium Levels with Preeclampsia: A Systematic Review and Meta-analysis

Several observational studies have shown inconclusive findings on the association between selenium levels and preeclampsia. This systematic review and meta-analysis was conducted to clarify the association between selenium levels and preeclampsia. The databases PubMed, Google Scholar, ScienceDirect, and the Cochrane Library were searched for studies which investigated selenium levels with preeclampsia and which were published up to April 2022. The overall standardized mean differences (SMD) of selenium levels between cases and controls were measured. Sensitivity analysis, reporting bias, subgroup analysis, and meta-regression were performed for the estimate. The meta-analysis was calculated using the "meta" package in the open-source software R. A total of 26 studies with 1855 preeclampsia cases compared with 3728 healthy pregnant controls were included. The level of selenium was significantly lower in cases of preeclampsia compared with the controls [SMD =  - 0.85; 95% confidence interval (CI): (- 1.46, - 0.25); P =  < 0.01). As there was significant heterogeneity [I² = 96%, Cochran's Q = 620.47; P =  < 0.01], the random effects model was used. A stratified meta-analysis revealed that selenium levels were significantly lower in the cases compared with the controls among pregnant women from the African continent [SMD =  - 1.15 (- 1.65, - 0.65); P =  < 0.01]. Likewise, the same pattern was observed among women from middle- and low-income countries [SMD =  - 1.32 (- 2.22, - 0.42); P =  < 0.01]. None of the investigated factors (Modified Newcastle-Ottawa Scale quality score, year of publication, and sample size) showed significant association with the selenium SMD. The level of certainty of this evidence is "low certainty," as calculated by the GRADEpro GDT online tool. This meta-analysis with low level of evidence certainty revealed that low selenium level is associated significantly with preeclampsia. This pattern is also observed in women from the African continent and women from low- or middle-income countries. Further studies with different prospective designs and detailed patient characteristics are needed to consolidate this evidence.

Individual, Independent, and Joint Associations of Toxic Metals and Manganese on Hypertensive Disorders of Pregnancy: Results from the MIREC Canadian Pregnancy Cohort

BACKGROUND

Toxic metals, such as lead (Pb), cadmium (Cd), arsenic (As), and mercury (Hg), may be associated with a higher risk of gestational hypertension and preeclampsia, whereas manganese (Mn) is an essential metal that may be protective.

OBJECTIVES

We estimated the individual, independent, and joint associations of Pb, Cd, As, Hg, and Mn on the risk of developing gestational hypertension and preeclampsia in a cohort of Canadian women.

METHODS

Metal concentrations were analyzed in first and third trimester maternal blood (n = 1,560 ). We measured blood pressure after 20 wk gestation to diagnose gestational hypertension, whereas proteinuria and other complications defined preeclampsia. We estimated individual and independent (adjusted for coexposure) relative risks (RRs) for each doubling of metal concentrations and examined interactions between toxic metals and Mn. We used quantile g-computation to estimate the joint effect of trimester-specific exposures.

RESULTS

Each doubling of third trimester Pb (RR = 1.54 ; 95% CI: 1.06, 2.22) and first trimester blood As (RR = 1.25 ; 95% CI: 1.01, 1.58) was independently associated with a higher risk of developing preeclampsia. First trimester blood As (RR = 3.40 ; 95% CI: 1.40, 8.28) and Mn (RR = 0.63 ; 95% CI: 0.42, 0.94) concentrations were associated with a higher and lower risk, respectively, of developing gestational hypertension. Mn modified the association with As such that the deleterious association with As was stronger at lower concentrations of Mn. First trimester urinary dimethylarsinic acid concentrations were not associated with gestational hypertension (RR = 1.31 ; 95% CI: 0.60, 2.85) or preeclampsia (RR = 0.92 ; 95% CI: 0.68, 1.24). We did not observe overall joint effects for blood metals.

DISCUSSION

Our results confirm that even low blood Pb concentrations are a risk factor for preeclampsia. Women with higher blood As concentrations combined with lower Mn in early pregnancy were more likely to develop gestational hypertension. These pregnancy complications impact maternal and neonatal health. Understanding the contribution of toxic metals and Mn is of public health importance. https://doi.org/10.1289/EHP10825.

Alterations in Antioxidant Micronutrient Concentrations in Placental Tissue, Maternal Blood and Urine and the Fetal Circulation in Pre-eclampsia

Trace elements such as selenium and zinc are vital components of many enzymes, including endogenous antioxidants, and can interact with each other. Women with pre-eclampsia, the hypertensive disease of pregnancy, have been reported as having changes in some individual antioxidant trace elements during pregnancy, which are related to maternal and fetal mortality and morbidity. We hypothesised that examination of the three compartments of (a) maternal plasma and urine, (b) placental tissue and (c) fetal plasma in normotensive and hypertensive pregnant women would allow identification of biologically significant changes and interactions in selenium, zinc, manganese and copper. Furthermore, these would be related to changes in the angiogenic markers, placental growth factor (PlGF) and Soluble Fms-Like Tyrosine Kinase-1 (sFlt-1) concentrations. Venous plasma and urine were collected from healthy non-pregnant women (n = 30), normotensive pregnant controls (n = 60) and women with pre-eclampsia (n = 50) in the third trimester. Where possible, matched placental tissue samples and umbilical venous (fetal) plasma were also collected. Antioxidant micronutrient concentrations were measured by inductively coupled plasma mass-spectrometry. Urinary levels were normalised to creatinine concentration. Plasma active PlGF and sFlt-1 concentrations were measured by ELISA. Maternal plasma selenium, zinc and manganese were all lower in women with pre-eclampsia (p < 0.05), as were fetal plasma selenium and manganese (p < 0.05 for all); maternal urinary concentrations were lower for selenium and zinc (p < 0.05). Conversely, maternal and fetal plasma and urinary copper concentrations were higher in women with pre-eclampsia (p < 0.05). Differences in placental concentrations varied, with lower overall levels of selenium and zinc (p < 0.05) in women with pre-eclampsia. Maternal and fetal PlGF were lower and sFlt-1 higher in women with pre-eclampsia; maternal plasma zinc was positively correlated with maternal plasma sFlt-1 (p < 0.05). Because of perceptions that early- and late-onset pre-eclampsia have differing aetiologies, we subdivided maternal and fetal data accordingly. No major differences were observed, but fetal sample sizes were small following early-onset. Disruption in these antioxidant micronutrients may be responsible for some of the manifestations of pre-eclampsia, including contributing to an antiangiogenic state. The potential benefits of mineral supplementation, in women with deficient intakes, during pregnancy to reduce pre-eclampsia remain an important area for experimental and clinical research.

A bibliometric review of 35 years of studies about preeclampsia

The purpose of this study is to investigate preeclampsia. It used the visualization tools of CiteSpace, VOSviewer, Gunnmap, Bibliometrix®, and Carrot2 to analyze 3,754 preeclampsia studies from 1985 to 2020 in Obstetrics and Gynecology areas. Carrot2 was used to explain each cluster in extra detail. The results found that there is an increasing trend in many publications related to preeclampsia from 1985 to 2020. The number of studies on preeclampsia has increased significantly in the last century. Analysis of the keywords found a strong relationship with preeclampsia concepts and keywords classified into five categories. Co-citation analysis was also performed which was classified into six categories. Reading the article offers important to support not only to grind the context of preeclampsia challenges but also to design a new trend in this field. The number of studies on preeclampsia has substantially improved over the decades ago. The findings of documents published from 1985 to 2020 showed three stages in research on this subject: 1985 to 1997 (a seeding stage), 1997-2005 (rapid growth stage), and 2005 onwards (development stage).

Maternal Mercury Exposure and Hypertensive Disorders of Pregnancy: A Systematic Review

OBJECTIVE

 The present review aimed to synthesize the evidence regarding mercury (Hg) exposure and hypertensive disorders of pregnancy (HDP).

DATA SOURCES

 The PubMed, BVS/LILACS, SciELO and UFRJ's Pantheon Digital Library databases were systematically searched through June 2021.

STUDY SELECTION

 Observational analytical articles, written in English, Spanish, or Portuguese, without time restriction.

DATA COLLECTION

 We followed the PICOS strategy, and the methodological quality was assessed using the Downs and Black checklist.

DATA SYNTHESIS

 We retrieved 77 articles, of which 6 met the review criteria. They comprised 4,848 participants, of which 809 (16.7%) had HDP and 4,724 (97.4%) were environmentally exposed to Hg (fish consumption and dental amalgam). Mercury biomarkers evaluated were blood (four studies) and urine (two studies). Two studies found a positive association between Hg and HDP in the group with more exposure, and the other four did not present it. The quality assessment revealed three satisfactory and three good-rated studies (mean: 19.3 ± 1.6 out 28 points). The absence or no proper adjustment for negative confounding factor, such as fish consumption, was observed in five studies.

CONCLUSION

 We retrieved only six studies, although Hg is a widespread toxic metal and pregnancy is a period of heightened susceptibility to environmental threats and cardiovascular risk. Overall, our review showed mixed results, with two studies reporting a positive association in the group with more exposure. However, due to the importance of the subject, additional studies are needed to elucidate the effects of Hg on HDP, with particular attention to adjusting negative confounding.

A global perspective of correlation between maternal blood lead levels and risks of preeclampsia: An updated systematic review and meta-analysis

Background

Preeclampsia (PE) is a specific hypertensive disorder in pregnancy. Lead (Pb) is a heavy metal that affects women's reproductive health. However, it is unclear whether lead exposure during can predispose maternal risk of developing preeclampsia. This systematic review and meta-analysis study aimed to explore the association.

Methods

We searched studies from three databases (PubMed, Web of Science, Embase). Only case-control, cross-sectional, and cohort studies reporting maternal blood lead levels (BLL) and PE were included from database inception to 31st July 2022. Pregnant women with blood lead levels measured were eligible. Those healthy pregnant women who did not develop preeclampsia were assessed as comparators. Letters, comments, case reports, and reviews were excluded. Newcastle-Ottawa Scale (NOS) and its adaptive form were applied for assessment. The random-effects method (REM) was applied to calculate the standardized mean difference (SMD) with a 95% confidence interval (CI). Stata 16.0 and RevMan 5.3 were the software used for data extraction and analysis.

Results

25 studies out of 1,808 articles made the finalist for systematic reviews, of which 21 underwent further quantity analysis. A total of 1,533 preeclamptic women and 10,998 healthy pregnant controls were included in the meta-analysis. The overall result revealed that maternal lead exposure was significantly higher in women with preeclampsia (SMD: 1.06, 95% CI 0.69, 1.43); (I ² = 96.40%; P = 0.000).

Conclusion

This study demonstrates that maternal lead exposure is associated with preeclampsia during pregnancy. The association is present even in low blood lead levels. The conclusion should be taken seriously and women should avoid unexpected exposure to a lead-containing environment as much as possible.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=347220, identifier: CRD42022347220.

Boston Birth Cohort Profile: Rationale and Study Design

In 1998, the Boston Birth Cohort (BBC) was initiated at Boston Medical Center (BMC) in response to persistently high rates of preterm birth (PTB, defined as birth before 37 weeks of gestation) in the US population and the longstanding profound PTB disparity among Black, Indigenous, and people of color (BIPOC). The BBC encompasses two linked study protocols: The Preterm Birth Study serves as the baseline recruitment in the BBC. It aims to address fundamental questions about the causes and consequences of PTB. The study oversamples preterm babies using a case/control study design, in which cases are defined as mothers who deliver a preterm and/or low birthweight baby (<2500 grams regardless of gestational age). Controls are enrolled at a 2:1 control/case ratio and matched by maternal age (±5 years), self-reported race and ethnicity, and date of delivery (± 7 days for case delivery). From inception, it was designed as a comprehensive gene-environmental study of PTB. As a natural extension, the Children's Health Study, under a separate but linked IRB protocol, is a longitudinal follow-up study of the participants who were recruited at birth in the Preterm Birth Study and who continue pediatric care at BMC. This linked model allows for investigation of early life origins of pediatric and chronic disease in a prospective cohort design. The BBC is one of the largest and longest NIH-funded prospective birth cohort studies in the US, consisting of 8733 mother-child dyads enrolled in the Preterm Birth Study at birth, and of those, 3,592 children have been enrolled in the Children's Health Study, with a median follow-up of 14.5 years. The BBC mirrors the urban, under-resourced and underrepresented BIPOC population served by BMC. A high proportion of BBC children were born prematurely and had chronic health conditions (e.g., asthma, obesity and elevated blood pressure) in childhood. The BBC's long-term goal has been to build a large, comprehensive database (epidemiological, clinical, multi-omics) and biospecimen repository to elucidate early life origins of pediatric and chronic diseases and identify modifiable upstream factors (e.g., psychosocial, environmental, nutritional) to improve health across the life course for BIPOC mothers and children.

Maternal cadmium exposure impairs placental angiogenesis in preeclampsia through disturbing thyroid hormone receptor signaling

Cadmium is a ubiquitous environmental pollutant, which can increase the risk of preeclampsia. This study was designed to determine the mechanism of cadmium exposure during pregnancy impaired placental angiogenesis that was associated with the occurrence of preeclampsia. The effects of cadmium exposure on placental thyroid hormone receptor signaling were explored. JEG3 cells were treated with CdCl₂ (20 μM) and the Dio2 inhibitor, IOP (100 μM). Cadmium levels in maternal blood and placentae were increased in preeclampsia group. Placental angiogenesis of preeclampsia was decreased with decreased expression of PLGF and VEGF and increased expression of sFlt1. Meanwhile, the expression and nuclear translocation of thyroid hormone receptor α were decreased in preeclampsia placenta, as well as the expression of Dio2, but not the expression and nuclear translocation of thyroid hormone receptor β. Furthermore, we found that cadmium exposure downregulated the expression of thyroid hormone receptor α and Dio2, but not the expression of thyroid hormone receptor β in JEG3 cells. Also, we found that cadmium exposure decreased the expression of PLGF and VEGF and increased the expression of sFlt1 in JEG3 cells. IOP pretreatment decreased the expression of PLGF and increased the expression of sFlt1. In conclusion, our results elucidated that cadmium exposure would impair placental angiogenesis in preeclampsia through disturbing thyroid hormone receptor signaling.

Boston Birth Cohort profile: rationale and study design

In1998, the Boston Birth Cohort (BBC) was initiated at Boston Medical Center (BMC) in response to persistently high rates of preterm birth (PTB, defined as birth before 37 weeks of gestation) in the US population and the longstanding profound PTB disparity among Black, Indigenous, and people of color (BIPOC). The BBC encompasses two linked study protocols: The PTB Study serves as the baseline recruitment in the BBC. It aims to address fundamental questions about the causes and consequences of PTB. The study oversamples preterm babies using a case/control study design, in which cases are defined as mothers who deliver a preterm and/or low birthweight baby (<2500 grams regardless of gestational age). Controls are enrolled at a 2:1 control/case ratio and matched by maternal age (±5 years), self-reported race and ethnicity, and date of delivery (± 7 days for case delivery). From inception, it was designed as a comprehensive gene-environmental study of PTB. As a natural extension, the Children's Health Study, under a separate but linked Institutional Review Board protocol, is a longitudinal follow-up study of the participants who were recruited at birth in the PTB Study and who continue pediatric care at BMC. This linked model allows for investigation of early life origins of pediatric and chronic disease in a prospective cohort design. The BBC is one of the largest and longest National Institutes of Health-funded prospective birth cohort studies in the United States, consisting of 8733 mother-child dyads enrolled in the PTB Study at birth, and of those, 3592 children have been enrolled in the Children's Health Study, with a median follow-up of 14.5 years. The BBC mirrors the urban, underresourced, and underrepresented BIPOC population served by BMC. A high proportion of BBC children were born prematurely and had chronic health conditions (e.g., asthma, obesity, and elevated blood pressure) in childhood. The BBC's long-term goal has been to build a large, comprehensive database (epidemiological, clinical, and multiomics) and biospecimen repository to elucidate early life origins of pediatric and chronic diseases and identify modifiable upstream factors (e.g., psychosocial, environmental, and nutritional) to improve health across the life course for BIPOC mothers and children.

The Relationship Between Preeclampsia and Arsenic Concentration in the Peripheral Blood

Preeclampsia (PE) is a pregnancy-specific disorder, which is one of the leading causes of maternal, fetal, and neonatal death, particularly in developing countries. Arsenic (As), which is commonly found in soil and groundwater, has been associated with various complications of pregnancy, such as spontaneous abortion, hypertension, and stillbirth. Hence, the study was used to explore the relationship between PE and blood concentration of As in this study. Blood concentration of As during pregnancy was measured by inductively coupled plasma mass spectrometry (ICP-MS). The results shown that the mean blood concentration of As was gradually increased from the control group to the severe PE group (P < 0.0001). Elevated blood concentration of As was associated with the prevalence of PE (OR = 12.81, 95% CI: 2.43-67.39 and 27.55, 1.75-433.43 for middle and high vs. low). Furthermore, elevated blood concentration of As was associated with the severity of PE. Additionally, we observed that blood concentration of As was associated with the hypoproteinemia (P = 0.001, rs = 0.37). Blood concentration of As was negatively corelated with the mean corpuscular volume (MCV) (P = 0.040, rs =  - 0.23) and positively corelated with the mean corpuscular hemoglobin concentration (MCHC) (P = 0.044, rs = 0.23). Overall, our results indicated that the blood concentration of As can significantly predict the occurrence of PE. Additionally, we provided evidence that blood concentration of As may affect the occurrence of hypoproteinemia. These findings may provide some ideas for the prevention of PE and pregnancy complications.

Exposure to metal mixtures and hypertensive disorders of pregnancy: A nested case-control study in China

Exposure to metals has been linked with the risk of hypertensive disorders of pregnancy (HDP), but little is known about the potential effects of exposure to metal mixtures. Thus, our study aimed to investigated the impact of a complex mixture of metals on HDP, especially the interactions among metal mixtures. We did a population-based nested case-control study from October 2013 to October 2016 in Wuhan, China, including 146 HDP cases and 292 controls. Plasma concentrations of Aluminum (Al), Barium (Ba), Cobalt (Co), Copper (Cu), Lead (Pb), Mercury (Hg), Molybdenum (Mo), Nickel (Ni), Selenium (Se), Strontium (Sr), Thallium (Tl), and Vanadium (V) were measured and collected between 10 and 16 gestational weeks. We employed quantile g-computation, conditional logistic regression models, and Bayesian Kernel Machine Regression (BKMR) to assess the association of individual metals and metal mixtures with HDP risk. In the quantile g-computation, the OR for a joint tertile increase in plasma concentrations was 3.67 (95% CI: 1.70, 7.91). Hg contributed the largest positive weights and followed by Al, Ni, and V. In conditional logistic regression models, concentrations of Hg, Al, Ni, and V were significantly associated with the risk of HDP (p-FDR < 0.05). Compared to the lowest tertiles, the ORs (95% CI) for the highest tertiles of these four metals were 2.67 (1.44, 4.95), 3.09 (1.70, 5.64), 5.31 (2.68, 10.53), and 4.52 (2.26, 9.01), respectively. In the BKMR analysis, we observed a linear positive association between Hg, Al, V, and HDP, and a nonlinear relationship between Ni and HDP. A potential interaction between Al and V was also identified. We found that exposure to metal mixtures in early pregnancy, both individually and as a mixture, was associated with the risk of HDP. Potential interaction effects of Al and V on the risk of HDP may exist.

Dietary factors that affect the risk of pre-eclampsia

Pre-eclampsia affects 3%-5% of pregnant women worldwide and is associated with a range of adverse maternal and fetal outcomes, including maternal and/or fetal death. It particularly affects those with chronic hypertension, pregestational diabetes mellitus or a family history of pre-eclampsia. Other than early delivery of the fetus, there is no cure for pre-eclampsia. Since diet or dietary supplements may affect the risk, we have carried out an up-to-date, narrative literature review to assess the relationship between nutrition and pre-eclampsia. Several nutrients and dietary factors previously believed to be implicated in the risk of pre-eclampsia have now been shown to have no effect on risk; these include vitamins C and E, magnesium, salt, ω-3 long-chain polyunsaturated fatty acids (fish oils) and zinc. Body mass index is proportionally correlated with pre-eclampsia risk, therefore women should aim for a healthy pre-pregnancy body weight and avoid excessive gestational and interpregnancy weight gain. The association between the risk and progression of the pathophysiology of pre-eclampsia may explain the apparent benefit of dietary modifications resulting from increased consumption of fruits and vegetables (≥400 g/day), plant-based foods and vegetable oils and a limited intake of foods high in fat, sugar and salt. Consuming a high-fibre diet (25-30 g/day) may attenuate dyslipidaemia and reduce blood pressure and inflammation. Other key nutrients that may mitigate the risk include increased calcium intake, a daily multivitamin/mineral supplement and an adequate vitamin D status. For those with a low selenium intake (such as those living in Europe), fish/seafood intake could be increased to improve selenium intake or selenium could be supplemented in the recommended multivitamin/mineral supplement. Milk-based probiotics have also been found to be beneficial in pregnant women at risk. Our recommendations are summarised in a table of guidance for women at particular risk of developing pre-eclampsia.

The Maternal-Neonatal Outcomes of Twin Pregnancies with Preeclampsia and Their Association with Assisted Reproductive Technology: A Retrospective Study

Objective: This study aimed to investigate the maternal−neonatal outcomes of twin pregnancies of mothers with preeclampsia and their association with assisted reproductive technology (ART). Methods: A retrospective study on the clinical and maternal−neonatal outcome data of 698 women with twin pregnancies who delivered in our hospital from December 2013 to September 2021 was conducted. Continuous variables were analyzed using a Student’s t-test or Wilcoxon rank-sum test. Categorical variables were analyzed using the Chi-square test. The risk factors of twin pregnancies with preeclampsia were analyzed by logistic regression. Results: The rate of twin pregnancy complicated by preeclampsia was 17.62% (123/698). Logistic regression analysis showed that ART increased the risk of preeclampsia in twin pregnancies (AOR: 1.868, 95% CI: 1.187−2.941). Mothers with preeclampsia carrying twins conceived with ART had a higher rate of delivery at gestational week < 34 (29.9% vs. 12.5%) and asphyxia of the neonate at 5 min after delivery (13.4% vs. 1.8%) than those with preeclampsia conceived without ART (p < 0.05). Conclusions: ART increases the risk of preeclampsia in twin pregnancies and the rate of adverse maternal−neonatal outcomes for twin pregnancies with preeclampsia. The policy of single embryo transfer is a method to reduce the adverse pregnancy outcomes of ART.

Maternal urinary OPE metabolite concentrations and blood pressure during pregnancy: The HOME study

BACKGROUND

Few studies have examined the association between maternal exposure to organophosphate esters (OPEs) and systolic/diastolic blood pressure (SBP/DBP) during pregnancy.

METHODS

We analyzed data from 346 women with a singleton live birth in the HOME Study, a prospective birth cohort in Cincinnati, Ohio, USA. We quantified four OPE metabolites in maternal spot urine samples collected at 16 and 26 weeks pregnancy, standardized by specific gravity. We calculated intraclass correlation coefficients (ICCs). We extracted the first two recorded BP measurements (<20 weeks), the two highest recorded BP measurements (≥20 weeks), and diagnoses of hypertensive disorders of pregnancy (HDP) via chart review. Women with two BP measurements ≥140/90 mmHg or HDP noted in the chart at ≥20 weeks pregnancy were defined as HDP cases. We used linear mixed models and modified Poisson regression with covariate adjustment to estimate associations between OPE concentrations as continuous variables or in tertiles with maternal BP and HDP.

RESULTS

ICCs of OPEs were 0.17-0.45. Diphenyl phosphate (DPHP) had the highest geometric mean concentration among OPE metabolites. Increasing the average bis(2-chloroethyl) phosphate (BCEP) concentrations were positively associated with two highest recorded DBP ≥20 weeks pregnancy. Compared with women in the 1st DPHP tertile, women in the 3rd tertile at 16 weeks pregnancy had 1.72 mmHg (95% CI: -0.01, 3.46) higher DBP <20 weeks pregnancy, and women in the 3rd tertile of the average DPHP concentrations had 2.25 mmHg (95% CI: 0.25, 4.25) higher DBP ≥20 weeks pregnancy. 33 women (9.5%) were identified with HDP. Di-n-butyl phosphate (DNBP) concentrations at 16 weeks were positively associated with HDP, with borderline significance (RR = 2.98, 95% CI 0.97-9.15). Other OPE metabolites were not significantly associated with HDP.

CONCLUSION

Maternal urinary BCEP and DPHP concentrations were associated with increased BP during pregnancy. Maternal urinary DNBP concentrations were associated with HDP, with borderline significance.

Associations of maternal blood mercury with preeclampsia and birth outcomes

BACKGROUND

Mercury (Hg) is a highly toxic substance, and its harmful effects on maternal and infant health have been reported. Yet, the associations of Hg exposure with preeclampsia (PE) and adverse birth outcomes are not well understood.

OBJECTIVE

The aim of this study was to investigate the potential effects of maternal Hg exposure on PE and birth outcomes.

METHODS

We conducted a case-control study with 84 participants in China. Logistic models were used to estimate odds ratios for PE risk and birth outcomes according to maternal blood Hg levels, adjusting for potential confounding factors.

RESULTS

Elevated blood Hg levels were associated with increased risks of mild PE (aOR, 7.03; 95% CI, 1.61, 30.62; P < 0.01) and severe PE (aOR, 47.55; 95% CI, 5.27, 429.05; P < 0.05). We also found that increased blood Hg levels were associated with low birth weight (aOR, 1.12; 95% CI, 1.00, 1.25; P < 0.05) and preterm birth (PTB) (aOR, 1.22; 95% CI, 1.08, 1.38; P < 0.05).

CONCLUSIONS

Our study provided evidence that elevated blood Hg levels were significantly associated with an increased risk of PE. In addition, our findings support that increased blood Hg levels might be associated with low birth weight and PTB.

Circulating trace elements for the prediction of preeclampsia and small for gestational age babies

INTRODUCTION

Poor gestational outcomes due to placental insufficiency can have lifelong consequences for mother and child.

OBJECTIVE

There is a need for better methods of diagnosis, and elemental metabolomics may provide a means to determine the risk of gestational disorders.

METHODS

This study used blood plasma samples collected at 36 weeks' gestation from women who later developed preeclampsia (n = 38), or small-for-gestational age babies (n = 91), along with matched controls (n = 193). Multi-element analysis was conducted by inductively coupled plasma mass spectrometer (ICP-MS), allowing simultaneous measurement of 28 elements.

RESULTS

Women who later developed PE, exhibited significantly increased concentrations of K, Rb and Ba. For SGA pregnancies, there was a significant increase in Cu and a decrease in As concentrations. Despite significant differences in single elements, the elemental profile of groups indicated no clustering of control, PE, or SGA samples. Positive predicative values correctly identified approximately 60% of SGA and 70% of PE samples.

CONCLUSION

This is the first-time elemental metabolomics has been used to predict SGA and PE at 36 weeks. Though significant changes were identified, routine clinical use may be limited but may contribute to a multi marker test. Future analysis should include other biomarkers, metabolic data or clinical measurements made throughout gestation.

Association of Placental Pathology With Childhood Blood Pressure Among Children Born Preterm

BACKGROUND

The in utero pathologies underlying the link between preterm birth and offspring high blood pressure (BP) are still unknown. We investigated the prospective associations of placental histopathological findings with childhood BP among children born preterm.

METHODS

Our study sample included 546 mother-child pairs with preterm birth (before 37 weeks gestation) enrolled from 1999 to 2013 at the Boston Medical Center. Early preterm birth was defined as gestational age between 23 and 34 weeks. We histologically classified maternal placental pathology using the latest recommended categories: no placental complications, histologic chorioamnionitis, maternal vascular malperfusion, and other placental complications. We calculated age-, sex-, and height-specific systolic BP (SBP) percentiles for children using the 2017 American Academy of Pediatrics Clinical Practice Guideline. We used linear regression models with generalized estimating equations to examine the associations.

RESULTS

The mean (standard deviation (SD)) postnatal follow-up of the study children was 9.29 (4.1) years. After adjusting for potential confounders, histologic chorioamnionitis was associated with a 5.42 percentile higher childhood SBP (95% confidence interval: 0.32, 10.52) compared with no placental pathologic findings. This association was stronger among early preterm children. Maternal vascular malperfusion was associated with a 8.44 percentile higher childhood SBP among early preterm children (95% confidence interval: 1.54, 15.34) but the association was attenuated (6.25, 95% confidence interval: -0.76, 13.26) after additional adjustment for child standardized birthweight, a potential mediator of the association.

CONCLUSIONS

These findings suggest that among children born preterm, especially those born early preterm, both placental histologic chorioamnionitis and vascular malperfusion may help to differentiate a child's risk of high BP.

The impacts of different anticoagulants and long-term frozen storage on multiple metal concentrations in peripheral blood: a comparative study

It is important but remains unclear whether ethylenediaminetetraacetic acid (EDTA) and sodium heparin anticoagulants have different impacts on the levels of various metals in peripheral blood after long-term frozen storage. The concentrations of 22 metals (Al, As, Ba, Ca, Cd, Cr, Co, Cu, Mn, Mg, Mo, Ni, Fe, Pb, Rb, Se, Sn, Sb, Sr, Ti, V, Zn) in whole blood, blood cells and plasma from 22 healthy participants were determined twice, 18 months apart, using inductively coupled plasma mass spectrometry (ICP-MS). The mean percentage error (MPE) and intraclass correlation coefficient (ICC) were calculated to evaluate the impact of the anticoagulants and long-term frozen storage on metal concentrations, respectively. The concentrations of Sb and Ba in whole blood, blood cells and plasma were significantly altered by EDTA and sodium heparin at two measurement timepoints (P < 0.05 and MPE > 80%). In EDTA tubes, the Ti and Ni concentrations in blood cells were changed significantly; and in heparin tubes, the concentrations of Ni and Mo in blood cells and Sb in plasma were also altered (P < 0.05 and MPE > 80%). The ICCs of 11 metals in whole blood, 15 metals in blood cells and 16 metals in plasma remained unchanged in EDTA tubes, and 16 metals in whole blood, 15 metals in blood cells and 17 metals in plasma remained unchanged in heparin tubes (ICC > 0.40). Our study suggested the use of EDTA tubes to determine Sb concentrations in peripheral blood and heparin tubes to determine Ba concentrations. Additionally, heparin tubes may be more suited for determining multiple metal concentrations in whole blood, whereas for blood cells and plasma either EDTA or heparin tubes could be used.

Exposure to heavy metals and trace minerals in first trimester and maternal blood pressure change over gestation

BACKGROUND

While several heavy metals and trace minerals have been linked with hypertensive disorders during pregnancy (HDP) in women, no studies have estimated the relationship of exposure to these chemicals, both independently and as a mixture, with systolic blood pressure (SBP) or diastolic blood pressure (DBP) over gestation.

OBJECTIVES

We examined individual and joint effects of 1^st trimester chemicals with SBP and DBP over gestation, and whether those chemicals were associated with HDP.

METHODS

We used data from 1832 non-obese pregnant women with low-risk antenatal profiles from the Eunice Kennedy Shriver National Institute of Child Health and Human Development Fetal Growth Studies - Singleton cohort (2009-2013). In plasma collected from women at 8-13 weeks' gestation (baseline enrollment), we measured heavy metals, barium (Ba), cesium (Cs), antimony (Sb), as well as trace minerals, cobalt (Co), copper (Cu), molybdenum (Mo), selenium (Se), and zinc (Zn). We obtained BP at baseline and throughout gestation until delivery and diagnosis of HDP from medical records. We used Bayesian Kernel Machine Regression (BKMR) as well as traditional linear and logistic regressions to examine the cross-sectional associations of chemicals with baseline BP and HDP. We used linear mixed effect regression to examine longitudinal associations between chemicals and rate of weekly change in BP in each trimester. We adjusted for sociodemographic and lifestyle factors and pre-pregnancy body mass index in all models.

RESULTS

BKMR revealed that comparing the entire chemical mixture at the 90^th percentile vs. the 50^th percentile was associated with a 1.61 mmHg (95% CI: 0.41, 2.81) higher SBP and a 1.09 mmHg (0.10, 2.09) higher DBP. No interactions were observed between chemicals. Accounting for chemical co-exposure in BKMR, each interquartile range (IQR) increment in Cu was associated with a 0.67 mmHg (0.02, 1.32) higher SBP and a 0.60 mmHg (0.08, 1.12) higher DBP at baseline; each IQR increment in Se was associated with a 0.67 mmHg (0.05, 1.29) higher SBP but not DBP. In longitudinal analyses, women with higher (i.e., above median concentration) baseline Cu had a 0.09 mmHg (0.01, 0.17) and 0.06 mmHg (0.001, 0.12) larger weekly decrease in SBP and DBP in 2^nd trimester, respectively. Women with higher baseline Ba had a 0.12 mmHg (0.04, 0.20) larger weekly increase in SBP in 2^nd trimester, while women with higher Cs had a 0.05 mmHg (0.01, 0.10) larger weekly increase in DBP in 3^rd trimester. None of the chemicals examined were significantly associated with HDP.

CONCLUSIONS

In this multi-ethnic cohort of women with low antenatal risk, plasma metals and trace minerals in early pregnancy, both individually and as a mixture, were statistically significantly associated with BP during gestation in small magnitude and in different directions, but not with HDP. The implications of these findings for women's postpartum BP and future cardiovascular health remains to be investigated.

In Utero Exposure to Heavy Metals and Trace Elements and Childhood Blood Pressure in a U.S. Urban, Low-Income, Minority Birth Cohort

BACKGROUND

In utero exposure to heavy metals lead (Pb), mercury (Hg), and cadmium (Cd) may be associated with higher childhood blood pressure (BP), whereas trace elements selenium (Se) and manganese (Mn) may have protective antioxidant effects that modify metal-BP associations.

OBJECTIVES

We examined the individual and joint effects of in utero exposure to Pb, Hg, Cd, Se, and Mn on childhood BP.

METHODS

We used data from the Boston Birth Cohort (enrolled 2002-2013). We measured heavy metals and trace elements in maternal red blood cells collected 24-72 h after delivery. We calculated child BP percentile per the 2017 American Academy of Pediatrics Clinical Practice Guideline. We used linear regression models to estimate the association of each metal, and Bayesian kernel machine regression (BKMR) to examine metal coexposures, with child BP between 3 to 15 years of age.

RESULTS

Our analytic sample comprised 1,194 mother-infant pairs (61% non-Hispanic Black, 20% Hispanic). Hg and Pb were not associated with child systolic BP (SBP). Se and Mn were inversely associated with child SBP percentiles, which, on average, were 6.23 points lower with a doubling of Se (95% CI: -11.51, -0.96) and 2.62 points lower with a doubling of Mn (95% CI: -5.20, -0.04). BKMR models showed similar results. Although Cd was not associated with child SBP overall, the inverse association between Mn and child SBP was stronger at higher levels of Cd (p-interaction=0.04). Consistent with this finding, in utero exposure to cigarette smoke modified the Mn-child SBP association. Among children whose mothers smoked during pregnancy, a doubling of Mn was associated with a 10.09-point reduction in SBP percentile (95% CI: -18.03, -2.15), compared with a 1.49-point reduction (95% CI: -4.21, 1.24) in children whose mothers did not smoke during pregnancy (p-interaction=0.08).

CONCLUSION

Se and Mn concentrations in maternal red blood cells collected 24-72 h after delivery were associated with lower child SBP at 3 to 15 years of age. There was an interaction between Mn and Cd on child SBP, whereby the protective association of Mn on child SBP was stronger among mothers who had higher Cd. The association of Mn and child SBP was also modified by maternal cigarette smoking-a source of Cd-during pregnancy. Optimizing in utero Se levels, as well as Mn levels in women who had high Cd or smoked during pregnancy, may protect offspring from developing high BP during childhood. https://doi.org/10.1289/EHP8325.

Exposure to toxic metals and per- and polyfluoroalkyl substances and the risk of preeclampsia and preterm birth in the United States: a review

Preeclampsia and preterm birth are among the most common pregnancy complications and are the leading causes of maternal and fetal morbidity and mortality in the United States. Adverse pregnancy outcomes are multifactorial in nature and increasing evidence suggests that the pathophysiology behind preterm birth and preeclampsia may be similar-specifically, both of these disorders may involve abnormalities in placental vasculature. A growing body of literature supports that exposure to environmental contaminants in the air, water, soil, and consumer and household products serves as a key factor influencing the development of adverse pregnancy outcomes. In pregnant women, toxic metals have been detected in urine, peripheral blood, nail clippings, and amniotic fluid. The placenta serves as a "gatekeeper" between maternal and fetal exposures, because it can reduce or enhance fetal exposure to various toxicants. Proposed mechanisms underlying toxicant-mediated damage include disrupted placental vasculogenesis, an up-regulated proinflammatory state, oxidative stressors contributing to prostaglandin production and consequent cervical ripening, uterine contractions, and ruptured membranes and epigenetic changes that contribute to disrupted regulation of endocrine and immune system signaling. The objective of this review is to provide an overview of studies examining the relationships between environmental contaminants in the US setting, specifically inorganic (eg, cadmium, arsenic, lead, and mercury) and organic (eg, per- and polyfluoroalkyl substances) toxicants, and the development of preeclampsia and preterm birth among women in the United States.

Association of blood lead levels with preeclampsia: A cohort study in China

BACKGROUND

Preeclampsia is the main cause of maternal and perinatal death, especially in developing countries. Multiple studies suggest that blood lead levels in pregnancy are a risk factor for preeclampsia, even with low levels of blood lead. But less knows the dose-effect relationship of preeclampsia in low blood lead levels.

OBJECTIVES

This study aims to assess the association between blood lead levels and preeclampsia and to explore its dose-effect relationship between low blood lead levels and preeclampsia.

METHODS

The retrospective cohort study was consecutively conducted in a comprehensive tertiary hospital in Foshan city of Guangdong Province, China, from August 1, 2019, to November 30, 2019. Blood lead levels were measured in maternal whole blood in 12-27 (+6) weeks of pregnancy, using atomic absorption spectrometer. Preeclampsia diagnosis was ascertained from the electronic medical records system. The risk of preeclampsia was estimated by multivariable logical regression analysis, and a two-stage linear regression model was established to find out the dose-effect.

RESULTS

A total of 2174 people were included in this study, and 59 (2.7%) women developed preeclampsia. The dose-effect analysis revealed a non-linear association between blood lead levels and the risk of preeclampsia, with a cut-off point at 4.2 μg/dl. When blood lead levels were over 4.2 μg/dl, the risk of preeclampsia increased significantly with an increase in blood lead levels (OR = 2.05, 95%CI: 1.50, 2.81). In the multivariate regression models, per 1 μg/dl increment in blood lead levels was associated with 43% higher risk of developing preeclampsia (OR = 1.43,95%CI:1.17,1.74). Moreover, the association between blood lead levels and preeclampsia was stable in different subgroups.

CONCLUSIONS

Low levels of lead exposure had a dose-effect relationship of preeclampsia, with a cut-off point at 4.2 μg/dl. Blood lead levels had a non-linear association with preeclampsia. When the blood lead levels were higher than 4.2 μg/dl, the risk of preeclampsia increases by 105% for every 1 μg/dl increase in blood lead levels.

A Nonlinear Relation Between Maternal Red Blood Cell Manganese Concentrations and Child Blood Pressure at Age 6-12 y: A Prospective Birth Cohort Study

BACKGROUND

Although manganese (Mn) is an essential trace element and a common component of most multivitamins on the market, an adverse effect on blood pressure (BP) has been reported in adults. In addition, the longitudinal relation between prenatal Mn status and childhood BP is still unknown.

OBJECTIVE

This study investigated the association between prenatal Mn concentrations and risk of elevated BP at ages 3-12 y.

METHOD

The analyses included 1268 mother-child dyads who were enrolled at birth and followed prospectively at the Boston Medical Center. Maternal RBC Mn concentrations were measured by inductively coupled plasma mass spectrometry, using RBCs collected within 1-3 d after delivery (reflecting late-pregnancy Mn exposure). Child elevated BP was defined as systolic or diastolic BP ≥90th percentile for a given age, sex and height. Multivariate logistic regression models were conducted. Path analysis was applied to mediation estimation.

RESULTS

The median (IQR) maternal RBC Mn concentration was 37.5 (29.2-48.5) μg/L. The rate of child elevated BP at ages 3-12 y was 25%. Both the lowest and highest quartiles of maternal RBC Mn concentrations were associated with higher risk of elevated BP among children aged 6-12 y (OR: 1.52; 95% CI: 1.04, 2.21 and OR: 1.65; 95% CI: 1.13, 2.40, respectively) compared with those in the second and third quartiles. Gestational age and fetal growth mediated the association between low maternal RBC Mn (first quartile) and child elevated BP, explaining 25% of the association, but not for high (fourth quartile) maternal RBC Mn concentrations. No association was found between maternal RBC Mn concentrations and BP among children aged 3-5 y.

CONCLUSION

We found a nonlinear association between maternal RBC Mn concentrations and elevated BP among children aged 6-12 y from a high-risk, predominantly minority population. Our findings warrant further investigation.