Associations of maternal blood mercury with preeclampsia and birth outcomes

Preeclampsia risk factors in French Guiana: a great heterogeneity among populations and geographic areas

BACKGROUND

French Guiana is France's largest overseas territory, accounting for 1/6th of mainland France. French Guiana has the highest fertility rate in France and Latin America. However, infant mortality, especially neonatal mortality, remains 2.6 times higher than in mainland France. Preeclampsia was found to be the most important pregnancy-related condition contributing to preterm birth in the primary analysis of risk factors for preterm birth in French Guiana.

METHODS

Therefore, by analyzing the Registre des Issues de Grossesse de Guyane (RIGI), we sought to better describe this condition and understand its risk factors in our area. A retrospective and comparative study was conducted using 2014-2020 data from the RIGI, which describes 53,522 viable births (≥22 weeks of amenorrhea) in all four perinatal facilities in French Guiana. The RIGI is performed by midwives after patients' delivery. It records data up to two hours postpartum.

RESULTS

During the study 12.9% of children were born preterm at less than 37 WA (weeks of amenorrhea). 4.5% of the study population had preeclampsia, of which almost half, 49.5%, were expected to deliver prematurely. The Afro-Caribbean population has a higher risk of preeclampsia than the white population, more than double that of the caucasians. Despite adjustment for place of birth, there are spatial heterogeneities in preeclampsia, with an increased risk for residents of towns in western French Guiana.

CONCLUSION

In conclusion, preeclampsia is a major cause of preterm birth and morbidity in French Guiana. The great heterogeneity between populations and geographical areas requires specific blood tests such as angiogenic balance or still heavy metal assays.

The association between mercury exposure during pregnancy and adverse birth outcomes: A systematic review and meta-analysis

Studies have shown that mercury (Hg) exposure during pregnancy is associated with adverse birth outcomes (ABO) in infants, but the association between the two has not been systematically summarized. Therefore, we conducted a systematic review and meta-analysis of existing observational studies on the association between maternal Hg exposure (MHE) during pregnancy and ABO in infants to evaluate the association between them. We comprehensively searched all relevant literature published in three electronic databases (Web of Science, PubMed, Embase) from 2004 to June 2024. According to the heterogeneity, fixed effect model (I2 ≤ 50 %) or random effect model (I2 > 50 %) was used to pool the associated effect values. The results showed a positive association between MHE and low birth weight (LBW) (OR = 1.079, 95 % CI: 1.032-1.128) and no statistically significant association between and preterm birth (PTB) (OR = 1.044, 95 % CI: 0.956-1.140) and small-for-gestational-age (SGA) (OR = 1.006, 95 % CI: 0.983-1.030). In addition, each 10-fold increase in MHE during pregnancy was associated with abnormal Birth Anthropometrics. These findings suggest that MHE is a risk factor for LBW and is associated with abnormal anthropometric measurements at birth. However, there is insufficient evidence for Hg exposure and SGA, PTB. Further population-based studies are warranted to investigate these associations.

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.

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.

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.

Periconceptional maternal diet quality influences blood heavy metal concentrations and their effect on low birth weight: the Japan Environment and Children's Study

BACKGROUND

Both poor maternal nutrition and toxic heavy metal exposure influence foetal growth and development. However, whether consumption of a variety of healthy foods modifies the association between prenatal heavy metal exposure and foetal growth is unknown.

OBJECTIVE

We examined whether long-term maternal diet quality in periconception modifies the associations between maternal circulating concentrations of heavy metals and foetal growth.

DESIGN

Data of 72,317 Japanese women who delivered singleton infants was extracted from the Japan Environment and Children's Study. Maternal diet over a 1-year before the first trimester of pregnancy was assessed using a validated food frequency questionnaire, and overall diet quality was determined using the balanced diet score based on the Japanese Food Guide Spinning Top. Maternal whole-blood concentrations of mercury (Hg), lead (Pb) and cadmium (Cd) were measured during the second/third trimester of pregnancy. Bayesian inference of multiple linear regression analysis was performed to evaluate the relationships between maternal diet quality and the blood concentrations of heavy metals; Bayesian logistic regression was used to analyse the risk of low birth weight (LBW; <2,500 g).

RESULTS

After controlling for confounders, a high maternal balanced diet score was associated with low concentrations of blood Pb and Cd and high Hg. While all heavy metals assessed were positively associated with LBW risk, a higher maternal balanced diet score was negatively associated with LBW risk. A high-quality maternal diet attenuated the effect of Pb on LBW, an effect that was more marked at high blood Pb concentrations.

CONCLUSION

A high-quality, 'well-balanced' diet prior to conception may reduce exposure to some heavy metals and mitigate the elevated risk of LBW associated with prenatal Pb exposure in Japanese mother-child pairs.