Is the Concentration of Cadmium, Lead, Mercury, and Selenium Related to Preterm Birth?

Australasian recurrent pregnancy loss clinical management guideline 2024, part II

Part II of the Australasian guideline for the investigation and management of recurrent pregnancy loss (RPL) provides evidence-based guidance on the management of RPL provided. The implications of inherited and acquired thrombophilia with respect to RPL and suggestions for clinical management are provided. Autoimmune factors, including human leukocyte antigen, cytokines, antinuclear antibodies and coeliac antibodies, and guidance for management are discussed. Infective, inflammatory and endometrial causes of RPL are discussed in detail. Environmental and lifestyle factors, male factor and unexplained causes are outlined. Levels of evidence and grades of consensus are provided for all evidence-based statements.

Potential role of selenium in modifying the effect of maternal methylmercury exposure on child neurodevelopment - A review

Selenium (Se) is an essential trace element for normal neurodevelopment. It is incorporated into multiple selenoenzymes which have roles in the brain and neurological function, the synthesis of thyroid hormones, the antioxidant defense system, DNA synthesis, and reproduction. Fish is a source of both Se and neurotoxic methylmercury (MeHg). Selenium is known to ameliorate the effects of MeHg in experimental animals, but studies in children exposed to both Se and MeHg through prenatal fish consumption have been inconclusive. Research on Se's implications for pregnancy and child neurodevelopment is limited. The aims of this review are to summarize the literature on the biological roles of Se during pregnancy and the potential role in mitigating the effects of MeHg exposure from fish consumption on human health. This review has shown that Se concentrations among pregnant women globally appear insufficient, with the majority of pregnant women reporting Se concentrations below 70 µg/L during pregnancy. The role of Se in child development and its interactions with MeHg in children are inconclusive. Further investigation of the interaction between Se and MeHg in relation to child neurodevelopment in high fish-eating populations is required to fully elucidate effects.

Serum Cu, Zn and IL-1β Levels May Predict Fetal Miscarriage Risk After IVF Cycles: A Nested Case-Control Study

To explore the association between serum-related indicators (levels of inflammatory cytokines and essential trace elements) and miscarriage risk among infertile women undergoing assisted reproductive techniques (ART) on the 14th day after embryo transfer, and to develop and establish a multivariable algorithm model that might predict pregnancy outcome. According to a nested case-control study design, a total of 100 miscarriage cases and 100 live birth controls were included in this study, and women in both groups were infertile and have underwent in vitro fertilization (IVF). Pregnancy tests were performed and serum levels of five essential trace elements (vanadium (V), copper (Cu), zinc (Zn), selenium (Se) and molybdenum (Mo)) and five inflammatory cytokines (interleukin-1β (IL-1β), IL-6, IL-8, IL-10 and tumor necrosis factor-α (TNF-α)) of the participants were measured on the 14th day after embryo transfer. The serum levels of five inflammatory cytokines were determined by multiple magnetic bead enzyme immunity analyzer; and the serum concentrations of five elements were determined simultaneously by inductively coupled plasma‒mass spectrometry (ICP ‒ MS). The logistic regression was used to evaluate the relationship between these serum indices and miscarriage risk among women undergoing ART, and a predictive model of pregnancy outcome based on these indices was established. The levels of IL-10, IL-1β and TNF-α of infertile women in the live birth group were significantly higher than those in the miscarriage group (p = 0.009, p < 0.001, p = 0.006), and the levels of V, Cu, Zn and Se of infertile women in the live birth group were also significantly higher than those in the miscarriage group (all p < 0.001). Through logistic regression analyses, we found that serum levels of IL-1β, TNF-α, V, Cu, Zn and Se were significantly and negatively associated with miscarriage risk. Different combination prediction models were generated according to the results of logistic regression analyses, and the combination of IL-1β, Cu and Zn had the best prediction performance. The area under the curve (AUC) was 0.776, the sensitivity of the model was 60% and the specificity was 84%. In conclusion, the serum-related indicators of women undergoing ART on the 14th day after embryo transfer, including the inflammatory cytokines such as IL-1β and TNF-α and the essential trace metal elements such as V, Cu, Zn and Se, were negatively correlated with miscarriage risk. A multivariate algorithm model to predict pregnancy outcome among women undergoing ART was established, which showed that IL-1β, Cu and Zn might synergistically predict pregnancy outcome.

Current Levels of Environmental Exposure to Cadmium in Industrialized Countries as a Risk Factor for Kidney Damage in the General Population: A Comprehensive Review of Available Data

The growing number of reports indicating unfavorable outcomes for human health upon environmental exposure to cadmium (Cd) have focused attention on the threat to the general population posed by this heavy metal. The kidney is a target organ during chronic Cd intoxication. The aim of this article was to critically review the available literature on the impact of the current levels of environmental exposure to this xenobiotic in industrialized countries on the kidney, and to evaluate the associated risk of organ damage, including chronic kidney disease (CKD). Based on a comprehensive review of the available data, we recognized that the observed adverse effect levels (NOAELs) of Cd concentration in the blood and urine for clinically relevant kidney damage (glomerular dysfunction) are 0.18 μg/L and 0.27 μg/g creatinine, respectively, whereas the lowest observed adverse effect levels (LOAELs) are >0.18 μg/L and >0.27 μg/g creatinine, respectively, which are within the lower range of concentrations noted in inhabitants of industrialized countries. In conclusion, the current levels of environmental exposure to Cd may increase the risk of clinically relevant kidney damage, resulting in, or at least contributing to, the development of CKD.

Maternal and fetal exposure to metal (loid)s, maternal nutrition status, and impact on prenatal growth in an energy rich zone and an urban area along the Persian Gulf

The main purposes of the study were to determine whether maternal and cord blood (MB and CB) levels of metal (loid)s (MLs) are different between industrial and urban areas. Subjects were derived from the petrochemical and gas area (PGA) of Asaluyeh County and the urban area (UA) of Bushehr County in Iran. Adjusted models revealed significant differences between the PGA and UA for maternal Fe, Cu, Mg, Cd, Zn, Ni, V and Pb levels, likewise cord Cu, V, Pb and Ni levels, which were higher in the PGA. Unadjusted models revealed there were decreases in neonatal weight and head circumference by 16.550 g and 0.059 cm, respectively for each Ln unit increase in maternal Cr levels. The mean blood levels of MLs significantly associated with food consumption frequency. The MLs were detected at higher levels in the body's fetuses and their mothers who resided in the PGA than those from the UA. So, the fetuses of mothers living in an industrial areas may be at higher risk from anthropometric measures. The impact of prenatal exposure to MLs on prenatal growth should be considered for better understanding in the further studies.

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.

Provision of Small-Quantity Lipid-Based Nutrient Supplements Increases Plasma Selenium Concentration in Pregnant Women in Malawi: A Secondary Outcome of a Randomized Controlled Trial

Background

Pregnant women in Malawi are at risk of selenium deficiency, which can have adverse effects on pregnancy outcomes. Interventions for improving selenium status are needed.

Objectives

To assess the effect of provision of small-quantity lipid-based nutrient supplements (SQ-LNSs) to Malawian women during pregnancy on their plasma selenium concentrations at 36 wk of gestation.

Methods

Pregnant women (≤20 wk of gestation) were randomly assigned to receive daily either: 1) iron and folic acid (IFA); 2) multiple micronutrients (MMN; 130 µg selenium per capsule); or 3) SQ-LNS (130 µg selenium/20 g). Plasma selenium concentrations were measured by inductively coupled plasma mass spectrometry at baseline and after ≥16 wk of intervention (at 36 wk of gestation) and compared by intervention group.

Results

At 36 wk of gestation, median (quartile 1, quartile 3) plasma selenium concentrations (micromoles per liter) were 0.96 (0.73, 1.23), 0.94 (0.78, 1.18), and 1.01 (0.85, 1.28) in the IFA, MMN, and SQ-LNS groups, respectively. Geometric mean (GM) plasma selenium concentration was 5.4% (95% CI: 1.8%, 9.0%) higher in the SQ-LNS group than in the MMN group and tended to be higher than in the IFA group (+4.2%; 95% CI: 1.0%, 7.8%). The prevalence of adjusted plasma selenium concentrations <1 µmol/L was 55.1%, 57.8%, and 47.3% in the IFA, MMN, and SQ-LNS groups, respectively; it was lower in the SQ-LNS group than in the MMN group, OR = 0.44 (95% CI: 0.24, 0.83), and tended to be lower than in the IFA group, OR = 0.54 (95% CI: 0.29, 1.03). There was a significant interaction between baseline plasma selenium concentration and intervention group (P = 0.003). In the lowest tertile of baseline selenium concentrations, GM plasma selenium concentration was higher, and the prevalence of low values was lower in the SQ-LNS group compared with the MMN and IFA groups at 36 wk of gestation (P ≤ 0.007).

Conclusions

Provision of SQ-LNS containing selenium to pregnant women can be an effective strategy for improving their selenium status.This trial was registered at clinicaltrials.gov (identifier: NCT01239693).

Distribution of mercury in serum and blood cells and risk of spontaneous preterm birth: A nested case-control study in China

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

Quadrupole inductively coupled plasma mass spectrometry and sector field ICP-MS: a comparison of analytical methods for the quantification of As, Pb, Cu, Cd, Zn, and U in drinking water

A comparison was carried out between quadrupole inductively coupled plasma mass spectrometry (ICP-QMS) detection and sector field ICP-MS (ICP-SFMS) detection for quantification of elements such as arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), zinc (Zn), and uranium (U) in drinking water. A drinking water sample obtained from the International Atomic Energy Agency was used for validation measurement methods. ICP-QMS and ICP-SFMS obtained recoveries of 95–107% and 95–105%, respectively. Moreover, the relative standard deviation for ICP-QMS was <5% in comparison with ICP-SFMS, which was <2%. The limits of detection obtained in ICP-MS and ICP-SFMS for each element were under ng L−1, except for Zn. Both methods were applied to evaluate these elements in drinking water for consumption in Mexico. According to Mexican Regulation for Human Drinking Water NOM-201-SSA1-2015 and Environmental Protection Agency (EPA) from the United States, the values are within the allowable limits. In conclusion, ICP-QMS and ICP-SFMS are excellent choices for measurements of these toxic elements in water samples because of high precision and accuracy in routine analysis minutes, while also exhibiting excellent precision and accuracy in routine analysis.

Prenatal Environmental Metal Exposure and Preterm Birth: A Scoping Review

Preterm birth (PTB) and its complications are the leading causes of under-five year old child deaths, accounting worldwide for an estimated one million deaths annually. The etiology of PTB is complex and multifactorial. Exposures to environmental metals or metalloids are pervasive and prenatal exposures to them are considered important in the etiology of PTB. We conducted a scoping review to determine the extent of prenatal exposures to four metals/metalloids (lead, mercury, cadmium and arsenic) and their association with PTB. We reviewed original research studies published in PubMed, Embase, the Cochrane Library, Scopus, POPLINE and the WHO regional indexes from 2000 to 2019; 36 articles were retained for full text review. We documented a higher incidence of PTB with lead and cadmium exposures. The findings for mercury and arsenic exposures were inconclusive. Metal-induced oxidative stress in the placenta, epigenetic modification, inflammation, and endocrine disruptions are the most common pathways through which heavy metals and metalloids affect placental functions leading to PTB. Most of the studies were from the high-income countries, reflecting the need for additional data from low-middle-income countries, where PTB rates are higher and prenatal exposure to metals are likely to be just as high, if not higher.

Serum nickel is associated with craniosynostosis risk: Evidence from humans and mice

BACKGROUND

To date, few studies have explored the effects of exposure to metal mixtures on adverse developmental outcomes, and no reported studies have linked metal exposure to craniosynostosis (CS). The purpose of this study is to investigate the association between metal exposure and the risk of CS by conducting epidemiological and experimental studies.

METHODS

Inductively coupled plasma mass spectrometry (ICP-MS) was used to measure the concentrations of 6 metals (chromium [Cr], nickel [Ni], tin [Sn], arsenic [As], thallium [Tl], and lead [Pb]) in serum samples from 174 CS patients and 85 control individuals. Non-syndromic patients with isolated sagittal suture closure were selected as the case group, and healthy children matched by sex and age were selected as controls. Bayesian kernel machine regression (BKMR) models were used to account for joint metal effects. Multiple logistic regression analysis was used to explore the association between metal concentration and CS occurrence, with adjustment for potential confounders. During pregnancy, mice were exposed to Ni (0, 0.05, or 0.1 g/kg/day) until weaning, and the widths of the sutures and shapes of the skull were analysed by micro-CT 3D imaging and histological analysis. MC3T3-E1 cells were treated with Ni (0, 0.005, or 0.05 μg/mL) for 72 h. Alkaline phosphate (ALP) staining and Alizarin red staining were performed to observe the development of osteoblasts. The expression levels of osteoblast-related genes were also detected.

RESULTS

A positive association between the metal mixture and CS risk was observed based on population data; the Ni group had the highest conditional posterior inclusion probability (PIP), at 0.8416, and in the fully adjusted model, the highest Ni exposure level had a more significant association with CS (coefficient = 2.65, 95% CI: 0.29, 5.02) than the lowest Ni exposure level. The mean widths of the sagittal sutures in mice were 8.8 ± 0.6 mm in the control group, 8.0 ± 0.8 mm in the 0.05 g/kg/day group and 6.8 ± 0.4 mm in the 0.1 g/kg/day group. After Ni exposure, ALP gene expression in skull tissue was increased, and ALP activity was increased in MC3T3-E1 cells. Moreover, increased collagen content in mouse skull sections and elevated osteocalcin (OCN) expression in MC3T3-E1 cells were observed in the Ni-treated groups compared to the control group.

CONCLUSIONS

This study is the first to provide evidence that increased serum Ni was associated with an increased risk of CS. Early life exposure to Ni promoted osteogenesis during skull growth, which may contribute to the development of CS.

Metal mixtures in pregnant women and umbilical cord blood at urban populations-Rio de Janeiro, Brazil

This study aims to assess interrelationships between serum lead (Pb), cadmium (Cd), arsenic (As), and mercury (Hg) concentrations in pregnant women in their third trimester and umbilical cord blood, while inter-metal correlations were also determined. This study is part of the PIPA project (Childhood and Environmental Pollutant Project), whose pilot study was carried out from October 2017 to August 2018 and will be presented here. Blood samples were obtained from 117 mother-umbilical cord pairs and analyzed concerning metal concentrations. A positive correlation was found between metal concentrations in mother and cord blood (R > 0.7, p < 0.001). The results indicate that mother metal concentrations are able to determine child metal concentrations (p < 0.001). The correlations between maternal blood metal concentrations were positive for all assessed metals except for As and Hg. The strongest correlations in this matrix were observed between Cd and Pb (R = 0.471 p = 0.000), Cd and Hg (R = 0.425 p = 0.000), and Pb and Hg (R = 0.427 p = 0.000). Umbilical cord correlations were lower compared to mother blood correlations. In general, the four analyzed metals displayed significant correlations to serum concentrations in both maternal and cord blood.

House J, L. Maguire R, G. Skinner H, Hoyo C. Associations between Maternal Cadmium Exposure with Risk of Preterm Birth and Low after Birth Weight Effect of Mediterranean Diet Adherence on Affected Prenatal Outcomes

Prenatal cadmium exposure at non-occupational levels has been associated with poor birth outcomes. The intake of essential metals, such as iron and selenium, may mitigate cadmium exposure effects. However, at high levels, these metals can be toxic. The role of dietary patterns rich in these metals is less studied. We used a linear and logistic regression in a cohort of 185 mother-infant pairs to assess if a Mediterranean diet pattern during pregnancy modified the associations between prenatal cadmium exposure and (1) birth weight and (2) preterm birth. We found that increased cadmium exposure during pregnancy was associated with lower birth weight (β = -210.4; 95% CI: -332.0, -88.8; p = 0.008) and preterm birth (OR = 0.11; 95% CI: 0.01, 0.72; p = 0.04); however, these associations were comparable in offspring born to women reporting high adherence to a Mediterranean diet (β = -274.95; 95% CI: -701.17, 151.26; p = 0.20) and those with low adherence (β = -64.76; 95% CI: -359.90, 230.37; p = 0.66). While the small sample size limits inference, our findings suggest that adherence to a Mediterranean dietary pattern may not mitigate cadmium exposure effects. Given the multiple organs targeted by cadmium and its slow excretion rate, larger studies are required to clarify these findings.

Low Selenium Levels in Amniotic Fluid Correlate with Small-For-Gestational Age Newborns

Background: Identifying women at risk for small-for-gestational-age newborns (SGA) is an important challenge in obstetrics. Several different risk factors have been suggested to contribute to the development of SGA. Previous research is inconclusive on the role selenium (Se) plays in the development of SGA. The aim of the study was therefore to explore the role of Se concentrations in amniotic fluid in order to understand its possible role in the development of SGA. Study Design: This prospective, single center study investigated the relationships between Se concentrations in amniotic fluid and pregnancy outcomes. Amniotic fluid was collected from pregnant women during amniocentesis at 16/17 weeks of pregnancy. Se values were determined using the electrothermal atomic absorption spectrometry and expressed in µg/L. Characteristics of mothers and newborns were obtained from women and delivery records. Results: 327 samples of amniotic fluid were evaluated. Patients with SGA newborns had significantly lower mean values of amniotic fluid concentrations of Se compared to appropriate-for-gestational-age (AGA) newborns (4.8 ± 1.9 µg/L versus 5.6 ± 2.5 µg/L (p = 0.017)). Adjusting for different risk factors, Se remained the only significant factor impacting the outcome of a newborn (b = −0.152, s.e. = 0.077; p < 0.048). Se levels in amniotic fluid did not correlate with pre-eclampsia or preterm delivery. Conclusion: Amniotic fluid Se levels represent a viable root of further investigation and assessment in order to identify women with low birth weight newborns early. Women with decreased Se levels had a statistically significant chance of developing SGA. Further research is needed to elucidate the link between Se, other trace elements, and other risk factors and their impact on the development of SGA newborns.

A Review of the Potential Interaction of Selenium and Iodine on Placental and Child Health

A healthy pregnancy is important for the growth and development of a baby. An adverse pregnancy outcome is associated with increased chronic disease risk for the mother and offspring. An optimal diet both before and during pregnancy is essential to support the health of the mother and offspring. A key mediator of the effect of maternal nutrition factors on pregnancy outcomes is the placenta. Complicated pregnancies are characterized by increased oxidative stress in the placenta. Selenium and iodine are micronutrients that are involved in oxidative stress in placental cells. To date, there has been no comprehensive review investigating the potential synergistic effect of iodine and selenium in the placenta and how maternal deficiencies may be associated with increased oxidative stress and hence adverse pregnancy outcomes. We undertook a hypothesis-generating review on selenium and iodine, to look at how they may relate to pregnancy complications through oxidative stress. We propose how they may work together to impact pregnancy and placental health and explore how deficiencies in these micronutrients during pregnancy may impact the future health of offspring.

Essential Mineral Intake During Pregnancy and Its Association With Maternal Health and Birth Outcomes in South East Queensland, Australia

Micronutrient supplements are often recommended during pregnancy, yet their role and necessity remain poorly understood in the Australian population. This study aimed to determine the essential mineral intake of a population of pregnant women in South East Queensland and investigate the effects of supplements on their micronutrient status and birth outcomes. Women completing the Oral Glucose Tolerance Test at two South East Queensland hospitals between 180 and 210 days gestation provided fasting blood samples and dietary data using the Maternal Outcomes and Nutrition Tool (n = 127). Birth outcomes were sourced from medical records. Serum elemental profiles were determined by inductively coupled plasma mass spectrometry (ICP-MS) analysis. Intake of 8 essential minerals was compared with Australian dietary recommendations; matched serum mineral levels were compared with the current Queensland pregnancy reference ranges. Data were examined using cross-sectional cohort design and independent sample t-tests. Supplement use had no significant influence on serum values of trace elements or the incidence of hypertensive disorders, gestational diabetes, preterm birth or infant birthweight. Dietary selenium, zinc and iodine were significantly higher in women birthing beyond 41 completed weeks; selenium (P = .026) and zinc (P = .034) both made unique contributions to the regression models when controlling for confounders. Women exhibited adequate to excessive serum micronutrient levels compared with pregnancy reference ranges, a finding consistent with dietary intake calculations. Data suggest that excessive essential mineral intake contributed to prolonged pregnancy in this cohort, supporting previous studies in this population. Further research is required to determine individual needs and eliminate the potential for harm before recommending pregnancy supplements.