DETERMINATION OF MATERNAL SERUM ZINC, IRON, CALCIUM AND MAGNESIUM DURING PREGNANCY IN PREGNANT WOMEN AND UMBILICAL CORD BLOOD AND THEIR ASSOCIATION WITH OUTCOME OF PREGNANCY

Association Between Iron, Folate, and Zinc Deficiencies During Pregnancy and Low Birth Weight: Systematic Review of Cohort Studies

CONTEXT

Iron, folate, and zinc deficiencies during the gestational period may be associated with negative perinatal outcomes, such as low birth weight (LBW), but these relationships are not yet fully established in the scientific literature and require further investigation.

OBJECTIVE

To systematically review the scientific production to investigate the association between iron, folate, and zinc deficiencies during pregnancy and LBW.

DATA SOURCES

The search was carried out using high-sensitivity descriptors in the English, Portuguese, and Spanish languages, combined with Boolean operators, adapted to each of the following indexed databases: MEDLINE via PubMed, Embase, LILACS via BVS, CENTRAL, and Web of Science. The eligibility criteria followed the PECOS (population, exposure, comparator, outcome, study) strategy.

DATA EXTRACTION

Data extraction was performed using an Excel spreadsheet with the study variables of interest. Subsequently, the information was analyzed and summarized in a table. The Newcastle-Ottawa Scale was used to perform the risk-of-bias analysis.

DATA ANALYSIS

A total of 21 042 references were identified, of which 7169 related to folate, 6969 to iron, and 6904 to zinc. After eligibility criteria application, 37 articles were included in this study, of which 18 referred to zinc nutritional status, 10 related to iron, and 9 related to folate. Studies of iron (40%), folate (66.66%), and zinc (50%) revealed a positive association between deficiencies of these micronutrients and LBW. The overall methodological quality of the studies included in this review was considered high.

CONCLUSIONS

Iron, folate, and zinc deficiencies are still present during gestation. Nevertheless, the association between deficiencies of these micronutrients and LBW is still contradictory, and more studies are needed, as is efficient nutritional monitoring before and during gestation.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42021284683.

Current understanding of essential trace elements in intrahepatic cholestasis of pregnancy

Trace elements are important components in the body and have fundamental roles in maintaining a healthy and balanced pregnancy process. Either deficiency or excess of trace elements, including selenium, iron, zinc, copper, and magnesium can lead to pregnancy complications. As a rare disorder during pregnancy of unknown aetiology, intrahepatic cholestasis of pregnancy (ICP) poses a significant risk to the fetus of perinatal mortality. ICP is a multifactorial complication of which the pathogenesis is still an enigma. Epidemiological studies have demonstrated the association of ICP with some trace elements. Evidence from retrospective studies in humans further revealed the possible contributing roles of trace elements in the pathogenesis of ICP. The published literature on the association of trace elements with ICP was reviewed. Recent advances in molecular biological techniques from animal studies have helped to elucidate the possible mechanisms by how these trace elements function in regulating oxidative reactions, inflammatory reactions and immune balance in the maternal-fetal interface, as well as the influence on hepato-intestinal circulation of bile acid. The scenario regarding the role of trace elements in the pathogenesis of ICP is still developing. The administration or depletion of these trace elements may have promising effects in alleviating the symptoms and improving the pregnancy outcomes of ICP.

Role of mineral nutrients other than iron in pregnancy: under recognized opportunities to improve maternal/fetal outcomes: a literature review

BACKGROUND

Anemia during pregnancy is an important global health concern, affecting 40% of women worldwide, and iron deficiency shares a significant proportion of the burden. From conception to birth, pregnancy is a period when women undergo metabolic and physiological changes. The nutritional needs are higher during pregnancy; thus, adequate nutrition is essential to maintain fetal growth and development. However, adverse effects due to deficiency in nutrition during pregnancy can result in maternal, fetal and neonatal complications. Despite the multifactorial etiology of anemia, iron deficiency is assumed as the primary cause of anemia during pregnancy and hence, mitigation strategy pivots around it for anemia management. Therefore, excluding other contributors, a single-micronutrient approach with iron supplements remains a myopic approach and this can exacerbate iron deficiency anemia. Micronutrient deficiencies are of particular concern as they may pose a silent threat to the survival and well-being of reproductive-age women and their infants.

AIM

Micronutrients, especially trace minerals, play a myriad of roles in pregnancy, and the lack of each one causes adverse complications to both the mother and the fetus. In this review paper, we attempt to piece together available information regarding the adverse effects of abnormal trace mineral levels along with iron deficiency on the mother and the fetus.

METHOD

A non-systematic literature search in PubMed, Google Scholar, and the Cochrane databases, for publications on minerals and vitamins during pregnancy and the possible influence of supplements on pregnancy outcomes.

CONCLUSION

Micronutrient deficiency exacerbates the pregnancy-induced anemia and other adverse birth outcomes. Micronutrient supplementation during pregnancy can combat anemia as well as reduce a number of adverse pregnancy outcomes in a comprehensive manner.

Effect of maternal serum magnesium and calcium levels on umbilical glial fibrillary acidic protein levels in preterm labor

Magnesium can prevent astrocyte cell death and Glial Fibrillary Acidic Protein (GFAP) secretion as inflammatory marker in preterm delivery. This study was performed to analyze differences in umbilical cord GFAP levels in preterm labor given magnesium sulfate (MgSO4) as treatment group and control group and analyze the correlation between magnesium and calcium levels with umbilical GFAP levels. This quasi-experimental study was performed on 68 patients at Dr. Hasan Sadikin General Hospital from February-June 2021 consisting of 34 patients in each group. Maternal-umbilical cord magnesium levels, calcium levels, and GFAP levels were examined using ELISA test. The result was statistically measured by IBM SPSS 24.0. We found that there was a significant difference between maternal and umbilical magnesium levels and GFAP umbilical cord blood levels between the treatment and the control group (P < 0.05) in which GFAP level was higher in the control group. The multivariate analysis showed no significant relevance between mother magnesium and calcium level to umbilical cord GFAP level in the MgSO4 group. As conclusions, umbilical cord blood GFAP levels in preterm labor given MgSO4 were lower than in preterm deliveries who were not given MgSO4. There was no correlation between magnesium, calcium, and GFAP levels in the treatment group.

Calcium, Potassium, Sodium, and Magnesium Concentrations in the Placenta, Umbilical Cord, and Fetal Membrane from Women with Multiple Pregnancies

Calcium (Ca), potassium (K), sodium (Na), and magnesium (Mg) are the elements responsible for the fundamental metabolic and biochemical processes in the cells of the body. The demand for these elements increases significantly during pregnancy, where an adequate supply protects women from the hypertension common in pre-eclampsia and preterm labor. This study aimed to evaluate the association between macro-elements (Ca, Mg, Na, and K) in the placenta, fetal membrane, and umbilical cord and the morphometric parameters of newborns from multiple pregnancies. The study involved 57 pregnant European women with healthy uncomplicated twin pregnancies (n = 52) and triple pregnancies (n = 5); 40 pairs of dichorionic diamniotic twins, 11 pairs of monochorionic diamniotic twins, 1 pair of monochorionic monoamniotic twins, 3 trichorionic triamniotic triplets, and 2 dichorionic triamniotic triplets. Placentas (n = 107), umbilical cords (n = 114), and fetal membranes (n = 112) were collected immediately following delivery, and then weighed and measured. The levels of Ca, K, Na, and Mg were determined using inductively coupled plasma atomic emission spectroscopy (ICP-OES) in a Thermo Scientific ICAP 7400 Duo (Waltham, MA, USA). The respective mean concentrations of Ca, K, Na, and Mg (mg/kg^-1 dry mass) were: 2466, 8873, 9323, and 436 in the placenta; 957, 6173, 26,757, and 326 in the umbilical cord, and 1252, 7460, 13,562, and 370 in the fetal membrane. In the studied materials from northwestern Poland, we found strong positive correlations between Ca and Mg concentrations in both the umbilical cord (r = 0.81, p = 0.00) and the fetal membrane (r = 0.73, p = 0.00); between K and Mg concentrations in the umbilical cord (r = 0.73, p = 0.00); between Ca and K concentrations in the fetal membrane (r = 0.73, p = 0.00), and we found moderately positive correlations between placental Ca concentration and placental weight (ρ = 0.42, p = 0.00) and between umbilical cord Mg concentrations and the length of the pregnancy (ρ = 0.42, p = 0.00). Negative correlations were found between Na and Ca concentrations in the fetal membrane (r = -0.40, p = 0.00) and Na concentrations in the fetal membrane and Mg concentrations in the placenta (r = -0.16, p = 0.02). Negative correlations were confirmed between the length of pregnancy and head circumference (ρ = -0.42; p = 0.00), infant weight (ρ = -0.42; p = 0.00), infant length (ρ = -0.49; p = 0.00), shoulder width (ρ = -0.49; p = 0.00); and between the infant weight and head circumference (ρ = -0.62; p = 0.00), weight before delivery (ρ = -0.36; p = 0.00), infant length (ρ = -0.45; p = 0.00), shoulder width (ρ = -0.63; p = 0.00), and weight gain during pregnancy (ρ = -0.31; p = 0.01). We found statistically significant correlations between cigarette smoking before pregnancy and the women's weight before delivery (ρ = 0.32, p = 0.00), and a negative correlation between the women's ages and infant head circumference (ρ = -0.20, p = 0.02). This is probably the first study to evaluate Ca, Na, K, and Mg concentrations in the afterbirth tissues of multiple pregnancies. It adds to the knowledge of elemental concentrations in multiple pregnancies and their possible effects on fetal morphometric parameters.

Natural copper isotopic abnormity in maternal serum at early pregnancy associated to risk of spontaneous preterm birth

Spontaneous preterm birth (SPB) has drawn public attention due to its increasing incidence and adverse effects on fetal growth. Effect of copper (Cu) imbalance in maternal bodies on the risk of SPB remains a subject of debate, and the related mechanisms are still unraveled. Here we applied natural stable copper isotopes to explore the underlying association and mechanism of copper imbalance with SPB using a nested case-control study. We collected maternal sera at the early pregnancy stage and then measured their copper isotopic ratio (⁶⁵Cu/⁶³Cu, expressed as δ⁶⁵Cu) as well as physiological and biochemical indexes from women with and without delivering SPB. We found that SPB cases had no significant difference in serum copper level from their controls, but their serum copper was significantly isotopically heavier than the controls (δ⁶⁵Cu value = 0.15 ± 0.34 ‰ versus -0.15 ± 0.17 ‰, P = 0.0149). Compared with the controls with lower δ⁶⁵Cu values, the crude odds ratio (OR) associated with SPB risk increased to 4.00 (95 % confidence interval (CI): 1.37-11.70) and the adjusted OR reached up to 11.35 (95 % CI: 1.35-95.60). Furthermore, via the copper isotopic fractionation, we revealed that dietary intake and blood ceruloplasmin may play more important roles than blood lipids and mother-to-child transmission in the copper imbalance associated with SPB. Further studies will be needed to understand the mechanisms of isotope fractionation related to reproductive health.

Longitudinal Assessment of Calcium and Magnesium Levels in Women with Preeclampsia

The present study reports the levels of maternal serum calcium and magnesium from early pregnancy until delivery, along with cord levels, in women who developed preeclampsia (PE) and compares them with those without PE. A total of 324 pregnant women (216 non-PE and 108 PE women) were included in this retrospective case-control study of prospectively collected data nested in an observational cohort study. Maternal blood was collected at 4 time points during pregnancy (V1 = 11-14 weeks, V2 = 18-22 weeks, V3 = 26-28 weeks, and V4 = at delivery) and umbilical cord blood at delivery. Independent t tests were used to compare calcium, magnesium, and their ratio between two groups, and their associations with PE were studied using regression models. Calcium levels were similar between groups at all time points. Magnesium levels were lower (p = 0.021) at V2 in PE group as compared with non-PE group. Maternal calcium and magnesium levels were negatively associated, with blood pressure in early pregnancy. In fully adjusted logistic regression analysis, lower magnesium levels were associated with an increased risk of PE at V2 (OR 0.25 [95% CI 0.07, 0.94] p = 0.04). Lower magnesium in mid-pregnancy was associated with higher risk of PE. These changes were observed before the diagnosis of PE, thereby suggesting that they may have a role in the etiology of PE.

The role of tropical small-scale fisheries in trace element delivery for a Small Island Developing State community, the Seychelles

The concentrations of 13 trace elements were determined in 1032 muscles of 54 small-scale fisheries species collected from the Seychelles waters between 2013 and 2019. Overall, profiles were dominated by zinc (Zn) > arsenic (As) > iron (Fe) > copper (Cu) > selenium (Se), with the spiny lobsters, spanner crab and octopus exhibiting the highest levels of As, Cu and Zn while fish had higher Fe concentrations. Both taxonomy-dependent processes and ecological factors explained the interspecific differences of trace element profiles observed. A benefit-risk assessment revealed that crustaceans and cephalopods were good sources of Cu and Zn. One portion of any fish could provide 30-100 % of daily Se needs, and one portion of demersal and pelagic teleost fish could bring 5-20 % of Cu, Fe and Zn needs, especially for young adult and adult women. Finally, our analysis showed that there was very low health risks associated with small-scale fisheries consumption for the Seychelles population.

Maternal Dietary Iron and Folate Intake in the Third Trimester and Birth Outcomes: A Prospective Cohort Study at a Teaching Hospital in Accra, Ghana

Dietary iron and folate are nutrients of great importance during pregnancy because of the role they play to ensure optimal birth outcomes. Dietary intake has been found to decline during the third trimester. This study sought to assess the dietary iron and folate intake in the third trimester and pregnancy outcomes of women in their third trimester attending antenatal clinics at Korle-Bu Teaching Hospital. Eighty-one participants at a gestational age of 32 weeks were recruited and monitored until delivery-from May 4, 2020 to July 1 2020-using a consecutive sampling method at the Department of Obstetrics and Gynecology, Korle-Bu Teaching Hospital. Dietary intake information was obtained based on a 52-item quantitative food frequency questionnaire. Daily supplement doses of participants were recorded. Serum concentrations of iron (ferritin) and folate were determined using ELISA microwells. The mean dietary intake of iron and folate was 13.5 ± 8.30 mg and 331.0 ± 114.0 μg, respectively. The mean intake of iron and folic acid supplements was 42.7 ± 48.8 mg and 5.5 ± 11.1 mg, respectively. Most of the participants had serum ferritin and folate levels in the normal range (82.7% and 87.7%, respectively). Almost all the participants had positive birth outcomes, and total dietary iron was a significant predictor of birth outcome (P = 0.041). The majority of pregnant women did not meet the daily recommendation for iron and folate, but adherence to daily supplement intake was good and could have accounted for the positive birth outcomes.

Association of the Serum Folate and Total Calcium and Magnesium Levels Before Ovarian Stimulation With Outcomes of Fresh In Vitro Fertilization Cycles in Normogonadotropic Women

Background

Women of reproductive age are recommended to consume folic acid and other supplements before conception and during pregnancy. We aimed to investigate the association of the serum folate and total magnesium (Mg) and calcium (Ca) levels before ovarian stimulation with the outcomes of assisted reproductive technology (ART) in normogonadotropic women.

Methods

We used a subanalysis of data obtained from a multicentre, randomized prospective study (NCT03088137). A total of 110 normogonadotropic, non-advanced aged, non-obese women with tubal and/or male infertility factors were enrolled for the single fresh ovarian stimulation GnRH antagonist cycle. The main outcome measures were the total oocyte yield, mature oocytes, fertilization rate, biochemical, clinical pregnancy, and live birth. Multivariable generalized linear models adjusted for covariates were used with a Poisson distribution and the log link function for adjusted oocyte counts, and a binomial distribution and the log link function were used for adjusted clinical ART outcomes.

Results

The medians (interquartile range (IQR)) were as follows: baseline serum folate, 20.55 ng/ml (10.8, 32.9); Mg, 19.4 mg/L (18.7, 20.7); Ca, 94 mg/L (91.2, 96.4); and Ca/Mg ratio, 4.78 (4.55, 5.02). Women with higher serum folate concentrations (Q4≥33.0 ng/ml) had significantly lower total numbers of oocytes retrieved (adjusted mean (95% CI) 9.2 (7.6-11.3) vs 12.9 (10.9-15.4, p-trend=0.006)) and lower odds ratios (ORs) (95% CI) of 0.12 (0.02, 0.79) for clinical pregnancy and 0.10 (0.01, 0.70) for live birth compared with women in the lowest quartile (<10.8 ng/ml), all p-trend<0.001. Women in the highest Ca/Mg ratio quartile (≥5.02) had ORs (95% CI) of 6.58 (1.31, 33.04) for biochemical pregnancy, 4.85 (1.02, 23.08) for clinical pregnancy and 4.07 (0.83, 19.9) for the live birth rate compared with women in the lowest quartile (<4.55), all p-trend<0.001.

Conclusions

Using multivariable models, we suggested that a baseline elevated serum folate level (≥33.0 ng/ml) and a lower Ca/Mg ratio were associated with worse ART outcomes in normogonadotropic women. Our findings might be useful for choosing safe dosages of folate, calcium, magnesium and complex supplementation for both fertile women and women undergoing infertility treatment. Further preconception large-scale studies with known micro- and macronutrient statuses of both parents and serum folate, Ca, Mg, and hormone levels, are needed.

Serum metal levels in a population of Spanish pregnant women

OBJECTIVE

To describe serum levels of calcium, copper, selenium, magnesium, iron and zinc and evaluate their relationship with maternal socio-demographic characteristics and dietary variables in women in the first trimester of pregnancy.

METHOD

Cross-sectional study with 1279 participants from the INMA cohorts.

RESULTS

The concentrations of the elements analyzed were within the normal range. Associations with higher levels of these metals were found for calcium with white meat intake (p=0.026), for copper with excess body weight (p <0.01), low social class (p=0.03) and being multipara (p <0.01), for magnesium with being over 35 years old (p=0.001), high social class (p=0.044), primiparous status (p=0.002) and low daily intake of bread (p=0.009) and legumes (p=0.020); for zinc with university education (p=0.039) and residence in Gipuzkoa (p <0.01), and for selenium with residence in Valencia (p <0.01), university education (p=0.001), vitamin B₆ supplementation (p=0.006), fish intake (> 71g/day) (p=0.014) and having been born in Spain (p=0.001). Further, lower iron levels were associated with being overweight (p=0.021) or obese (p <0.001) and vitamin B₁₂ supplementation (p=0.006).

CONCLUSIONS

Our results suggest that trace elements in the analyzed cohorts are adequate for this stage of pregnancy. The variability in these elements is mainly linked to socio-demographic and anthropometric variables.

Plasma and red blood cells distribution of total mercury, inorganic mercury, and selenium in maternal and cord blood from a group of Japanese women

Fetuses are a high-risk group for methylmercury (MeHg) exposure. The main objective of this study was to compare the characteristic profiles of total mercury (THg), inorganic mercury (IHg), MeHg, and selenium in plasma and red blood cells (RBCs) between maternal and cord blood at parturition collected from a group of Japanese women. Furthermore, correlations of THg in RBCs, which is a biomarker of MeHg, and THg in plasma, which is an IHg exposure biomarker, were examined in maternal and cord blood. Fifty-five pairs of maternal and cord blood samples obtained at parturition were collected from pregnant women in Fukuoka, Japan. THg in RBCs and plasma were significant correlated between maternal and cord blood. THg in RBCs was 13.9 ng/mL for cord and 9.16 ng/mL for maternal blood, with a cord:maternal RBCs ratio for THg of 1.58, suggesting that MeHg is actively transferred from the mother to the fetus via the placenta. THg in plasma showed a positive correlation with THg in RBCs for maternal and cord blood. This result suggests that measuring THg in plasma can overestimate the exposure level to IHg in fish-eating populations. The percentages of IHg in cord plasma and RBCs were 31% and 1.7%, respectively, and those in maternal plasma and RBCs were 46% and 5.9%, respectively. These results suggest that cord blood is rich in MeHg and can easily transfer to the fetal brain. Selenium in cord plasma was 67 ng/mL and that in maternal plasma was 97 ng/mL, with a cord:maternal plasma ratio for Se of 0.69, suggesting that the protective effects of Se against MeHg toxicity in fetuses may be weaker than those expected in adult mothers.

The Role of Fe, Zn, and Cu in Pregnancy

Iron (Fe), copper (Cu), and zinc (Zn) are microelements essential for the proper functioning of living organisms. These elements participatein many processes, including cellular metabolism and antioxidant and anti-inflammatory defenses, and also influence enzyme activity, regulate gene expression, and take part in protein synthesis. Fe, Cu, and Zn have a significant impact on the health of pregnant women and in the development of the fetus, as well as on the health of the newborn. A proper concentration of these elements in the body of women during pregnancy reduces the risk of complications such as anemia, induced hypertension, low birth weight, preeclampsia, and postnatal complications. The interactions between Fe, Cu, and Zn influence their availability due to their similar physicochemical properties. This most often occurs during intestinal absorption, where metal ions compete for binding sites with transport compounds. Additionally, the relationships between these ions have a great influence on the course of reactions in the tissues, as well as on their excretion, which can be stimulated or delayed. This review aims to summarize reports on the influence of Fe, Cu, and Zn on the course of single and multiple pregnancies, and to discuss the interdependencies and mechanisms occurring between Fe, Cu, and Zn.

Plasma mineral (selenium, zinc or copper) concentrations in the general pregnant population, adjusted for supplement intake, in relation to thyroid function

The present study reports on first-trimester reference ranges of plasma mineral Se/Zn/Cu concentration in relation to free thyroxine (FT4), thyrotropin (TSH) and thyroid peroxidase antibodies (TPO-Ab), assessed at 12 weeks' gestation in 2041 pregnant women, including 544 women not taking supplements containing Se/Zn/Cu. The reference range (2·5th-97·5th percentiles) in these 544 women was 0·72-1·25 µmol/l for Se, 17·15-35·98 µmol/l for Cu and 9·57-16·41 µmol/l for Zn. These women had significantly lower mean plasma Se concentration (0·94 (sd 0·12) µmol/l) than those (n 1479) taking Se/Zn/Cu supplements (1·03 (sd 0·14) µmol/l; P < 0·001), while the mean Cu (26·25 µmol/l) and Zn (12·55 µmol/l) concentrations were almost identical in these sub-groups. Women with hypothyroxinaemia (FT4 below reference range with normal TSH) had significantly lower plasma Zn concentrations than euthyroid women. After adjusting for covariates including supplement intake, plasma Se (negatively), Zn and Cu (positively) concentrations were significantly related to logFT4; Se and Cu (but not Zn) were positively and significantly related to logTSH. Women taking additional Se/Zn/Cu supplements were 1·46 (95 % CI 1·09, 2·04) times less likely to have elevated titres of TPO-Ab at 12 weeks of gestation. We conclude that first-trimester Se reference ranges are influenced by Se-supplement intake, while Cu and Zn ranges are not. Plasma mineral Se/Zn/Cu concentrations are associated with thyroid FT4 and TSH concentrations. Se/Zn/Cu supplement intake affects TPO-Ab status. Future research should focus on the impact of trace mineral status during gestation on thyroid function.

Prevalence of calcium and vitamin D deficiency and their association with feto-maternal outcomes in a sample of Iranian pregnant women

BACKGROUND

Calcium and vitamin D deficiency is common among Iranian women of childbearing age and poses adverse effects on pregnancy outcomes. The aim of the current study was to determine the prevalence of vitamin D and calcium in a sample of Iranian pregnant women and to assess its correlation with the feto-maternal outcomes.

METHODS

In this prospective cross-sectional study, a sample of pregnant women between 15 to 45 years who were in the third trimester were recruited from a number of hospitals in Tehran. Data were collected by the means of a self-developed questionnaire, interviews, physical examination, and paraclinical tests including measuring the serum level of calcium, vitamin D, parathormone (PTH) and phosphorous (Pi). The questionnaire obtained information on age, level of education, socio-economic status, parity, gravidity, calcium intake during pregnancy, as well as feto-maternal outcomes.

RESULTS

We included a total number of 233 singleton pregnancies. Most of the subjects (58.4%) had vitamin D deficiency and 12.0% suffered from severe vitamin D deficiency. Vitamin D deficiency was adversely associated with the years of education (p= 0.007), serum level of parathormone (p< 0.001). The Metabolic Equivalent of Task (MET) (p< 0.001), the exercise sequence per week (p< 0.001), sun exposure (p< 0.001), higher rate of sunscreen usage (p= 0.011) and higher BMI (p= 0.005). Vitamin D deficiency was associated with higher rate of cesarean delivery (p= 0.024), higher rate of diastolic hypertension (p= 0.019), higher rate of neonatal jaundice (p= 0.009) and higher rate of neonatal respiratory infections (p< 0.001). Serum level of PTH was a significant risk factor for severe vitamin D deficiency while calcium D supplementation, MET and sunscreen were significant protective factors.

CONCLUSION

The prevalence of vitamin D deficiency during pregnancy among Iranian women is extremely high and is associated with adverse pregnancy outcomes including cesarean delivery, neonatal jaundice and neonatal respiratory infections. Low vitamin D supplementation and sun exposure, lack of physical activity and high BMI are the etiologies. Increasing the knowledge along with vitamin D supplementation during the pregnancy is recommended in Iranian population.

Predictors of urinary and blood Metal(loid) concentrations among pregnant women in Northern Puerto Rico

Given the potential adverse health effects related to toxic trace metal exposure and insufficient or excessive levels of essential trace metals in pregnant women and their fetuses, the present study characterizes biomarkers of metal and metalloid exposure at repeated time points during pregnancy among women in Puerto Rico. We recruited 1040 pregnant women from prenatal clinics and collected urine, blood, and questionnaire data on demographics, product use, food consumption, and water usage at up to three visits. All samples were analyzed for 16 metal(loid)s: arsenic (As), barium (Ba), beryllium (Be), cadmium (Cd), cobalt (Co), chromium (Cr), cesium (Cs), copper (Cu), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), titanium (Ti), uranium (U), vanadium (V), and zinc (Zn). Urine samples were additionally analyzed for molybdenum (Mo), platinum (Pt), antimony (Sb), tin (Sn), and tungsten (W). Mean concentrations of most metal(loid)s were higher among participants compared to the general US female population. We found weak to moderate correlations for inter-matrix comparisons, and moderate to strong correlations between several metal(loid)s measured within each biological matrix. Blood concentrations of Cu, Zn, Mn, Hg, and Pb were shown to reflect reliable biomarkers of exposure. For other metals, repeated samples are recommended for exposure assessment in epidemiology studies. Predictors of metal(loid) biomarkers included fish and rice consumption (urinary As), fish and canned food (blood Hg), drinking public water (blood Pb), smoking (blood Cd), and iron/folic acid supplement use (urinary Cs, Mo, and Sb). Characterization of metal(loid) biomarker variation over time and between matrices, and identification of important exposure sources, may inform future epidemiology studies and exposure reduction strategies.

Role of Zinc Supplementation in the Improvement of Acute Respiratory Infections among Iranian Children: A Systematic Review

BACKGROUND

Respiratory infectious disease is considered as one of the most serious problems among children in developing countries. The importance of zinc in the improvement of respiratory disease has been indicated. However, there are some unanswered questions and uncertainty. This systematic review aimed at assessing the therapeutic benefits of zinc supplementation on respiratory infections of Iranian children.

MATERIALS AND METHODS

Databases, such as PubMed, Scopus, Embase, Magiran, and IranDoc, were searched for randomized controlled trials published from January 1998 to December 2017 on Zinc supplementation for the treatment or improvement of acute respiratory disease among Iranian children, during March 2018. Studies were screened according to the PICO framework, and irrelevant studies were excluded.

RESULTS

A total of 5 studies conducted on 522 children were included in this review. Except for one study, others had indicated the beneficial effect of zinc supplement on improving signs and symptoms of respiratory infectious disease and earlier discharge from the hospital.

CONCLUSION

Although studies on the efficacy of zinc on respiratory infectious disease of children in Iran have not widely considered and more studies should be conducted, all published articles (except for one of them) had indicated the effectiveness of zinc supplementation on respiratory infections among children. Other criteria, such as age, gender, birth weight, diet, and type of respiratory infections, should be considered during zinc therapy. Controlling these confounding variables and measuring the level of blood zinc are necessary to understand how much zinc should be prescribed for respiratory treatment of children.

Protective effect of high zinc levels on preterm birth induced by mercury exposure during pregnancy: A birth cohort study in China

OBJECTIVE

The aims of our study were to determine whether prenatal mercury levels are associated with the risk of preterm birth (PTB) and whether high maternal serum zinc (Zn) levels alleviate any negative effects of maternal mercury (Hg) exposure regarding PTB.

METHODS

Serum concentrations of Zn and Hg were measured in 3025 pregnant women from the Ma'anshan Birth Cohort. Before the collection of blood samples, they underwent examinations via the completion of questionnaires. The delivery records of the women were obtained from a series of medical records. We divided the study population into tertiles according to the participants' Hg levels: the low-Hg group (the first tertile, <0.30 μg/L), the medium-Hg group (the second tertile, 0.30-0.43 μg/L) and the high-Hg group (the third tertile, ≥0.43 μg/L). The associations of Hg exposure with both the risk of PTB and gestational age (weeks) at birth were estimated using a binary logistic regression model and multivariable linear regression analysis, respectively. Afterwards, we conducted a repeated analyses test after the participants were stratified according to their Zn levels, using the 75th percentile division method.

RESULTS

Overall, the medians and the interquartile ranges of Hg and Zn in the second trimester were 0.36 (0.27, 0.48) μg/L and 812.34 (731.26, 896.59) μg/L, respectively. Hg levels were associated with PTB [adjusted odds ratio (OR) and 95% confidence interval (95% CI): 1.91 (1.17, 3.12) for the third tertile vs. the first tertile of the serum Hg levels]. In the stratification analysis of the participants in the low-Zn group, the high-Hg group exhibited a significant odds ratio of PTB [adjusted OR (95% CI): 1.87 (1.08, 3.24)], compared to the low-Hg group. However, in the participants from the high-Zn group, the high-Hg group exhibited a non-significant OR of PTB [adjusted OR (95% CI): 2.32 (0.73, 7.42)]. In the multivariate linear regression analysis, gestational age (weeks) at delivery was significantly and inversely associated with the ln-transformed Hg concentrations [adjusted β (95% CI): -0.16 (-0.26, -0.06)]. Similarly, after the stratification analysis in the high-Zn group, there were no significant associations between PTB and the Hg levels [adjusted β (95% CI): -0.12 (-0.33, 0.09)].

CONCLUSION

Prenatal Hg exposure adversely affected PTB, and high Zn levels alleviate this effect, which indicates that a more stringent control of Hg and a sufficient intake of Zn are necessary to help birth outcomes.

The time of Calcium Feeding Affects the Productive Performance of Sows

Simple Summary

Calcium (Ca) is an important factor that affects the reproductive and lactation performance of sows. Circadian clocks and nutrient metabolism interact. We found that maternal feeding of Ca, varying with feeding time, improved the profile of some mineral elements in umbilical serum and milk, which contribute toward improving the productive performance of sows. This study confirmed that the absorption and metabolism of Ca in mammals also have circadian rhythms.

Abstract

This study aims to investigate the effect of Calcium (Ca) feeding time on a sow’s productive performance and the profiles of serum mineral elements during late pregnancy and lactation. A total of 75 pregnant sows were assigned to three groups: The control (C), earlier-later (E-L), and later-earlier (L-E) groups. During late pregnancy, the C group was fed an extra 4.5 g Ca (in the form of CaCO₃) at both 06:00 and 15:00, the E-L group was fed an extra 9 g Ca at 06:00, and the L-E group was fed an extra 9 g Ca at 15:00. Similar treatments with double the amount of Ca were applied during lactation. The results show that, compared with the C group, L-E feeding decreased the number of stillbirths and the duration of farrowing and placenta expulsion (FARPLA) and increased the average daily weight gain (ADG) of piglets. Similarly, E-L feeding increased the ADG of piglets (p < 0.05). Furthermore, both E-L and L-E feeding increased the Ca levels in sow serum and umbilical serum, and the Fe levels in umbilical serum, but decreased the Ca levels in the placenta and colostrum (p < 0.05). Experiments on the genes involved in mineral element transport showed that E-L feeding activated the mRNA expression of TRPV5, S100G, SLC30A7, SLC39A4, and Ferroportin1, while it inhibited the mRNA expression of ATP7A in the placenta (p < 0.05). Moreover, L-E feeding up-regulated the mRNA expression of ATP2B and IREB2, while it down-regulated the mRNA expression of ATP7B in the placenta (p < 0.05). In conclusion, the present study demonstrated that maternal Ca feeding at 15:00 h during late pregnancy and lactation decreased FARPLA and stillbirths and improved the growth performance of suckling piglets by altering the mineral element of the metabolism in the umbilical serum and milk, compared to conventional feeding regimes.

Trace element profiles in pregnant women's sera and umbilical cord sera and influencing factors: Repeated measurements

In utero exposure to toxic heavy metals and deficient or excessive essential trace elements during pregnancy may have adverse effects on pregnant women and their offsprings, which are of great concern. The objective of the present study was to characterize serum concentrations of multiple trace elements at multiple time points during pregnancy in Chinese women. Three thousand four hundred and sixteen pregnant women in total were included from MABC (Ma'anshan Birth Cohort) study. Fasting sera in the morning and questionnaires were obtained at three separate follow-up visits. Nineteen trace elements from serum samples were analyzed, including aluminum (Al), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), selenium (Se), cadmium (Cd), barium (Ba), thallium (Tl), lead (Pb), calcium (Ca), magnesium (Mg), mercury (Hg) and molybdenum (Mo). The total detection rates for most elements were 100% rather than Ni (99.98%), As (99.97%), Cd (99.6%), Ba (99.9%), Pb (99.8%), Hg (99.8%). The concentration distributions of 19 elements varied vastly. Median concentrations for all trace elements ranged from 38.5 ng/L to 102.9 mg/L. The moderate interclass correlation coefficients (ICCs) were observed for Co, Cu, Se and Hg, ranging from 0.40 to 0.62; the lower ICCs, ranging from 0.13 to 0.32 were for Fe, Zn, Cd, Ba, Tl, Mg and Mo. The intraclass correlation effects were not observed for the remaining elements, such as Al, V, Cr, Mn, Ni, As and Pb. The concentrations of each element between three time points were significantly different; significant differences were also found between any two time points except for Ni, Cd and Mo. Many factors could affect the levels of trace elements, and a very important factor of them was season. Consequently, a single measurement of elements in sera seems not enough to describe exposure levels throughout pregnancy; additionally, season affected exposure levels of trace elements with moderate ICCs showed certain regularity. Future analyses should take sampling seasons into consideration carefully.

Relationship between pre-pregnancy body mass index and mineral concentrations in serum and amniotic fluid in pregnant women during labor

The aim of the study was to determine the correlations between body mass index (BMI) values before pregnancy and the concentrations of selected elements (Mg, Co, Cu, Zn, Sr, Cd, Ba, Pb, U, Ca, Cr, Al, Mn, V, Fe) in blood serum and amniotic fluid (AF) in pregnant women. Elemental analysis of serum and amniotic fluid in 225 Polish women (Caucasian/white) showed a relationship between the concentration of minerals in the above-mentioned samples and the pre-pregnancy BMI. Analysis of blood serum was performed by using ICP-MS and it demonstrated that iron concentration was significantly lower in overweight and obese women. Being underweight in pregnant women was associated with a significantly lower concentration of magnesium and cobalt in the blood serum. Both underweight and overweight women were associated with significantly lower concentrations of calcium and strontium in the blood serum. The concentration of cobalt was significantly higher in underweight women. The concentration of lead in the blood serum of overweight and obese women was significantly higher than in other groups. Analysis of the AF showed that the concentration of copper was significantly lower in overweight and obese women, and the concentration of manganese and vanadium significantly higher than in other groups of women. A deficiency in essential minerals and an excess of heavy metals in women may be associated with abnormal body weight and this is important in the etiopathogenesis of pregnancy and fetal development disorders.

Evaluation of Mineral Concentrations in Maternal Serum Before and After Birth and in Newborn Cord Blood Postpartum-Preliminary Study

The mineral levels in maternal serum change during pregnancy and may be correlated with those of newborn cord blood. The aim of this study was to evaluate the concentrations of calcium (Ca), magnesium (Mg), zinc (Zn), iron (Fe), and copper (Cu) in maternal blood before and after delivery and in umbilical cord vein and artery serum. The study was carried out in 64 Caucasian pregnant women who delivered in a district hospital in Greater Poland region, aged 28.1 ± 5.4 years, with a mean gestational age of 39.2 ± 1.3 weeks. Blood samples were taken from women 2-8 h before delivery and immediately after childbirth. The umbilical cord artery and vein blood of newborns was obtained immediately after childbirth. The levels of minerals in serum were determined by flame atomic absorption spectrometry. A significant drop in the concentrations of Mg (17.71 ± 1.51 vs 17.07 ± 1.61 μg/ml; p < 0.007), Fe (1.08 ± 0.46 vs 0.82 ± 0.35 μg/ml; p < 0.0004), and Zn (0.63 ± 0.17 vs 0.46 ± 0.16; p < 0.0001) in maternal serum was found after delivery. Moreover, higher levels of Ca, Fe, and Zn and lower levels of Cu were observed in the umbilical vein (Ca: 102.80 ± 7.80 μg/ml; p < 0.0001, Fe: 1.96 ± 0.43 μg/ml; p < 0.0001, Zn: 0.65 ± 0.16 μg/ml; p < 0.0001, Cu: 0.36 ± 0.09 μg/ml; p < 0.0001) and in the umbilical artery cord blood (Ca: 98.07 ± 8.18 μg/ml; p < 0.0001, Fe: 1.63 ± 0.30 μg/ml; p < 0.0001, Zn: 0.65 ± 0.15 μg/ml; p < 0.0001, and Cu: 0.36 ± 0.10 μg/ml; p < 0.0001) compared to the maternal serum (Ca: 85.05 ± 10.76 μg/ml, Fe: 0.82 ± 0.35 μg/ml, Zn: 0.46 ± 0.16 μg/ml, and Cu: 1.90 ± 0.35 μg/ml). Fe levels in the cord artery serum negatively correlated with blood loss during delivery (R = -0.48; p = 0.01), while the Ca concentration in the maternal serum after birth decreased with the age of the women (R = -0.25; p = 0.03). In conclusion, it seems that the process of birth alters the mineral levels in pregnant women's blood. Moreover, it was found that blood loss and the age of the mother are associated with mineral concentrations in the maternal serum and cord artery blood.

Assessment of dietary intake and mineral status in pregnant women

Purpose

To evaluate the dietary intake of pregnant women and their nutritional status of Ca, Mg, Fe, Zn, and Cu, as the nutritional status of pregnant women is an important factor for the proper progression of a pregnancy and the development and health of the foetus.

Methods

The study was conducted on 108 pregnant women ages 18–42, at 6–32 weeks of gestation. We used a questionnaire and a 24-h recall nutrition interview. Hair samples were taken for testing and the level of each mineral was assessed using atomic absorption spectrometry. The results were analysed using the Dietetyk and Statistica 10 software.

Results

Low levels of Fe, Zn, Ca, Mg, vitamin D, and folic acid intake were seen in the pregnant women, with the use of dietary supplements significantly increasing their intake of Fe, Zn, and folic acid. The concentration of zinc and magnesium in the women’s hair was shown to be affected by their age and, in the case of magnesium, by the week of pregnancy.

Conclusions

It was observed that the diet of pregnant women is characterised by low levels of Fe, Zn, Ca, Mg, vitamin D, and folic acid. Dietary supplementation with vitamins and minerals significantly increases the daily Fe and folic acid intake in pregnant women. The concentration of Zn and Mg in hair depends on the age of pregnant women and Mg level in the hair of women decreases during pregnancy.

Serum cobalt status during pregnancy and the risks of pregnancy-induced hypertension syndrome: A prospective birth cohort study

Cobalt (Co) is an essential trace element and has been suggested to be involved in blood pressure regulation, but few studies have focused on serum Co status during pregnancy and the risks of pregnancy-induced hypertension syndrome (PIH). The aim of this study was to prospectively assess the association between serum Co levels during pregnancy and the risks of PIH, and to explore how the maternal Co status contributes to the incidence of PIH. 3260 non-hypertensive women before pregnancy with singleton births in Ma'anShan birth cohort study (MABC) were recruited with the assessment of maternal Co concentrations, additionally, the levels of 7 inflammatory factors and 3 stress factors in placentas were also determined. Relative risks (RRs) [95% confidence intervals (CIs)] for the risks of PIH were assessed and the relationships between 10 factors and maternal Co status during pregnancy were evaluated as well. A total of 194 (5.95%) women were diagnosed with PIH. The concentrations of Co varied from the first trimester to the second trimester, and maternal serum Co concentrations during pregnancy were negatively associated with the incidence of PIH in a linear fashion. There was a clear trend in RRs according to decreasing exposure to Co levels in the second trimester (RR^a=1.80, 95% CI (1.26, 2.56); RR^b=1.73, 95% CI (1.21, 2.46) and RR^c=1.43, 95% CI (1.02, 2.04) when low Co levels comparing with high Co levels before and after adjustment for confounders; and RR^a=1.29, 95% CI (0.88, 1.88); RR^b=1.28, 95% CI (0.87, 1.87) and RR^c=1.25, 95% CI (0.86, 1.82) when medium Co levels comparing with high Co levels before and after adjustment for confounders). In addition, the trend for the first trimester was nearly identifical to those for the second trimester (RR^a=1.35, 95% CI (0.94, 1.93); RR^b=1.33, 95% CI (0.93, 1.91); RR^c=1.22, 95%CI (0.86, 1.73) when low Co levels comparing with high Co levels before and after adjustment for confounders; and RR^a=1.10, 95% CI (0.76, 1.60); RR^b=1.13, 95% CI (0.77, 1.64) and RR^c=1.12, 95% CI (0.77, 1.63) before and after adjustment for confounders). Interestingly, Co concentrations in the second trimester were also inversely associated with the levels of some inflammatory factors and all three stress factors in placentas. This prospective study suggested that lower maternal serum Co concentration in the second trimester may associate with the incidence of PIH in Chinese population. Additionally, the maternal Co concentrations in the second trimester could reduce inflammatory and oxidative damage to the placenta. Further evidence is needed to support the findings and assess the mechanisms underlying the association.

Strontium and oxidative stress in normal pregnancy

BACKGROUND

Pregnancy brings about metabolic and oxidative changes that involve various trace elements and oxidative stress. Strontium (Sr) is a trace element scarcely studied in this context, although it has been suggested that it may play a role in the pathophysiology of preeclampsia. The main aim of this study was to evaluate Sr concentrations and oxidative status in normal pregnancy.

METHODS

The study population included non-pregnant women (n=31), healthy pregnant women in the first (n=50), second (n=51) and third (n=53) trimesters of gestation, and women in postpartum period (n=31). Additionally, samples from another twenty pregnant women were obtained in the three trimesters. Strontium, copper, selenium and zinc were measured by inductively coupled plasma-mass spectrometry. Calcium (Ca), uric acid (UA), lipid peroxidation and total antioxidant activity (TAA) were measured by spectrophotometric assays.

RESULTS

Strontium remained unchanged until the third trimester of pregnancy, in which significantly higher levels were found (p=0.001). The other elements showed diverse trends during pregnancy. Uric acid levels were significantly different in all groups (p<0.001), increasing gradually as the pregnancy progresses. In serial samples, there was a statistically significant positive correlation between Sr and gestational week of sampling (r=0.31, p=0.01), UA (r=0.40, p=0.001) and lipid peroxidation/TAA ratio (r=0.38, p=0.0002). Additionally, Sr correlated negatively with TAA (r=-0.40, p=0.0001).

CONCLUSION

Strontium seems to play a physiological role in the oxidative status of the human organism. Further studies involving Sr and pathologies of pregnancy are warranted.

Serum Magnesium Levels in Preterm Infants Are Higher Than Adult Levels: A Systematic Literature Review and Meta-Analysis

Magnesium (Mg) is an essential mineral in the body, impacting the synthesis of biomacromolecules, bone matrix development, energy production, as well as heart, nerve, and muscle function. Although the importance of Mg is evident, reference values for serum Mg (sMg) in pediatric patients (more specifically, in neonates) are not well established. This systematic literature review and meta-analysis (using 47 eligible studies) aims to quantify normal and tolerable ranges of sMg concentrations during the neonatal period and to highlight the factors influencing Mg levels and the importance of regulating sMg levels during pregnancy and birth. In newborns without Mg supplementation during pregnancy, magnesium levels at birth (0.76 (95% CI: 0.52, 0.99) mmol/L) were similar to that of mothers during pregnancy (0.74 (95% CI: 0.43, 1.04) mmol/L), but increased during the first week of life (0.91 (95% CI: 0.55, 1.26) mmol/L) before returning to adult levels. This pattern was also seen in newborns with Mg supplementation during pregnancy, where the average was 1.29 (95% CI: 0.50, 2.08) mmol/L at birth and 1.44 (95% CI: 0.61, 2.27) mmol/L during the first week of life. Factors influencing these levels include prenatal Mg supplementation, gestational age, birth weight, renal maturity/function, and postnatal Mg intake. Elevated Mg levels (>2.5 mmol/L) have been associated with an increased risk of mortality, admission into intensive care, hypotonia, hypotension, and respiratory depression but sMg concentrations up to 2.0 mmol/L appear to be well tolerated in neonates, requiring adequate survey and minimal intervention.

Determine Multiple Elements Simultaneously in the Sera of Umbilical Cord Blood Samples-a Very Simple Method

Analyzing the concentrations of heavy metals in the sera of umbilical cord blood samples can provide useful information about prenatal exposure to environmental agents. An analytical method based on ICP-MS to simultaneously determine multiple elements in umbilical cord blood samples was developed for assessing the in utero exposure to metallic and metalloid elements. The method only required as little as 100 μL of serum diluted 1:25 for direct analysis. Matrix-matched protocol was used to eliminate mass matrix interference and kinetic energy discrimination mode was used to eliminate the polyatomic ion interference. The assay was completed on average within 4 min with the detection limits ranging from 0.0002 to 44.4 μg/L for all the targeted elements. The detection rates for most of elements were 100 % other than cadmium (Cd), lead (Pb), and mercury (Hg). The testing results of the certified reference materials were ideal. The method is simple and sensitive, so it is suitable for the monitoring of large quantities of samples.

Prevalence of anemia and its risk factors among pregnant women in Khorramabad (Iran) 2010-2014

PURPOSE

Anemia's adverse effects on physical and behavioral development and on the reduction of efficiency have been proven. The aim of this study was to determine the prevalence of anemia in pregnant women referred to the health care centers of Khorramabad from 2010 to 2014.

MATERIALS AND METHODS

In this cross-sectional study, 2821 prenatal care cases of pregnant women referred to health care centers of Khorramabad were studied. Studied variables included the following: hemoglobin, hematocrit, age, parity, trimester of pregnancy status, number of deliveries, number of abortions, number of children, weight, height, time gap from previous delivery, negative RH, history of eclampsia/preeclampsia, coagulation disorder and blood pressure.

RESULTS

The mean age of the studied women was 26.7 ± 5.5. The mean levels of hemoglobin and hematocrit from the population was 12 ± 1.1 and 36.1 ± 9.2, respectively. The prevalence of anemia was 16.8%. Prevalence of anemia among pregnant women referred to health care centers of Khorramabad was found to be high.

CONCLUSIONS

Staff working at different parts of health care centers were advised to pay more attention to this problem. They should also try to control and treat anemia by regular distribution of iron supplements among women referred to health care centers.