Cord blood zinc status effects on pregnancy outcomes and its relation with maternal serum zinc levels: a systematic review and meta-analysis

Zinc, antioxidant enzymes in preeclampsia, and association with newborn outcome

BACKGROUND

The etiology of preeclampsia (PE) may be associated with the increased of production of reactive species and decreased antioxidant activity of enzymes. Inadequate intake of Zn can affect gestational health due to its biological functions, such as its role in the antioxidant defense system. The study aimed to assess the nutritional status of Zn and antioxidant enzymes in postpartum women and its correlation with neonatal outcomes.

METHODS

A cross-sectional analytical study was carried out at a referral gynecology and obstetrics hospital. A total of 119 women (PE = 58, HP = 61) participated in the study. A quantitative food-frequency questionnaire was used to assess food consumption and further analyze the dietary Zn levels. Zinc levels in plasma and erythrocytes samples were analyzed by flame atomic absorption spectrometry, catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) levels were determined by UV-Vis spectrophotometry.

RESULTS

Plasma and dietary intake Zn results were considered adequate and without statistical difference between groups. SOD levels were significantly higher in the HP group (p = 0.011), and CAT levels were higher in the PE group (p = 0.050). There was a positive correlation between SOD activity in women with PE and the weight of their newborns (r = 0.336, p=0.021).

CONCLUSION

The results showed adequate Zn levels (consumption and serum levels) in the groups studied, although with a reduction of plasma Zn in the PE group compared to the PH group. Zinc in plasma fractions and erythrocytes are important markers for oxidative stress, in particular, plasma Zn seems to be related to the rapid response to preeclampsia. The activity of antioxidant enzymes was elevated in the groups studied. Better SOD activity improves birth weight in children of pregnant women with preeclampsia.

Associations of maternal exposure to multiple plasma trace elements with the prevalence of fetal congenital heart defects: A nested case-control study

BACKGROUND

Scanty knowledge prevails regarding the combined impact of multiple plasma trace elements and main contributors on the prevalence of congenital heart defects (CHDs) in offspring. Thus, we performed a nested case-control analysis in a neonates cohort to investigate this important public health issue.

METHODS

We selected 164 pairs of cases and non-malformed controls from live births registered in the parent cohort (n = 11,578) at the same hospital. Plasma levels of 14 trace elements were determined by inductively coupled plasma-mass spectrometry. The odds ratios (ORs) of exposure were compared between cases and controls. Bayesian Kernel Machine Regression (BKMR) and Quantile g-Computation (QgC) models were employed to assess the cumulative effect of exposure to trace elements.

RESULTS

We found positive associations and linear dose-response relationships between plasma Pb and Sn and CHD. BKMR models indicated that the overall effect of the trace element mixture was associated with CHDs below the 45th percentile or above the 50th percentile, and the combined effect was primarily attributed to Sn and Pb. The QgC model indicated significantly increased odds of CHD with simultaneous exposure to all studied trace elements (OR: 2.19, 95%CI: 1.44-3.33).

CONCLUSIONS

This study is the first to report an association between elevated levels of mixed trace elements in maternal plasma with an increased prevalence of fetal CHDs, particularly in the case of Pb and Sn. Findings from this study provide further evidence of the important of heavy metal pollution to human health, and can help stakeholders prioritize policies and develop interventions to target the leading contributors to human exposure.

Content of selected heavy metals in the umbilical cord blood and anthropometric data of mothers and newborns in Poland: preliminary data

The ability to accumulate metals in organs and tissues leads to disturbances in the physiological functioning of the body, causing oxidative stress. This negatively affects the functioning of the placenta and may result in miscarriages, premature birth and fetal growth disorders. The aim of the study was to examine the relationship between the levels of selected heavy metals in umbilical cord blood and anthropometric parameters of mothers and the newborns. Content of elements in umbilical cord blood has been assessed by high-resolution inductively coupled plasma optical emission spectroscopy (ICP-OES). The study results were collected and statistically analyzed using IBM SPSS Statistics software (PS IMAGO). The Pearson correlation coefficient was used to test for associations between selected variables. Regression analysis was conducted to identify predictors of anthropometric parameters of studied women and newborns. The study group consisted of women aged 19-41, whose pregnancy was uncomplicated and were not exposed to heavy metals due to their work or smoking. The following metals were identified in all collected cord blood samples: lead (26.25 ± 9.32 µg/L), zinc (2025.24 ± 717.83 µg/L), copper (749.85 ± 203.86 µg/L), manganese (32.55 ± 13.58 µg/L), chromium (8.34 ± 2.16 µg/L) and selenium (158.46 ± 41.58 µg/L). The conducted statistical analysis indicated the relationship between the copper content in the umbilical cord blood and the weight gain of pregnant women. A significant relationship was observed between newborn head circumference and chromium content. In addition, significant positive correlations were found between the content of zinc and copper, manganese and lead, manganese and selenium, lead and selenium, and lead and chromium in umbilical cord blood. The ratio of zinc to copper concentrations was related to neonatal head circumference. Weight gain in pregnant women is positively correlated with the copper level in umbilical cord blood. There is an association between head circumference at birth and the chromium concentration in umbilical cord blood. Copper and zinc levels in umbilical cord blood are positively correlated with head circumference at birth.

Birth Size Outcomes in Relation to Maternal Blood Levels of Some Essential and Toxic Elements

Exposures to toxic trace elements and deficiencies of essential trace elements during pregnancy may impact fetal growth. This study was conducted to determine the association between maternal blood levels of essential elements including manganese (Mn), copper (Cu), and zinc (Zn) and toxic elements including arsenic (As), cadmium (Cd), and lead (Pb) at the first trimester with neonatal anthropometric parameters. This cross-sectional study was conducted in 2019-2020 in Isfahan, Iran. Overall, 263 mother-infant pairs were recruited in the first trimester of pregnancy. Maternal whole blood was collected, and essential and toxic elements were determined by mass spectrometry (ICP-MS)-based method. Birth size measurements were performed according to standardized protocols. Geometric means and standard deviations of maternal blood concentrations of Mn, Cu, Zn, As, Cd, and Pb were 3.94 ± 0.82, 5.22 ± 0.57, 7.67 ± 0.58, 2.21 ± 0.77, - 0.59 ± 0.98, and 3.23 ± 0.72 µg/l, respectively. Mean age of mothers was 29.94 ± 5.22 years. Thirty-one (12.1%) neonates were preterm. Maternal blood Pb levels were negatively correlated with birth weight (β = - 0.22 (CI 95%: - 0.38, - 0.05) p = 0.010) and marginally with birth head circumference (β = - 0.14(CI 95%: - 0.29, 0.02), P = 0.094) after adjustment for potential confounder variables. There was no significant association between Mn, Cu, Zn, As, Cd, and birth size measurements. Reverse association was found between maternal blood Pb levels and birth weight and birth head circumference. There is limited evidence related to the association between essential and toxic elements during pregnancy with birth size measurements and pregnancy disorders. More studies are suggested to assess of the effect of the trace elements and birth outcomes.

Impact of Zinc Deficiency During Prenatal and/or Postnatal Life on Cardiovascular and Metabolic Diseases: Experimental and Clinical Evidence

This review summarizes the latest findings, from animal models and clinical studies, regarding the cardiovascular and metabolic consequences in adult life of zinc deficiency (ZD) during prenatal and early postnatal life. The effect of zinc supplementation (ZS) and new insights about sex differences in the phenotype and severity of cardiovascular and metabolic alterations are also discussed. Zinc has antioxidant, anti-inflammatory, and antiapoptotic properties and regulates the activity of enzymes involved in regulation of the metabolic, cardiovascular, and renal systems. Maternal ZD is associated with intrauterine growth restriction and low birth weight (LBW). Breast-fed preterm infants are at risk of ZD due to lower zinc uptake during fetal life and reduced gut absorption capacity. ZS is most likely to increase growth in preterm infants and survival in LBW infants in countries where ZD is prevalent. Studies performed in rats revealed that moderate ZD during prenatal and/or early postnatal growth is a risk factor for the development of hypertension, cardiovascular and renal alterations, obesity, and diabetes in adult life. An adequate zinc diet during postweaning life does not always prevent the cardiovascular and metabolic alterations induced by zinc restriction during fetal and lactation periods. Male rats are more susceptible to this injury than females, and some of the mechanisms involved include: 1) alterations in organogenesis, 2) activation of oxidative, apoptotic, and inflammatory processes, 3) dysfunction of nitric oxide and renin-angiotensin-aldosterone systems, 4) changes in glucose and lipid metabolism, and 5) adipose tissue dysfunction. Safeguarding body zinc requirements during pregnancy, lactation, and growth periods could become a new target in the prevention and treatment of cardiovascular and metabolic disorders. Further research is needed to elucidate the efficacy of ZS during early stages of growth to prevent the development of these diseases later in life.

Maternal and Placental Zinc and Copper Status in Intra-Uterine Growth Restriction

BACKGROUND AND AIM

Zinc and copper are essential trace elements for cell growth and proliferation. Their deficiency may contribute to intrauterine growth restriction (IUGR). We aimed to determine the zinc and copper status of maternal serum and placenta samples of pregnant women with fetal IUGR and age-matched pregnant women without IUGR.

METHOD

Serum and placenta samples obtained from 37 IUGR and 21 healthy pregnant women were analyzed at delivery.

RESULTS

Placenta zinc concentrations and placenta zinc/copper ratio were significantly lower in the IUGR group compared to controls (p < 0.05). Placenta zinc concentrations correlated with birth weight (p: 0.01, r: 0.31). Maternal levels of zinc and copper were similar between pregnant women with IUGR and controls.

CONCLUSIONS

Lower placental zinc and zinc/copper ratio levels in pregnancies with IUGR may indicate that placenta zinc and placental zinc/copper status might be involved in IUGR.

Zinc homeostasis in immunity and its association with preterm births

Preterm birth is among the most common adverse pregnancy outcomes and is the leading cause of neonatal mortality and morbidity. While trace elements are essential for humans, their specific roles in the prenatal period remain unexplored. Zinc, a ubiquitous element plays a pivotal role in protein synthesis, cell division, nucleic acid metabolism, apoptosis, ageing, reproduction, immunological as well as antioxidant defense mechanism. Although zinc quantities are very small in body tissue, it is involved in every conceivable biochemical pathway which is critical for the performance of various functions necessary to sustain life. Owing to the multifactorial role of zinc, it is not possible to attribute a certain zinc dependent mechanism in pre-term births. Although the effect of zinc deficiency on immunity, its impact on maternal function and health as well as its role in the developing foetus is well documented, much less attention has been given to the understanding of micronutrient zinc homeostasis in immunity and its association with preterm births. Despite extensive research, the pathway by which zinc regulates pregnancy outcomes as well as the function of immune cells in controlling the delivery status (term/ preterm) is still obscure. The present review aims to focus on the understanding of relationship of micronutrient zinc homeostasis in immunity and its association with preterm births.

Zinc and iron adequacy and relative importance of zinc/iron storage and intakes among breastfed infants

Neonatal nutrient storage and supplies from breast milk contribute to nutrient status and growth of infants during their early life. This study investigated the adequacy of zinc and iron intakes among breastfed infants during the first 4 months and determined the relative importance of zinc/iron storage versus nutrient intakes with infant's biochemical status and growth. A longitudinal study followed lactating women and their breastfed infants from birth to 4 months postpartum. Cord zinc and ferritin concentrations, as indicators of nutrient storages, were determined. Zinc and iron intakes from breast milk were determined by measurement of breast milk volume together with milk zinc and iron concentrations at 2 and 4 months postpartum. Inadequacy of nutrient intakes was determined using average requirement (AR) which were 1.6 and 0.24 mg/day for zinc and iron respectively. Infant's serum zinc and ferritin were determined at 4 months of age. The data were collected from 64 and 56 participants at 2 months and 4 months postpartum. Inadequate zinc intake was found in 14.5 and 40% of infants at 2 and 4 months old, respectively. The prevalence of biochemical zinc and iron deficiency in infants were 76 and 11%, respectively. Iron endowment was significantly associated with serum ferritin at 4 months. The cumulative zinc intake was positively associated with weight gain and weight-for-length Z-score, but not length. This study provides quantitative data on zinc and iron intakes, and demonstrates the relative importance of nutrient storage versus intakes on biochemical status and growth of breastfed infants.

Essentiality of Trace Elements in Pregnancy, Fertility, and Gynecologic Cancers-A State-of-the-Art Review

Gynecological neoplasms pose a serious threat to women's health. It is estimated that in 2020, there were nearly 1.3 million new cases worldwide, from which almost 50% ended in death. The most commonly diagnosed are cervical and endometrial cancers; when it comes to infertility, it affects ~48.5 million couples worldwide and the number is continually rising. Ageing of the population, environmental factors such as dietary habits, environmental pollutants and increasing prevalence of risk factors may affect the reproductive potential in women. Therefore, in order to identify potential risk factors for these issues, attention has been drawn to trace elements. Trace mineral imbalances can be caused by a variety of causes, starting with hereditary diseases, finishing with an incorrect diet or exposure to polluted air or water. In this review, we aimed to summarize the current knowledge regarding trace elements imbalances in the case of gynecologic cancers as well as female fertility and during pregnancy.

Effect of maternal zinc supplementation or zinc status on pregnancy complications and perinatal outcomes: An umbrella review of meta-analyses

Zinc is an essential trace element involved in different physiological functions. During pregnancy, it plays a crucial role in healthy embryogenesis. This umbrella review, therefore, aimed to summarize the existing literature of meta-analyses evaluating the effect of maternal zinc supplementation or zinc status on maternal and neonatal outcomes. Two databases, PubMed and Scopus, were selected to search the available literature without any temporal restriction. The literature search was performed during October 2020 and a total of 192 records were identified through the literature search. After screening the titles and applying the inclusion/exclusion criteria, finally, 15 articles were included in this umbrella review. This umbrella review showed that maternal zinc supplements reduce the risk of preterm birth. Although no substantial effect of zinc supplements was found for other feto-maternal outcomes. Also, we found a significant relationship between low maternal zinc status and risk of pregnancy complications. Zinc supplements reduce the risk of preterm birth. Long-term interventions and cohort studies are needed for future research directions. Further studies and a thorough investigation will help to decide the recommended zinc dose or intake during pregnancy.

Zinc

Since the discovery of manifest Zn deficiency in 1961, the increasing number of studies demonstrated the association between altered Zn status and multiple diseases. In this chapter, we provide a review of the most recent advances on the role of Zn in health and disease (2010-20), with a special focus on the role of Zn in neurodegenerative and neurodevelopmental disorders, diabetes and obesity, male and female reproduction, as well as COVID-19. In parallel with the revealed tight association between ASD risk and severity and Zn status, the particular mechanisms linking Zn2+ and ASD pathogenesis like modulation of synaptic plasticity through ProSAP/Shank scaffold, neurotransmitter metabolism, and gut microbiota, have been elucidated. The increasing body of data indicate the potential involvement of Zn2+ metabolism in neurodegeneration. Systemic Zn levels in Alzheimer's and Parkinson's disease were found to be reduced, whereas its sequestration in brain may result in modulation of amyloid β and α-synuclein processing with subsequent toxic effects. Zn2+ was shown to possess adipotropic effects through the role of zinc transporters, zinc finger proteins, and Zn-α2-glycoprotein in adipose tissue physiology, underlying its particular role in pathogenesis of obesity and diabetes mellitus type 2. Recent findings also contribute to further understanding of the role of Zn2+ in spermatogenesis and sperm functioning, as well as oocyte development and fertilization. Finally, Zn2+ was shown to be the potential adjuvant therapy in management of novel coronavirus infection (COVID-19), underlining the perspectives of zinc in management of old and new threats.

Role of zinc in neonatal growth and brain growth: review and scoping review

This manuscript includes (1) a narrative review of Zinc as an essential nutrient for fetal and neonatal growth and brain growth and development and (2) a scoping review of studies assessing the effects of Zinc supplementation on survival, growth, brain growth, and neurodevelopment in neonates. Very preterm infants and small for gestational age infants are at risk for Zinc deficiency. Zinc deficiency can cause several complications including periorificial lesions, delayed wound healing, hair loss, diarrhea, immune deficiency, growth failure with stunting, and brain atrophy and dysfunction. Zinc is considered essential for oligodendrogenesis, neurogenesis, neuronal differentiation, white matter growth, and multiple biological and physiological roles in neurobiology. Data support the possibility that the critical period of Zinc delivery for brain growth in the mouse starts at 18 days of a 20-21-day pregnancy and extends during lactation and in human may start at 26 weeks of gestation and extend until at least 44 weeks of postmenstrual age. Studies are needed to better elucidate Zinc requirement in extremely low gestational age neonates to minimize morbidity, optimize growth, and brain growth, prevent periventricular leukomalacia and optimize neurodevelopment. IMPACT: Zinc is essential for growth and brain growth and development. In the USA, very preterm small for gestational age infants are at risk for Zinc deficiency. Data support the possibility that the critical period of Zinc delivery for brain growth in the mouse starts at 18 days of a 20-21-day pregnancy and extends during lactation and in human may start at 26 weeks' gestation and extend until at least 44 weeks of postmenstrual age. Several randomized trials of Zinc supplementation in neonates have shown improvement in growth when using high enough dose, for long duration in patients likely to or proven to have a Zinc deficiency. Studies are needed to better elucidate Zinc requirement in extremely low gestational age neonates to minimize morbidity, optimize growth and brain growth, prevent periventricular leukomalacia and optimize neurodevelopment.

Effect of Maternal Nutritional Status and Mode of Delivery on Zinc and Iron Stores at Birth

Zinc and iron deficiencies among infants aged under 6 months may be related with nutrient store at birth. This study aimed to investigate the association between zinc and iron stores at birth with maternal nutritional status and intakes during pregnancy. 117 pregnant women were enrolled at the end of second trimester and followed until delivery. Clinical data during pregnancy, including pre-pregnancy body mass index (BMI) and at parturition were collected from medical record. Zinc and iron intakes were estimated from a food frequency questionnaire. Serum zinc and ferritin were determined in maternal blood at enrollment and cord blood. Mean cord blood zinc and ferritin were 10.8 ± 2.6 µmol/L and 176 ± 75.6 µg/L, respectively. Cord blood zinc was associated with pre-pregnancy BMI (adj. ß 0.150; p = 0.023) and serum zinc (adj. ß 0.115; p = 0.023). Cord blood ferritin was associated with pre-pregnancy BMI (adj. ß -5.231; p = 0.009). Cord blood zinc and ferritin were significantly higher among those having vaginal delivery compared to cesarean delivery (adj. ß 1.376; p = 0.007 and 32.959; p = 0.028, respectively). Maternal nutritional status and mode of delivery were significantly associated with zinc and iron stores at birth. Nutrition during preconception and pregnancy should be ensured to build adequate stores of nutrients for infants.

The Effects of Zinc Supplementation on C-Reactive Protein and Inflammatory Cytokines: A Meta-Analysis and Systematical Review

Zinc is known for anti-inflammatory and antioxidant roles. In this meta-analysis, we aim to evaluate the impact of zinc supplementation on inflammatory markers, acute-phase reactants, and serum zinc level during inflammatory and infectious diseases. PubMed, Scopus, and Web of Science databases were screened systematically with the terms "zinc supplementation" AND "CRP" OR "IL-1β" OR "IL-2" OR "IL-6" OR "IL-10" OR "IL-12" OR "TNF-α" OR "TGF-β" OR "IFN-γ" OR "WBC (clinical trial)" OR "macrophage (clinical trial)" OR "lymphocyte (clinical trial)" OR "neutrophil (clinical trial)" OR "virus (clinical trial)" OR "antiviral (clinical trial)" for all databases. A total of 2,258 publications were screened, and 73 articles had suitable data for the meta-analysis. Serum zinc level was significantly higher in supplementation group compared with controls [P = 0.0006, mean difference: 11.35 (4.84, 17.87)] (n = 37). Zinc supplementation downregulates acute-phase reactants, especially serum C-reactive protein (CRP) in adults [P < 0.00001, mean difference: -0.75 (-0.98, -0.52)] (n = 22) and pregnant women [FEM P < 0.00001, mean difference: -1.77 (-2.53, -1.00)] (n = 3) but not in children [REM P = 0.10, mean difference: -0.85 (-1.86, 0.17)] (n = 3). In subgroups analysis of chronic inflammatory diseases, serum CRP [REM P < 0.00001, mean difference: -0.57 (-0.76, -0.38)] were significantly lower in zinc-supplemented patients compared with no intervention group. Zinc supplementation (mg/day) correlated with serum interferon-gamma (IFN-γ) level (P = 0.018, r = 1,000). In the nonsupplemented group, serum zinc correlated with serum interleukin-6 (IL-6) level (P = 0.041, r = -0.829) and serum tumor necrosis factor alpha (TNF-α) level (P = 0.063, r = 0.730). Zinc intake correlated with serum zinc (P = 0.0428, r = 0.5115) and TNF-α (P = 0.0043, r = -0.9461). This meta-analysis shows that zinc supplementation improves CRP levels in adults and pregnant women. It might have modulatory effects on cytokine secretions and blood cells in inflammatory and infectious diseases. For the first time, we investigated the effects of zinc supplementation on inflammatory cytokine.

Determining the Actual Zinc and Iron Intakes in Breastfed Infants: Protocol for a Longitudinal Observational Study

BACKGROUND

Zinc and iron deficiencies among breastfed infants during the first 6 months of life have been reported in previous studies. The amounts of zinc and iron intakes from breast milk are factors that contribute to the zinc and iron status of breastfed infants.

OBJECTIVE

This study aims to quantitatively determine zinc and iron intakes by breastfed infants during the first 4 months of life and to investigate the factors that predict zinc and iron status in breastfed infants.

METHODS

Pregnant women at 28 to 34 weeks of gestation were enrolled. Zinc and iron status during pregnancy was assessed. At delivery, cord blood was analyzed for zinc and iron levels. Participants and their babies were followed at 2 and 4 months postpartum. Maternal dietary intakes and anthropometric measurements were performed. The amount of breast milk intake was assessed using the deuterium oxide dose-to-mother technique. Breast milk samples were collected for determination of zinc and iron levels. The amount of zinc and iron consumed by infants was calculated. Zinc and iron status was determined in mothers and infants at 4 months postpartum.

RESULTS

A total of 120 pregnant women were enrolled, and 80 mother-infant pairs completed the study (56 provided full breastfeeding, and 24 provided breast milk with infant formula). All data are being managed and cleaned. Statistical analysis will be done.

CONCLUSIONS

This study will provide information on zinc and iron intakes in exclusively breastfed infants during the first 4 months of life and explore predictive factors and the possible association of zinc and iron intakes with infant growth and nutrient status.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/19119.

Zinc deficiency limiting head growth to discharge in extremely low gestational age infants with insufficient linear growth: a cohort study

OBJECTIVE

To assess the relationship of size for age with zinc deficiency in extremely low gestational age (GA) infants (23-28 weeks, ELGANs) who had insufficient linear growth despite optimizing other nutrients and to analyze changes in fronto-occipital circumference (FOC), weight and length with zinc supplementation.

STUDY DESIGN

Retrospective cohort study.

RESULTS

Among 302 ELGANs, a serum zinc concentration was obtained in 52 with insufficient linear growth (17%). Zinc deficiency (serum concentration <0.74 mcg/ml) was diagnosed in 8 of 24 (33%) small for GA (SGA) compared to 35 of 278 (13%) non-SGA infants (P = 0.01). Zinc supplementation for >2 weeks improved FOC growth to discharge or 50 weeks postmenstrual age in infants with Zn deficiency. However, neither linear growth nor weight gain improved with Zn supplementation.

CONCLUSION

Zinc deficiency was diagnosed in 14% ELGANs in this cohort. Zinc supplementation for >2 weeks improved FOC growth but not linear growth or weight gain.