Effects of Selenium Deficiency on Electrocardiogram and Oxidative Stress Level of Pregnant Women and Neonates in Northeast China

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Methods A cohort of 1515 women and 200 neonates from contrasting selenium status regions underwent ECG evaluations, selenium content determination and oxidative stress level assessments. Results Through the application of relevant kit detection, study revealed lower selenium & heightened oxidative stress level in deficient groups (P < 0.01). Pregnant women from deficient regions exhibited prolonged ECG intervals, whereas non-pregnant showed reduced intervals. Neonates with selenium deficiency manifested altered ECG waves. Animal models are consistent with human studies, confirming ECG abnormalities & oxidative stress exacerbation in selenium scarcity. Conclusions Our results imply that inadequate selenium intake may not only perturb the intricate balance of oxidative stress but also precipitate alterations in ECG patterns, thereby posing potential risks to cardiovascular health. Selenium deficiency electrocardiography pregnancy oxidative stress neonates Figures Figure 1 1. Introduction Selenium is an essential trace element that plays a crucial role in various physiological functions in the human body, including antioxidant defense mechanisms [ 1 ] . Selenium deficiency has been linked to various cardiovascular diseases, such as Keshan disease, arrhythmia, myocardial fibrosis, and congestive heart failure [ 2 ] . Electrocardiogram (ECG) is a non-invasive diagnostic tool that can provide valuable information about cardiac function [ 3 ] . However, there is limited research on the relationship between selenium deficiency, ECG changes, and oxidative stress levels in pregnant women and neonates. Pregnancy is a critical period for both the mother and the developing fetus, and adequate selenium intake is crucial for optimal maternal and fetal health [ 4 ] . Selenium deficiency during pregnancy can lead to high oxidative stress levels in the maternal body, which can have adverse effects on fetal development [ 5 ] . Therefore, it is essential to investigate the relationship between selenium deficiency, ECG changes, and oxidative stress levels in pregnant women and neonates. This study aimed to assess the effects of selenium deficiency on ECG changes and oxidative stress levels in women with and without pregnancy and neonates. The findings of this study could provide valuable insights into the prevention and management of cardiovascular diseases associated with selenium deficiency during pregnancy and early life. 2. Methods 2.1 Study Design: The study involved 1515 female participants, including 626 pregnant participants with more than 37 weeks of pregnancy (selenium deficient of pregnant group, SD of pregnant group), 77 non-pregnant participants in a selenium deficient area (selenium deficient of non-pregnant group, SD of non-pregnant group), 489 pregnant participants with more than 37 weeks of pregnancy (control of pregnant group), and 100 non-pregnant participants in a control area (control of non-pregnant group). Additionally, 200 neonates were included, with 100 from the selenium deficient area (selenium deficient of neonatal group, SD of neonatal group) and 100 from the control area (control of neonatal group). Through studying the changes of selenium content, electrocardiogram and oxidative stress level in full-term parteriums and neonates in two regions with different selenium content, this paper reveals the changes of electrocardiogram in mothers and neonates caused by selenium deficiency, and studies the internal relationship between electrocardiogram and oxidative stress level, electrocardiogram and selenium deficiency. Meanwhile, the animal model of selenium deficiency was established with slight modifications according to the method of Vanderlelie et al [ 6 ] . Animal models were used to simulate the distribution of selenium deficiency in important organs, the relationship between oxidative stress level and myocardial damage and electrocardiogram changes, and the results of clinical studies were verified from the perspective of in vivo experiments. 2.2 Selection Criteria of Participants: Selenium deficient (SD) of pregnant group: Pregnant women over 37 weeks of age who were treated in Maternal and Child Health Care Hospital of Fuyu County or People's Hospital of Fuyu County, from March 2011 to August 2012. Subjects need to live in the area continuously for more than 6 months, and chronic diseases such as hypertension and diabetes must be ruled out. It is also necessary to exclude all pregnancy-related complications, including but not limited to gestational hypertension, gestational diabetes, eclampsia and preeclampsia. It didn't matter whether the subjects ultimately chose vaginal or cesarean delivery. The age of the SD of pregnant groups were 25.9 ± 4.55 years. Selenium deficient (SD) of non-pregnant group: The non-pregnant women of gestational age were selected from Fuyu County Maternal and Child Health Care Hospital or physical examination department of Fuyu County People's Hospital. The age of the SD of non- pregnant groups were 23.7 ± 5.31 years. Selenium deficient (SD) of neonatal group: After the women in SD of pregnant group gave birth, 100 full-term newborns were selected to participate in the study. The newborns participating in the study were required to undergo prenatal testing to rule out all congenital and genetic disorders. Control of pregnant group: Pregnant women over 37 weeks of age who were treated in The First Affiliated Hospital of Harbin Medical University, from March 2011 to August 2012. Subjects need to live in the area continuously for more than 6 months, and chronic diseases such as hypertension and diabetes must be ruled out. It is also necessary to exclude all pregnancy-related complications, including but not limited to gestational hypertension, gestational diabetes, eclampsia, preeclampsia et al. It didn't matter whether the subjects ultimately chose vaginal or cesarean delivery. The age of the SD of pregnant groups were 30.4 ± 4.05 years. Control of non-pregnant group: The non-pregnant women of gestational age were selected from physical examination department of The First Affiliated Hospital of Harbin Medical University, from March 2011 to August 2012. The age of the SD of non- pregnant groups were 29.7 ± 4.19 years. Control of neonatal group: After the women in Control of pregnant group gave birth, 100 full-term newborns were selected to participate in the study. The newborns participating in the study were required to undergo prenatal testing to rule out all congenital and genetic disorders. All subjects have signed informed consent forms. Whether newborns participate in the study is up to their mothers. This study was approved by the Ethical Review Committee of Qiqihar Medical University and is in accordance with the Declaration of Helsinki. 2.3 Animal model: Adult female Vista rats weighing 180–220 g (8–10 weeks old) were housed in a pathogen-free environment at room temperature (22–25 ℃) and maintained on basal diet and tap water ad libitum before achieving the selenium deficient state. The rats were divided into two groups (N = 12 per group). Rats in the selenium deficient group were fed a special mouse food containing 4.5 µg/kg total selenium for 4 weeks, while control rats were fed standard mouse food containing 219 µg/kg total selenium for 4 weeks. After 4 weeks, six female rats were randomly selected from each group for measurement of ECG and were sacrificed by severing the spinal cord for measurement of selenium content and oxidative stress status. The hearts, livers, and kidneys were perfused with ice-cold physiological saline (0.9% NaCl) until the blood was sufficiently removed. The remaining female rats were mated with male rats when the selenium deficient model was established successfully. Two weeks after mating, the pregnant female rats were kept feeding alone. Neonatal rats were fed by breast milk for 4 weeks to measure ECG, selenium content, and oxidative stress levels. Animal experiments in this study followed ARRIVE guidelines. The animal protocols were reviewed and approved by the Animal Care and Ethics Committee of Qiqihar Medical College, Qiqihar, China. 2.4 Electrocardiogram Analysis: Standard 12-lead ECGs were performed on participants, and limb lead ECGs were performed on neonates immediately after birth. The paper speed was set to 25 mm/s, sensitivity to 10 mm/mV, and frequency to 0.6–100 Hz. The RM6240B/C biological signal collecting and processing system was used to describe the ECG of neonatal rats at a sweep speed of 10 ms/div, sensitivity of 1 mm/mV, and frequency of 100 Hz. Electrocardiogram data were recorded under relaxation and sleep anesthesia state, with the animals anesthetized by intraperitoneal injection with 20% urethane solution (0.1 ml urethane injection per 20 g body weight). A cardiologist completed the analyses of ECG, using digital calipers (Range 150 mm, Precision 0.01 mm, Type 16EWR, HAMR) to measure the duration of P and QRS wave, PR interval, QT interval, RR interval, and the QTc were calculated by Bazzett’s formula [ 6 ] . 2.5 Selenium Content Analysis: The selenium contents of maternal blood, umbilical blood, placenta, and umbilical cord of pregnant groups, blood of non-pregnant groups, and blood, hearts, livers, and kidneys of maternal and neonatal rats were measured by hydride generation atomic fluorescence spectrometry. Hydride was generated with a model 10.004 hydride generator (PS Analytical, Orrington, UK) according to the manufacturer's instructions. Signals were acquired with a microcomputer using commercial software (Avalon 2.0, PS Analytical). All solutions were prepared with doubly deionized water with 18.2 Mo cm resistances. Selenium stock solutions (1000 mg/l) were prepared from selenite (Na2SeO3 99%), selenate (Na2SeO4 99%), seleno-DL-cystine (SeCys), seleno-DL-methionine (SeMet) (all from Sigma-Aldrich, St Louis, MO, USA) and trimethylselenonium iodide (TMeSeI, Organometallics, and Hampstead, NH, USA). SeCys and SeMet were weighed under nitrogen to prevent sample degradation and dissolved in 0.5% (v/v) hydrochloric acid. 2.6 Oxidative Stress Analysis: The tissues of the heart, liver, and kidney of maternal rats were homogenized with a 5-fold v/w of cell lysate in ice. The homogenates were centrifuged at 850 g for 15 min, and their supernatants were stored at -80℃. Total (Cu/Zn and Mn) superoxide dismutase (SOD) activity was determined by reagents from Nanjing Jiancheng Bioengineering Institute (Nanjing, China) according to the manufacturer's instructions, based on the inhibition rate of nitroblue tetrazolium (NBT) reduction, with the xanthine-xanthine oxidase system as a superoxide generator. Absorbance was detected spectrophotometrically at 550 nm. Maternal and umbilical blood of pregnant groups and hearts, livers, and kidneys of maternal rats were used for the determination of MDA content. Homogenates were bathed in distilled water for 15 min at 100 ℃, and centrifuged for 10 min at 1000 g after cooling to room temperature. 200 µl supernatant was used to measure MDA level using a commercially available kit (Nanjing Jiancheng Bioengineering Institute) according to the manufacturer's recommended protocol. Absorbance was measured at 532 nm. 2.7 Statistical Analysis: Statistical analyses were performed using GraphPad Prism 5.0 (GraphPad Software, La Jolla, CA, USA). Data were presented as mean with standard deviation. Statistical significance was determined using ANOVA-test. A P-value < 0.05 was statistically significant. 3. Results 3.1 Electrocardiogram Analysis In the pregnant groups, the ECGs of the selenium deficient group showed an increase in R wave, T wave, and heart rate compared to the control group. In the non-pregnant groups, the T wave and heart rate were accelerated in the selenium deficient group compared to the control group. The specific numerical data were shown in Table 1 . There were many differences between the control and selenium deficient neonatal groups, such as P wave, R wave, PR interval, QT interval, etc. The specific numerical data were shown in Table 2 . Compared to the control group, the ECGs of neonatal rats in the selenium deficient group showed an increase in R wave, T wave, significant QT interval elongation, ST segment elevation, and heart rate reduction. Table 1 The measurement results of ECG of women with and without pregnancy in low and control selenium area. Group P wave duration(ms) PR interval(ms) QRS duration(ms) RR interval(ms) QT interval(ms) QTC (ms) Heart rate(BPM) Low selenium pregnancy (N = 626) 80.1 ± 11.8 * 135.1 ± 16.9 * 74.5 ± 6.9 789.6 ± 82.6 * 344.5 ± 29.9 ** 412.3 ± 12.6 91.4 ± 18.6 ** Control selenium pregnancy (N = 489) 66.3 ± 6.7 116.2 ± 12.9 74.5 ± 15.2 581.4 ± 49.3 312.5 ± 17.6 402.2 ± 17.9 103.9 ± 8.9 Low selenium non-pregnancy (N = 77) 83.6 ± 3.7 # 157.9 ± 18.1 70.4 ± 5.1 # 755.9 ± 74.9 ## 357.5 ± 9.5 # 395.1 ± 19.9 ## 80 ± 4.5 # Control selenium non-pregnancy (N = 100) 88.1 ± 3.9 139.8 ± 4.5 81.2 ± 6.2 914.7 ± 132.7 377.5 ± 16.9 419 ± 15.4 66.9 ± 9.5 Data presented as mean ± SD. P - values obtained from the ANOVA-test. Table 2 The measurement results of limb lead of neonates in low and control selenium area. P wave duration(ms) P wave amplitude(mm) PR interval(ms) QT interval(ms) QRS duration(ms) QRS amplitude(mm) Low selenium neonates (n = 100) Lead I 68.8 ± 19.3 1.03 ± 0. 38 ** 108 ± 17.8 273.5 ± 25.1 ** 45.5 ± 8.9 ** 9.54 ± 4.05 ** Lead II 66 ± 15.6 1.38 ± 0. 39 * 106 ± 14.5 277.3 ± 24.2 * 52 ± 9.8 9.29 ± 2.98 Lead III 55 ± 15 ** 0. 74 ± 0. 29 102 ± 17.2 290.5 ± 34.4 53.8 ± 9.4 * 12.24 ± 4.90 Lead aVR 71.3 ± 17.6 1.16 ± 0. 35 * 113.5 ± 19.2 269 ± 23.2 ** 47.5 ± 9.7 ** 6.94 ± 2.36 ** Lead aVL 56.5 ± 18.2 * 0. 61 ± 0. 26 96 ± 20.1 272 ± 36.8 ** 45.3 ± 10.5 10.28 ± 3.59 Lead aVF 59.5 ± 12.8 0. 97 ± 0. 34 * 104.5 ± 16.4 278 ± 25.6 * 54.8 ± 7.7 * 9.60 ± 3.16 Control selenium neonates (n = 100) Lead I 63.5 ± 12 0. 86 ± 0. 30 103.8 ± 14.9 298.5 ± 18 55.5 ± 8.6 12.08 ± 4.03 Lead II 60.5 ± 9.7 1.13 ± 0. 38 105.3 ± 16.4 301.5 ± 20.7 54.8 ± 8.4 9.92 ± 4.28 Lead III 48.8 ± 9.5 0. 69 ± 0. 28 94.5 ± 16.1 303 ± 27.4 58.8 ± 8.4 12.87 ± 5.22 Lead aVR 69.5 ± 14.3 1.00 ± 0. 30 113 ± 14.5 301.5 ± 20.6 55.5 ± 8.7 8.56 ± 2.52 Lead aVL 49.3 ± 12.9 0. 53 ± 0. 19 89.5 ± 13.4 293 ± 27.7 54.8 ± 8.4 11.93 ± 4.33 Lead aVF 55.8 ± 12.0 0. 79 ± 0. 34 103.5 ± 15.6 303 ± 28.4 58.8 ± 8.4 9.75 ± 4.52 Data presented as mean ± SD. P - values obtained from the ANOVA-test. In the pregnant groups, the P wave duration, PR interval, RR interval, and QT interval of the selenium deficient group were longer than their corresponding control group. The heart rate of the selenium deficient group was slower than the control group, and QRS duration and QTC showed no statistical significance between the selenium deficient and control groups. In the non-pregnant groups, compared to the control group, the P wave duration, QRS wave duration, QT interval, QTc, and RR interval of the selenium deficient group were decreased, and the heart rate of the selenium deficient group was faster, but PR interval was not significantly different. Compared to the control group, the ECGs of neonates in the selenium deficient group indicated that P wave amplitude increased and QT interval and QRS amplitude decreased. Besides, P wave duration was longer than the control in Lead Ⅲ and aVL, and QRS voltage of the selenium deficient group was lower than the control group in Lead Ⅰ and aVR. There was no significant difference in PR interval between the selenium deficient and control groups of neonates. 3.2 Selenium Content Analysis Selenium concentrations in the maternal blood and umbilical blood, placenta, and umbilical cord of the selenium deficient puerperal were lower than their corresponding controls. Selenium concentrations in the blood of the participants without pregnancy in the selenium deficient area were also lower than the corresponding control. Selenium concentrations in the hearts, livers, kidneys, and blood of selenium deficient maternal rats were lower than their corresponding control group. Selenium concentrations in the hearts, livers, kidneys, and blood of selenium deficient neonatal rats were also lower than their corresponding control group. 3.3 Oxidative Stress Analysis SOD activity was lower in the liver and kidney of selenium deficient maternal rats compared to their corresponding controls but showed no significant difference in the heart compared to the control. MDA concentrations in blood (maternal blood and umbilical blood) were significantly higher in the selenium deficient pregnant group compared to their corresponding controls, and MDA concentrations in the heart, liver, and kidney of maternal rats in the selenium deficient group were significantly higher than their corresponding controls. The results were shown in Fig. 1. 4. Discussion The study demonstrated that selenium deficiency increased oxidative stress levels in pregnant and non-pregnant women and neonates. Changes in ECG were also apparent in women in the selenium deficient area, as revealed by measurement of electrocardiogram. These results suggested that selenium deficiency could induce elevation of oxidative stress levels and changes in electrocardiogram. The study is the first investigation on the impacts of selenium deficiency on both puerperas and neonates. Selenium is an essential element in animals, and its deficiency has been attributed to a number of mammalian selenoproteins [ 7 ] . Keshan disease, a dilated cardiomyopathy endemic in China, has been found to be closely related to a selenium-deficient diet [ 8 ] . A selenium-deficient diet can induce oxidative injury, which may lead to myocardial injury and subsequent cardiac dysfunction [ 9 ] . Evidence shows that selenium deficiency may cause myocardial failure [ 10 ] . Oxidative stress leads to lipid peroxidation, and sulfhydryl group oxidation seems to be among the mechanisms that may produce membrane defects, causing cardiac contractile dysfunction in the myocardium [ 11 ] . We found that the selenium content of women (with and without pregnancy) and neonates in selenium-deficient areas were lower, and the content of MDA was higher than that in the control area. This study confirmed that women and neonates in selenium-deficient areas have low selenium content and high oxidative stress status. Although typical clinical symptoms of cardiovascular disease did not appear in selenium-deficient women and neonates, these alterations may cause a certain degree of injury to myocardial cells with prolonged selenium deficiency and high oxidative stress states. They are more prone to diseases caused by selenium deficiency or an increase in oxidative stress. In addition, ECG is also a cornerstone in the assessment of cardiovascular functions, which has a close relationship with the action potential of myocardial cells [ 12 ] . In the ECG, every waveform represents a specific meaning. For example, P wave duration, QRS wave duration, PR interval, QT interval, and RR interval indicate the process of depolarization of the atrium and ventricle, the process of repolarization of the atrium, the total time of ventricular activation, and the cardiac cycle, respectively [ 13 ] . Research shows that P wave amplitude and duration were significantly associated with cardiovascular disease and mortality [ 14 ] . PR prolongation was associated with increased risks of AF and death [ 15 ] , the wide QRS duration as underlying etiology might affect the frequency of interventricular dyssynchrony indices [ 16 ] , and shortened and prolonged QT-interval durations, even within a reference range, were associated with increased mortality risk in the general population [ 17 ] . We found that compared with pregnant women in control areas, the duration of P wave, interval of PR, RR, and QT of pregnant women in selenium-deficient areas prolonged, and heart rate slowed, but QRS duration and QTC had no statistical significance between SD and control groups. Compared with non-pregnant women in control areas, the duration of P and QRS wave, RR and QT interval, and QTC shortened, and heart rate accelerated, but PR interval had no significant difference between SD and control groups. These results showed that selenium deficiency may cause ECG changes in women (pregnant and non-pregnant women) without the typical clinical symptoms of cardiovascular disease in selenium deficient and high oxidative stress status. This research suggests a higher possibility of the occurrence of cardiovascular diseases in selenium-deficient non-pregnant women than corresponding controls because of prolonged selenium deficiency and high oxidative stress status. Pregnant women are more prone to myocardial ischemia and hypoxia due to a significant increase in effective circulating blood volume, velocity of blood flow acceleration [ 18 ] , cardiac output [ 19 ] , and myocardial oxygen consumption increase [ 20 ] . Meanwhile, with the increased time of pregnancy, pregnant women are more prone to myocardial labor injury [ 21 ] after months of high workloads. The possibility of the occurrence of cardiovascular diseases in pregnant women in selenium-deficient areas greatly increased. The results of neonatal ECG in SD and control areas showed that the P wave amplitude increased, and QT interval and QRS duration reduced in SD neonates. The organic heart disease is not enough to prove in neonate of low selenium area, but if the neonates of selenium-deficient areas are in low selenium levels and high oxidative stress status for a long time, whether selenium deficiency would impact the growth and development of neonate remains to be further studied. The body must constantly assimilate selenium from the outside to maintain the dynamic equilibrium of selenium in the body. Thus, a rat model on a selenium-deficient diet can be used in the following experiments, replacing patients in selenium-deficient areas. Rats in selenium-deficient groups in the present study had significantly lower concentrations of selenium in the heart, liver, brain, and blood compared with control groups (receiving the normal diet). SOD activity and MDA concentrations were measured as indicators of oxidative stress. Severe oxidative stress was found in several organs in the selenium-deficient groups, indicating that this constituted a good animal model of oxidative stress: one that could be useful in investigating the relationship between selenium deficiency and ECG. We found that the ECGs of neonatal rats in the selenium-deficient group had significant changes. Compared with the control group, ECGs of neonatal rats in the selenium-deficient group showed an increase in R wave and T wave, significant QT interval prolongation, ST segment elevation, and heart rate decrease. Myocardial injury of selenium-deficient rats has been confirmed by histopathological and ultrastructure studies in our previous research [ 9 ] . Meanwhile, the changes of ECG in the animal model further proved that selenium deficiency could affect cardiac function. The result of the animal model was consistent with that of human participants. Selenium deficiency could cause cardiac dysfunction in women (with and without pregnancy) and neonates without the clinical performance. Conclusion Selenium deficiency could cause electrocardiogram changes and elevation of oxidative stress levels in women with and without pregnancy and neonates. Declarations Competing Interests The authors declare that they have no competing interests. Guidelines and Regulations Statement This study complied with relevant national and local regulations, and all experiments were conducted in accordance with relevant guidelines and regulations. Ethics approval and consent to participate The study was approved by the Experimental Animal Ethics Committee of Qiqihar Medical College [approval number: 2022139(QMU-AECC-2022-39)]. Informed consent was waived because of the retrospective study design, and the data analyses used data containing no personally identifiable information. Consent for publication Not applicable. Competing interests The authors declare that there are no potential competing interests, whether financial or personal, that could be perceived as influencing this work. Funding This study was supported by Key cultivation project of Qiqihar Academy of Medical Sciences (2022-ZDPY-015). Author Contribution Chu Erfu: Writing -original draft, Resources, Methodology. Pan Farong: Writing-review & editing. Liang Zhaowen: Writing-review & editing. Qu Weiting: Methodology, Resources, Writing -original draft. Sun Xingyuan: Conceptualization, Resources, Data curation. Lu Junkun: Writing-review & editing, Supervision, Project administration, Funding acquisition, Conceptualization. Acknowledgement Not applicable. Data Availability Data supporting the findings of this study can be obtained from the corresponding author upon request. References Gui JY, Rao S, Huang X, Liu X, Cheng S, Xu F. Interaction between selenium and essential micronutrient elements in plants: A systematic review. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7819841","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":549309867,"identity":"7b5f328f-8f54-4be1-9c17-80c60abb1c99","order_by":0,"name":"Chu Erfu","email":"","orcid":"","institution":"The third affiliated hospital of Qiqihar medical university","correspondingAuthor":false,"prefix":"","firstName":"Chu","middleName":"","lastName":"Erfu","suffix":""},{"id":549309868,"identity":"7b0c0fca-bfe4-482f-9848-c4c28f2f8dfb","order_by":1,"name":"Pan Farong","email":"","orcid":"","institution":"Guangzhou University of Chinese 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university","correspondingAuthor":false,"prefix":"","firstName":"Sun","middleName":"","lastName":"Xingyuan","suffix":""},{"id":549309872,"identity":"d0106c39-0644-4e24-a524-1f171103a39b","order_by":5,"name":"Junkun Lu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAoUlEQVRIiWNgGAWjYBACPoZjIMqGh5+/gUgtbBAtaTKSMw4QrYUNRB22MWhIIFYL47E0ad628zwGDAcYP3zMIc5hx4BabvOYMzcwS87cRpSW421gLZYNB9iYeUnQco7H4EAC0VrADjtAmpZkyznnknkkZxxsJs4v/BLHDG+8KbOz5+dvPvjhIzFaGCQOwFiMDcSoB1lDrMJRMApGwSgYuQAA98kxe1adBggAAAAASUVORK5CYII=","orcid":"","institution":"Guangzhou University of Chinese Medicine","correspondingAuthor":true,"prefix":"","firstName":"Junkun","middleName":"","lastName":"Lu","suffix":""}],"badges":[],"createdAt":"2025-10-09 16:53:19","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7819841/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7819841/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":96617862,"identity":"ec263f3f-6dc9-480a-b492-e8400aeaef09","added_by":"auto","created_at":"2025-11-24 10:33:14","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":63414,"visible":true,"origin":"","legend":"","description":"","filename":"ElectrocardiogramandOxidativeStress.docx","url":"https://assets-eu.researchsquare.com/files/rs-7819841/v1/66010fa4db1652e7a8a289b9.docx"},{"id":96708405,"identity":"3e722c05-42d8-45b9-9069-04ab8c350d3c","added_by":"auto","created_at":"2025-11-25 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10:33:14","extension":"html","order_by":18,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":96838,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7819841/v1/0121fdab37a7b8563c1ae5ba.html"},{"id":96617863,"identity":"901b9a6f-d48e-4c87-a1b7-3c7905d232b7","added_by":"auto","created_at":"2025-11-24 10:33:14","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":394958,"visible":true,"origin":"","legend":"\u003cp\u003eSee image above for figure legend\u003c/p\u003e","description":"","filename":"Figure117.png","url":"https://assets-eu.researchsquare.com/files/rs-7819841/v1/9d7cf3d37dfe5804cb77aa9d.png"},{"id":96712733,"identity":"174d2fcc-649d-40af-9145-16924f2bf741","added_by":"auto","created_at":"2025-11-25 10:16:20","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1250362,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7819841/v1/f707db0a-e6bb-48de-81a0-26ca81d94e5d.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Effects of Selenium Deficiency on Electrocardiogram and Oxidative Stress Level of Pregnant Women and Neonates in Northeast China","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eSelenium is an essential trace element that plays a crucial role in various physiological functions in the human body, including antioxidant defense mechanisms \u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]\u003c/sup\u003e. Selenium deficiency has been linked to various cardiovascular diseases, such as Keshan disease, arrhythmia, myocardial fibrosis, and congestive heart failure \u003csup\u003e[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/sup\u003e. Electrocardiogram (ECG) is a non-invasive diagnostic tool that can provide valuable information about cardiac function \u003csup\u003e[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/sup\u003e. However, there is limited research on the relationship between selenium deficiency, ECG changes, and oxidative stress levels in pregnant women and neonates. Pregnancy is a critical period for both the mother and the developing fetus, and adequate selenium intake is crucial for optimal maternal and fetal health \u003csup\u003e[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/sup\u003e. Selenium deficiency during pregnancy can lead to high oxidative stress levels in the maternal body, which can have adverse effects on fetal development \u003csup\u003e[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e. Therefore, it is essential to investigate the relationship between selenium deficiency, ECG changes, and oxidative stress levels in pregnant women and neonates. This study aimed to assess the effects of selenium deficiency on ECG changes and oxidative stress levels in women with and without pregnancy and neonates. The findings of this study could provide valuable insights into the prevention and management of cardiovascular diseases associated with selenium deficiency during pregnancy and early life.\u003c/p\u003e"},{"header":"2. Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e2.1 Study Design:\u003c/h2\u003e\u003cp\u003eThe study involved 1515 female participants, including 626 pregnant participants with more than 37 weeks of pregnancy (selenium deficient of pregnant group, SD of pregnant group), 77 non-pregnant participants in a selenium deficient area (selenium deficient of non-pregnant group, SD of non-pregnant group), 489 pregnant participants with more than 37 weeks of pregnancy (control of pregnant group), and 100 non-pregnant participants in a control area (control of non-pregnant group). Additionally, 200 neonates were included, with 100 from the selenium deficient area (selenium deficient of neonatal group, SD of neonatal group) and 100 from the control area (control of neonatal group). Through studying the changes of selenium content, electrocardiogram and oxidative stress level in full-term parteriums and neonates in two regions with different selenium content, this paper reveals the changes of electrocardiogram in mothers and neonates caused by selenium deficiency, and studies the internal relationship between electrocardiogram and oxidative stress level, electrocardiogram and selenium deficiency.\u003c/p\u003e\u003cp\u003eMeanwhile, the animal model of selenium deficiency was established with slight modifications according to the method of Vanderlelie et al \u003csup\u003e[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e. Animal models were used to simulate the distribution of selenium deficiency in important organs, the relationship between oxidative stress level and myocardial damage and electrocardiogram changes, and the results of clinical studies were verified from the perspective of in vivo experiments.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003e2.2 Selection Criteria of Participants:\u003c/h2\u003e\u003cp\u003eSelenium deficient (SD) of pregnant group: Pregnant women over 37 weeks of age who were treated in Maternal and Child Health Care Hospital of Fuyu County or People's Hospital of Fuyu County, from March 2011 to August 2012. Subjects need to live in the area continuously for more than 6 months, and chronic diseases such as hypertension and diabetes must be ruled out. It is also necessary to exclude all pregnancy-related complications, including but not limited to gestational hypertension, gestational diabetes, eclampsia and preeclampsia. It didn't matter whether the subjects ultimately chose vaginal or cesarean delivery. The age of the SD of pregnant groups were 25.9\u0026thinsp;\u0026plusmn;\u0026thinsp;4.55 years.\u003c/p\u003e\u003cp\u003eSelenium deficient (SD) of non-pregnant group: The non-pregnant women of gestational age were selected from Fuyu County Maternal and Child Health Care Hospital or physical examination department of Fuyu County People's Hospital. The age of the SD of non- pregnant groups were 23.7\u0026thinsp;\u0026plusmn;\u0026thinsp;5.31 years.\u003c/p\u003e\u003cp\u003eSelenium deficient (SD) of neonatal group: After the women in SD of pregnant group gave birth, 100 full-term newborns were selected to participate in the study. The newborns participating in the study were required to undergo prenatal testing to rule out all congenital and genetic disorders.\u003c/p\u003e\u003cp\u003eControl of pregnant group: Pregnant women over 37 weeks of age who were treated in The First Affiliated Hospital of Harbin Medical University, from March 2011 to August 2012. Subjects need to live in the area continuously for more than 6 months, and chronic diseases such as hypertension and diabetes must be ruled out. It is also necessary to exclude all pregnancy-related complications, including but not limited to gestational hypertension, gestational diabetes, eclampsia, preeclampsia et al. It didn't matter whether the subjects ultimately chose vaginal or cesarean delivery. The age of the SD of pregnant groups were 30.4\u0026thinsp;\u0026plusmn;\u0026thinsp;4.05 years.\u003c/p\u003e\u003cp\u003eControl of non-pregnant group: The non-pregnant women of gestational age were selected from physical examination department of The First Affiliated Hospital of Harbin Medical University, from March 2011 to August 2012. The age of the SD of non- pregnant groups were 29.7\u0026thinsp;\u0026plusmn;\u0026thinsp;4.19 years.\u003c/p\u003e\u003cp\u003eControl of neonatal group: After the women in Control of pregnant group gave birth, 100 full-term newborns were selected to participate in the study. The newborns participating in the study were required to undergo prenatal testing to rule out all congenital and genetic disorders.\u003c/p\u003e\u003cp\u003eAll subjects have signed informed consent forms. Whether newborns participate in the study is up to their mothers. This study was approved by the Ethical Review Committee of Qiqihar Medical University and is in accordance with the Declaration of Helsinki.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003e2.3 Animal model:\u003c/h2\u003e\u003cp\u003eAdult female Vista rats weighing 180\u0026ndash;220 g (8\u0026ndash;10 weeks old) were housed in a pathogen-free environment at room temperature (22\u0026ndash;25 ℃) and maintained on basal diet and tap water ad libitum before achieving the selenium deficient state. The rats were divided into two groups (N\u0026thinsp;=\u0026thinsp;12 per group). Rats in the selenium deficient group were fed a special mouse food containing 4.5 \u0026micro;g/kg total selenium for 4 weeks, while control rats were fed standard mouse food containing 219 \u0026micro;g/kg total selenium for 4 weeks. After 4 weeks, six female rats were randomly selected from each group for measurement of ECG and were sacrificed by severing the spinal cord for measurement of selenium content and oxidative stress status. The hearts, livers, and kidneys were perfused with ice-cold physiological saline (0.9% NaCl) until the blood was sufficiently removed. The remaining female rats were mated with male rats when the selenium deficient model was established successfully. Two weeks after mating, the pregnant female rats were kept feeding alone. Neonatal rats were fed by breast milk for 4 weeks to measure ECG, selenium content, and oxidative stress levels.\u003c/p\u003e\u003cp\u003eAnimal experiments in this study followed ARRIVE guidelines. The animal protocols were reviewed and approved by the Animal Care and Ethics Committee of Qiqihar Medical College, Qiqihar, China.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003e2.4 Electrocardiogram Analysis:\u003c/h2\u003e\u003cp\u003eStandard 12-lead ECGs were performed on participants, and limb lead ECGs were performed on neonates immediately after birth. The paper speed was set to 25 mm/s, sensitivity to 10 mm/mV, and frequency to 0.6\u0026ndash;100 Hz. The RM6240B/C biological signal collecting and processing system was used to describe the ECG of neonatal rats at a sweep speed of 10 ms/div, sensitivity of 1 mm/mV, and frequency of 100 Hz. Electrocardiogram data were recorded under relaxation and sleep anesthesia state, with the animals anesthetized by intraperitoneal injection with 20% urethane solution (0.1 ml urethane injection per 20 g body weight). A cardiologist completed the analyses of ECG, using digital calipers (Range 150 mm, Precision 0.01 mm, Type 16EWR, HAMR) to measure the duration of P and QRS wave, PR interval, QT interval, RR interval, and the QTc were calculated by Bazzett\u0026rsquo;s formula \u003csup\u003e[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u003ch2\u003e2.5 Selenium Content Analysis:\u003c/h2\u003e\u003cp\u003eThe selenium contents of maternal blood, umbilical blood, placenta, and umbilical cord of pregnant groups, blood of non-pregnant groups, and blood, hearts, livers, and kidneys of maternal and neonatal rats were measured by hydride generation atomic fluorescence spectrometry. Hydride was generated with a model 10.004 hydride generator (PS Analytical, Orrington, UK) according to the manufacturer's instructions. Signals were acquired with a microcomputer using commercial software (Avalon 2.0, PS Analytical). All solutions were prepared with doubly deionized water with 18.2 Mo cm resistances. Selenium stock solutions (1000 mg/l) were prepared from selenite (Na2SeO3 99%), selenate (Na2SeO4 99%), seleno-DL-cystine (SeCys), seleno-DL-methionine (SeMet) (all from Sigma-Aldrich, St Louis, MO, USA) and trimethylselenonium iodide (TMeSeI, Organometallics, and Hampstead, NH, USA). SeCys and SeMet were weighed under nitrogen to prevent sample degradation and dissolved in 0.5% (v/v) hydrochloric acid.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003e2.6 Oxidative Stress Analysis:\u003c/h2\u003e\u003cp\u003eThe tissues of the heart, liver, and kidney of maternal rats were homogenized with a 5-fold v/w of cell lysate in ice. The homogenates were centrifuged at 850 g for 15 min, and their supernatants were stored at -80℃. Total (Cu/Zn and Mn) superoxide dismutase (SOD) activity was determined by reagents from Nanjing Jiancheng Bioengineering Institute (Nanjing, China) according to the manufacturer's instructions, based on the inhibition rate of nitroblue tetrazolium (NBT) reduction, with the xanthine-xanthine oxidase system as a superoxide generator. Absorbance was detected spectrophotometrically at 550 nm. Maternal and umbilical blood of pregnant groups and hearts, livers, and kidneys of maternal rats were used for the determination of MDA content. Homogenates were bathed in distilled water for 15 min at 100 ℃, and centrifuged for 10 min at 1000 g after cooling to room temperature. 200 \u0026micro;l supernatant was used to measure MDA level using a commercially available kit (Nanjing Jiancheng Bioengineering Institute) according to the manufacturer's recommended protocol. Absorbance was measured at 532 nm.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\u003ch2\u003e2.7 Statistical Analysis:\u003c/h2\u003e\u003cp\u003eStatistical analyses were performed using GraphPad Prism 5.0 (GraphPad Software, La Jolla, CA, USA). Data were presented as mean with standard deviation. Statistical significance was determined using ANOVA-test. A P-value\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was statistically significant.\u003c/p\u003e\u003c/div\u003e"},{"header":"3. Results","content":"\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003e3.1 Electrocardiogram Analysis\u003c/h2\u003e\u003cp\u003eIn the pregnant groups, the ECGs of the selenium deficient group showed an increase in R wave, T wave, and heart rate compared to the control group. In the non-pregnant groups, the T wave and heart rate were accelerated in the selenium deficient group compared to the control group. The specific numerical data were shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. There were many differences between the control and selenium deficient neonatal groups, such as P wave, R wave, PR interval, QT interval, etc. The specific numerical data were shown in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. Compared to the control group, the ECGs of neonatal rats in the selenium deficient group showed an increase in R wave, T wave, significant QT interval elongation, ST segment elevation, and heart rate reduction.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eThe measurement results of ECG of women with and without pregnancy in low and control selenium area.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"8\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGroup\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eP wave duration(ms)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003ePR interval(ms)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eQRS duration(ms)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eRR interval(ms)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eQT interval(ms)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eQTC\u003c/p\u003e\u003cp\u003e(ms)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eHeart rate(BPM)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eLow selenium pregnancy\u003c/b\u003e(N\u0026thinsp;=\u0026thinsp;626)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e80.1\u0026thinsp;\u0026plusmn;\u0026thinsp;11.8\u003c/b\u003e\u003csup\u003e\u003cb\u003e*\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e\u003cb\u003e135.1\u0026thinsp;\u0026plusmn;\u0026thinsp;16.9\u003c/b\u003e\u003csup\u003e\u003cb\u003e*\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e74.5\u0026thinsp;\u0026plusmn;\u0026thinsp;6.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e789.6\u0026thinsp;\u0026plusmn;\u0026thinsp;82.6\u003c/b\u003e\u003csup\u003e\u003cb\u003e*\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003e344.5\u0026thinsp;\u0026plusmn;\u0026thinsp;29.9\u003c/b\u003e\u003csup\u003e\u003cb\u003e**\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e412.3\u0026thinsp;\u0026plusmn;\u0026thinsp;12.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e\u003cp\u003e\u003cb\u003e91.4\u0026thinsp;\u0026plusmn;\u0026thinsp;18.6\u003c/b\u003e\u003csup\u003e\u003cb\u003e**\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eControl selenium pregnancy\u003c/b\u003e(N\u0026thinsp;=\u0026thinsp;489)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e66.3\u0026thinsp;\u0026plusmn;\u0026thinsp;6.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e116.2\u0026thinsp;\u0026plusmn;\u0026thinsp;12.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e74.5\u0026thinsp;\u0026plusmn;\u0026thinsp;15.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e581.4\u0026thinsp;\u0026plusmn;\u0026thinsp;49.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e312.5\u0026thinsp;\u0026plusmn;\u0026thinsp;17.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e402.2\u0026thinsp;\u0026plusmn;\u0026thinsp;17.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e\u003cp\u003e103.9\u0026thinsp;\u0026plusmn;\u0026thinsp;8.9\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eLow selenium non-pregnancy\u003c/b\u003e(N\u0026thinsp;=\u0026thinsp;77)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e\u003cb\u003e83.6\u0026thinsp;\u0026plusmn;\u0026thinsp;3.7\u003c/b\u003e\u003csup\u003e\u003cb\u003e#\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e157.9\u0026thinsp;\u0026plusmn;\u0026thinsp;18.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e\u003cb\u003e70.4\u0026thinsp;\u0026plusmn;\u0026thinsp;5.1\u003c/b\u003e\u003csup\u003e\u003cb\u003e#\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e\u003cb\u003e755.9\u0026thinsp;\u0026plusmn;\u0026thinsp;74.9\u003c/b\u003e\u003csup\u003e\u003cb\u003e##\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e\u003cb\u003e357.5\u0026thinsp;\u0026plusmn;\u0026thinsp;9.5\u003c/b\u003e\u003csup\u003e\u003cb\u003e#\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e\u003cb\u003e395.1\u0026thinsp;\u0026plusmn;\u0026thinsp;19.9\u003c/b\u003e\u003csup\u003e\u003cb\u003e##\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e\u003cp\u003e\u003cb\u003e80\u0026thinsp;\u0026plusmn;\u0026thinsp;4.5\u003c/b\u003e\u003csup\u003e\u003cb\u003e#\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eControl selenium non-pregnancy\u003c/b\u003e(N\u0026thinsp;=\u0026thinsp;100)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e\u003cp\u003e88.1\u0026thinsp;\u0026plusmn;\u0026thinsp;3.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e139.8\u0026thinsp;\u0026plusmn;\u0026thinsp;4.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e81.2\u0026thinsp;\u0026plusmn;\u0026thinsp;6.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e\u003cp\u003e914.7\u0026thinsp;\u0026plusmn;\u0026thinsp;132.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c6\"\u003e\u003cp\u003e377.5\u0026thinsp;\u0026plusmn;\u0026thinsp;16.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c7\"\u003e\u003cp\u003e419\u0026thinsp;\u0026plusmn;\u0026thinsp;15.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c8\"\u003e\u003cp\u003e66.9\u0026thinsp;\u0026plusmn;\u0026thinsp;9.5\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"8\"\u003eData presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD. \u003cem\u003eP\u003c/em\u003e - values obtained from the ANOVA-test.\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eThe measurement results of limb lead of neonates in low and control selenium area.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"14\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c13\" colnum=\"13\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c14\" colnum=\"14\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e\u003cp\u003eP wave duration(ms)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e\u003cp\u003eP wave amplitude(mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e\u003cp\u003ePR interval(ms)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e\u003cp\u003eQT interval(ms)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c11\" namest=\"c10\"\u003e\u003cp\u003eQRS duration(ms)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"2\" nameend=\"c13\" namest=\"c12\"\u003e\u003cp\u003eQRS\u003c/p\u003e\u003cp\u003eamplitude(mm)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"1\" nameend=\"c14\" namest=\"c14\"\u003e\u0026nbsp;\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colspan=\"13\" nameend=\"c13\" namest=\"c1\"\u003e\u003cp\u003eLow selenium neonates (n\u0026thinsp;=\u0026thinsp;100)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"1\" nameend=\"c14\" namest=\"c14\"\u003e\u0026nbsp;\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eLead I\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e68.8\u0026thinsp;\u0026plusmn;\u0026thinsp;19.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003e\u003cb\u003e1.03\u0026thinsp;\u0026plusmn;\u0026thinsp;0. 38\u003c/b\u003e\u003csup\u003e\u003cb\u003e**\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e108\u0026thinsp;\u0026plusmn;\u0026thinsp;17.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e\u003cp\u003e\u003cb\u003e273.5\u0026thinsp;\u0026plusmn;\u0026thinsp;25.1\u003c/b\u003e\u003csup\u003e\u003cb\u003e**\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c12\" namest=\"c11\"\u003e\u003cp\u003e\u003cb\u003e45.5\u0026thinsp;\u0026plusmn;\u0026thinsp;8.9\u003c/b\u003e\u003csup\u003e\u003cb\u003e**\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003e\u003cb\u003e9.54\u0026thinsp;\u0026plusmn;\u0026thinsp;4.05\u003c/b\u003e\u003csup\u003e\u003cb\u003e**\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eLead II\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e66\u0026thinsp;\u0026plusmn;\u0026thinsp;15.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003e\u003cb\u003e1.38\u0026thinsp;\u0026plusmn;\u0026thinsp;0. 39\u003c/b\u003e\u003csup\u003e\u003cb\u003e*\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e106\u0026thinsp;\u0026plusmn;\u0026thinsp;14.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e\u003cp\u003e\u003cb\u003e277.3\u0026thinsp;\u0026plusmn;\u0026thinsp;24.2\u003c/b\u003e\u003csup\u003e\u003cb\u003e*\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c12\" namest=\"c11\"\u003e\u003cp\u003e52\u0026thinsp;\u0026plusmn;\u0026thinsp;9.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003e9.29\u0026thinsp;\u0026plusmn;\u0026thinsp;2.98\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eLead III\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e\u003cb\u003e55\u0026thinsp;\u0026plusmn;\u0026thinsp;15\u003c/b\u003e\u003csup\u003e\u003cb\u003e**\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003e0. 74\u0026thinsp;\u0026plusmn;\u0026thinsp;0. 29\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e102\u0026thinsp;\u0026plusmn;\u0026thinsp;17.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e\u003cp\u003e290.5\u0026thinsp;\u0026plusmn;\u0026thinsp;34.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c12\" namest=\"c11\"\u003e\u003cp\u003e\u003cb\u003e53.8\u0026thinsp;\u0026plusmn;\u0026thinsp;9.4\u003c/b\u003e\u003csup\u003e\u003cb\u003e*\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003e12.24\u0026thinsp;\u0026plusmn;\u0026thinsp;4.90\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eLead aVR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e71.3\u0026thinsp;\u0026plusmn;\u0026thinsp;17.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003e\u003cb\u003e1.16\u0026thinsp;\u0026plusmn;\u0026thinsp;0. 35\u003c/b\u003e\u003csup\u003e\u003cb\u003e*\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e113.5\u0026thinsp;\u0026plusmn;\u0026thinsp;19.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e\u003cp\u003e\u003cb\u003e269\u0026thinsp;\u0026plusmn;\u0026thinsp;23.2\u003c/b\u003e\u003csup\u003e\u003cb\u003e**\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c12\" namest=\"c11\"\u003e\u003cp\u003e\u003cb\u003e47.5\u0026thinsp;\u0026plusmn;\u0026thinsp;9.7\u003c/b\u003e\u003csup\u003e\u003cb\u003e**\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003e\u003cb\u003e6.94\u0026thinsp;\u0026plusmn;\u0026thinsp;2.36\u003c/b\u003e\u003csup\u003e\u003cb\u003e**\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eLead aVL\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e\u003cb\u003e56.5\u0026thinsp;\u0026plusmn;\u0026thinsp;18.2\u003c/b\u003e\u003csup\u003e\u003cb\u003e*\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003e0. 61\u0026thinsp;\u0026plusmn;\u0026thinsp;0. 26\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e96\u0026thinsp;\u0026plusmn;\u0026thinsp;20.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e\u003cp\u003e\u003cb\u003e272\u0026thinsp;\u0026plusmn;\u0026thinsp;36.8\u003c/b\u003e\u003csup\u003e\u003cb\u003e**\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c12\" namest=\"c11\"\u003e\u003cp\u003e45.3\u0026thinsp;\u0026plusmn;\u0026thinsp;10.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003e10.28\u0026thinsp;\u0026plusmn;\u0026thinsp;3.59\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eLead aVF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e59.5\u0026thinsp;\u0026plusmn;\u0026thinsp;12.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003e0. 97\u0026thinsp;\u0026plusmn;\u0026thinsp;0. 34\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e104.5\u0026thinsp;\u0026plusmn;\u0026thinsp;16.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e\u003cp\u003e\u003cb\u003e278\u0026thinsp;\u0026plusmn;\u0026thinsp;25.6\u003c/b\u003e\u003csup\u003e\u003cb\u003e*\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c12\" namest=\"c11\"\u003e\u003cp\u003e\u003cb\u003e54.8\u0026thinsp;\u0026plusmn;\u0026thinsp;7.7\u003c/b\u003e\u003csup\u003e\u003cb\u003e*\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003e9.60\u0026thinsp;\u0026plusmn;\u0026thinsp;3.16\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"13\" nameend=\"c13\" namest=\"c1\"\u003e\u003cp\u003e\u003cb\u003eControl selenium neonates (n\u0026thinsp;=\u0026thinsp;100)\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"1\" nameend=\"c14\" namest=\"c14\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eLead I\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e63.5\u0026thinsp;\u0026plusmn;\u0026thinsp;12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003e0. 86\u0026thinsp;\u0026plusmn;\u0026thinsp;0. 30\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e103.8\u0026thinsp;\u0026plusmn;\u0026thinsp;14.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e\u003cp\u003e298.5\u0026thinsp;\u0026plusmn;\u0026thinsp;18\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c12\" namest=\"c11\"\u003e\u003cp\u003e55.5\u0026thinsp;\u0026plusmn;\u0026thinsp;8.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003e12.08\u0026thinsp;\u0026plusmn;\u0026thinsp;4.03\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eLead II\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e60.5\u0026thinsp;\u0026plusmn;\u0026thinsp;9.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003e1.13\u0026thinsp;\u0026plusmn;\u0026thinsp;0. 38\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e105.3\u0026thinsp;\u0026plusmn;\u0026thinsp;16.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e\u003cp\u003e301.5\u0026thinsp;\u0026plusmn;\u0026thinsp;20.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c12\" namest=\"c11\"\u003e\u003cp\u003e54.8\u0026thinsp;\u0026plusmn;\u0026thinsp;8.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003e9.92\u0026thinsp;\u0026plusmn;\u0026thinsp;4.28\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eLead III\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e48.8\u0026thinsp;\u0026plusmn;\u0026thinsp;9.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003e0. 69\u0026thinsp;\u0026plusmn;\u0026thinsp;0. 28\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e94.5\u0026thinsp;\u0026plusmn;\u0026thinsp;16.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e\u003cp\u003e303\u0026thinsp;\u0026plusmn;\u0026thinsp;27.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c12\" namest=\"c11\"\u003e\u003cp\u003e58.8\u0026thinsp;\u0026plusmn;\u0026thinsp;8.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003e12.87\u0026thinsp;\u0026plusmn;\u0026thinsp;5.22\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eLead aVR\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e69.5\u0026thinsp;\u0026plusmn;\u0026thinsp;14.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003e1.00\u0026thinsp;\u0026plusmn;\u0026thinsp;0. 30\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e113\u0026thinsp;\u0026plusmn;\u0026thinsp;14.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e\u003cp\u003e301.5\u0026thinsp;\u0026plusmn;\u0026thinsp;20.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c12\" namest=\"c11\"\u003e\u003cp\u003e55.5\u0026thinsp;\u0026plusmn;\u0026thinsp;8.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003e8.56\u0026thinsp;\u0026plusmn;\u0026thinsp;2.52\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eLead aVL\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e49.3\u0026thinsp;\u0026plusmn;\u0026thinsp;12.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003e0. 53\u0026thinsp;\u0026plusmn;\u0026thinsp;0. 19\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e89.5\u0026thinsp;\u0026plusmn;\u0026thinsp;13.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e\u003cp\u003e293\u0026thinsp;\u0026plusmn;\u0026thinsp;27.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c12\" namest=\"c11\"\u003e\u003cp\u003e54.8\u0026thinsp;\u0026plusmn;\u0026thinsp;8.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003e11.93\u0026thinsp;\u0026plusmn;\u0026thinsp;4.33\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u003cp\u003eLead aVF\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e\u003cp\u003e55.8\u0026thinsp;\u0026plusmn;\u0026thinsp;12.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e\u003cp\u003e0. 79\u0026thinsp;\u0026plusmn;\u0026thinsp;0. 34\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e\u003cp\u003e103.5\u0026thinsp;\u0026plusmn;\u0026thinsp;15.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c10\" namest=\"c9\"\u003e\u003cp\u003e303\u0026thinsp;\u0026plusmn;\u0026thinsp;28.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c12\" namest=\"c11\"\u003e\u003cp\u003e58.8\u0026thinsp;\u0026plusmn;\u0026thinsp;8.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"2\" nameend=\"c14\" namest=\"c13\"\u003e\u003cp\u003e9.75\u0026thinsp;\u0026plusmn;\u0026thinsp;4.52\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"14\"\u003eData presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD. \u003cem\u003eP\u003c/em\u003e - values obtained from the ANOVA-test.\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eIn the pregnant groups, the P wave duration, PR interval, RR interval, and QT interval of the selenium deficient group were longer than their corresponding control group. The heart rate of the selenium deficient group was slower than the control group, and QRS duration and QTC showed no statistical significance between the selenium deficient and control groups. In the non-pregnant groups, compared to the control group, the P wave duration, QRS wave duration, QT interval, QTc, and RR interval of the selenium deficient group were decreased, and the heart rate of the selenium deficient group was faster, but PR interval was not significantly different. Compared to the control group, the ECGs of neonates in the selenium deficient group indicated that P wave amplitude increased and QT interval and QRS amplitude decreased. Besides, P wave duration was longer than the control in Lead Ⅲ and aVL, and QRS voltage of the selenium deficient group was lower than the control group in Lead Ⅰ and aVR. There was no significant difference in PR interval between the selenium deficient and control groups of neonates.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003e3.2 Selenium Content Analysis\u003c/h2\u003e\u003cp\u003eSelenium concentrations in the maternal blood and umbilical blood, placenta, and umbilical cord of the selenium deficient puerperal were lower than their corresponding controls. Selenium concentrations in the blood of the participants without pregnancy in the selenium deficient area were also lower than the corresponding control. Selenium concentrations in the hearts, livers, kidneys, and blood of selenium deficient maternal rats were lower than their corresponding control group. Selenium concentrations in the hearts, livers, kidneys, and blood of selenium deficient neonatal rats were also lower than their corresponding control group.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003e3.3 Oxidative Stress Analysis\u003c/h2\u003e\u003cp\u003eSOD activity was lower in the liver and kidney of selenium deficient maternal rats compared to their corresponding controls but showed no significant difference in the heart compared to the control. MDA concentrations in blood (maternal blood and umbilical blood) were significantly higher in the selenium deficient pregnant group compared to their corresponding controls, and MDA concentrations in the heart, liver, and kidney of maternal rats in the selenium deficient group were significantly higher than their corresponding controls. The results were shown in Fig.\u0026nbsp;1.\u003c/p\u003e\u003c/div\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eThe study demonstrated that selenium deficiency increased oxidative stress levels in pregnant and non-pregnant women and neonates. Changes in ECG were also apparent in women in the selenium deficient area, as revealed by measurement of electrocardiogram. These results suggested that selenium deficiency could induce elevation of oxidative stress levels and changes in electrocardiogram. The study is the first investigation on the impacts of selenium deficiency on both puerperas and neonates.\u003c/p\u003e\u003cp\u003eSelenium is an essential element in animals, and its deficiency has been attributed to a number of mammalian selenoproteins \u003csup\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003e. Keshan disease, a dilated cardiomyopathy endemic in China, has been found to be closely related to a selenium-deficient diet \u003csup\u003e[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eA selenium-deficient diet can induce oxidative injury, which may lead to myocardial injury and subsequent cardiac dysfunction \u003csup\u003e[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/sup\u003e. Evidence shows that selenium deficiency may cause myocardial failure \u003csup\u003e[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/sup\u003e. Oxidative stress leads to lipid peroxidation, and sulfhydryl group oxidation seems to be among the mechanisms that may produce membrane defects, causing cardiac contractile dysfunction in the myocardium \u003csup\u003e[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eWe found that the selenium content of women (with and without pregnancy) and neonates in selenium-deficient areas were lower, and the content of MDA was higher than that in the control area. This study confirmed that women and neonates in selenium-deficient areas have low selenium content and high oxidative stress status. Although typical clinical symptoms of cardiovascular disease did not appear in selenium-deficient women and neonates, these alterations may cause a certain degree of injury to myocardial cells with prolonged selenium deficiency and high oxidative stress states. They are more prone to diseases caused by selenium deficiency or an increase in oxidative stress.\u003c/p\u003e\u003cp\u003eIn addition, ECG is also a cornerstone in the assessment of cardiovascular functions, which has a close relationship with the action potential of myocardial cells \u003csup\u003e[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/sup\u003e. In the ECG, every waveform represents a specific meaning. For example, P wave duration, QRS wave duration, PR interval, QT interval, and RR interval indicate the process of depolarization of the atrium and ventricle, the process of repolarization of the atrium, the total time of ventricular activation, and the cardiac cycle, respectively \u003csup\u003e[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/sup\u003e. Research shows that P wave amplitude and duration were significantly associated with cardiovascular disease and mortality \u003csup\u003e[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/sup\u003e. PR prolongation was associated with increased risks of AF and death \u003csup\u003e[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]\u003c/sup\u003e, the wide QRS duration as underlying etiology might affect the frequency of interventricular dyssynchrony indices \u003csup\u003e[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e, and shortened and prolonged QT-interval durations, even within a reference range, were associated with increased mortality risk in the general population \u003csup\u003e[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eWe found that compared with pregnant women in control areas, the duration of P wave, interval of PR, RR, and QT of pregnant women in selenium-deficient areas prolonged, and heart rate slowed, but QRS duration and QTC had no statistical significance between SD and control groups. Compared with non-pregnant women in control areas, the duration of P and QRS wave, RR and QT interval, and QTC shortened, and heart rate accelerated, but PR interval had no significant difference between SD and control groups. These results showed that selenium deficiency may cause ECG changes in women (pregnant and non-pregnant women) without the typical clinical symptoms of cardiovascular disease in selenium deficient and high oxidative stress status.\u003c/p\u003e\u003cp\u003eThis research suggests a higher possibility of the occurrence of cardiovascular diseases in selenium-deficient non-pregnant women than corresponding controls because of prolonged selenium deficiency and high oxidative stress status. Pregnant women are more prone to myocardial ischemia and hypoxia due to a significant increase in effective circulating blood volume, velocity of blood flow acceleration \u003csup\u003e[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e, cardiac output \u003csup\u003e[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]\u003c/sup\u003e, and myocardial oxygen consumption increase \u003csup\u003e[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]\u003c/sup\u003e. Meanwhile, with the increased time of pregnancy, pregnant women are more prone to myocardial labor injury \u003csup\u003e[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]\u003c/sup\u003e after months of high workloads. The possibility of the occurrence of cardiovascular diseases in pregnant women in selenium-deficient areas greatly increased.\u003c/p\u003e\u003cp\u003eThe results of neonatal ECG in SD and control areas showed that the P wave amplitude increased, and QT interval and QRS duration reduced in SD neonates. The organic heart disease is not enough to prove in neonate of low selenium area, but if the neonates of selenium-deficient areas are in low selenium levels and high oxidative stress status for a long time, whether selenium deficiency would impact the growth and development of neonate remains to be further studied.\u003c/p\u003e\u003cp\u003eThe body must constantly assimilate selenium from the outside to maintain the dynamic equilibrium of selenium in the body. Thus, a rat model on a selenium-deficient diet can be used in the following experiments, replacing patients in selenium-deficient areas. Rats in selenium-deficient groups in the present study had significantly lower concentrations of selenium in the heart, liver, brain, and blood compared with control groups (receiving the normal diet). SOD activity and MDA concentrations were measured as indicators of oxidative stress. Severe oxidative stress was found in several organs in the selenium-deficient groups, indicating that this constituted a good animal model of oxidative stress: one that could be useful in investigating the relationship between selenium deficiency and ECG.\u003c/p\u003e\u003cp\u003eWe found that the ECGs of neonatal rats in the selenium-deficient group had significant changes. Compared with the control group, ECGs of neonatal rats in the selenium-deficient group showed an increase in R wave and T wave, significant QT interval prolongation, ST segment elevation, and heart rate decrease. Myocardial injury of selenium-deficient rats has been confirmed by histopathological and ultrastructure studies in our previous research \u003csup\u003e[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/sup\u003e. Meanwhile, the changes of ECG in the animal model further proved that selenium deficiency could affect cardiac function. The result of the animal model was consistent with that of human participants. Selenium deficiency could cause cardiac dysfunction in women (with and without pregnancy) and neonates without the clinical performance.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eSelenium deficiency could cause electrocardiogram changes and elevation of oxidative stress levels in women with and without pregnancy and neonates.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eCompeting Interests\u003c/h2\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003ch2\u003eGuidelines and Regulations Statement\u003c/h2\u003e\n\u003cp\u003eThis study complied with relevant national and local regulations, and all experiments were conducted in accordance with relevant guidelines and regulations.\u003c/p\u003e\n\u003ch2\u003eEthics approval and consent to participate\u003c/h2\u003e\n\u003cp\u003eThe study was approved by the Experimental Animal Ethics Committee of Qiqihar Medical College [approval number: 2022139(QMU-AECC-2022-39)]. Informed consent was waived because of the retrospective study design, and the data analyses used data containing no personally identifiable information.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003ch2\u003eCompeting interests\u003c/h2\u003e\n\u003cp\u003eThe authors declare that there are no potential competing interests, whether financial or personal, that could be perceived as influencing this work.\u003c/p\u003e\n\u003ch2\u003eFunding\u003c/h2\u003e\n\u003cp\u003eThis study was supported by Key cultivation project of Qiqihar Academy of Medical Sciences (2022-ZDPY-015).\u003c/p\u003e\n\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\n\u003cp\u003eChu Erfu: Writing -original draft, Resources, Methodology. Pan Farong: Writing-review \u0026amp; editing. Liang Zhaowen: Writing-review \u0026amp; editing. Qu Weiting: Methodology, Resources, Writing -original draft. Sun Xingyuan: Conceptualization, Resources, Data curation. Lu Junkun: Writing-review \u0026amp; editing, Supervision, Project administration, Funding acquisition, Conceptualization.\u003c/p\u003e\n\u003ch2\u003eAcknowledgement\u003c/h2\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003ch2\u003eData Availability\u003c/h2\u003e\n\u003cp\u003eData supporting the findings of this study can be obtained from the corresponding author upon request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eGui JY, Rao S, Huang X, Liu X, Cheng S, Xu F. Interaction between selenium and essential micronutrient elements in plants: A systematic review. Sci Total Environ. 2022;853:158673.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAl-Mubarak AA, Grote Beverborg N, Zwartkruis V, van Deutekom C, de Borst MH, Gansevoort RT, Bakker SJL, Touw DJ, de Boer RA, van der Meer P et al. Micronutrient deficiencies and new-onset atrial fibrillation in a community-based cohort: data from PREVEND. Clin Res cardiology: official J German Cardiac Soc 2023.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhu YH, Wang XF, Yang G, Wei J, Tan WH, Wang LX, Guo X, Lammi MJ, Xu JH. Efficacy of Long-term Selenium Supplementation in the Treatment of Chronic Keshan Disease with Congestive Heart Failure. Curr Med Sci. 2019;39(2):237\u0026ndash;42.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSherlock LG, McCarthy WC, Grayck MR, Solar M, Hernandez A, Zheng L, Delaney C, Tipple TE, Wright CJ, Nozik ES. Neonatal Selenium Deficiency Decreases Selenoproteins in the Lung and Impairs Pulmonary Alveolar Development. Antioxid (Basel) 2022, 11(12).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHabibi N, Labrinidis A, Leemaqz SY, Jankovic-Karasoulos T, McCullough D, Grieger JA, Gilbert S, Ricciardelli C, Zhou SJ, Perkins AV et al. Effect of Selenium and Iodine on Oxidative Stress in the First Trimester Human Placenta Explants. Nutrients 2021, 13(3).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAmir M, Irwan, Syafaryuni M, Levina. Prevalence and characteristics of atrial fibrillation in Makassar city population: A telemedicine study. Gac Sanit. 2021;35(Suppl 2):S510\u0026ndash;4.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePappas AC, Zoidis E, Chadio SE. Maternal Selenium and Developmental Programming. Antioxid (Basel) 2019, 8(5).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhang L, Gao Y, Feng H, Zou N, Wang K, Sun D. Effects of selenium deficiency and low protein intake on the apoptosis through a mitochondria-dependent pathway. J Trace Elem Med Biol. 2019;56:21\u0026ndash;30.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCui J, Zhong R, Chu E, Zhang XF, Zhang WG, Fang CF, Dong Q, Li FL, Li H. Correlation between oxidative stress and L-type calcium channel expression in the ventricular myocardia of selenium-deficient mice. J Int Med Res. 2012;40(5):1677\u0026ndash;87.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSun W, Zhu J, Li S, Tang C, Zhao Q, Zhang J. Selenium supplementation protects against oxidative stress-induced cardiomyocyte cell cycle arrest through activation of PI3K/AKT. Metallomics: Integr biometal Sci. 2020;12(12):1965\u0026ndash;78.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDhalla NS, Golfman L, Takeda S, Takeda N, Nagano M. Evidence for the role of oxidative stress in acute ischemic heart disease: a brief review. Can J Cardiol. 1999;15(5):587\u0026ndash;93.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLee W, Ng B, Mangala MM, Perry MD, Subbiah RN, Vandenberg JI, Hill AP. Action Potential Morphology Accurately Predicts Proarrhythmic Risk for Drugs With Potential to Prolong Cardiac Repolarization. Circulation Arrhythmia Electrophysiol. 2023;16(7):399\u0026ndash;410.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLiu J, Jin Y, Liu Y, Li Z, Qin C, Chen X, Zhao L, Liu C. A novel P-QRS-T wave localization method in ECG signals based on hybrid neural networks. Comput Biol Med. 2022;150:106110.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMagnani JW, Gorodeski EZ, Johnson VM, Sullivan LM, Hamburg NM, Benjamin EJ, Ellinor PT. P wave duration is associated with cardiovascular and all-cause mortality outcomes: the National Health and Nutrition Examination Survey. Heart rhythm. 2011;8(1):93\u0026ndash;100.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eCheng S, Keyes MJ, Larson MG, McCabe EL, Newton-Cheh C, Levy D, Benjamin EJ, Vasan RS, Wang TJ. Long-term outcomes in individuals with prolonged PR interval or first-degree atrioventricular block. JAMA. 2009;301(24):2571\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMontazeri M, Rezvanfard M, Kazemisaeid A, Lotfi Tokaldany M, Mardanloo AS, Darabi F, Fathollahi MS, Sadeghian H. Assessment of Left Ventricular Dyssynchrony in Heart Failure Patients Regarding Underlying Etiology and QRS Duration. J Tehran Heart Cent. 2011;6(4):193\u0026ndash;201.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhang Y, Post WS, Dalal D, Blasco-Colmenares E, Tomaselli GF, Guallar E. QT-interval duration and mortality rate: results from the Third National Health and Nutrition Examination Survey. Arch Intern Med. 2011;171(19):1727\u0026ndash;33.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eYang D, Zhang HF, Zhang J. [Clinical characteristics and pregnancy outcome of 14 pregnant women with history of atherosclerotic cardiovascular disease]. Zhonghua yi xue za zhi. 2020;100(42):3309\u0026ndash;13.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMulder EG, de Haas S, Mohseni Z, Schartmann N, Abo Hasson F, Alsadah F, van Kuijk S, van Drongelen J, Spaanderman M, Ghossein-Doha C. Cardiac output and peripheral vascular resistance during normotensive and hypertensive pregnancy - a systematic review and meta-analysis. BJOG: Int J Obstet Gynecol. 2022;129(5):696\u0026ndash;707.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eO'Kelly AC, Ludmir J, Wood MJ. Acute Coronary Syndrome in Pregnancy and the Post-Partum Period. J Cardiovasc Dev disease 2022, 9(7).\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAldo C, Martina Z, Alberto A, Mario P. Cardiovascular risk evaluation in pregnancy: focus on cardiac specific biomarkers. \u003cem\u003eClinical chemistry and laboratory medicine\u003c/em\u003e 2023.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-pregnancy-and-childbirth","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"prch","sideBox":"Learn more about [BMC Pregnancy and Childbirth](http://bmcpregnancychildbirth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/prch/default.aspx","title":"BMC Pregnancy and Childbirth","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Selenium deficiency, electrocardiography, pregnancy, oxidative stress, neonates","lastPublishedDoi":"10.21203/rs.3.rs-7819841/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7819841/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eSelenium deficiency is a critical health concern, this project was studied for its impact on ECG parameters and oxidative stress in women (pregnant \u0026amp; non-pregnant) and neonates.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eA cohort of 1515 women and 200 neonates from contrasting selenium status regions underwent ECG evaluations, selenium content determination and oxidative stress level assessments.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eThrough the application of relevant kit detection, study revealed lower selenium \u0026amp; heightened oxidative stress level in deficient groups (P\u0026thinsp;\u0026lt;\u0026thinsp;0.01). Pregnant women from deficient regions exhibited prolonged ECG intervals, whereas non-pregnant showed reduced intervals. Neonates with selenium deficiency manifested altered ECG waves. Animal models are consistent with human studies, confirming ECG abnormalities \u0026amp; oxidative stress exacerbation in selenium scarcity.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e\u003cp\u003eOur results imply that inadequate selenium intake may not only perturb the intricate balance of oxidative stress but also precipitate alterations in ECG patterns, thereby posing potential risks to cardiovascular health.\u003c/p\u003e","manuscriptTitle":"Effects of Selenium Deficiency on Electrocardiogram and Oxidative Stress Level of Pregnant Women and Neonates in Northeast China","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-24 10:33:09","doi":"10.21203/rs.3.rs-7819841/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-04-29T17:30:28+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-25T03:21:35+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-19T14:44:32+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"328929374751096164614154693428610197202","date":"2025-11-15T06:15:18+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"250377195161483296536316065047493138374","date":"2025-11-13T15:37:50+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-11-13T06:13:00+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-10-16T21:17:17+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-10-13T03:21:36+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-10-13T03:20:04+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Pregnancy and Childbirth","date":"2025-10-09T16:47:14+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-pregnancy-and-childbirth","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"prch","sideBox":"Learn more about [BMC Pregnancy and Childbirth](http://bmcpregnancychildbirth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/prch/default.aspx","title":"BMC Pregnancy and Childbirth","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"33887ec3-44bc-48f9-9fe1-b087b981be7e","owner":[],"postedDate":"November 24th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-13T16:53:10+00:00","versionOfRecord":[],"versionCreatedAt":"2025-11-24 10:33:09","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7819841","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7819841","identity":"rs-7819841","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}