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Year : 2022  |  Volume : 49  |  Issue : 3  |  Page : 298-303

Bibliometric study of placenta in pregnancy-induced hypertension

1 Department of Anatomy, Army Medical College Chattogram, Bangladesh, South Asia
2 Doctoral Student, University of Dhaka; and Librarian, Army Medical College Chattogram, Bangladesh, South Asia

Date of Submission20-Jan-2022
Date of Acceptance09-Jul-2022
Date of Web Publication27-Dec-2022

Correspondence Address:
Md. Monirul Islam
Doctoral Student, University of Dhaka; and Librarian, Army Medical College Chattogram
South Asia
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jss.jss_9_22

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Background: The placenta is a responsible organ for nourishing and protecting the fetus during pregnancy. It is a key limb for pregnancy evolution and fetal expansion that acts on maternal-fetal exchanges of gas and nutrients. Materials and Methods: This bibliometric analysis investigated the publications that were produced from 1977 to 2021 and indexed in PubMed database. The database was inspected for all documents related to placenta in pregnancy. About 298 documents were found and examined in database. The VOSviewer software was used to imagine the co-occurrence arrangement. Results: The analysis found the greatest publications resulted out from the “USA” (n = 282), “China” (n = 185), and “Australia” (n = 153). In addition, the results found that most of the publications are journal article (n = 222). “Pregnancy Hypertension” supplied the majority of documents. Almost all documents were produced in the last decade (2011–2021). The study found the most relevant affiliations where University of Melbourne ranked first (n = 80), King's College London ranked second (n = 54), and University of Mississippi Medical Center ranked third (n = 50). The study found Hannan NJ (n = 10, TC = 1.22) as the most productive author in the field. The co-occurrence scrutiny confirmed that the study formed five clusters. The study found that “pregnancy,” “female,” “human,” “pre-eclampsia,” and “adult” are the most useful keywords on the topic. Conclusion: Assessment of placenta is an enormously important interpreter, which helps to progress the result of pregnancy. This bibliometric study illustrates the overall research scenery, trends, growth, impact, and collaborative work among scholars in the field of placenta in pregnancy-induced hypertension.

Keywords: Bibliometric, placenta, pregnancy, hypertension, PubMed database

How to cite this article:
Alam MS, Islam M. Bibliometric study of placenta in pregnancy-induced hypertension. J Sci Soc 2022;49:298-303

How to cite this URL:
Alam MS, Islam M. Bibliometric study of placenta in pregnancy-induced hypertension. J Sci Soc [serial online] 2022 [cited 2023 Jan 31];49:298-303. Available from: https://www.jscisociety.com/text.asp?2022/49/3/298/365184

  Introduction Top

Placenta is a forecaster of conclusion of pregnancy. Placental assessments embrace a significant contribution in developing positive ending of pregnancy.[1] Bibliometric analysis is an arithmetical process which could quantitative analysis of the intellectual research papers concerned about one particular topic via statistical ways.[2] The growing transform in clinical activities in the recent decades, how can health doctors reflect on the importance of research outputs?[3] Bibliometric is one kind of quantitative method that adopts different processes like co-authorship, and co-occurrence analysis to evaluate research outputs and research trends.[4] Co-occurrence and co-authorship study is the most scientific system of scientometric analysis that is applied in the assorted area to recognize the subfields, interactions among the subfields, and therefore the improvement and variations in the area of computer programs in biomedicine, hypertension clinical guidelines, and other areas of medicine.[5] Pregnancy is a gestational trophoblastic disease described by an anomalous development of placental tissues because of a nonviable pregnancy. The understanding of the management of pregnancy has considerably enhanced in the modern ages.[6]

Numerous techniques have appeared to scrutinize a huge amount of publications on both macroscopic and microscopic levels.[7] Bibliometrics is one of them, which is used to perform the statistical and mathematical analysis study publication. The existence of bibliometrics in medicine and health research enables the researchers to scrutinize lots of researcher outputs and their document patterns on macroscopic and infinitesimal stages.[8] These types of analysis are an ever more key element of a broader “toolbox” of assessment technique accessible to policymakers to hold up administrative power.[9] Basically, bibliometric approach has been used in discovering the invention of science for inspection, as was done in a study to find out rising tendency and knowledge formation of epilepsy during pregnancy.[10] Bibliometric studies have also recognized the most prolific scholars, journal source, and countries in particular fields including obstetrics and gynecology.[11],[12],[13],[14]

It is observed that the scientometric analysis conducted in the field of placenta is quite limited. This study attempted to identify and examine the placenta, pregnancy, and hypertension-related publications during the period of 1977–2021. The study aims to analyze the intellectual output on placenta. Applying co-authorship and co-occurrence approach, this research is completed by searching the documents indexed in PubMed database. Adopting these methods, and by calculating the journal articles, research paper, and other documents, we aim to be familiar with and compare the co-occurrence and impact of the scientific research in the field.

  Materials and Methods Top

The research applied a bibliometric technique to examine the production in the area of placenta. The study analyzed the most prolific authors, affiliations, sources, countries, visualizing the co-authorship analysis and co-occurrence keywords of the publications in the chosen field. The research searched the databases first and identified the best study's necessities. Entitled studies were chosen from PubMed database from 1977 to January 2021.

In the study, the researchers restricted the early search to documents that integrated “Placenta,” “Pregnancy,” and “Hypertension” in the “Title.” In the preliminary search, total 298 publications were scrutinized. Among the total retried documents, 222 (74%) were “Journal Article,” 3 (1.00%) were “case reports; abstract; review,” 15 (5.03%) were”clinical trial; comparative study,” 8 (2.68%) were “multicenter study; observational study,” 10 (3.35%) were “multicenter study; observational study,” 5 (1.67%) were” randomized controlled trial,” and 35 (11.74%) were “systematic review and others” [Table 1].
Table 1: Main information about data retrieved from PubMed database (1977-2021)

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In [Figure 1], a large amount of publications were produced during the period of 2011 and 2021 years and the least numbers of documents were produced in 1979, 1997, and 2007 years. The increasing pattern of placenta studies between 2011 and 2021, and the sequential circulation revealed four stages in the producing tendency [Figure 1]. VOSviewer (version 1.6.17) software was applied for imagination of the research networks.[15] Strategic maps are built using Biblioshiny program that was established by Aria and Cuccurullo.[16]
Figure 1: Annual scientific production on placenta in pregnancy-induced hypertension

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The researchers used co-occurrence method in this investigation. Co-authorship is districted as two authors; those are authored together in single article. Those documents are usually quoted jointly are bunched collectively, and located on the map both intimately and remotely based on the figure of authorship.[17] Co-authorship analysis is the recurrent method used in scientometric analysis and has been used to identify the collaborative works of co-authors, which allow scholars to find insight for the growing practice, information stand, and scientific structure of scholarly research.[18]

  Results Top

The most frequently fractionalized papers included Hannan NJ (n = 10, AF = 1.22), Tong S (n = 10, AF = 1.22), Kaitu'u-Lino TJ (n = 9, AF = 1.13), Huppertz B (n = 7, AF = 3.72), and Rana S (n = 7, AF = 1.02), respectively. [Table 2] shows the top 10 recent (2015–2021) and fractionalized papers along with details of the published articles in the research area, where the author Hannan, NJ. is appeared as the most productive author in the area.
Table 2: The top 10 recent and fractionalized papers in placenta area in PubMed database

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The top most prolific authors, affiliations, journal sources, and country

[Table 3] demonstrates the 20 authors, affiliations, sources, and countries, with the most research article. The top 5 scholars publishing articles were Hannan NJ (TS = 10), Tong S (TS = 10), Huppertz B (TS = 9), Rana S (TS = 7), and Cannon P (TS = 6). The “University of Melbourne” with 80 total studies, “King's College London” with 54 total studies, and “University of Mississippi Medical Center” with 50 total studies and Harvard Medical School with 47 total studies are the most dominant institutions/affiliations correspondingly. “The pregnancy in hypertension” is the most prolific resource journal, with the 249 total documents. The “American Journal of Obstetrics and Gynecology,” with 4 total studies; “Clinics in Obstetrics and Gynaecology,” with 4 total studies; and “Acta Obstetricia et Gynecologica Scandinavica,” with 3 total studies, absorbed the succeeding publications. The “USA” is the top most productive country in producing the topic-related research, with the 32 total studies. “China,” with 26 total studies; “Australia,” with 22 total studies; “Germany,” with 15 total studies; and the “United Kingdom,” with 15 total studies place the subsequent countries.
Table 3: Top 20 Prolific Authors, Affiliations, Journals, and Countries in the field

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Co-authorship analysis

[Figure 2] visualizes the collaborative authorship study of the scholars, who produced placenta-related documents. Therefore, the current analysis cautiously preferred the authors, where the minimum number of documents of an author is 2 of the 1538 authors.
Figure 2: Co-authorship analysis (minimum number of an author 2 of 1538)

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Co-occurrence keyword analysis

Examination of keywords is one of the outstanding justifications of bibliometric era. As can be demonstrated in [Figure 3] and [Table 4], a total of 109 keywords were recorded into 5 clusters: cluster 1 with “red color” (n = 25 objects), cluster 2 with “green color” (n = 24 objects), cluster 3 with “blue color” (n = 23 objects), cluster 4 with “yellow color” (n = 19 objects), and cluster 5 with violet “color” (n = 18). The leading five keywords are “pregnancy (203),” female (200), “human (193),” “pre-eclampsia (162),” and “adult (131).” The total link strength was 15261. As new topics come out in the research area, associated keywords will emerge and earlier keywords will vanish. Adversely, some of these keywords stay unaffected over time.
Figure 3: Analysis of co-occurrence keywords

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Table 4: The analysis of co-occurrence keywords

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  Discussion Top

The placenta forms a functional unit between the mother and the fetus. It is the most accurate record of infant's prenatal experience. This research used two different scientometric research methods to examine placenta-induced hypertension documents produced in the period 1977–2021, and the 20 top recent articles were identified. The sequential allocation got three steps in the outputs. The study exposed that “Pregnancy Hypertension,” “American Journal of Obstetrics and Gynecology,” “Clinics in Obstetrics and Gynaecology,” “Acta Obstetricia et Gynecologica Scandinavica,” and “Acta Medica Scandinavica. Supplementum” published around 87% of papers in placenta-induced hypertension area. Moreover, the “USA,” “China,” “Australia,” “Germany,” and the “UK” were the most productive nations, and 'University of Melbourne, “King's College London,” and “University of Mississippi Medical Center” were the most prolific organizations correspondingly. Our paper, however, revealed that research articles were the most regular category of “journal article.” Likewise, the scrutiny of co-occurrence of keywords exposed five clusters. The most useful and top keywords were “pregnancy,” “human,” “pre-eclampsia,” “adult” and “placenta.” The etiology of preeclampsia is not well known. Some theories are taken into consideration, such as an improper placentation leads to the development of a placenta with poor blood flow. Endothelial dysfunction of the spiral artery of the uterus triggers widespread vasoconstriction of the maternal circulatory system. Genetic, racial, family history and comorbid disease are predisposing factors for the development pregnancy-induced hypertension or preeclampsia.[19] The most common theories of pathogenesis for the development of preeclampsia are angiogenic factors and oxidative stress. Imbalance pattern of increases anti-angiogenic factors sFlt-1, sEng and decreases pro-angiogenic factor vascular endothelial growth factor, transforming growth factor-β. Other hypotheses included imbalance between free oxygen radicals and scavengers and also pro- and anti-inflammatory cytokines. Ultimately, all factors are different ways to develop decreased vasodilation, inadequate vascular remodeling, increased vasoconstriction, and vascular resistance.[20]

Even though some literature was reviewed to be familiar with the formation of the placental range, there was no research activity in visualization aspect. The present attempt observed the construction of the placenta-induced hypertension-related research outputs from 1977 to 2021 and attempted to describe the modification in the sense of bibliometric analysis. Investigating placental coverage could make significant contributions to health organizers, health professionals, medical students, and medical doctors in gynecology and obstetrics. The investigation attempted to recognize the 10 most recent papers and draw the map of co-authorship and co-occurrence using PubMed. The study may facilitate doctors to trace the prolific authors, affiliations, country, source, and upcoming inclination in placenta field contributing inclusive examination along with prepared data on the study. The publications also symbolized the visualizing maps with the help of Biblioshiny and VOSviewer software. The study measured co-authorship and co-occurrence descriptive analysis. The procedures can offer research scholars and doctors with better understanding and mounting consequence of any research field. Upcoming researches adopting different styles and databases could propose diverse networks of the topic. The study is the initial strive to examine the co-authorship and networking process in revealing the present trend of placenta and hypertension areas. The relevance of keywords in this manner assists to expose the topics, and methodology absorption in a particular research era, that could be mentioned in a forthcoming study on other research fields. The outputs, hence, show various points associated with placenta, pregnancy, and hypertension area that are covered in the parental, obstetrics, and gynecology area.


Despite the fact that our paper presents an inclusive review of the placenta-induced hypertension production during the period of 1977–2021, it has some confines. Initially, our research area is confined with only PubMed as a media. In spite of the distinguished dataset, it holds a tiny part of the whole medical-related publications obtainable. Hence, the prototype and measures shaped in the study might not be expanded toward placenta and hypertension-related publications. We merely examine the annual scientific production, co-authorship, productive affiliations, sources, countries, and co-occurrence keywords; others can work on co-citation, social structure, newplot, and citation networks. The study utilized the VOSviewer and Biblioshiny; further analyses adopting further scientometric media can be used and broaden the investigative results.

  Conclusion Top

The investigation demonstrated the study tendency, effect as well as group efforts amid of scholars in the area of placenta-induced hypertension from 1977 to 2021. The study stated the progress of research movement in this field which emphasizes the placenta research trend. This study shows the demand to amplify research aid and research outputs in pregnancy in the globe. The study will enhance the understanding of the pregnancy issues and may discover local and racial dissimilarity in medical and health environment.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

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  [Figure 1], [Figure 2], [Figure 3]

  [Table 1], [Table 2], [Table 3], [Table 4]


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