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. 2023 Feb 2;14:1110399. doi: 10.3389/fphys.2023.1110399

A bibliometric review of 35 years of studies about preeclampsia

Razieh Akbari 1,*, Sedigheh Hantoushzadeh 1, Zahra Panahi 1, Sajedeh Bahonar 2, Marjan Ghaemi 1
PMCID: PMC9932928  PMID: 36818438

Abstract

The purpose of this study is to investigate preeclampsia. It used the visualization tools of CiteSpace, VOSviewer, Gunnmap, Bibliometrix®, and Carrot2 to analyze 3,754 preeclampsia studies from 1985 to 2020 in Obstetrics and Gynecology areas. Carrot2 was used to explain each cluster in extra detail. The results found that there is an increasing trend in many publications related to preeclampsia from 1985 to 2020. The number of studies on preeclampsia has increased significantly in the last century. Analysis of the keywords found a strong relationship with preeclampsia concepts and keywords classified into five categories. Co-citation analysis was also performed which was classified into six categories. Reading the article offers important to support not only to grind the context of preeclampsia challenges but also to design a new trend in this field. The number of studies on preeclampsia has substantially improved over the decades ago. The findings of documents published from 1985 to 2020 showed three stages in research on this subject: 1985 to 1997 (a seeding stage), 1997–2005 (rapid growth stage), and 2005 onwards (development stage).

Keywords: bibliometric; preeclampsia; web of science database; co-citation; co-occurrence, theme evolution

Introduction

As one of the multisystem diseases during pregnancy, pre-eclampsia is a considerable cause of maternal and infant morbidity and mortality worldwide (Steegers et al., 2010). Over the past century, the term pre-eclampsia has evolved from a kidney-specific disease causing chronic nephritis to a state of toxaemia caused by circulating toxins (Phipps et al., 2016), characterized by hypertension and proteinuria appearing after 20 weeks of gestation. Pre-eclampsia affects approximately 5–7% of pregnancies (Witlin & Sibai, 1998). Recently, it has been redefined as de novo hypertension that manifests after 20 weeks of pregnancy and is accompanied by proteinuria (N300 mg/day), maternal organ dysfunction (including renal insufficiency, liver involvement, neurological or haematological problems), or uteroplacental dysfunction (potential cause of fetal growth restriction) (Tranquilli et al., 2014).

Bibliometric or citation analysis evaluates frequently cited articles in various disciplines, reviews the redundancy of the literature, assesses the quality of publications, highlights trends in research interest, and/or the evolution of scholarly publications over time. It is widely used in different medical fields and several studies using this approach have been published (Lee et al., 2019; Yadava et al., 2019), such as traumatic brain injury (Karydakis et al., 2019), artificial intelligence in the treatment of cerebrovascular disease and heart disease (Tran et al., 2019), IUGR (Kazemi Aski et al., 2020), and oral leukoplakia (Liu W et al., 2019).

To the best of our knowledge, no bibliometric research on preeclampsia has been performed. This study was therefore designed as a bibliometric analysis to evaluate pre-eclampsia articles from 1985 to 2020. To examine the data present in the WoS database, a quantitative literature search was employed. The relationships and impacts of key publications and related factors in this field were assessed using literature metrics, article ratings, and institutional and country ratings.

Our article makes several contributions to the advancement of literature. To uncover thinking flows, essential concepts, and developing issues with the potential to be included in future studies, we first utilized the quantitative bibliometric analysis method, which enables many numerous robust structured, and thorough inspections of this research subject. Subsequently, in order to demonstrate how the preeclampsia domain’s bounds have changed over time and give readers an immediate understanding of the deftly constructed increasing. Finally, we connected evolutionary paths with upcoming study directives to promote new preeclampsia study flows in the Obstetrics and Gynecology field.

Methods

Bibliometrics method

Bibliometrics is a systematic method that is broadly defined as a quantitative examination of published documents (Broadus, 1987; De Bellis, 2009). Using approaches such as content analysis, text analysis, citation analysis, keyword co-occurrence, co-citation analysis, or co-authoring analysis, Pritchard described bibliometrics as the application of mathematics and statistical methodologies to books and other media of communication (Pritchard, 1969; Dias, 2019). By highlighting the most significant articles, the bibliometric analysis might help the scholar avoid becoming overwhelmed by the massive amount of publications (Karydakis et al., 2019). Utilizing citation data, citation analysis quantifies the study’s influence as a reflection of the volume of citations a publication accumulates over time (Yadava et al., 2019). Additionally, citation analysis is employed to assess academic impacts (Liu et al., 2013). The papers with a high citation count are assumed to contain insightful suggestions for further studies (Jeung et al., 2011) and their authors are regarded as significant figures in the field (Butt et al., 2019).

The majority of bibliometric studies used citation analysis to determine the most popular papers, authors, journals, countries, co-authorship of authors, and keyword co-occurrences (Alarcon-Ruiz et al., 2019; Lee et al., 2019). Citation analysis has been applied in a variety of fields to identify the most significant publications (States et al., 2019). The frequency with which a text has been cited by other researchers can be determined using techniques of citation analysis (Xu et al., 2015). Citation analysis methods have recently made their way into the medical studies (Chen, 2004; Gupta et al., 2019).

Eligibility requirements, study selection, and data extraction

The study had nothing to do with the approval of ethical committees. The WoS database was used to retrieve the data for our study. Data were gathered in December 2020 utilizing the WoS database’s internet search engine. In this study, the authors conducted a comprehensive search of all papers using the term “Preeclampsia” as the search query. Only the “TITLE” was the subject of keyword searches. As a result, a group of 3754 papers written between 1985 and 2020 were gathered. Then, this collection was fixed as the foundation for all ensuing VOSviewer analyses. The application CiteSpace and VOSviewer (1.6.11) was used to create bibliometric network visualizations (Chen, 2004; Van Eck & Waltman, 2009).

A review of the literature revealed that 14,230 publications about preeclampsia were published between 1985 and 2020. Article (3,754), Proceedings Paper (221), Early Access (62), and book chapter are among these publications (13). In this study, 7,653 of the 7,869 English-language papers that fall under the category of obstetrics and gynaecology were examined. The total number of articles eventually decreased to 3,754 (Figure 1).

FIGURE 1.

FIGURE 1

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Methodological approach (Author’s Presentation).

Data synthesis

Country maps were created using Gunnmap. VOSviewer software was used to examine the bibliometric co-occurrence keyword analysis, CiteSpace for the analysis of keywords trends, Carrot2 for the analysis of bibliometric document co-citations, and Bibliometrix® for the analysis of the strategic map.

Results

Distribution of published preeclampsia papers per year

A total of 3,495 papers were included. Figure 2 shows the growth in preeclampsia research from 1985 to 2020 in terms of publications (total studies/TS) and citations (total citations/TC) each year. Over half of the articles (51% of them) were published within the last 10 years.

FIGURE 2.

FIGURE 2

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Number of publications and citations per year from 1985 to 2020.

Authors with the most publications in the preeclampsia discipline

The top 20 document-producing authors, nations/regions, and organizations/institutions are recognized. The ranked authors who reproduced preeclampsia articles between 1985 and 2020 were Sibai, B.M. (TS = 98); Roberts, J.M. (TS = 64); Romero, R. (TS = 55); Nicolaides, K.H. (TS = 48); Martin, JN (TS = 32); Chaiworapongsa, T (TS = 30); Hassan, S.S. (TS = 29); Steegers EAP (TS = 28); Baker PN (TS = 27); Saade GR (TS = 27); Staff, A.C. (TS = 28); Dekker, G.A. (TS = 26); Erez O (TS = 26); Van Pampus MG (TS = 26); Nisell H (TS = 25); Karumanchi, S.A. (TS = 24); Redman CWG (TS = 24); Von Dadelszen P (TS = 24); Wang YP (TS = 24); and Franx A (TS = 22).

Countries/regions with the most publications in the preeclampsia discipline

The number of articles generated by each region and the total number of citations each country has on the examined study area define the impact of the most productive regions. We select the top 20 document-producing areas in the preeclampsia field of research. The “United States” is the first dominant region (TS = 1200, TC = 49,692), and after that “Peoples R China” (TS = 311, TC = 3307) and “England” (TS = 262, TC = 12,342). Another region with a high number of publications is Turkey (TS = 232), followed by the Netherlands (TS = 196), Canada (TS = 162), Italy (TS = 152), Japan (TS = 149), Australia (TS = 145), Israel (TS = 131), Germany (TS = 130), Norway (TS = 101), Sweden (TS = 93), Brazil (TS = 91), India (TS = 80), Spain (TS = 79), South Korea (TS = 72), Iran (TS = Figure 3 displays a map of the study-based regions in red (highest) and green (lowest) colours.

FIGURE 3.

FIGURE 3

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Regions map based on documents.

Organizations/institutions with the most publications in the preeclampsia discipline

The study includes 2359 institutions from various geographical areas. The top 20 organisations with the most publications are listed below. The impact of the most productive organisations in the preeclampsia discipline is determined by the total number of documents printed by each organisation and the total number of citations. The three most significant universities are the “University of Texas system” (TS = 108, TC = 3845), “Harvard University” (TS = 104, TC = 4124), and “The Pennsylvania Commonwealth System of Higher Education/PCSHE” (TS = 99, TC = 5616). Other institutions with the highest publications include, ‘The University of London’ (TS = 97, TC = 97), ‘The University of Pittsburgh’ (TS = 95, TC = 5463); ‘NIH USA’ (TS = 92, TC = 5949), ‘The University of Tennessee system’ (TS = 86, TC = 6219), ‘University of Tennessee health science center’ (TS = 84, TC = 6150), ‘NIH Eunice Kennedy Shriver national institute of child health human development NICHD’ (TS = 79, TC = 5448), ‘University of California system’ (TS = 78, TC = 4319); ‘Wayne State University’ (TS = 76, TC = 4518); ‘Magee Women’s research institute’ (TS = 69, TC = 4082), and ‘Kings College London’ (TS = 67, TC = 3426), ‘University of Oslo’ (TS = 59, TC = 2117); ‘Karolinska Institutet’ (TS = 57, TC = 1320), and ‘Erasmus university Rotterdam’ (TS = 54, TC = 1248); ‘The University of Cincinnati’ (TS = 52, TC = 3118), ‘The University of Groningen’ (TS = 52, TC = 1361), ‘King S College Hospital’ (TS = 51, TC = 2435), and ‘King S college hospital NHS foundation trust’ (TS = 51, TC = 2435).

Journals with the most publications in the preeclampsia discipline

This section introduces the 20 top Journals in order. The ‘AJOG’ is the most influential journal, with 41,991 total citations (TS = 622). The ‘Hypertension in Pregnancy’ (7247 citations, TS = 447), the ‘Journal of Maternal Fetal and Neonatal Medicine’ (3911 citations, TS = 297), the ‘Pregnancy hypertension an international journal of Womens cardiovascular health’ (1691 citations, TS = 280), the ‘Obstetrics and Gynecology’ (15,156 citations, TS = 267), the ‘Placenta’ (6038 citations, TS = 209), the ‘European journal of obstetrics gynecology and reproductive biology’ (3599 citations, TS = 152), the ‘Acta Obstetricia et Gynecologica Scandinavica’ (2763 citations, TS = 113), the ‘Reproductive sciences’ (1988 citations, TS = 113), the ‘Gynecologic and obstetric investigation’ (1948 citations, TS = 109), the ‘Archives of gynecology and obstetrics’ (1077 citations, TS = 88), the ‘American Journal of Perinatology’ (1029 citations, TS = 82), the ‘BMC Pregnancy and Childbirth’ (826 citations, TS = 79), the ‘Journal of Perinatal Medicine’ (1295 citations, TS = 79), the ‘Prenatal diagnosis’ (1377 citations, TS = 52), the ‘Clinical and Experimental Obstetrics Gynecology’ (277 citations, TS = 47), the ‘Fetal diagnosis and therapy’ (1159 citations, TS = 44), the ‘Journal of Reproductive Medicine’ (451 citations, TS = 43), the ‘British Journal of Obstetrics and Gynaecology’ (BJOJ) (3928 citations, TS = 41), the ‘Journal of the society for gynecologic investigation’ (1048 citations, TS = 40).

Most-cited documents in preeclampsia discipline

The most cited documents involved Roberts et al. (1989) (N = 1466); Khong et al. (1986) (N = 1247); Sacks et al. (1998) (N = 607) and Walsh (1985) (N = 546) respectively (Table 1). Also, the results found that 24 (out of 30 most cited) of the documents were clinical and research papers and 6 of the documents were literature reviews. About 18 articles were published in ‘AJOG’. Table 2.

TABLE 1.

The most cited authors, countries, organizations, and journals in the preeclampsia discipline.

Authors TS TC Countries/Regions TS TC Organizations/Institution TS TC Journals TS TC
1 SibaiB.M. 98 7420 United States of America 1200 49,708 University of Texas System 108 3845 AJOG 622 41,991
2 RobertsJ.M. 64 5824 Peoples R China 311 3311 Harvard University 104 4124 Hypertension in Pregnancy 447 7247
3 Romero, R 55 3900 England 262 12,347 PCSHE 99 5616 Journal of Maternal-Fetal and Neonatal Medicine 297 3911
4 NicolaidesK.H. 48 2154 Turkey 232 3163 University of London 97 4191 Pregnancy hypertension an international journal of Women’s cardiovascular health 280 1691
5 Martin, JN 32 1414 Netherlands 196 6583 University of Pittsburgh 95 5463 Obstetrics and Gynecology 267 15,156
6 Chaiworapongsa, T 30 2108 Canada 162 5922 NIH United States of America 92 5949 Placenta 209 6038
7 HassanS.S. 29 1612 Italy 152 3712 University of Tennessee system 86 6219 European journal of obstetrics gynaecology and reproductive biology 152 3599
8 Steegers EAP 28 701 Japan 149 3545 University of Tennessee health science center 84 6150 Acta Obstetricia et Gynecologica Scandinavica 113 2763
9 Baker PN 27 990 Australia 145 3019 NIH Eunice Kennedy Shriver national institute of child health human development NICHD 79 5448 Reproductive sciences 113 1988
10 Saade GR 27 1052 Israel 131 3490 University of California system 78 4319 Gynecologic and obstetric investigation 109 1948
11 StaffA.C. 27 1087 Germany 130 3148 Wayne State University 76 4518 Archives of gynaecology and obstetrics 88 1077
12 DekkerG.A. 26 1719 Norway 101 4276 MAGEE Womens research institute 69 4082 American Journal of Perinatology 82 1029
13 Erez O 26 1167 Sweden 93 2715 Kings College London 67 3426 BMC Pregnancy and Childbirth 79 826
14 Van Pampus MG 26 548 Brazil 91 1148 University of Oslo 59 2117 Journal of Perinatal Medicine 79 1295
15 Nisell H 25 622 India 80 696 Karolinska Institutet 57 1320 Prenatal diagnosis 52 1377
16 KarumanchiS.A. 24 1254 Spain 79 1631 ERASMUS University Rotterdam 54 1248 Clinical and Experimental Obstetrics Gynecology 47 277
17 Redman CWG 24 1838 South Korea 72 1708 University of Cincinnati 52 3118 Fetal diagnosis and therapy 44 1159
18 Von Dadelszen P 24 1401 Iran 69 491 University of Groningen 52 1361 Journal of Reproductive Medicine 43 451
19 Wang YP 24 1149 Finland 65 2423 King S College Hospital 51 2435 British Journal of Obstetrics and Gynaecology 41 3928
20 Franx A 22 632 France 53 967 King S College hospital NHS foundation trust 51 2435 Journal of the society for gynecologic investigation 40 1048
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TABLE 2.

The top studies within the preeclampsia discipline.

References Source Citation Citation per year Research type
Roberts et al. (1989) AJOG 1466 44.42 Literature review
Khong et al. (1986) BJOJ 1247 34.64 Literature review
Sacks et al. (1998) AJOG 607 25.29 Clinical
Walsh (1985) AJOG 546 14.76 Clinical
Gilstrap & Ramin (2002) Obstetrics and Gynecology 534 26.7 Clinical
von Dadelszen et al. (2003) Hypertension in Pregnancy 475 25 Literature review
Romero et al. (2008) Journal of Maternal-Fetal & Neonatal Medicine 454 32.43 Clinical
Sibai et al. (1986b) AJOG 445 12.36 Clinical
Roberts & Hubel (2009) Placenta 441 33.92 Literature review
Dekker, et al. (1995) AJOG 424 15.7 Clinical
MacKay et al. (2001) Obstetrics and Gynecology 414 19.71 Clinical
Kurki et al. (2000) Obstetrics and Gynecology 390 17.73 Clinical
Ness & Roberts (1996) AJOG 382 14.69 Literature review
Ishihara et al. (2002) AJOG 380 19 Clinical
Sibai et al. (1995) AJOG 362 13.41 Clinical
Sibai et al. (1997) AJOG 361 14.44 Clinical
Saftlas et al. (1990) AJOG 358 11.19 Clinical
Lisonkova & Joseph (2013) AJOG 347 38.56 Clinical
Vince et al. (1995) BJOJ 338 12.52 Clinical
Yallampalli & Garfield (1993) AJOG 330 11.38 Clinical
Pineles et al. (2007) AJOG 322 21.47 Clinical
Allaire et al. (2000) Obstetrics and Gynecology 320 14.55 Clinical
Seligman et al. (1994) AJOG 314 11.21 Clinical
Villar et al. (2006) AJOG 307 19.19 Clinical
Sibai et al. (1994) AJOG 301 10.75 Clinical
Akolekar et al. (2013) Fetal Diagnosis and Therapy 287 31.89 Clinical
Ødegård et al. (2000) Obstetrics and Gynecology 281 12.77 Clinical
Sibai et al. (1986a) AJOG 276 7.67 Clinical
Rodgers et al. (1988) AJOG 270 7.94 Clinical
Burton et al. (2009) Placenta 269 20.69 Literature review
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Hot topics in the preeclampsia research

One of the best bibliometrics methods is keyword analysis. The evolution of a scientific domain is discovered using the co-occurrence method (Zhu et al., 2019). The co-occurrence technique is reliable and useful for selecting the most beneficial themes over time (Wang et al., 2018). Figure 4 shows the five clusters that were created from the 60 keywords (minimum keywords, 10 times): cluster one (n = 18 items), cluster two (n = 16), cluster three (n = 13), cluster four (n = 7), and cluster five (n = 6 things). The material for each cluster is displayed in Table 3.

FIGURE 4.

FIGURE 4

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Co-occurrence map.

TABLE 3.

Classification of keywords based on clusters.

Cluster Keywords
Cluster 1: 18 items
Management of Preeclampsia		 Cardiovascular-Disease, Complications, Disease, Disorders, Dysfunction, Eclampsia, Fetal, Gestational Hypertension, Hypertension, Hypertensive Disorders, Impact, Management, Mortality, Outcomes, Pregnancy, Proteinuria, Risk-Factors, Women
Cluster 2: 16 items
Diagnosis of Preeclampsia		 Activation, Angiogenesis, Cancer, Endothelial Dysfunction, Expression, Hypoxia, Invasion, Migration, Oxidative Stress, Pathogenesis, Placenta, Plasma, Preeclampsia, Proliferation, Receptor, Trophoblast
Cluster 3: 13 items
The role of Biomarkers in Preeclampsia		 Angiogenic Factors, Biomarker, Biomarkers, Early-Onset, Early-Onset Preeclampsia, Fetal, Growth Restriction, Late-Onset Preeclampsia, Normal-Pregnancy, Plgf, Serum, Severe, Preeclampsia, Soluble Endoglin, Tyrosine Kinase-1
Cluster 4: 7 items
The role of Asprin in Preeclampsia		 Aspirin, Growth Restriction, Low-Dose Aspirin, Prediction, Pregnancies, Preterm, Uterine Artery Doppler
Cluster 5: 6 items
Preeclampsia and IUGR		 Association, Blood-Pressure, Inflammation, Intrauterine Growth Restriction, Pathophysiology, Polymorphism
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Keywords trend

Topics that are expanding quickly in the field of preeclampsia were found by analyzing the frequency of keywords in subject categories. In Table 4, there are a few thematic groups with bursts and thorough details on the 25 thematic groups with the most powerful citation bursts. Preeclampsia, prostacyclin, endothelium, and thromboxane are identified by CiteSpace’s burst detection as the five topic areas with the most intense citation bursts. During a specific time, these topics were active research areas. Table 5 displays every colour section according to a timeline. A red line segment showing the beginning and finish of the burst duration is used to denote the length of a burst in a subject category. Pregnancy-induced hypertension, for instance, revealed a time of burst from 1992 to 2006 with a burst strength of 39.91 at the top of the list. The number of documents in the “pregnancy-induced hypertension” domain increased significantly between 1992 and 2006, indicating that preeclampsia research in this field was active at the time. Preeclampsia research has recently focused on topics including “cardiovascular disease,” “diagnosis,” “early onset,” “fetal growth restriction,” and “aspirin”.

TABLE 4.

Top keywords with the strongest citation bursts.

Keywords Year Freq Burst Degree Centrality Strength Begin End 1992–2020
Pregnancy Induced Hypertension 1992 123 39.91 24 0.14 36.9 1992 2006 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx7.jpg
Preeclampsia 1992 64 33.83 15 0.02 31.25 1992 2003 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx8.jpg
Prostacyclin 1992 42 22.15 19 0.06 20.35 1992 2003 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx9.jpg
Endothelium 1992 24 12.63 12 0.01 11.41 1992 2004 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx10.jpg
Thromboxane 1992 23 12.10 12 0.01 11.29 1992 2003 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx11.jpg
Endothelial Cell 1992 44 19.22 22 0.06 15.51 1993 2003 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx12.jpg
Rat 1992 27 - 17 0.04 12.51 1994 2000 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx13.jpg
Nitric Oxide 1992 59 24.35 20 0.06 18.51 1995 2007 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx14.jpg
Activation 1992 74 21.53 21 0.06 18.81 1996 2009 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx15.jpg
Lipid Peroxidation 1992 42 18.22 14 0.02 11.86 1996 2005 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx16.jpg
Insulin Resistance 1992 42 17.61 9 0.01 13.25 2005 2012 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx17.jpg
Soluble Endoglin 1992 66 17.93 12 0.01 15.37 2007 2014 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx18.jpg
Gene Expression 1992 40 11.75 4 0.00 12.05 2009 2015 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx19.jpg
Circulating Angiogenic Factor 1992 39 12.59 14 0.02 13.44 2010 2014 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx20.jpg
Placental Growth Factor 1992 100 14.61 15 0.02 12.95 2012 2020 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx21.jpg
Angiogenic Factor 1992 170 16.46 18 0.03 19.15 2013 2017 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx22.jpg
Biomarker 1992 103 16.65 15 0.02 18.06 2013 2020 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx23.jpg
Prediction 1992 200 4.44 19 0.05 13.77 2013 2020 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx24.jpg
Uterine Artery Doppler 1992 136 11.33 14 0.01 11.08 2013 2016 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx25.jpg
Prevention 1992 119 18.43 14 0.03 14.97 2014 2020 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx26.jpg
Cardiovascular Disease 1992 75 12.58 6 0.00 13.42 2014 2020 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx27.jpg
Diagnosis 1992 93 18.33 13 0.02 21.72 2015 2020 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx28.jpg
Early Onset 1992 40 16.56 2 0.00 14.1 2016 2020 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx29.jpg
Fetal Growth Restriction 1992 63 14.97 6 0.00 13.5 2016 2020 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx30.jpg
Aspirin 1992 54 16.81 13 0.02 14.1 2017 2020 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx31.jpg
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TABLE 5.

The first five authors contribute to selected clusters.

Freq Burst Centrality Source References Cluster Carrot analysis
32 19.57 0.17 Lancet Roberts and Redman (1993) 0 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx1.jpg
24 13.98 0.06 Am J Obstet Gynecol Dekker and Sibai (1998) 0
23 14.13 0.19 Am J Obstet Gynecol Dekker et al. (1995) 0
22 12.23 0.19 New Engl J Med Kupferminc et al. (1999) 0
17 10.20 0.00 New Engl J Med Schobel et al. (1996) 0
25 16.41 0.10 Am J Obstet Gynecol Roberts et al. (1989) 1 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx2.jpg
20 12.03 0.35 Am J Obstet Gynecol Seligman et al. (1994) 1
13 8.15 0.00 Clin Perinatol Friedman et al. (1991) 1
12 7.52 0.05 Am J Obstet Gynecol Pinto et al. (1991) 1
11 6.89 0.01 Am J Hypertens Roberts et al. (1991) 1
70 36.46 0.15 New Engl J Med Levine et al. (2004) 2 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx3.jpg
55 29.76 0.54 J Clin Invest Maynard et al. (2003) 2
52 31.12 0.03 Am J Obstet Gynecol AuthorAnonymous (2000) 2
40 23.39 0.59 Am J Obstet Gynecol Redman et al. (1999) 2
33 18.93 0.25 Lancet Roberts & Cooper (2001) 2
186 93.38 0.20 Obstet Gynecol Roberts JM et al. (2013) 3 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx4.jpg
63 00.00 0.02 Pregnancy Hypertens Tranquilli et al. (2014) 3
62 29.47 0.09 New Engl J Med Rolnik et al. (2018) 3
51 23.56 0.05 Lancet Mol et al. (2016) 3
49 22.62 0.03 New Engl J Med Zeisler et al. (2016) 3
82 41.70 0.02 Lancet Steegers et al. (2010) 4 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx5.jpg
50 27.55 0.03 Semin Perinatol Duley (2009) 4
45 18.83 0.27 Am J Obstet Gynecol Lisonkova & Joseph (2013) 4
45 16.07 0.08 Fetal Diagn Ther Akolekar et al. (2013) 4
43 21.53 0.01 Obstet Gynecol Bujold et al. (2010) 4
73 39.03 0.00 Lancet Sibai et al. (2005) 5 graphic file with name FPHYS_fphys-2023-1110399_wc_tfx6.jpg
67 35.74 0.00 Science Redman & Sargent (2005) 5
62 31.23 0.23 New Engl J Med Levine et al. (2006) 5
47 23.53 0.20 Nat Med Venkatesha et al. (2006) 5
47 22.53 0.76 J Matern-Fetal Neo M Romero et al. (2008) 5
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Co-citation network

Co-citation analysis is an effective technique that has gained widespread acceptance in several fields for accurately defining and visualising the intellectual structure of a study topic. In light of this, we decided to analyse the discipline’s structure using co-citation network analysis. Citespace software was used to investigate the preeclampsia discipline, which has its intellectual foundation in particular in the cited references. A network with 187 nodes and 598 edges was generated using document co-citation reference analysis in Citespace and the parameter settings: Slice length = 5; pruning: pathfinder; top N per slice: 30; top N%: 10%. (Figure 5). The LLR algorithm and title were used to cluster articles. Six clusters were ultimately procured, and Citespace gave them names automatically.

FIGURE 5.

FIGURE 5

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Co-citation grid of cited references.

By using Carrot2, the clusters were deduced. To discover more about these clusters, the Carrot2 using the lingo algorithm was utilised on each cluster. The results showed that clusters #3 and #4 were the most recent clusters, while cluster #0 was the largest and oldest. Silhouette values of all clusters are bigger than 0.93. With 34 articles spread across 16 years, from 1985 to 2001, Cluster #0 is the largest cluster. Cluster #0 has a high degree of consistency, as evidenced by its Silhouette value of 0.936. Considering that Cluster #0 is the main cluster, its themes have been spread very widely. Carrot2 is capable of algorithmically managing the primary themes that are gleaned from the titles, keywords, and abstracts of cited documents (Table 5). The second-largest cluster, Cluster #1, contains 33 articles over the 10 years of 1985–1995 (Silhouette = 0.952). Cluster #3 is the most recent cluster (Silhouette = 0.992), and replicates significant events related to the risk of preeclampsia, placenta, sFlt-1, trimester, and growth restriction. Clusters #2, #4, and #5 all have silhouette values of 0.957, 0.949, and 0.935, respectively.

Theme evolution: Strategic map in preeclampsia

Many keywords only occasionally appeared, therefore they undoubtedly had a significant impact on the key topic of preeclampsia. We involved the study’s title keywords. Using Bibliometrix®, a strategic map is created to examine the most important highlighted keywords in the preeclampsia field. The highly related keywords are gathered into clusters, and the themes are named using the most highly related terms (Wang et al., 2019). The strategic map is divided into four sections (Cobo et al., 2011), as indicated by Callon et al. (1991) including the basic themes (bottom right), emerging themes (bottom left), motor themes (top right), and highly developed themes (right-left). Motor themes have strong relationships and are quite determined. Themes that are thoroughly developed and isolated have strong internal connections but weak external links. Themes that are developing or declining have a slight density and concentration, signifying weak interior and outer relations. Finally, basic and transversal themes, which are represented by topics with weak internal ties but large exterior links, have a high concentration and low density (Cobo et al., 2011). The first five keywords and the number of times they appeared were as follows:

Highly developed and isolated themes: Hypertensive Disorders (249), Angiogenic Factors (149), Uterine Artery Doppler (122), Tyrosine Kinase-1 (86), and Soluble Endoglin (86).

Motor themes: Expression (355), Normal-Pregnancy (168), Plasma (164), Oxidative Stress (146), and Pathogenesis (142).

Emerging or declining themes: Pregnancy-induced hypertension (152), Pre-eclampsia (101), Elevated liver enzymes (84), Hemolysis (49), and Therapy (33).

Basic and transversal themes: Pregnancy (1084), Women (798), Hypertension (590), Risk (516), and Eclampsia (168).

Discussion

In this study, by using bibliometric analysis, our research has explored and studied the trend of preeclampsia discipline between 1985 and 2020. The paper has valued the study and articles’ performance of authors, journals, organizations, and regions. To better recognize the configuration of the preeclampsia discipline, the authors advanced and studied co-citation, co-occurrence, strategic, and keywords maps. The chronological distribution displays three times in the publication movements in the preeclampsia discipline. The most cited document, ‘preeclampsia - an endothelial-cell disorder’ was published in the ‘AJOG’ (Roberts et al., 1989). The article’s from the ‘BJOJ’ was the second-most quoted piece of writing (Khong et al., 1986). Sacks article’s ‘AJOG’, which received the third-highest number of citations, was authored (Sacks et al., 1998). Sibai, Roberts, and Romero had the most preeclampsia-related documents among the authors. The United States, China, and England were the three most productive countries. The most effective institutions were ‘the University of Texas system’, ‘Harvard University’, and ‘PCSHE’. In terms of the number of articles, the overall number of citations, and productive organisations, the United States comes out on top. The ‘AJOG’, ‘Hypertension in Pregnancy’, and ‘Journal of Maternal-Fetal and Neonatal Medicine’ are the journals with the greatest impact.

We discovered that preeclampsia is a developing but still challenging field of medicine, particularly obstetrics and gynaecology. The results of documents released between 1985 and 2020 revealed three stages in this field’s research: a seeding stage from 1985 to 1997, a rapid growth stage from 1997 to 2005, and a post-2005 stage (development stage). An examination of the keywords revealed a close connection to preeclampsia themes. As a result, the findings regarding the primary structuring of the mentioned sources were made clear by the keywords. This stability suggests that an appropriate study on this topic was developed along the progress process. Investigating the keywords revealed a network of keywords with five clusters in the study. According to this finding, the management, diagnosis, biomarker’s involvement in preeclampsia, aspirin’s role in preeclampsia, and the relationship between preeclampsia and IUGR are the primary areas of investigation in the preeclampsia field. The strategic keyword map’s findings revealed that a number of the keywords represent fundamental themes. The majority of motor topics have focused on expression, healthy pregnancy, plasma, oxidative stress, and pathophysiology, as shown in Figure 6 pregnancy-induced hypertension, preeclampsia prostacyclin, endothelium, and thromboxane were also the keywords with the greatest spikes in citations, but more recently, the focus of preeclampsia articles has shifted to include aspirin, cardiovascular disease, and early-onset, and fetal growth restriction. In other words, these areas have received more focus to evaluate the fetal and maternal impact of preeclampsia. Even though in previous years, these areas have received virtually little attention.

FIGURE 6.

FIGURE 6

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Strategic map in preeclampsia.

Six clusters were identified based on the results of co-citation, with clusters #3 and #4 being the most recent clusters and cluster #0 being the largest and oldest. Recently, the themes of chronic hypertension and conflicting risk models were studied. As a result, research on chronic hypertension and the competing risks model was focused on, along with studies on preeclampsia from lowered risks and the pathogenetic function. Researchers have been working on the chronic hypertension (Banala et al., 2020; Bramham et al., 2020; Hernández-Pacheco et al., 2020) as well as the competing risks model (Larroca et al., 2014; O’Gorman et al., 2016; Tsiakkas et al., 2016) in recent years.

Conclusions and implications

The main cause of maternal and neonatal morbidity and mortality is preeclampsia (Liu T et al., 2019). Preeclampsia is a complication in pregnancy mainly described by the occurrence of hypertension, and proteinuria after ≥20 weeks of gestation, edema in pregnancy and accompanied by signs of damage to other organ systems (Moghaddami Tabrizi et al., 2001; Roberts et al., 2013). It is associated with a higher risk of impending death, cardiovascular disease, cerebrovascular illness, and persistent hypertension (Leslie & Briggs, 2016). Acute renal failure, liver rupture, pulmonary edema, and cerebrovascular accidents are among the preeclampsia complications that can cause maternal death (Adu-Bonsaffoh et al., 2013). Preeclampsia is managed by preventing seizures, reducing maternal hypertension, and having the fetus delivered on schedule (Yeo et al., 2014). Although the pathogenesis of this significant obstetric condition is still unknown (Chaiworapongsa et al., 2014; Burton et al., 2019; Phipps et al., 2019). Every study in our research is significant and deserving of examination by obstetricians and gynecologists in active practice. According to a bibliometric examination of highly referenced works in the field, the AJOG is the best leading journal in the preeclampsia discipline. More than 60% of these articles were published in the AJOG. Despite these constraints, many of the most popular articles in other fields are supported by the top-cited papers, co-citations, and co-occurrence maps. All scholars in the field of healthcare can use the bibliometric method to examine the trend in the chosen field.

Contribution

This work makes a variety of contributions to theory and practice. The finding of this study was that the group of recently hot topics in this field that emerged from our research can serve as the foundation for future research. This study makes a significant contribution for researchers involved in preeclampsia because not only we shape, structure, and recognize the key universities, journals, documents and authors to be taken into consideration when conducting future research on preeclampsia but also to design a new trend in this field.

Strengths and limitations

This study has several restrictions. The WoS database is the only one that may be used for this research. Although it is the source with the most documentation, the information it contains is limited. This database does not index certain journals. As a result, other sources like PubMed, Google Scholar, and Scopus are available for use by other researchers. The second restriction is that an author could only have a minimum of 10 documents and a maximum of 10 keyword phrases. Third, this bibliometric analysis only considers publications in the fields of obstetrics and gynecology; other researchers may look into the fields of reproductive biology, physiology, general internal medicine, developmental biology, and biochemistry molecular biology. This study’s greatest asset was the thorough review of articles from the very beginning to the present.

Author contributions

All authors listed have made a substantial, direct, and intellectual contribution to the work and approved it for publication.

Conflict of interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Publisher’s note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranted or endorsed by the publisher.

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