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<front>
<journal-meta>
<journal-id journal-id-type="publisher-id">Front. Cell Dev. Biol.</journal-id>
<journal-title>Frontiers in Cell and Developmental Biology</journal-title>
<abbrev-journal-title abbrev-type="pubmed">Front. Cell Dev. Biol.</abbrev-journal-title>
<issn pub-type="epub">2296-634X</issn>
<publisher>
<publisher-name>Frontiers Media S.A.</publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="publisher-id">1115622</article-id>
<article-id pub-id-type="doi">10.3389/fcell.2023.1115622</article-id>
<article-categories>
<subj-group subj-group-type="heading">
<subject>Cell and Developmental Biology</subject>
<subj-group>
<subject>Original Research</subject>
</subj-group>
</subj-group>
</article-categories>
<title-group>
<article-title>Serum D-dimer is not predictive of placenta-mediated complications in pregnancy at high risk: The multicentric prospective cohort AngioPred study</article-title>
<alt-title alt-title-type="left-running-head">Hovine et al.</alt-title>
<alt-title alt-title-type="right-running-head">
<ext-link ext-link-type="uri" xlink:href="https://doi.org/10.3389/fcell.2023.1115622">10.3389/fcell.2023.1115622</ext-link>
</alt-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname>Hovine</surname>
<given-names>Agathe</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author">
<name>
<surname>Chauleur</surname>
<given-names>C&#xe9;line</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
<uri xlink:href="https://loop.frontiersin.org/people/1733712/overview"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname>Gauld</surname>
<given-names>Christophe</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author">
<name>
<surname>Rancon</surname>
<given-names>Florence</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
</contrib>
<contrib contrib-type="author">
<name>
<surname>Gris</surname>
<given-names>Jean-Christophe</given-names>
</name>
<xref ref-type="aff" rid="aff5">
<sup>5</sup>
</xref>
<xref ref-type="aff" rid="aff6">
<sup>6</sup>
</xref>
<xref ref-type="aff" rid="aff7">
<sup>7</sup>
</xref>
<uri xlink:href="https://loop.frontiersin.org/people/480116/overview"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname>Tardy</surname>
<given-names>Brigitte</given-names>
</name>
<xref ref-type="aff" rid="aff8">
<sup>8</sup>
</xref>
</contrib>
<contrib contrib-type="author">
<name>
<surname>Giraud</surname>
<given-names>Antoine</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
<xref ref-type="aff" rid="aff9">
<sup>9</sup>
</xref>
<uri xlink:href="https://loop.frontiersin.org/people/424410/overview"/>
</contrib>
<contrib contrib-type="author" corresp="yes">
<name>
<surname>Raia-Barjat</surname>
<given-names>Tiphaine</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
<xref ref-type="corresp" rid="c001">&#x2a;</xref>
<uri xlink:href="https://loop.frontiersin.org/people/1127848/overview"/>
</contrib>
</contrib-group>
<aff id="aff1">
<sup>1</sup>
<institution>Department of Gynecology and Obstetrics</institution>, <institution>Centre Hospitalier Universitaire de Saint-&#xc9;tienne</institution>, <addr-line>Saint-&#xc9;tienne</addr-line>, <country>France</country>
</aff>
<aff id="aff2">
<sup>2</sup>
<institution>INSERM U1059 SAINBIOSE</institution>, <institution>Universit&#xe9; Jean Monnet</institution>, <addr-line>Saint-&#xc9;tienne</addr-line>, <country>France</country>
</aff>
<aff id="aff3">
<sup>3</sup>
<institution>Department of Psychiatry</institution>, <institution>Centre Hospitalier Universitaire de Saint-&#xc9;tienne</institution>, <addr-line>Saint-&#xc9;tienne</addr-line>, <country>France</country>
</aff>
<aff id="aff4">
<sup>4</sup>
<institution>INSERM</institution>, <institution>Centre d&#x2019;Investigation Clinique 1408</institution>, <addr-line>Saint-&#xc9;tienne</addr-line>, <country>France</country>
</aff>
<aff id="aff5">
<sup>5</sup>
<institution>Laboratory of Hematology</institution>, <institution>Centre Hospitalier Universitaire de N&#xee;mes</institution>, <institution>et universit&#xe9; de Montpellier</institution>, <addr-line>Saint-&#xc9;tienne</addr-line>, <country>France</country>
</aff>
<aff id="aff6">
<sup>6</sup>
<institution>I.M. Sechenov First Moscow State Medical University</institution>, <addr-line>Moscow</addr-line>, <country>Russia</country>
</aff>
<aff id="aff7">
<sup>7</sup>
<institution>Institut Desbrest d&#x2019;Epid&#xe9;miologie et de Sant&#xe9; Publique UMR INSERM - Universit&#xe9; de Montpellier</institution>, <addr-line>Montpellier</addr-line>, <country>France</country>
</aff>
<aff id="aff8">
<sup>8</sup>
<institution>Laboratory of Hematology</institution>, <institution>Centre Hospitalier Universitaire de Saint-&#xc9;tienne</institution>, <addr-line>Saint-&#xc9;tienne</addr-line>, <country>France</country>
</aff>
<aff id="aff9">
<sup>9</sup>
<institution>Neonatal Intensive Care Unit</institution>, <institution>Centre Hospitalier Universitaire de Saint-&#xc9;tienne</institution>, <addr-line>Saint-&#xc9;tienne</addr-line>, <country>France</country>
</aff>
<author-notes>
<fn fn-type="edited-by">
<p>
<bold>Edited by:</bold> <ext-link ext-link-type="uri" xlink:href="https://loop.frontiersin.org/people/1449848/overview">Arjun Singh</ext-link>, Memorial Sloan Kettering Cancer Center, United States</p>
</fn>
<fn fn-type="edited-by">
<p>
<bold>Reviewed by:</bold> <ext-link ext-link-type="uri" xlink:href="https://loop.frontiersin.org/people/2137146/overview">Hadi Askarifirouzjaei</ext-link>, Memorial Sloan Kettering Cancer Center, United States</p>
<p>
<ext-link ext-link-type="uri" xlink:href="https://loop.frontiersin.org/people/2147292/overview">Anand Ramaian Santhaseela</ext-link>, Memorial Sloan Kettering Cancer Center, United States</p>
</fn>
<corresp id="c001">&#x2a;Correspondence: Tiphaine Raia-Barjat, <email>tiphaine.barjat@chu-st-etienne.fr</email>
</corresp>
<fn fn-type="other">
<p>This article was submitted to Molecular and Cellular Pathology, a section of the journal Frontiers in Cell and Developmental Biology</p>
</fn>
</author-notes>
<pub-date pub-type="epub">
<day>12</day>
<month>01</month>
<year>2023</year>
</pub-date>
<pub-date pub-type="collection">
<year>2023</year>
</pub-date>
<volume>11</volume>
<elocation-id>1115622</elocation-id>
<history>
<date date-type="received">
<day>04</day>
<month>12</month>
<year>2022</year>
</date>
<date date-type="accepted">
<day>05</day>
<month>01</month>
<year>2023</year>
</date>
</history>
<permissions>
<copyright-statement>Copyright &#xa9; 2023 Hovine, Chauleur, Gauld, Rancon, Gris, Tardy, Giraud and Raia-Barjat.</copyright-statement>
<copyright-year>2023</copyright-year>
<copyright-holder>Hovine, Chauleur, Gauld, Rancon, Gris, Tardy, Giraud and Raia-Barjat</copyright-holder>
<license xlink:href="http://creativecommons.org/licenses/by/4.0/">
<p>This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.</p>
</license>
</permissions>
<abstract>
<p>
<bold>Background:</bold> The theory that D-dimer level might has a predictive or diagnostic role in preeclampsia needs to be explored. Aim of the study was to evaluate the association between serum D-dimer level and the occurrence of placenta-mediated complications (PMC) in a pregnant population at high risk.</p>
<p>
<bold>Methods:</bold> A prospective multicenter cohort study including 200 pregnant women was conducted.</p>
<p>
<bold>Results:</bold> Serum D-dimer increases throughout pregnancy, with the highest levels at the end of gestation. Serum D-dimer level was similar for women with PMC and with no complication. Serum D-dimer level was not different in women with preeclampsia <italic>versus</italic> uncomplicated women. Serum D-dimer level was not different in women with early or late preeclampsia <italic>versus</italic> uncomplicated women.</p>
<p>
<bold>Conclusion:</bold> This result suggests that serum D-dimer level was not predictive of the PMC occurrence. This corroborates the fact that the origin of PMC based more on immunity than in hemostasis.</p>
</abstract>
<kwd-group>
<kwd>preeclampsia</kwd>
<kwd>D-dimer</kwd>
<kwd>longitudinal study</kwd>
<kwd>hypercoagulability</kwd>
<kwd>placental dysfunction</kwd>
</kwd-group>
</article-meta>
</front>
<body>
<sec id="s1">
<title>Introduction</title>
<p>Placenta-mediated complications (PMC) are a heterogeneous group of multisystemic disorders. These can be maternal (preeclampsia (PE), eclampsia, placental abruption, hemolysis elevated liver enzymes low platelets (HELLP) syndrome) or fetoplacental (intrauterine growth retardation (IUGR), <italic>in utero</italic> fetal death, recurrent spontaneous miscarriages). PMC complicates between 2% and 8% of pregnancies (<xref ref-type="bibr" rid="B4">Duley, 2009</xref>). Predicting and preventing these potentially serious complications is a major challenge for patients and their fetuses. The risk factors for PMC are well identified, but there is no validated screening strategy to predict the occurrence of PMC in these high-risk patients (<xref ref-type="bibr" rid="B6">Eskenazi et al., 1991</xref>; <xref ref-type="bibr" rid="B3">Duckitt and Harrington, 2005</xref>). The pathogenesis of PE is not fully understood but is considered to be multifactorial, centered on endothelial dysfunction and complex interactions between inflammatory and coagulation pathways. It is associated with a fibrin deposit in the micro-vascularization, responsible for lack of placental perfusion, intrauterine growth retardation, and dysfunction of maternal organs (<xref ref-type="bibr" rid="B17">Phipps et al., 2019</xref>). Several studies have investigated whether PMC are associated with changes in the hemostatic system (<xref ref-type="bibr" rid="B7">Gris et al., 2019</xref>). Previous studies have already looked at the use of angiogenic factor assay to predict PMC (<xref ref-type="bibr" rid="B20">Raia-Barjat et al., 2019</xref>).</p>
<p>D-dimer is the smallest fragment of fibrin degradation products. Fibrinolysis is the process of physiological dissolution of blood clots or thrombi made up of fibrin by plasmin. Plasmatic D-dimer is an indirect marker of the activation of coagulation followed by thrombolysis (<xref ref-type="bibr" rid="B16">Olson, 2015</xref>). D-dimer level is used for the diagnosis of venous thromboembolic disease (VTE) in the non-pregnant population. D-dimer level is significantly increased during pregnancy and proportional to gestational age (<xref ref-type="bibr" rid="B15">Nishii et al., 2009</xref>; <xref ref-type="bibr" rid="B13">Jeremiah et al., 2012</xref>; <xref ref-type="bibr" rid="B24">Wang et al., 2013</xref>; <xref ref-type="bibr" rid="B10">Hedengran et al., 2016</xref>). This makes it a non-specific test during pregnancy (<xref ref-type="bibr" rid="B1">Baboolall et al., 2019</xref>). D-dimer values during pregnancy are above normal in 15% of patients in the first trimester, 71% in the second trimester, and 96% in the third trimester (<xref ref-type="bibr" rid="B24">Wang et al., 2013</xref>). The use of standard D-dimer thresholds during pregnancy leads to misinterpretation of the results. Recent studies have attempted to establish new reference intervals for the level of D-dimer in pregnant women based on the trimester of pregnancy in order to discuss the value of their analysis (<xref ref-type="bibr" rid="B9">Hansen et al., 2011</xref>; <xref ref-type="bibr" rid="B21">R&#xe9;ger et al., 2013</xref>; <xref ref-type="bibr" rid="B24">Wang et al., 2013</xref>). An increased level of D-dimer in pregnant women with PE was described compared to pregnant women with normal blood pressure (<xref ref-type="bibr" rid="B22">Schjetlein et al., 1997</xref>). Since activation of blood coagulation occurs at the early stage of the disease, the increase in D-dimer could therefore occur before the onset of hypertension. Thus, the theory that D-dimer level might has a predictive or diagnostic role in preeclampsia needs to be explored (<xref ref-type="bibr" rid="B19">Portelinha et al., 2009</xref>). It seems important to identify sensitive and specific biomarkers to facilitate the screening of patients at risk of occurrence or recurrence of PMC, allowing a more rapid diagnosis and improving monitoring. However, few studies have compared D-dimer for predicting PE and IUGR in a high-risk population.</p>
<p>The main objective of this study was to evaluate the relation between serum D-dimer level and the occurrence of PMC. Secondary objectives were (<xref ref-type="bibr" rid="B4">Duley, 2009</xref>) to evaluate the association between serum D-dimer level and the occurrence of PE with or without IUGR and IUGR alone; (<xref ref-type="bibr" rid="B6">Eskenazi et al., 1991</xref>); to compare serum D-dimer levels between patients with early PE &#x3c; 34&#xa0;weeks, with late PE &#x2265; 34&#xa0;weeks and uncomplicated patients.</p>
</sec>
<sec sec-type="materials|methods" id="s2">
<title>Materials and methods</title>
<sec id="s2-1">
<title>Study population</title>
<p>Our study is based on data from the AngioPred study, as described (<xref ref-type="bibr" rid="B20">Raia-Barjat et al., 2019</xref>). The AngioPred study is a prospective multicenter cohort study conducted between June 2008 and October 2010 in the Obstetrics and Gynecology department of Saint-&#xc9;tienne and N&#xee;mes University Hospitals and the Laboratory of Hematology in Nimes University Hospital.</p>
<p>Inclusion criteria were: (<xref ref-type="bibr" rid="B4">Duley, 2009</xref>): diabetes (in diet or with insulin therapy), <xref ref-type="bibr" rid="B6">Eskenazi et al. (1991)</xref> hypertension (previously treated before pregnancy or hypertension &#x3e;140/90 twice before 20&#xa0;weeks), <xref ref-type="bibr" rid="B3">Duckitt and Harrington (2005)</xref> obesity (Body Mass Index &#x2265;30&#xa0;kg&#xa0;m<sup>&#x2212;2</sup>) (<xref ref-type="bibr" rid="B17">Phipps et al., 2019</xref>) maternal age older than 38&#xa0;years, <xref ref-type="bibr" rid="B7">Gris et al. (2019)</xref> chronic kidney disease (proteinuria &#x2265;300&#xa0;mg for 24&#xa0;h or creatininemia &#x2265;1.5&#xa0;mg/dl before 20&#xa0;weeks), <xref ref-type="bibr" rid="B20">Raia-Barjat et al. (2019)</xref> systemic lupus erythematosus; <xref ref-type="bibr" rid="B16">Olson (2015)</xref> antiphospholipid syndrome; <xref ref-type="bibr" rid="B10">Hedengran et al. (2016)</xref> family history of cardiovascular disease or venous thromboembolism (VTE) in first degree relatives (<xref ref-type="bibr" rid="B15">Nishii et al., 2009</xref>) biological thrombophilia without any personal history of VTE or PMC, <xref ref-type="bibr" rid="B13">Jeremiah et al. (2012)</xref> a history of one or more episodes of PMC or (<xref ref-type="bibr" rid="B24">Wang et al., 2013</xref>) personal history of VTE. The exclusion criteria were: (<xref ref-type="bibr" rid="B4">Duley, 2009</xref>): twin pregnancies; (<xref ref-type="bibr" rid="B6">Eskenazi et al., 1991</xref>); patients with a history of fetal death due to congenital malformations, Rh incompatibility, or infectious cause; (<xref ref-type="bibr" rid="B3">Duckitt and Harrington, 2005</xref>); IUGR which etiology was of chromosomal, genetic, or infectious origin; (<xref ref-type="bibr" rid="B17">Phipps et al., 2019</xref>); the presence of any PMC or VTE at inclusion.</p>
<p>All patients were included before 20&#xa0;weeks and gave their written consent. At inclusion, demographic data were collected by interview, physical examination, and consultation of the obstetrical medical record. Blood samples provided in the protocol were taken in complement to the conventional laboratory tests for the monitoring of pregnancy.</p>
</sec>
<sec id="s2-2">
<title>Blood collection</title>
<p>Blood samples were collected at the collection center of the University Hospital of Saint-&#xc9;tienne and N&#xee;mes at 20, 24, 28, 32, and 36&#xa0;weeks of gestation, totaling five samples per patient. The samples were immediately sent to laboratories for analysis, then centrifuged, aliquoted, and stored at &#x2212;80&#xb0;C. Each analysis was then performed blind to other analyses. All samples from the same patient were grouped in the same series of assays.</p>
</sec>
<sec id="s2-3">
<title>Biological analysis</title>
<p>The assays were carried out by the hematology laboratory of Saint-&#xc9;tienne University Hospital. The analyzes were carried out after thawing in a water bath at 37&#xb0;C., 10&#xa0;min. A sandwich-type enzyme-linked immunosorbent assay (ELISA) with the ASSERACHROM<sup>&#xae;</sup> D-DI kit (Diagnostica STAGO) was carried out for the determination of serum D-dimer level at 20, 24, 28, 32, and 36&#xa0;weeks.</p>
</sec>
<sec id="s2-4">
<title>Evaluation criteria</title>
<p>The primary outcome was the occurrence or recurrence of any PMC diagnosed according to the following criteria: (<xref ref-type="bibr" rid="B4">Duley, 2009</xref>): PE with or without IUGR. PE was defined according to the ISSHP (International Society for the Study of Hypertension in Pregnancy criteria) (<xref ref-type="bibr" rid="B23">Tranquilli et al., 2014</xref>). PE was diagnosed if a previously normotensive woman had new-onset hypertension (&#x3e;140&#xa0;mmHg systolic or &#x3e;90&#xa0;mmHg diastolic) after 20&#xa0;weeks of gestation associated with proteinuria (spot urine protein/creatinine &#x3e;30&#xa0;mg/mmol [0.3&#xa0;mg/mg] or &#x3e;300&#xa0;mg/day or at least 1&#xa0;g/L [&#x2018;2 &#x2b; &#x2019;] on dipstick testing) or other maternal organ dysfunction (renal insufficiency, liver involvement, neurological complications, hematological complications); (<xref ref-type="bibr" rid="B6">Eskenazi et al., 1991</xref>); IUGR without PE defined by a birthweight &#x2264; to the 10th centile (According to the AUDIPOG formula) with umbilical Doppler abnormalities. This formula calculates the exact percentile of birth weight from gestational age at birth, sex, and birth weight (<xref ref-type="bibr" rid="B14">Mamelle et al., 1996</xref>).</p>
<p>The secondary outcomes were: (<xref ref-type="bibr" rid="B4">Duley, 2009</xref>): the occurrence or recurrence of a PE with our without IUGR as defined just before; (<xref ref-type="bibr" rid="B6">Eskenazi et al., 1991</xref>); the occurrence of early PE (&#x3c;34&#xa0;weeks) and late PE (&#x2265;34&#xa0;weeks).</p>
</sec>
<sec id="s2-5">
<title>Statistical analysis</title>
<p>Statistical analyses were performed using XlSTAT<sup>&#xae;</sup>. Qualitative data were presented as absolute and relative frequencies (expressed in %). The qualitative variables were compared by the Chi-square test or by Fisher&#x2019;s exact test if the numbers were insufficient. Quantitative variables were described by mean and standard deviation, and median and interquartile range and were compared by Student&#x2019;s <italic>t</italic>-test. In the case of a non-normally distributed variable (assessed by Shapiro&#x2212;Wilk test), a Wilcoxon-Mann&#x2212;Whitney test was performed. For comparison of D-dimer level at each gestational age and for comparison between patients with PE, with IUGR, and uncomplicated patients, group differences were assessed using the Kruskal-Wallis test. As distribution was skewed, a Dunn <italic>post hoc</italic> test was assessed for differences between the two groups. Results were reported as boxplots. All hypothesis tests were performed at the 0.05 significance level, so <italic>p</italic> &#x3c; 0.05 was considered significant.</p>
</sec>
<sec id="s2-6">
<title>Ethics</title>
<p>The Ethics Committee and Institutional Review Board of the University Hospital of Saint-&#xc9;tienne approved the protocol in March 2008. The study is registered with the <ext-link ext-link-type="uri" xlink:href="http://ClinicalTrials.gov">ClinicalTrials.gov</ext-link> (identifier NCT00695942). The clinical investigation was performed according to the Helsinki Declaration of 1975, as revised in 1996. All women had given their informed consent to participate.</p>
</sec>
</sec>
<sec sec-type="results" id="s3">
<title>Results</title>
<sec id="s3-1">
<title>Clinical characteristics</title>
<p>Between June 2008 and October 2010, 200 pregnant women were included in the study. Demographic data and inclusion criteria are summarized in <xref ref-type="table" rid="T1">Table 1</xref>. History of PMC concerned 69.95% of the study population. During the study, 45 patients had a PMC. PE occurred in 24 patients, including 9 with IUGR. Nine patients presented an early PE &#x3c; 34&#xa0;weeks and 15 a late PE &#x2265; 34&#xa0;weeks. Conversely, there was a significant difference between the two groups for chronic hypertension and personal history of PVP (<italic>p</italic> &#x3c; 0.05; <xref ref-type="table" rid="T1">Table 1</xref>). The patients with PMC experienced more chronic hypertension and had more PMC history compared to uncomplicated. Other demographic characteristics and inclusion criteria were not different between the groups. For all population, the level of D-dimer increases throughout pregnancy, with the highest levels at the end of gestation (<xref ref-type="fig" rid="F1">Figure 1</xref>).</p>
<table-wrap id="T1" position="float">
<label>TABLE 1</label>
<caption>
<p>Patient characteristics at inclusion.</p>
</caption>
<table>
<thead valign="top">
<tr>
<th align="left"/>
<th align="left">Total 200 patients</th>
<th align="left">PMC 45 patients</th>
<th align="left">Uncomplicated 155 patients</th>
<th align="left">
<italic>p</italic>-Value</th>
</tr>
</thead>
<tbody valign="top">
<tr>
<td colspan="5" align="left">Maternal characteristics</td>
</tr>
<tr>
<td align="left">Age, years, mean (SD)</td>
<td align="center">31.8 (5.0)</td>
<td align="center">31.4 (5.1)</td>
<td align="center">31.9 (5.0)</td>
<td align="center">0.62</td>
</tr>
<tr>
<td align="left">Gestity, mean (SD)</td>
<td align="center">2.9 (1.9)</td>
<td align="center">2.9 (2.0)</td>
<td align="center">2.9 (1.9)</td>
<td align="center">0.80</td>
</tr>
<tr>
<td align="left">Parity, mean (SD)</td>
<td align="center">1.2 (0.9)</td>
<td align="center">1.3 (0.8)</td>
<td align="center">1.2 (1.0)</td>
<td align="center">0.59</td>
</tr>
<tr>
<td align="left">BMI, kg/m<sup>2</sup>, mean (SD)</td>
<td align="center">25.4 (6.3)</td>
<td align="center">26.1 (6.3)</td>
<td align="center">25.2 (6.3)</td>
<td align="center">0.26</td>
</tr>
<tr>
<td align="left">BMI&#x3e;30 (kg/m<sup>2</sup>)</td>
<td align="center">37 (19.4)</td>
<td align="center">9 (21.4)</td>
<td align="center">28 (18.8)</td>
<td align="center">0.70</td>
</tr>
<tr>
<td align="left">Smoking, n (%)</td>
<td align="center">26 (13.4)</td>
<td align="center">7 (15.6)</td>
<td align="center">19 (12.8)</td>
<td align="center">0.63</td>
</tr>
<tr>
<td align="left">Diabetes, n (%)</td>
<td align="center">8 (4.1)</td>
<td align="center">3 (6.7)</td>
<td align="center">5 (3.3)</td>
<td align="center">0.32</td>
</tr>
<tr>
<td align="left">Kidney disease, n (%)</td>
<td align="center">5 (2.6)</td>
<td align="center">2 (4.4)</td>
<td align="center">3 (2.0)</td>
<td align="center">0.36</td>
</tr>
<tr>
<td align="left">Hypertension, n (%)</td>
<td align="center">18 (9.2)</td>
<td align="center">10 (22.2)</td>
<td align="center">8 (5.3)</td>
<td align="center">0.001</td>
</tr>
<tr>
<td align="left">Lupus, n (%)</td>
<td align="center">15 (7.7)</td>
<td align="center">2 (4.4)</td>
<td align="center">13 (8.6)</td>
<td align="center">0.36</td>
</tr>
<tr>
<td align="left">Antiphospholipid Syndrome, n (%)</td>
<td align="center">6 (3.1)</td>
<td align="center">1 (2.2)</td>
<td align="center">5 (3.3)</td>
<td align="center">0.70</td>
</tr>
<tr>
<td align="left">Personal history of VTE, n (%)</td>
<td align="center">38 (19.3)</td>
<td align="center">7 (15.6)</td>
<td align="center">31 (20.4)</td>
<td align="center">0.47</td>
</tr>
<tr>
<td align="left">Personal history of PMC, n (%)</td>
<td align="center">135 (68.9)</td>
<td align="center">38 (84.4)</td>
<td align="center">97 (64.2)</td>
<td align="center">0.01</td>
</tr>
<tr>
<td align="left">Familial history of cardiovascular disease or VTE, n (%)</td>
<td align="center">39 (19.9)</td>
<td align="center">6 (13.3)</td>
<td align="center">33 (21.9)</td>
<td align="center">0.21</td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<fn>
<p>Categorical variables reported as frequency (percentage) and continuous variables reported as mean &#xb1; standard deviation. Abbreviations: BMI, body mass index; VTE, venous thromboembolism; PMC, Placenta-mediated complication.</p>
</fn>
</table-wrap-foot>
</table-wrap>
<fig id="F1" position="float">
<label>FIGURE 1</label>
<caption>
<p>Evolution of D-dimer levels during pregnancy for all population. The central horizontal bars are the medians. The lower and upper limits of the boxes are the first and third quartiles. &#x2a;<italic>p</italic>-value &#x3c; .05; &#x2a;&#x2a;<italic>p</italic>-value &#x3c; .001.</p>
</caption>
<graphic xlink:href="fcell-11-1115622-g001.tif"/>
</fig>
</sec>
<sec id="s3-2">
<title>Relationship between D-dimer levels and the occurrence of placenta-mediated complications</title>
<p>D-dimer levels were not different between uncomplicated <italic>versus</italic> PMC patients at each gestational age. Results are reported in <xref ref-type="fig" rid="F2">Figure 2</xref>.</p>
<fig id="F2" position="float">
<label>FIGURE 2</label>
<caption>
<p>Evolution of D-dimer levels during pregnancy depending on the occurrence of PMC. The central horizontal bars are the medians. The lower and upper limits of the boxes are the first and third quartiles. PMC: placenta-mediated complication.</p>
</caption>
<graphic xlink:href="fcell-11-1115622-g002.tif"/>
</fig>
</sec>
<sec id="s3-3">
<title>Relationship between D-dimer levels and the occurrence of preeclampsia and IUGR</title>
<p>D-dimer levels were not different in patients with preeclampsia <italic>versus</italic> uncomplicated patients at 28, 32 and 36&#xa0;weeks (1146.3 <italic>versus</italic> 957.5&#xa0;ng/ml <italic>p</italic> &#x3d; 0.48, 1367 <italic>versus</italic> 1167.9&#xa0;ng/ml 0.31, and 1952 <italic>versus</italic> 1426.94&#xa0;ng/ml 0.13 respectively). Patients with IUGR had identical serum D-dimer levels than uncomplicated patients. Results are summarized in <xref ref-type="fig" rid="F3">Figure 3</xref>.</p>
<fig id="F3" position="float">
<label>FIGURE 3</label>
<caption>
<p>D-dimer levels at each gestational age for patients with PE, IUGR and uncomplicated patients. The central horizontal bars are the medians. The lower and upper limits of the boxes are the first and third quartiles. PMC: placenta-mediated complication.</p>
</caption>
<graphic xlink:href="fcell-11-1115622-g003.tif"/>
</fig>
</sec>
<sec id="s3-4">
<title>Relationship between D-dimer levels and the occurrence of early and late placenta-mediated complications</title>
<p>Serum D-dimer levels were not different in patients with early preeclampsia <italic>versus</italic> uncomplicated patients at 28 and 32&#xa0;weeks (1725.7 <italic>versus</italic> 957.5&#xa0;ng/ml <italic>p</italic> &#x3d; 0.28 and 2353.5 <italic>versus</italic> 1167.9&#xa0;ng/ml <italic>p</italic> &#x3d; 0.16 respectively). Patients with late preeclampsia had identical serum D-dimer levels than uncomplicated patients at 36&#xa0;weeks (1952 <italic>versus</italic> 1426.9&#xa0;ng/ml <italic>p</italic> &#x3d; .08). Results are summarized in <xref ref-type="fig" rid="F4">Figure 4</xref>.</p>
<fig id="F4" position="float">
<label>FIGURE 4</label>
<caption>
<p>D-dimer levels at each gestational age for patients with early and late PE and for uncomplicated patients. The central horizontal bars are the medians. The lower and upper limits of the boxes are the first and third quartiles. PMC: placenta-mediated complication.</p>
</caption>
<graphic xlink:href="fcell-11-1115622-g004.tif"/>
</fig>
</sec>
</sec>
<sec sec-type="discussion" id="s4">
<title>Discussion</title>
<p>The level of D-dimer increases throughout pregnancy, with the highest levels at the end of gestation. D-dimer level was not predictive of the PMC occurrence. D-dimer levels could be interesting for the prediction of PE, especially for early PE.</p>
<p>Several authors have studied the evolution of D-dimer levels during pregnancy and in the <italic>postpartum</italic> period and have revealed a gradual increase in the concentration according to gestational age, a conclusion identical to ours. The percentage of patients above the reference threshold of D-dimer (500&#xa0;ng/ml) for each trimester was 15% in the first, 71% in the second, and 96% of women in the third trimester (<xref ref-type="bibr" rid="B24">Wang et al., 2013</xref>).</p>
<p>Three studies with a small number of patients proposed a longitudinal follow-up of D-dimer level throughout pregnancy in a high-risk population. Two studies found no difference in D-dimer level between patients who developed a PE and uncomplicated patients (REF). One study investigated the dosage of D-dimer during pregnancy in patients with a history of PE (<xref ref-type="bibr" rid="B11">Higgins et al., 1998</xref>; <xref ref-type="bibr" rid="B8">Hale et al., 2012</xref>). One study found an increasing evolution of D-dimer throughout pregnancy, but retained two important periods. Between 12 and 19&#xa0;weeks, the D-dimer rate was markedly lower in patients in the PE group. Then rapid increase in D-dimer with a peak at 30&#x2013;34&#xa0;weeks where the rate of D-dimer was significantly higher in the group of PE patients. We found the same results in the third trimester, but we only assessed D-dimer from 20&#xa0;weeks and did not have early dosing in the first trimester.</p>
<p>Several authors have studied D-dimer in patients at the time of PE. A meta-analysis in 2012 highlighted a possible diagnostic role for D-dimer level in preeclampsia, particularly in the third trimester of pregnancy (<xref ref-type="bibr" rid="B2">de Barros Pinheiro et al., 2012</xref>). On seven studies comparing the rate of D-dimer in PE and normal pregnancies, five studies found a slightly higher rate of D-dimer than in controls, while the other two showed no difference.</p>
<p>D-dimer levels have also been studied to predict the severity of PE. When D-dimer dosage was performed at the time of PE, D-dimer level was increased for patients with severe PE compared to moderate PE (<xref ref-type="bibr" rid="B18">Pinheiro et al., 2014</xref>; <xref ref-type="bibr" rid="B1">Baboolall et al., 2019</xref>). The dosage of D-dimer appears to be more relevant when PE occurs, with a low predictive value. This result suggests that the D-dimer level is a consequence of PMC and not of a modification preceding its occurrence.</p>
<p>PE is a condition associated with a noticeable exacerbation of hypercoagulation status compared to a normal pregnancy (<xref ref-type="bibr" rid="B8">Hale et al., 2012</xref>; <xref ref-type="bibr" rid="B18">Pinheiro et al., 2014</xref>). Although the pathogenesis of PE is not fully understood, the activation of inflammatory cytokines and coagulation pathways play a central role. It has been documented that in PE, endothelial dysfunction leads to an increase in tissue plasminogen activator (tPA) and plasminogen activator inhibitor type 1 (PAI-1), with a clear result of hypercoagulability and fibrinolysis (<xref ref-type="bibr" rid="B5">Dusse et al., 2011</xref>; <xref ref-type="bibr" rid="B12">Ismail and Higgins, 2011</xref>). However, as a manifestation of placental insufficiency, PAI-2, which plays a local role in placental function during pregnancy, is more diminished in severe PE (19,21). Thus, in severe PE, a lower concentration of PAI-2 upregulates the fibrinolytic system, leading to a higher circulating D-dimer level. The high concentration of D-dimer in severe PE is the result of an exaggerated hypercoagulable state and continuous fibrinolysis. This correlates with the concept of the pathophysiology of PE, according to which the formation of microthrombi and excessive deposition of D-dimer affecting several maternal organs as well as the placenta. The result is a placental hypoperfusion and therefore is responsible for complications of PE. Abnormalities in hemostasis appear to be a consequence of PMCs. The origin of PMC based on in genetics factors, pre-existing factors and immunological factors (<xref ref-type="bibr" rid="B17">Phipps et al., 2019</xref>).</p>
<p>The strength of the study is the examination of a population of patients at high risk of PMC who were recruited prospectively and followed from 20&#xa0;weeks to delivery. A limit is to not have a control group of pregnant women at low risk without PMC risk factor.</p>
<p>D-dimer level does not predict the onset of PMC. An increase in the D-dimer level in pregnant women was found in relation to gestational age. Changes in hemostasis appear to occur late in PE onset without knowing whether they are the cause or the consequence of the event. The D-dimer level was more interesting to predict the severity at the time of the onset of PE or IUGR. This corroborates the fact that the origin of PMCs based more on immunity than in hemostasis.</p>
</sec>
</body>
<back>
<sec sec-type="data-availability" id="s5">
<title>Data availability statement</title>
<p>The raw data supporting the conclusion of this article will be made available by the authors, without undue reservation.</p>
</sec>
<sec id="s6">
<title>Ethics statement</title>
<p>The studies involving human participants were reviewed and approved by Ethics Committee and Institutional Review Board of the University Hospital of Saint-&#xc9;tienne approved the protocol in March 2008. The study is registered with the ClinicalTrials.gov (identifier NCT00695942). The patients/participants provided their written informed consent to participate in this study.</p>
</sec>
<sec id="s7">
<title>Author contributions</title>
<p>AH and TR-B wrote the main manuscript text. AH, CG, and TR-B did the analysis of the data. CC, FR, and BT contributions to the conception and design of the work. J-CG and AG revised the work. All authors reviewed the manuscript.</p>
</sec>
<sec id="s8">
<title>Funding</title>
<p>The study was sponsored by the Saint Etienne university hospital and was supported by a grant from the local call for tender 2009.</p>
</sec>
<sec sec-type="COI-statement" id="s9">
<title>Conflict of interest</title>
<p>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.</p>
</sec>
<sec sec-type="disclaimer" id="s10">
<title>Publisher&#x2019;s note</title>
<p>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 guaranteed or endorsed by the publisher.</p>
</sec>
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