Risk factors for blood transfusion during cesarean section in women with major placenta previa

Risk factors for blood transfusion during cesarean section in women with major placenta previa | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Risk factors for blood transfusion during cesarean section in women with major placenta previa Evgeni Baev, Karin Roth, Jana Nagel, Janine Krämer, Ralf Dittrich, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6813541/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 03 Jan, 2026 Read the published version in Scientific Reports → Version 1 posted 11 You are reading this latest preprint version Abstract Purpose The aim of this study was to evaluate risk factors for blood transfusion during cesarean section in women with major placenta previa. Methods A retrospective single-center cohort study was conducted, including 110 women treated in the tertiary-care Department of Obstetrics and Gynecology at Karlsruhe Municipal Hospital from January 2014 till December 2021 who underwent cesarean section due to major placenta previa as defined in the new classification. The patients were divided into two groups: those who received a blood transfusion and those who did not. The two groups were compared to identify potential risk factors for blood transfusion. Results No remarkable differences between the two groups relative to the need for blood transfusion were seen after an analysis of six risk factors — maternal age, gestational age at delivery, indication for cesarean section, antepartum bleeding, use of assisted reproductive technology, and a history of previous curettage. A patient history including a previous cesarean section was the only statistically significant risk factor for blood transfusion in patients with major placenta previa. Conclusion A medical history including a previous cesarean section was the only independent statistically significant risk factor for blood transfusion in women with major placenta previa. This should be taken into account when cesarean sections are carried out in women with major placenta previa. Health sciences/Health care Health sciences/Risk factors Health sciences/Medical research/Outcomes research Placenta previa Cesarean section Blood transfusion Figures Figure 1 Introduction Placenta previa is one of the most demanding obstetric conditions and may have devastating consequences for both the fetus and the mother, resulting in catastrophic blood loss that requires a cesarean hysterectomy and massive blood transfusion. The prevalence of placenta previa is estimated to be 0.4–0.5%, with very large regional differences across the globe [ 1 , 2 ]. The number of women with placenta previa has been rising drastically, alongside the increasing numbers of cesarean deliveries in recent years all over the world. In a prospective study covering a 19-year period, Kollmann et al. reported that the incidence of placenta previa increased by 50% [ 3 ]. In general, placenta previa is defined as ultrasound evidence of placental tissue lying over or adjacent to the internal cervical os beyond 20 weeks of gestation [ 4 ]. Almost 90% of cases of placenta previa resolve before term, due to the so-called “migration” of the placenta away from the cervix, a phenomenon also known as trophotropism [ 5 ]. In September 2018, a working group of the American Institute of Ultrasound in Medicine (AIUM) made a widely accepted suggestion that the use of the terms “partial,” “marginal,” and “total” should be abandoned, so that the term “placenta previa” is now only used when the placenta is lying directly over the internal cervical os [ 6 , 7 ]. Historically, descriptions of the relationship between the lower placental edge and the internal cervical os were used to classify placenta previa into “low-lying” (when the distance between the lower placental edge is ≤ 2 cm from, but not over, the internal cervical os); “marginal” (when it reaches the internal cervical os but does not cover it); “partial” (when it covers a substantial area but not the whole surface of the internal cervical os); and “total” (when the internal cervical os is completely covered by placental tissue). Low-lying and marginal placenta previa were classified as “minor,” on the one hand, and partial and total placenta previa were classified as “major” on the other [ 2 , 8 ]. The purpose of the new classification is to provide better stratification of the risk factors for placenta previa in order to improve the management of the patients concerned. Major and minor risk factors have been associated with a higher probability of blood transfusion and maternal morbidity in patients with placenta previa [ 3 , 9 , 10 ]. The two most important major risk factors for the occurrence of placenta previa are previous placenta previa and previous cesarean delivery, due to a combination of endometrial damage and uterine scarring [ 2 , 9 – 11 ]. Minor risk factors are considered to include a history of uterine surgical procedures, increasing parity and increasing maternal age, infertility treatment, maternal smoking and cocaine use, male fetus, prior uterine artery embolization, endometriosis, and either spontaneous or induced abortion [ 2 , 9 , 10 ]. Most previous studies on hemorrhage in patients with placenta previa have included very heterogeneous groups of patients and have covered the whole range of minor and major forms of placenta previa as defined in the older classification [ 2 , 9 , 11 – 17 ]. The aim of the present study was to evaluate risk factors for blood transfusion during cesarean section in women with major placenta previa. Patients and methods This retrospective cohort study analyzed all women with placenta previa who underwent a cesarean section in Karlsruhe Municipal Hospital between 2014 and 2021. The women were identified using International Classification of Diseases (ICD) diagnostic codes O44.00 and O44.01 (placenta previa without bleeding), O44.11 and O44.10 (placenta previa with bleeding). On the basis of the new classification, it was decided to exclude women with low-lying placenta and marginal placenta previa — termed “minor placenta previa” in the new classification — and to focus only on women with major placenta previa pregnancies, in order to obtain a more nuanced assessment of maternal hemorrhage and risk factors for needing a blood transfusion during cesarean section. The women were divided into two groups: those who received transfusions of packed red blood cells during the cesarean procedure or before discharge from the hospital, and those who did not receive blood transfusions. The preoperative ultrasound findings and the patients’ histories were analyzed using the complete patient chart to identify possible risk factors for needing a blood transfusion. Figure 1 shows the patient selection process. This study was approved by the Institutional Review Board (IRB) at the Karlsruhe Institute of Technology (KIT) ,"Ethics Committee of KIT. All methods were performed in strict accordance with the relevant guidelines and regulations of conducting a retrospective observational study of clinical practice in Germany. Ethical approval was not sought because it was waived by the Institutional Review Board (IRB) at the Karlsruhe Institute of Technology (KIT) ,"Ethics Committee of KIT, because of the retrospective nature of this study. Informed consent is not required according to the Institutional Review Board (IRB) at the Karlsruhe Institute of Technology (KIT) ,"Ethics Committee of KIT, as the published information is anonymized and does not contain any images that could identify an individual. Statistical analysis Continuous data were summarized as means with standard deviation. Categorical data were summarized as frequencies and percentages. The primary study aim was to identify risk factors for a blood transfusion in patients with placenta previa. For this purpose, the study population was divided into two groups: those who received a blood transfusion and those who did not. Potential risk factors in the two groups of patients were compared using an appropriate two-sided statistical test, with significance set at α = 0.05. Student’s t -tests were used for continuous characteristics (age, gestational week of the cesarean section). Chi-square tests or Fisher’s exact tests were used for categorical characteristics (elective cesarean section, antepartum bleeding, previous cesarean section, assisted reproductive technology, previous curettage — each binary: yes/no). The chi-square test was used when all expected frequencies were greater than five, and Fisher’s exact test was used otherwise. The P values for the statistical tests were corrected using the Bonferroni–Holm method to take the problem of multiple testing into account. This means that a risk factor with a corrected P value of less than 0.05 is considered significant. Calculations were carried out using the R system for statistical computing (version 4.3.0; R Development Core Team, Vienna, Austria, 2023). Data availability The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request. Results The study included 110 patients with major placenta previa as defined in the new classification who underwent cesarean sections. The patient characteristics are shown in Table 1. Twenty of the women received a blood transfusion and 90 did not, representing a transfusion rate of 18.18%. A mean of 1.2 units of packed red blood cells were transfused, with a minimum of 1 unit and a maximum of 18. Table 2 shows the comparison between patients who received a blood transfusion and those who did not, relative to potential risk factors. No significant differences between the two groups were observed with regard to nonmodifiable clinical factors such as maternal age, gestational week at delivery, the indication for cesarean section (elective or urgent), the occurrence of antepartum bleeding, a history of previous curettage, or the use of assisted reproductive technology (ART). The proportion of patients with a previous cesarean section was larger in patients who received a blood transfusion (10 of 20 patients, 50%) than in those who did not (16 of 90 patients, 17.8%), and was the only significant risk factor, especially after multiple testing. A cesarean hysterectomy was necessary in 11 women, 10 of whom had a histologically confirmed placenta increta. Eight of these 10 patients also received blood transfusions, representing a transfusion rate of 80%, while two did not require transfusions. The transfusion rate was 18% overall, while in patients with a previous cesarean section it was 50% and in those with placenta increta it was 80%. Discussion Cesarean section is the most common obstetric operation worldwide. Various modifications of the surgical techniques used have been introduced over time [ 18 , 19 ]. Cesarean section is the only possible delivery mode for pregnant women who present with major placenta previa as defined in the new classification, which distinguishes between major placenta previa (when the placenta overlaps the internal os of the cervix) and minor placenta previa (when the placenta is in the lower uterine segment near the internal os of the cervix, but not overlapping it) [ 6 , 7 ]. The correlation between cesarean delivery in these women and the need for blood transfusions has always been of medical interest, as it is associated with a high risk for blood transfusions during the peripartum period [ 20 ]. Various studies have also shown that a previous cesarean birth increases the risk for placenta previa and that increasing numbers of cesarean births are associated with further increases in the risk [ 11 , 12 , 21 – 23 ]. In a retrospective study of 514 patients who underwent cesarean deliveries due to placenta previa, Fox et al. reported that placenta previa —observed in 58% of the patients — was the most significant risk factor for transfusion [ 24 ]. In another study of primary cesarean births for placenta previa, the probability of blood transfusion was increased nearly fourfold and the likelihood of hysterectomy more than fivefold in comparison with no placenta previa at cesarean section [ 25 ]. The risk of blood transfusion becomes especially high in patients who have both placenta previa and placenta increta [ 21 , 26 , 27 ]. This was also seen in the present analysis, with the highest transfusion rates in these women. It was deliberately decided not to exclude patients with placenta increta, as it is well known that placenta increta remains undiagnosed antepartum in 50–65% of all cases [ 28 , 29 ]. The present study confirms published data showing that a previous cesarean section is a crucial independent risk factor for the incidence of blood transfusion in these patients [ 13 – 16 ]. By contrast, data reported by Oya et al. did not show any correlation between a previous cesarean section and the need for blood transfusion [ 17 ]. A possible explanation for this discrepancy might be the fact that 65 of the 129 patients (50.4%) included in the study by Oya et al. had marginal placenta previa, also known as minor placenta previa, and these patients were excluded from the present analysis. Women with minor placenta previa were excluded because a systematic review of 11 studies including 600 patients showed that an increasing rate of emergency cesarean sections was associated with a reduction of the distance between the placental edge and the internal cervical os from 10–45%. However, the data did not show any differences in the blood transfusion rate or postpartum hemorrhage among these women [ 30 ]. In a retrospective study including 2210 patients, Chua et al. estimated that the risk of blood transfusion in elective versus emergency cesarean sections was 3.9 per 1000 and 9.8 per 1000, respectively. The authors’ suggested explanations for this were the absence of an experienced multidisciplinary team, limited institutional resources, standard of care protocols that were poor or absent, and the presence of massive hemorrhage before the start of the operation [ 31 ]. In the present study, however, no differences in the blood transfusion rate were observed relative to whether the cesarean section was elective or urgent. Nor were any differences noted between women with or without antepartum bleeding, although the majority of women in both groups presented with antepartum bleeding. In contrast, Titapant and Chongsomboonsuk reported that the majority of women with preoperative and perioperative bleeding also had a need for blood transfusion. However, the authors did not distinguish between women with major and minor placenta previa [ 16 ]. The Society for Maternal-Fetal Medicine, in agreement with the American College of Obstetricians and Gynecologists, has proposed leaving a wide gap of 2 weeks (36 + 0 to 37 + 6 gestational weeks) for cesarean section in pregnancies with uncomplicated placenta previa [ 32 ]. Oya et al. found that gestational age did not correlate with the incidence of blood transfusions [ 17 ]. However, Boyle et al. reported that delivery at a gestational age of 32–35 weeks was a predictor of the need for blood transfusion during cesarean section in women with placenta previa [ 15 ]. This might have been due to the wide heterogeneity among the patients included in the study by Boyle et al., with all types of placenta previa pregnancies and a large number of patients (n = 246). In the present study, although the gestational age at the time of the cesarean section in patients who received blood transfusions was earlier (32 + 2 gestational weeks) than among those who did not receive blood transfusions (33 + 6 gestational weeks), this was only a trend and did not reach the level of significance. Ohkuchi et al. were among the first to note that a maternal age of ≥ 35 years is an independent risk factor for excessive blood loss both during both vaginal and cesarean delivery, irrespective of additional risk factors [ 33 ]. The combination of placenta previa and advanced maternal age (≥ 35 years) was associated with a maternal blood loss of 1500 mL [ 33 ]. Oya et al. also investigated this relationship and found that, in their group of 129 patients with placenta previa, advanced maternal age was a risk factor for blood transfusion [ 17 ]. However, it should be noted that only 64 of the 129 patients included had major placenta previa as defined in the new classification. In addition, the general transfusion rate of 33% in the study was quite high and differed widely from the rate of 18% in the present study. A similar transfusion rate was reported by Titapant and Chongsomboonsuk, and maternal age was also not a significant risk factor for blood transfusion in their study [ 16 ]. ART may be risk factor for risk of placenta previa, but the risk of hemorrhage during cesarean section is unknown, as various risk factors are associated with infertility itself [ 33 – 35 ]. Intrauterine surgical procedures such as curettage may increase the risk of developing an abnormal, invasive placenta [ 36 ]. Oya et al. reported that curettage was an independent variable for the perioperative need for blood transfusion [ 17 ]. However, no significant differences were observed in the present study. Conclusions This study found that only a medical history including a previous cesarean section was an independent statistically significant variable associated with an increased risk of blood transfusion in women with placenta previa and cesarean section. One strength of the study is its highly selected group of patients, clearly defined as including only women with major placenta previa as defined in the new classification. The limitations of the study lie in its retrospective nature and the small number of patients included. Strategies for preventing massive bleeding from placenta previa during cesarean section vary depending on the surgeon’s level of experience and local institutional resources. To the best of our knowledge, there have been no prospective randomized trials directly comparing different intraoperative strategies for reducing blood loss in the cases of life-threatening hemorrhage during cesarean section. The key to reducing obstetric hemorrhage and the need for blood transfusion in patients with placenta previa may lie in identifying patients who are at risk at an early stage and planning an interdisciplinary approach at the time of delivery. Declarations Acknowledgments The present study was performed in fulfillment of the requirements for obtaining the degree of “Dr. med.” The research published here has been used for E. Baev’s doctoral thesis in the Medical Faculty of Friedrich Alexander University of Erlangen–Nuremberg (FAU). Author contributions EB: data collection, data management, data analysis, manuscript writing, manuscript editing. KR: project development. JN: project development. JK: data management. LH: data analysis. RD: manuscript editing. AM: project development, manuscript editing. Funding This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors . Data availability The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request. Declarations Conflict of interest The authors declare that they have no conflicts of interest. The authors have no relevant financial or nonfinancial interests to disclose. Ethical approval Ethical approval was not sought, as this was a retrospective observational study of clinical practice. Informed consent Not applicable. Consent is not required, as the published information is anonymized and does not contain any images that could identify an individual. References Cresswell JA, Ronsmans C, Calvert C, Filippi V (2013) Prevalence of placenta praevia by world region: a systematic review and meta-analysis. Trop Med Int Health 18:712–724. https://doi.org/10.1111/tmi.12100 Faiz AS, Ananth CV (2003) Etiology and risk factors for placenta previa: an overview and meta-analysis of observational studies. 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Patient characteristics, showing means and standard deviation (SD) or frequencies and percentages Characteristic Summary statistics Age (years) Mean (SD) 34.7 (4.8) Gestational week at cesarean section Mean (SD) 33.6 (3.5) Elective cesarean section No 62 (56.4) Yes 48 (43.6) Antepartum bleeding No 24 (21.8) Yes 86 (78.2) Previous cesarean section No 84 (76.4) Yes 26 (23.6) Assisted reproductive technology (ART) No 93 (84.5) Yes 17 (15.5) Previous curettage No 69 (62.7) Yes 41 (37.3) Table 2. Comparison between patients who received a blood transfusion and those who did not relative to possible risk factors, showing summary statistics (means and standard deviation or frequencies and percentages), with P values from statistical tests Characteristic Blood transfusion P value No (n = 90) Yes (n = 20) Raw Corrected a Age (years) Mean (SD) 34.8 (4.9) 34.6 (4.4) 0.890 1.000 Gestational week at cesarean section Mean (SD) 33.9 (3.2) 32.2 (4.3) 0.108 0.539 Elective cesarean section No 50 (55.6) 12 (60.0) 0.717 1.000 Yes 40 (44.4) 8 (40.0) Antepartum bleeding No 21 (23.3) 3 (15.0) 0.556 1.000 Yes 69 (76.7) 17 (85.0) Previous cesarean section No 74 (82.2) 10 (50.0) 0.007 0.049 Yes 16 (17.8) 10 (50.0) Assisted reproductive technology (ART) No 76 (84.4) 17 (85.0) 1.000 1.000 Yes 14 (15.6) 3 (15.0) Previous curettage No 61 (67.8) 8 (40.0) 0.020 0.120 Yes 29 (32.2) 12 (60.0) a Bonferroni–Holm correction. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 03 Jan, 2026 Read the published version in Scientific Reports → Version 1 posted Editorial decision: Revision requested 22 Aug, 2025 Reviews received at journal 22 Aug, 2025 Reviewers agreed at journal 04 Aug, 2025 Reviews received at journal 25 Jun, 2025 Reviewers agreed at journal 19 Jun, 2025 Reviewers agreed at journal 17 Jun, 2025 Reviewers invited by journal 17 Jun, 2025 Editor assigned by journal 17 Jun, 2025 Editor invited by journal 17 Jun, 2025 Submission checks completed at journal 16 Jun, 2025 First submitted to journal 03 Jun, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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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-6813541","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":473241635,"identity":"78ae104b-40c6-43ee-ab41-bfae2a845951","order_by":0,"name":"Evgeni Baev","email":"data:image/png;base64,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","orcid":"","institution":"Karlsruhe Municipal Hospital","correspondingAuthor":true,"prefix":"","firstName":"Evgeni","middleName":"","lastName":"Baev","suffix":""},{"id":473241636,"identity":"a6d64526-52f2-4da5-b64f-55f2099fede5","order_by":1,"name":"Karin Roth","email":"","orcid":"","institution":"Karlsruhe Municipal Hospital","correspondingAuthor":false,"prefix":"","firstName":"Karin","middleName":"","lastName":"Roth","suffix":""},{"id":473241637,"identity":"bb833298-25d3-48f4-a26b-17a67d60a9e2","order_by":2,"name":"Jana Nagel","email":"","orcid":"","institution":"Karlsruhe Municipal Hospital","correspondingAuthor":false,"prefix":"","firstName":"Jana","middleName":"","lastName":"Nagel","suffix":""},{"id":473241638,"identity":"98ac9bf2-4fbd-4ea3-b321-504ca7c03475","order_by":3,"name":"Janine Krämer","email":"","orcid":"","institution":"Karlsruhe Municipal Hospital","correspondingAuthor":false,"prefix":"","firstName":"Janine","middleName":"","lastName":"Krämer","suffix":""},{"id":473241639,"identity":"332dd821-bd9e-40fe-849a-7fd8ea42709a","order_by":4,"name":"Ralf Dittrich","email":"","orcid":"","institution":"Friedrich Alexander University of Erlangen–Nuremberg","correspondingAuthor":false,"prefix":"","firstName":"Ralf","middleName":"","lastName":"Dittrich","suffix":""},{"id":473241640,"identity":"583dccf2-3f77-4201-9ed4-ed0d923b935f","order_by":5,"name":"Lothar Häberle","email":"","orcid":"","institution":"Friedrich Alexander University of Erlangen–Nuremberg","correspondingAuthor":false,"prefix":"","firstName":"Lothar","middleName":"","lastName":"Häberle","suffix":""},{"id":473241641,"identity":"6b661592-82d7-4350-a025-e96a7acc0123","order_by":6,"name":"Andreas Müller","email":"","orcid":"","institution":"Karlsruhe Municipal Hospital","correspondingAuthor":false,"prefix":"","firstName":"Andreas","middleName":"","lastName":"Müller","suffix":""}],"badges":[],"createdAt":"2025-06-03 17:08:16","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6813541/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6813541/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1038/s41598-025-34425-1","type":"published","date":"2026-01-03T15:58:02+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":85172017,"identity":"698917ff-deb3-4329-8f57-de4228023d2c","added_by":"auto","created_at":"2025-06-23 05:49:01","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":21704,"visible":true,"origin":"","legend":"\u003cp\u003ePatient selection between 2014 and 2021. The analysis only included women with placenta previa major\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6813541/v1/a21891cee1e7db331f4c3b94.png"},{"id":99545529,"identity":"8976e897-8899-4ab3-9888-b94dd3e88cca","added_by":"auto","created_at":"2026-01-05 16:08:20","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":508172,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6813541/v1/ccbf1111-fa77-4dd4-b124-790d7d46452f.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Risk factors for blood transfusion during cesarean section in women with major placenta previa","fulltext":[{"header":"Introduction","content":"\u003cp\u003ePlacenta previa is one of the most demanding obstetric conditions and may have devastating consequences for both the fetus and the mother, resulting in catastrophic blood loss that requires a cesarean hysterectomy and massive blood transfusion. The prevalence of placenta previa is estimated to be 0.4\u0026ndash;0.5%, with very large regional differences across the globe [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. The number of women with placenta previa has been rising drastically, alongside the increasing numbers of cesarean deliveries in recent years all over the world. In a prospective study covering a 19-year period, Kollmann et al. reported that the incidence of placenta previa increased by 50% [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn general, placenta previa is defined as ultrasound evidence of placental tissue lying over or adjacent to the internal cervical os beyond 20 weeks of gestation [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Almost 90% of cases of placenta previa resolve before term, due to the so-called \u0026ldquo;migration\u0026rdquo; of the placenta away from the cervix, a phenomenon also known as trophotropism [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn September 2018, a working group of the American Institute of Ultrasound in Medicine (AIUM) made a widely accepted suggestion that the use of the terms \u0026ldquo;partial,\u0026rdquo; \u0026ldquo;marginal,\u0026rdquo; and \u0026ldquo;total\u0026rdquo; should be abandoned, so that the term \u0026ldquo;placenta previa\u0026rdquo; is now only used when the placenta is lying directly over the internal cervical os [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Historically, descriptions of the relationship between the lower placental edge and the internal cervical os were used to classify placenta previa into \u0026ldquo;low-lying\u0026rdquo; (when the distance between the lower placental edge is \u0026le;\u0026thinsp;2 cm from, but not over, the internal cervical os); \u0026ldquo;marginal\u0026rdquo; (when it reaches the internal cervical os but does not cover it); \u0026ldquo;partial\u0026rdquo; (when it covers a substantial area but not the whole surface of the internal cervical os); and \u0026ldquo;total\u0026rdquo; (when the internal cervical os is completely covered by placental tissue). Low-lying and marginal placenta previa were classified as \u0026ldquo;minor,\u0026rdquo; on the one hand, and partial and total placenta previa were classified as \u0026ldquo;major\u0026rdquo; on the other [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe purpose of the new classification is to provide better stratification of the risk factors for placenta previa in order to improve the management of the patients concerned. Major and minor risk factors have been associated with a higher probability of blood transfusion and maternal morbidity in patients with placenta previa [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. The two most important major risk factors for the occurrence of placenta previa are previous placenta previa and previous cesarean delivery, due to a combination of endometrial damage and uterine scarring [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan additionalcitationids=\"CR10\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Minor risk factors are considered to include a history of uterine surgical procedures, increasing parity and increasing maternal age, infertility treatment, maternal smoking and cocaine use, male fetus, prior uterine artery embolization, endometriosis, and either spontaneous or induced abortion [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Most previous studies on hemorrhage in patients with placenta previa have included very heterogeneous groups of patients and have covered the whole range of minor and major forms of placenta previa as defined in the older classification [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan additionalcitationids=\"CR12 CR13 CR14 CR15 CR16\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe aim of the present study was to evaluate risk factors for blood transfusion during cesarean section in women with major placenta previa.\u003c/p\u003e"},{"header":"Patients and methods","content":"\u003cp\u003eThis retrospective cohort study analyzed all women with placenta previa who underwent a cesarean section in Karlsruhe Municipal Hospital between 2014 and 2021. The women were identified using International Classification of Diseases (ICD) diagnostic codes O44.00 and O44.01 (placenta previa without bleeding), O44.11 and O44.10 (placenta previa with bleeding). On the basis of the new classification, it was decided to exclude women with low-lying placenta and marginal placenta previa — termed “minor placenta previa” in the new classification — and to focus only on women with major placenta previa pregnancies, in order to obtain a more nuanced assessment of maternal hemorrhage and risk factors for needing a blood transfusion during cesarean section. The women were divided into two groups: those who received transfusions of packed red blood cells during the cesarean procedure or before discharge from the hospital, and those who did not receive blood transfusions. The preoperative ultrasound findings and the patients’ histories were analyzed using the complete patient chart to identify possible risk factors for needing a blood transfusion. Figure 1 shows the patient selection process.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThis study was approved by the Institutional Review Board (IRB) at the Karlsruhe Institute of Technology (KIT) ,\"Ethics Committee of KIT. All methods were performed in strict accordance with the relevant guidelines and regulations of conducting a retrospective observational study of clinical practice in Germany.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eEthical approval was not sought because it was waived by the Institutional Review Board (IRB) at the Karlsruhe Institute of Technology (KIT) ,\"Ethics Committee of KIT, because of the retrospective nature of this study.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eInformed consent is not required according to the Institutional Review Board (IRB) at the Karlsruhe Institute of Technology (KIT) ,\"Ethics Committee of KIT, as the published information is anonymized and does not contain any images that could identify an individual.\u003c/p\u003e\n\u003ch2\u003eStatistical analysis\u003c/h2\u003e\n\u003cp\u003eContinuous data were summarized as means with standard deviation. Categorical data were summarized as frequencies and percentages. The primary study aim was to identify risk factors for a blood transfusion in patients with placenta previa. For this purpose, the study population was divided into two groups: those who received a blood transfusion and those who did not. Potential risk factors in the two groups of patients were compared using an appropriate two-sided statistical test, with significance set at\u0026nbsp;α\u0026nbsp;= 0.05. Student’s \u003cem\u003et\u003c/em\u003e-tests were used for continuous characteristics (age, gestational week of the cesarean section). Chi-square tests or Fisher’s exact tests were used for categorical characteristics (elective cesarean section, antepartum bleeding, previous cesarean section, assisted reproductive technology, previous curettage — each binary: yes/no). The\u0026nbsp;chi-square test was used when all expected frequencies were greater than five, and Fisher’s exact test was used otherwise. The \u003cem\u003eP\u003c/em\u003e values for the statistical tests were corrected using the Bonferroni–Holm method to take the problem of multiple testing into account. This means that a risk factor with a corrected \u003cem\u003eP\u003c/em\u003e value of less than 0.05 is considered significant. Calculations were carried out using the R system for statistical computing (version 4.3.0; R Development Core Team, Vienna, Austria, 2023).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eThe study included 110 patients with major placenta previa as defined in the new classification who underwent cesarean sections. The patient characteristics are shown in Table 1. Twenty of the women received a blood transfusion and 90 did not, representing a transfusion rate of 18.18%. A mean of 1.2 units of packed red blood cells were transfused, with a minimum of 1 unit and a maximum of 18. Table 2 shows the comparison between patients who received a blood transfusion and those who did not, relative to potential risk factors. No significant differences between the two groups were observed with regard to nonmodifiable clinical factors such as maternal age, gestational week at delivery, the indication for cesarean section (elective or urgent), the occurrence of antepartum bleeding, a history of previous curettage, or the use of assisted reproductive technology (ART). The proportion of patients with a previous cesarean section was larger in patients who received a blood transfusion (10 of 20 patients, 50%) than in those who did not (16 of 90 patients, 17.8%), and was the only significant risk factor, especially after multiple testing. A cesarean hysterectomy was necessary in 11 women, 10 of whom had a histologically confirmed placenta increta. Eight of these 10 patients also received blood transfusions, representing a transfusion rate of 80%, while two did not require transfusions. The transfusion rate was 18% overall, while in patients with a previous cesarean section it was 50% and in those with placenta increta it was 80%.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eCesarean section is the most common obstetric operation worldwide. Various modifications of the surgical techniques used have been introduced over time [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Cesarean section is the only possible delivery mode for pregnant women who present with major placenta previa as defined in the new classification, which distinguishes between major placenta previa (when the placenta overlaps the internal os of the cervix) and minor placenta previa (when the placenta is in the lower uterine segment near the internal os of the cervix, but not overlapping it) [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe correlation between cesarean delivery in these women and the need for blood transfusions has always been of medical interest, as it is associated with a high risk for blood transfusions during the peripartum period [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Various studies have also shown that a previous cesarean birth increases the risk for placenta previa and that increasing numbers of cesarean births are associated with further increases in the risk [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan additionalcitationids=\"CR22\" citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn a retrospective study of 514 patients who underwent cesarean deliveries due to placenta previa, Fox et al. reported that placenta previa \u0026mdash;observed in 58% of the patients \u0026mdash; was the most significant risk factor for transfusion [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn another study of primary cesarean births for placenta previa, the probability of blood transfusion was increased nearly fourfold and the likelihood of hysterectomy more than fivefold in comparison with no placenta previa at cesarean section [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. The risk of blood transfusion becomes especially high in patients who have both placenta previa and placenta increta [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. This was also seen in the present analysis, with the highest transfusion rates in these women. It was deliberately decided not to exclude patients with placenta increta, as it is well known that placenta increta remains undiagnosed antepartum in 50\u0026ndash;65% of all cases [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. The present study confirms published data showing that a previous cesarean section is a crucial independent risk factor for the incidence of blood transfusion in these patients [\u003cspan additionalcitationids=\"CR14 CR15\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. By contrast, data reported by Oya et al. did not show any correlation between a previous cesarean section and the need for blood transfusion [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. A possible explanation for this discrepancy might be the fact that 65 of the 129 patients (50.4%) included in the study by Oya et al. had marginal placenta previa, also known as minor placenta previa, and these patients were excluded from the present analysis.\u003c/p\u003e \u003cp\u003eWomen with minor placenta previa were excluded because a systematic review of 11 studies including 600 patients showed that an increasing rate of emergency cesarean sections was associated with a reduction of the distance between the placental edge and the internal cervical os from 10\u0026ndash;45%. However, the data did not show any differences in the blood transfusion rate or postpartum hemorrhage among these women [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn a retrospective study including 2210 patients, Chua et al. estimated that the risk of blood transfusion in elective versus emergency cesarean sections was 3.9 per 1000 and 9.8 per 1000, respectively. The authors\u0026rsquo; suggested explanations for this were the absence of an experienced multidisciplinary team, limited institutional resources, standard of care protocols that were poor or absent, and the presence of massive hemorrhage before the start of the operation [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. In the present study, however, no differences in the blood transfusion rate were observed relative to whether the cesarean section was elective or urgent. Nor were any differences noted between women with or without antepartum bleeding, although the majority of women in both groups presented with antepartum bleeding. In contrast, Titapant and Chongsomboonsuk reported that the majority of women with preoperative and perioperative bleeding also had a need for blood transfusion. However, the authors did not distinguish between women with major and minor placenta previa [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe Society for Maternal-Fetal Medicine, in agreement with the American College of Obstetricians and Gynecologists, has proposed leaving a wide gap of 2 weeks (36\u0026thinsp;+\u0026thinsp;0 to 37\u0026thinsp;+\u0026thinsp;6 gestational weeks) for cesarean section in pregnancies with uncomplicated placenta previa [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. Oya et al. found that gestational age did not correlate with the incidence of blood transfusions [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. However, Boyle et al. reported that delivery at a gestational age of 32\u0026ndash;35 weeks was a predictor of the need for blood transfusion during cesarean section in women with placenta previa [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. This might have been due to the wide heterogeneity among the patients included in the study by Boyle et al., with all types of placenta previa pregnancies and a large number of patients (n\u0026thinsp;=\u0026thinsp;246). In the present study, although the gestational age at the time of the cesarean section in patients who received blood transfusions was earlier (32\u0026thinsp;+\u0026thinsp;2 gestational weeks) than among those who did not receive blood transfusions (33\u0026thinsp;+\u0026thinsp;6 gestational weeks), this was only a trend and did not reach the level of significance.\u003c/p\u003e \u003cp\u003eOhkuchi et al. were among the first to note that a maternal age of \u0026ge;\u0026thinsp;35 years is an independent risk factor for excessive blood loss both during both vaginal and cesarean delivery, irrespective of additional risk factors [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. The combination of placenta previa and advanced maternal age (\u0026ge;\u0026thinsp;35 years) was associated with a maternal blood loss of 1500 mL [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. Oya et al. also investigated this relationship and found that, in their group of 129 patients with placenta previa, advanced maternal age was a risk factor for blood transfusion [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. However, it should be noted that only 64 of the 129 patients included had major placenta previa as defined in the new classification. In addition, the general transfusion rate of 33% in the study was quite high and differed widely from the rate of 18% in the present study. A similar transfusion rate was reported by Titapant and Chongsomboonsuk, and maternal age was also not a significant risk factor for blood transfusion in their study [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. ART may be risk factor for risk of placenta previa, but the risk of hemorrhage during cesarean section is unknown, as various risk factors are associated with infertility itself [\u003cspan additionalcitationids=\"CR34\" citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. Intrauterine surgical procedures such as curettage may increase the risk of developing an abnormal, invasive placenta [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. Oya et al. reported that curettage was an independent variable for the perioperative need for blood transfusion [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. However, no significant differences were observed in the present study.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThis study found that only a medical history including a previous cesarean section was an independent statistically significant variable associated with an increased risk of blood transfusion in women with placenta previa and cesarean section. One strength of the study is its highly selected group of patients, clearly defined as including only women with major placenta previa as defined in the new classification. The limitations of the study lie in its retrospective nature and the small number of patients included.\u003c/p\u003e \u003cp\u003eStrategies for preventing massive bleeding from placenta previa during cesarean section vary depending on the surgeon\u0026rsquo;s level of experience and local institutional resources. To the best of our knowledge, there have been no prospective randomized trials directly comparing different intraoperative strategies for reducing blood loss in the cases of life-threatening hemorrhage during cesarean section. The key to reducing obstetric hemorrhage and the need for blood transfusion in patients with placenta previa may lie in identifying patients who are at risk at an early stage and planning an interdisciplinary approach at the time of delivery.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe present study was performed in fulfillment of the requirements for obtaining the degree of \u0026ldquo;Dr. med.\u0026rdquo; The research published here has been used for E. Baev\u0026rsquo;s doctoral thesis in the Medical Faculty of Friedrich Alexander University of Erlangen\u0026ndash;Nuremberg (FAU).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u0026nbsp;\u003c/strong\u003eEB: data collection, data management, data analysis, manuscript writing, manuscript editing. KR: project development. JN: project development. JK: data management. LH: data analysis. RD: manuscript editing. AM: project development, manuscript editing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003eThis research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors\u003cstrong\u003e.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003eDeclarations\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no conflicts of interest. The authors have no relevant financial or nonfinancial interests to disclose.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical approval\u003c/strong\u003e\u0026emsp;Ethical approval was not sought, as this was a retrospective observational study of clinical practice.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eInformed consent\u003c/strong\u003e\u0026emsp;Not applicable. Consent is not required, as the published information is anonymized and does not contain any images that could identify an individual.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eCresswell JA, Ronsmans C, Calvert C, Filippi V (2013) Prevalence of placenta praevia by world region: a systematic review and meta-analysis. Trop Med Int Health 18:712\u0026ndash;724. https://doi.org/10.1111/tmi.12100\u003c/li\u003e\n\u003cli\u003eFaiz AS, Ananth CV (2003) Etiology and risk factors for placenta previa: an overview and meta-analysis of observational studies. J Matern Fetal Neonatal Med 13:175\u0026ndash;190. https://doi.org/10.1080/jmf.13.3.175.190\u003c/li\u003e\n\u003cli\u003eKollmann M, Gaulhofer J, Lang U, Klaritsch P (2016) Placenta praevia: incidence, risk factors and outcome. J Matern Fetal Neonatal Med 29:1395\u0026ndash;1398. https://doi.org/10.3109/14767058.2015.1049152\u003c/li\u003e\n\u003cli\u003eAnderson-Bagga FM, Sze A (2025) Placenta previa. In: StatPearls. StatPearls Publishing, Treasure Island (FL). Available at: http://www.ncbi.nlm.nih.gov/books/NBK539818/\u003c/li\u003e\n\u003cli\u003eOyelese Y (2009) Placenta previa: the evolving role of ultrasound. Ultrasound Obstet Gynecol 34:123\u0026ndash;126. https://doi.org/10.1002/uog.7312\u003c/li\u003e\n\u003cli\u003eJauniaux E, Alfirevic Z, Bhide AG, et al (2019) Placenta praevia and placenta accreta: diagnosis and management: Green-top Guideline No. 27a. BJOG 126:e1\u0026ndash;e48. https://doi.org/10.1111/1471-0528.15306\u003c/li\u003e\n\u003cli\u003eReddy UM, Abuhamad AZ, Levine D, Saade GR; Fetal Imaging Workshop Invited Participants (2014) Fetal imaging: executive summary of a joint Eunice Kennedy Shriver National Institute of Child Health and Human Development, Society for Maternal-Fetal Medicine, American Institute of Ultrasound in Medicine, American College of Obstetricians and Gynecologists, American College of Radiology, Society for Pediatric Radiology, and Society of Radiologists in Ultrasound Fetal Imaging Workshop. J Ultrasound Med 33:745\u0026ndash;757. https://doi.org/10.7863/ultra.33.5.745\u003c/li\u003e\n\u003cli\u003eThurmond A, Mendelson E, B\u0026ouml;hm-V\u0026eacute;lez M, et al (2000) Role of imaging in second and third trimester bleeding. American College of Radiology. ACR Appropriateness Criteria. Radiology 215 Suppl:895\u0026ndash;897\u003c/li\u003e\n\u003cli\u003eSilver RM, Landon MB, Rouse DJ, et al (2006) Maternal morbidity associated with multiple repeat cesarean deliveries. Obstet Gynecol 107:1226\u0026ndash;1232. https://doi.org/10.1097/01.AOG.0000219750.79480.84\u003c/li\u003e\n\u003cli\u003eDownes KL, Hinkle SN, Sjaarda LA, Albert PS, Grantz KL (2015) Previous prelabor or intrapartum cesarean delivery and risk of placenta previa. Am J Obstet Gynecol 212:669.e1\u0026ndash;6. https://doi.org/10.1016/j.ajog.2015.01.004\u003c/li\u003e\n\u003cli\u003eAnanth CV, Smulian JC, Vintzileos AM (1997) The association of placenta previa with history of cesarean delivery and abortion: a metaanalysis. Am J Obstet Gynecol 177:1071\u0026ndash;1078. https://doi.org/10.1016/s0002-9378(97)70017-6\u003c/li\u003e\n\u003cli\u003eKlar M, Michels KB (2014) Cesarean section and placental disorders in subsequent pregnancies\u0026mdash;a meta-analysis. J Perinat Med 42:571\u0026ndash;583. https://doi.org/10.1515/jpm-2013-0199\u003c/li\u003e\n\u003cli\u003eBaba Y, Ohkuchi A, Usui R, Suzuki H, Kuwata T, Matsubara S (2015) Calculating probability of requiring allogeneic blood transfusion using three preoperative risk factors on cesarean section for placenta previa. Arch Gynecol Obstet 291:281\u0026ndash;285. https://doi.org/10.1007/s00404-014-3451-x\u003c/li\u003e\n\u003cli\u003eHasegawa J, Matsuoka R, Ichizuka K, et al (2009) Predisposing factors for massive hemorrhage during Cesarean section in patients with placenta previa. Ultrasound Obstet Gynecol 34:80\u0026ndash;84. https://doi.org/10.1002/uog.6426\u003c/li\u003e\n\u003cli\u003eBoyle RK, Waters BA, O\u0026rsquo;Rourke PK (2009) Blood transfusion for caesarean delivery complicated by placenta praevia. Aust N Z J Obstet Gynaecol 49:627\u0026ndash;630. https://doi.org/10.1111/j.1479-828X.2009.01089.x\u003c/li\u003e\n\u003cli\u003eTitapant V, Chongsomboonsuk T (2019) Associated factors of blood transfusion for Caesarean sections in pure placenta praevia pregnancies. Singapore Med J 60:409\u0026ndash;413. https://doi.org/10.11622/smedj.2019029\u003c/li\u003e\n\u003cli\u003eOya A, Nakai A, Miyake H, Kawabata I, Takeshita T (2008) Risk factors for peripartum blood transfusion in women with placenta previa: a retrospective analysis. J Nippon Med Sch 75:146\u0026ndash;151. https://doi.org/10.1272/jnms.75.146\u003c/li\u003e\n\u003cli\u003eHofmeyr GJ, Mathai M, Shah A, Novikova N (2008) Techniques for caesarean section. Cochrane Database Syst Rev 2008:CD004662. https://doi.org/10.1002/14651858.CD004662.pub2\u003c/li\u003e\n\u003cli\u003eTully L, Gates S, Brocklehurst P, McKenzie-McHarg K, Ayers S (2002) Surgical techniques used during caesarean section operations: results of a national survey of practice in the UK. Eur J Obstet Gynecol Reprod Biol 102:120\u0026ndash;126. https://doi.org/10.1016/s0301-2115(01)00589-9\u003c/li\u003e\n\u003cli\u003ePatterson JA, Roberts CL, Bowen JR, et al (2014) Blood transfusion during pregnancy, birth, and the postnatal period. Obstet Gynecol 123:126\u0026ndash;133. https://doi.org/10.1097/AOG.0000000000000054\u003c/li\u003e\n\u003cli\u003eClark SL, Koonings PP, Phelan JP (1985) Placenta previa/accreta and prior cesarean section. Obstet Gynecol 66:89\u0026ndash;92\u003c/li\u003e\n\u003cli\u003eGetahun D, Oyelese Y, Salihu HM, Ananth CV (2006) Previous cesarean delivery and risks of placenta previa and placental abruption. Obstet Gynecol 107:771\u0026ndash;778. https://doi.org/10.1097/01.AOG.0000206182.63788.80\u003c/li\u003e\n\u003cli\u003eGilliam M, Rosenberg D, Davis F (2002) The likelihood of placenta previa with greater number of cesarean deliveries and higher parity. Obstet Gynecol 99:976\u0026ndash;980. https://doi.org/10.1016/s0029-7844(02)02002-1\u003c/li\u003e\n\u003cli\u003eFox NS, Spiegelman J, Mourad M, et al (2017) 812: Risk factors for blood transfusion in patients undergoing high-order cesarean delivery [poster presentation]. Am J Obstet Gynecol 216:S465. https://doi.org/10.1016/j.ajog.2016.11.545\u003c/li\u003e\n\u003cli\u003eGibbins KJ, Einerson BD, Varner MW, Silver RM (2018) Placenta previa and maternal hemorrhagic morbidity. J Matern Fetal Neonatal Med 31:494\u0026ndash;499. https://doi.org/10.1080/14767058.2017.1289163\u003c/li\u003e\n\u003cli\u003eKastner ES, Figueroa R, Garry D, Maulik D (2002) Emergency peripartum hysterectomy: experience at a community teaching hospital. Obstet Gynecol 99:971\u0026ndash;975. https://doi.org/10.1016/s0029-7844(02)01999-3\u003c/li\u003e\n\u003cli\u003eWu S, Kocherginsky M, Hibbard JU (2005) Abnormal placentation: twenty-year analysis. Am J Obstet Gynecol 192:1458\u0026ndash;1461. https://doi.org/10.1016/j.ajog.2004.12.074\u003c/li\u003e\n\u003cli\u003eBailit JL, Grobman WA, Rice MM, et al (2015) Morbidly adherent placenta treatments and outcomes. Obstet Gynecol 125:683\u0026ndash;689. https://doi.org/10.1097/AOG.0000000000000680\u003c/li\u003e\n\u003cli\u003eThurn L, Lindqvist PG, Jakobsson M, et al (2016) Abnormally invasive placenta \u0026ndash; prevalence, risk factors and antenatal suspicion: results from a large population-based pregnancy cohort study in the Nordic countries. BJOG 123:1348\u0026ndash;1355. https://doi.org/10.1111/1471-0528.13547\u003c/li\u003e\n\u003cli\u003eJansen C, de Mooij YM, Blomaard CM, et al (2019) Vaginal delivery in women with a low-lying placenta: a systematic review and meta-analysis. BJOG 126:1118\u0026ndash;1126. https://doi.org/10.1111/1471-0528.15622\u003c/li\u003e\n\u003cli\u003eChua SC, Joung SJ, Aziz R (2009) Incidence and risk factors predicting blood transfusion in caesarean section. Aust N Z J Obstet Gynaecol 49:490\u0026ndash;493. https://doi.org/10.1111/j.1479-828X.2009.01042.x\u003c/li\u003e\n\u003cli\u003eAmerican College of Obstetricians and Gynecologists\u0026rsquo; Committee on Obstetric Practice, Society for Maternal-Fetal Medicine (2021) Medically indicated late-preterm and early-term deliveries: ACOG Committee Opinion, number 831. Obstet Gynecol 138:e35\u0026ndash;e39. https://doi.org/10.1097/AOG.0000000000004447\u003c/li\u003e\n\u003cli\u003eOhkuchi A, Onagawa T, Usui R, et al (2003) Effect of maternal age on blood loss during parturition: a retrospective multivariate analysis of 10,053 cases. J Perinat Med 31:209\u0026ndash;215. https://doi.org/10.1515/JPM.2003.028\u003c/li\u003e\n\u003cli\u003eRomundstad LB, Romundstad PR, Sunde A, von D\u0026uuml;ring V, Skjaerven R, Vatten LJ (2006) Increased risk of placenta previa in pregnancies following IVF/ICSI; a comparison of ART and non-ART pregnancies in the same mother. Hum Reprod 21:2353\u0026ndash;2358. https://doi.org/10.1093/humrep/del153\u003c/li\u003e\n\u003cli\u003eAizawa M, Ishihara S, Yokoyama T (2023) Singleton pregnancy using in vitro fertilization or intracytoplasmic sperm injection does not increase risk of bleeding in cesarean delivery: a retrospective cohort study. J Anesth 37:769\u0026ndash;774. https://doi.org/10.1007/s00540-023-03234-z\u003c/li\u003e\n\u003cli\u003eTang D, Cheng Y, Feng X, Li X, Coyte PC (2023) The use of IVF/ICSI and risk of postpartum hemorrhage: A retrospective cohort study of 153,765 women in China. Front Public Health 11:1016457. https://doi.org/10.3389/fpubh.2023.1016457\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cstrong\u003eTable\u0026nbsp;1.\u003c/strong\u003e\u003cstrong\u003e\u0026emsp;\u003c/strong\u003ePatient characteristics, showing means and standard deviation (SD) or frequencies and percentages\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eCharacteristic\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eSummary statistics\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eAge (years)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eMean (SD)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e34.7 (4.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eGestational week at cesarean section\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eMean (SD)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e33.6 (3.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eElective cesarean section\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e62 (56.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eYes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e48 (43.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eAntepartum bleeding\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e24 (21.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eYes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e86 (78.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003ePrevious cesarean section\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e84 (76.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eYes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e26 (23.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eAssisted reproductive technology (ART)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e93 (84.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eYes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e17 (15.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003ePrevious curettage\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e69 (62.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eYes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003e41 (37.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eTable\u0026nbsp;2.\u003c/strong\u003e\u003cstrong\u003e\u0026emsp;\u003c/strong\u003eComparison between patients who received a blood transfusion and those who did not relative to possible risk factors, showing summary statistics (means and standard deviation or frequencies and percentages), with \u003cem\u003eP\u003c/em\u003e values from statistical tests\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"596\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"bottom\" style=\"width: 173px;\"\u003e\n \u003cp\u003eCharacteristic\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"bottom\" style=\"width: 88px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 184px;\"\u003e\n \u003cp\u003eBlood transfusion\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"bottom\" style=\"width: 152px;\"\u003e\n \u003cp\u003e\u003cem\u003eP\u003c/em\u003e value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eNo\u003cbr\u003e\u0026nbsp;(n = 90)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eYes\u003cbr\u003e\u0026nbsp;(n = 20)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eRaw\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\"\u003e\n \u003cp\u003eCorrected \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eAge (years)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMean (SD)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e34.8 (4.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e34.6 (4.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.890\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eGestational week at cesarean section\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eMean (SD)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e33.9 (3.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e32.2 (4.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.108\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.539\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003eElective cesarean section\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e50 (55.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e12 (60.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.717\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eYes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e40 (44.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e8 (40.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003eAntepartum bleeding\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e21 (23.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e3 (15.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.556\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eYes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e69 (76.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e17 (85.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003ePrevious cesarean section\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e74 (82.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e10 (50.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.007\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.049\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eYes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e16 (17.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e10 (50.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003eAssisted reproductive technology (ART)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e76 (84.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e17 (85.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.000\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e1.000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eYes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e14 (15.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e3 (15.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\"\u003e\n \u003cp\u003ePrevious curettage\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e61 (67.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e8 (40.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.020\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.120\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eYes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e29 (32.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e12 (60.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003csup\u003ea\u003c/sup\u003e Bonferroni\u0026ndash;Holm correction.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Placenta previa, Cesarean section, Blood transfusion","lastPublishedDoi":"10.21203/rs.3.rs-6813541/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6813541/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e \u003cp\u003eThe aim of this study was to evaluate risk factors for blood transfusion during cesarean section in women with major placenta previa.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003e A retrospective single-center cohort study was conducted, including 110 women treated in the tertiary-care Department of Obstetrics and Gynecology at Karlsruhe Municipal Hospital from January 2014 till December 2021 who underwent cesarean section due to major placenta previa as defined in the new classification. The patients were divided into two groups: those who received a blood transfusion and those who did not. The two groups were compared to identify potential risk factors for blood transfusion.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eNo remarkable differences between the two groups relative to the need for blood transfusion were seen after an analysis of six risk factors \u0026mdash; maternal age, gestational age at delivery, indication for cesarean section, antepartum bleeding, use of assisted reproductive technology, and a history of previous curettage. A patient history including a previous cesarean section was the only statistically significant risk factor for blood transfusion in patients with major placenta previa.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eA medical history including a previous cesarean section was the only independent statistically significant risk factor for blood transfusion in women with major placenta previa. This should be taken into account when cesarean sections are carried out in women with major placenta previa.\u003c/p\u003e","manuscriptTitle":"Risk factors for blood transfusion during cesarean section in women with major placenta previa","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-06-23 05:48:56","doi":"10.21203/rs.3.rs-6813541/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-08-22T21:17:56+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-08-22T09:03:36+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"98187944267512973170900332553212371422","date":"2025-08-04T14:43:46+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-06-25T19:18:23+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"200172707510003584166800020237536902342","date":"2025-06-19T21:11:25+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"331744425976559761371530773808538933270","date":"2025-06-18T01:21:10+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-06-17T19:52:21+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-06-17T19:50:10+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-06-17T07:34:36+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-06-16T11:55:41+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2025-06-03T17:01:20+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"a922a88f-77e5-478e-8439-f33c0da94117","owner":[],"postedDate":"June 23rd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[{"id":50259781,"name":"Health sciences/Health care"},{"id":50259782,"name":"Health sciences/Risk factors"},{"id":50259783,"name":"Health sciences/Medical research/Outcomes research"}],"tags":[],"updatedAt":"2026-01-05T16:06:12+00:00","versionOfRecord":{"articleIdentity":"rs-6813541","link":"https://doi.org/10.1038/s41598-025-34425-1","journal":{"identity":"scientific-reports","isVorOnly":false,"title":"Scientific Reports"},"publishedOn":"2026-01-03 15:58:02","publishedOnDateReadable":"January 3rd, 2026"},"versionCreatedAt":"2025-06-23 05:48:56","video":"","vorDoi":"10.1038/s41598-025-34425-1","vorDoiUrl":"https://doi.org/10.1038/s41598-025-34425-1","workflowStages":[]},"version":"v1","identity":"rs-6813541","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6813541","identity":"rs-6813541","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}