Risk factors of severe postpartum hemorrhage in pregnant women with placenta previa or low-lying placenta: a retrospective cohort study

Risk factors of severe postpartum hemorrhage in pregnant women with placenta previa or low-lying placenta: a retrospective cohort study | 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 Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Risk factors of severe postpartum hemorrhage in pregnant women with placenta previa or low-lying placenta: a retrospective cohort study Huiying Hu, Liying Wang, Jinsong Gao, Ziyi Chen, Xiaoxu Chen, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4875600/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 15 Oct, 2024 Read the published version in BMC Pregnancy and Childbirth → Version 1 posted 11 You are reading this latest preprint version Abstract Background The severe postpartum hemorrhage (SPPH) leads to dangerous maternal conditions, and its rate is still increasing and the trend in related risk factors is changing. Placenta-related problems remain the high-risk factor for SPPH. The object is to investigate the prevalence and the risk factors of the severe postpartum hemorrhage in pregnant women with placenta previa or low-lying placenta. Method A retrospective analysis of pregnant women with placenta previa or low-lying placenta after 28 weeks gestation from May 2018 to May 2023 in the Peking Union Medical College Hospital was conducted. The primary outcome was severe postpartum hemorrhage defined as blood loss ≥ 1000 mL within 24 h of childbirth, or with signs or symptoms of low blood volume requiring transfusion of ≥ 4U of red blood cells. Univariate and multivariate logistic regression was used to identify potential risk factors of severe postpartum hemorrhage and receiver operating curve to evaluate the prediction performance. Results Of the 14964 women, 201 met the inclusive criteria. Severe PPH rate was 1.3% overall and 18.9% in women with placenta previa or low-lying placenta. Weight (aOR = 0.93, 95%CI 0.87–0.99), increta or percreta placenta (aOR = 7.93, 95%CI 2.53–24.77) were the risk factors. The area under the ROC curve was 0.69(95%CI 0.59–0.80) for increta or percreta placenta alone, and 0.72(95%CI 0.62–0.82) for the combination of times of cesarean sections and anterior placenta. Conclusions Placenta accreta spectrum was the key independent risk factor of SPPH in women with placenta previa or low-lying placenta. Antenatal risk assessment of severe PPH in these population is highly desirable and optimal intervention could be planned. placenta previa low-lying placenta severe postpartum hemorrhage risk factors Figures Figure 1 Background Postpartum hemorrhage (PPH) is the leading cause of maternal morbidity and mortality globally( 1 , 2 ). Compared to normal postpartum hemorrhage, severe postpartum hemorrhage (SPPH) lead to both severe maternal and infant complications and death( 3 , 4 ). Once severe postpartum hemorrhage is predicted accurately, prompt management may significantly improve the outcomes. Despite all efforts, the severe postpartum hemorrhage rate is still increasing and the trend in related risk factors is changing( 5 ). Placenta previa remains the high-risk factor for severe PPH. Several studies ( 6 – 9 )have investigated the prediction model for PPH in pregnancies with placenta previa or low-lying placenta. However, all studies are at high risk of bias due to the limited sample size( 5 ). And the definition of severe PPH varied from 1000 to 2000 ml blood loss or from 4 to 8U red blood cells transfusion. Thus, there is still a lack of reliable prediction method for the SPPH. The aim of this study is to identify the risk factors for severe postpartum hemorrhage defined by the Chinese guideline( 10 ) in women with placenta previa or low-lying placenta and enable planned intervention to decrease severe PPH. Methods The retrospective study was performed in women gave birth in the Peking Union Medical College Hospital from May 2018 to May 2023. The inclusive criteria were: maternal age of above 18 years, giving birth after 28 weeks of gestational, with placenta previa or low-lying placenta. Placenta previa is defined as when placenta adjacent to, reached or covered the cervical os according to the last obstetrical ultrasound assessment. It includes placenta previa (placenta completely or partially covering the cervix os) and low-lying placenta (placental edge measuring ＜ 2 cm from the cervical os)(11). The outcome was severe postpartum hemorrhage defined as blood loss ≥1000 mL within 24 h of childbirth, or with signs or symptoms of low blood volume requiring transfusion of ≥ 4U of red blood cells, regardless of the mode of delivery(10). Placenta accreta spectrum was suspected by the ultrasound or the magnetic resonance imaging, and diagnosed by the failure of placenta detachment during delivery. PAS was classified into accreta, increta, or percreta according to increasing depth of perceived invasion within the myometrium(12). Based on previous relevant studies and medical files, the data of the maternal characteristics, obstetric-related factors, maternal and neonatal outcomes were collected. The maternal characteristics were: age, weight, height, gravidity, parity. The obstetric-related factors were: weight gain during pregnancy, method of conception, fetus number, hematology before delivery (hemoglobin, hematocrit, platelet count, weight blood cell), pregnant complications (hypertensive disorders of pregnancy, gestational diabetes mellitus), times of abortions, mode of abortion, gestational week of delivery, times of previous cesarean sections, type of placenta previa, main position of placenta, type of placenta accreta spectrum. The maternal and neonatal outcomes were: mode of delivery, uterine artery embolization or ligation, hysterectomy, length of hospital stay, maternal admission to the intensive care unit, premature birth, neonatal asphyxia, neonatal admission to the intensive care unit. Ethical approval for the study was obtained from the ethics committee of Peking Union Medical College Hospital (reference number, I-22PJ720). Written informed consent was waived due to the retrospective study. Medians, interquartile ranges, and Mann–Whitney U test were used for data description and comparision for continuous variables; numbers, percentages and χ2 or Fisher’s exact test for categorical variables. The risk factors were analyzed by univariable and multivariable analysis. Statistical software package SPSS 27.0 was used for data analyses. Results Study population A total of 14964 women gave birth in Peking Union Medical College Hospital from May 2018 to May 2023. There are 201 (1.34%) women had placenta previa or low-lying placenta and the incidence of severe PPH (18.9%, 38/201) is much higher than the general population (1.3%). The characteristics and the relevant factors are summarized in Table 1. The median (IQR) maternal age was 35.5 (32.0–38.0) years, median height was 162.0 (160.0-165.0) centimeters, median weight was 59.0(54.8–62.0) kilograms, median gravidity was 2.0 (1.0–3.0) times, median hemoglobin was 119.0( 111.0-127.0) g/L, median platelet count was 194.0(164.5–228.0) *10 9 g/L; 120 (59.7%) were nulliparous, 82 (40.8%) were preterm birth, 137(68.2%) were with placenta previa and 64(31.8%) with low-lying placenta, 51 (25.4%) were with placenta accreta spectrum and of whom 33(16.4%) with increta or percreta placenta and 18(9.0%) with accreta placenta. The incidence of SPPH was 42.5% in women with previous cesarean sections in the context of the placenta previa or low-lying placenta, 33.9% in women with anterior-placenta, 54.5% in women with increta or percreta placenta, 73.3% in women with anterior-placenta and previous cesarean sections. Tabel 1. Characteristics of the women with placenta previa. non-SPPH (n = 163) SPPH (n = 38) p-value Height(cm) 162(160–165) 161.8(158-164.3) 0.067 Weight(kg) 59(55-62.5) 58(51.5–60) 0.046 BMI(kg/m 2 ) 21.9(20.5–23.9) 22.3(20.1–23.5) 0.594 Weight gain during pregnancy(kg) 11.4( 8 – 14 ) 11.7( 9 – 14 ) 0.541 Maternal age <35yares 80(49.1) 13(34.2) 0.098 ≥ 35years 83(50.9) 25(65.8) Gravidity 2( 1 – 3 ) 3( 2 – 4 ) 0.010 Parity 0 105(64.4) 15(39.5) 0.005 ≥ 1 58(35.6) 23(60.5) Gestational weeks at delivery 28–36 + 6 weeks 55(33.7) 27(71.1) <0.001 ≥ 37 weeks 108(66.3) 11(28.9) Fetus number 1 155(95.1) 34(89.5) 0.349 2 8(4.9) 4(10.5) Method of conception Natural 113(69.3) 25(65.8) 0.672 In vitro fertilization 50(30.7) 13(34.2) Regular prenatal visit Yes 153(93.9) 36(94.7) 1.000 No 10(6.1) 2(5.3) Fetal position Head presentation 141(86.5) 29(76.3) 0.117 Non-head presentation 22(13.5) 9(23.7) Hematology before delivery Hemoglobin(g/L) 119(112–127) 122(109.5-126.8) 0.778 platelet count (*10 9 /L) 197(167–232) 185(158.8-201.3) 0.126 Hematocrit(%) 35.1(33–37) 35.1(34–37) 0.764 white blood cell (*10 12 /L) 8.2(7-9.4) 8(6.9–8.6) 0.210 Pregnant complications Hypertensive disorders of pregnancy 3(1.8) 1(2.6) 0.571 Gestational diabetes mellitus 33(20.2) 7(18.4) 0.800 Times of abortions 0(0–1) 1(0–2) 0.028 Type of abortion Surgical abortion 55(33.7) 18(47.4) 0.116 Medial abortion 14(8.6) 3(7.9) 1.000 Natural abortion 32(19.6) 13(34.2) 0.052 Times of previous cesarean sections 0 time 140(85.9) 21(55.3) <0.001 1 time 18(11.0) 10(26.3) ≥ 2 times 5(3.1) 7(18.4) Main position of placenta Anterior-placenta 41(25.2) 21(55.3) <0.001 Non-anterior placenta 122(74.8) 17(44.7) Type of placenta previa Low-lying placenta 57(35) 7(18.4) 0.049 Placenta previa 106(65) 31(81.6) Increta or percreta placenta 15(9.2) 18(47.4) <0.001 Accreta placenta 13(8.0) 5(13.2) 0.489 Risk factors of severe PPH In the univariate analysis, factors associated with a higher risk of SPPH were: weight, gravidity, parity, gestational week of delivery, times of abortion, times of previous cesarean sections, type of placenta previa, main position of placenta, increta or percreta placenta. In the multivariate analysis, the independent risk factors were increta or percreta placenta (aOR = 7.93, 95%CI 2.53–24.77) and weight (aOR = 0.93, 95%CI 0.87–0.99). Table 2 Risk factors for severe postpartum hemorrhage: univariate and multivariate analysis. variables OR(95%CI) aOR(95%CI)* Height 0.93(0.86-1.00) 0.98(0.94–1.01) Weight 0.95(0.90–0.99) 0.93(0.87–0.99) Gravidity 1.30(1.05–1.60) 0.50(0.21–1.22) Parity 2.78(1.34–5.73) 2.49(0.70–8.85) Gestational weeks 0.21(0.10–0.45) 0.42(0.16–1.12) Times of abortions 1.35(1.02–1.78) 2.37(0.88–6.40) Times of previous cesarean sections 3.23(1.85–5.62) 2.58(0.83–8.05) Hemoglobin 0.99(0.96–1.02) 1.01(0.97–1.05) Platelet count 1.00(0.99-1.00) 1.00(0.99-1.00) Increta placenta 1.75(0.58–5.24) 2.73(0.67–11.22) Increta or percreta placenta 8.88(3.88–20.35) 7.93(2.53–24.77) Anterior placenta 3.68(1.77–7.63) 1.63(0.59–4.50) Placenta previa 2.38(0.99–5.75) 1.39(0.45–4.29) aOR, adjusted odds ratio; OR, odds ratio * Multivariate logistic regression model with multiple imputation including variables listed in the column. Receiver operating characteristic curves (ROC) The ROC curves of different factors to predict SPPH were presented in Fig. 1 . The area under the ROC curve was 0.66(95%CI 0.55–0.77) for the times of previous cesarean sections, 0.58(95%CI 0.49–0.68) for type of placenta previa, 0.65(95%CI 0.55–0.75) for main position of placenta, 0.69(95%CI 0.59–0.80) for increta or percreta placenta, and 0.72(95%CI 0.62–0.82) for combination of times of cesarean sections and anterior placenta . Maternal and neonatal outcomes Maternal and neonatal outcomes were showed in Table 3 and Table 4 . Women with severe PPH had higher rates of uterine artery embolization or ligation, hysterectomy, length of hospital stay and maternal admission to the intensive care unit; their babies had higher rates of premature birth, neonatal asphyxia and neonatal admission to the intensive care unit. Table 3 Maternal outcomes non-SPPH (n = 163) SPPH (n = 38) p-value Mode of delivery Vaginal delivery 9(5.5) 1(2.6) 0.746 Cesarean section 154(94.5) 37(97.4) Uterine artery embolization or ligation 1(0.6) 3(7.9) 0.022 Hysterectomy 0(0) 2(5.3) 0.035 Length of hospital stay (day) 5( 4 – 7 ) 8(5-9.3) 0.013 Admission to ICU 2(1.2) 12(31.6) <0.001 Table 4 Neonatal outcomes. non-SPPH (n = 171) SPPH (n = 42) p-value Birth weight(gram) 2860(2570–3150) 2575(2263.8-2912.5) 0.012 Premature birth 62(36.3) 31(73.8) <0.001 1min Apgar score 10( 10 – 10 ) 10(9.8–10) 0.411 5min Apgar score 10( 10 – 10 ) 10( 10 – 10 ) 0.386 Neonatal asphyxia 2(1.2) 2(4.8) 0.175 Admission to NICU 49(28.7) 21(50) 0.008 Discussion The temporal most rapid increasing risk factors for severe PPH are the placenta-related problems( 5 , 13 ). Our study focused on the high-risk population, namely with placenta previa or low-lying placenta, and investigated the risk factors for severe PPH based on this context. Antenatal prediction of severe PPH in these population is highly desirable because outcomes are optimized when pregnancies are transferred and deliveries occur at high level maternal care facility. The rate and definition of severe PPH varied according to different nation guidelines. Given the varied individual tolerance, the definition of blood loss ≥ 1000 mL within 24 h of childbirth, or with signs or symptoms of low blood volume requiring transfusion of ≥ 4U of red blood cells are more reliable in Chinese population. The rate of SPPH of our study is 18.9%, which is in accordance with the Asian data in the previous meta-analysis( 14 ). Women with placenta previa or low-lying placenta are at high risk of adverse outcomes, including PPH( 15 ). Compared with low-lying placenta, placenta previa have a higher risk of PPH( 16 , 17 ). In terms of severe PPH, whether low-lying placenta and placenta previa were statistically significant for severe PPH is not consistent( 6 – 9 , 18 ). Our study indicated that the severity of placenta previa is not the risk factor for severe PPH. The location of the placenta was studied and the anterior placenta was the risk factor for both severe PPH( 9 ) and placenta accreta spectrum( 19 , 20 ) in women with placenta previa. Our study demonstrated that the anterior placenta was risk factor in univariate analysis but not independent in multivariate analysis, which may imply that the anterior placenta may cause severe PPH through placenta accreta spectrum. The placenta accreta spectrum underwent the largest increasing change for PPH due to the increasing cesarean delivery rate in China and across the world( 5 , 13 , 21 , 22 ). Consistent to previous studies 6–9 , our study showed that placenta accreta spectrum was the key independent risk factor for severe PPH in women with placenta previa. The risk factors for placenta accreta spectrum in our population were presented in Table S1. and further illustrate that the times of cesarean section and anterior placenta may cause severe PPH by increasing the rate of placenta accreta spectrum. However, the prenatal diagnosis of placenta accreta spectrum and placental implantation degree is complex( 23 , 24 ) and the definite diagnosis was made after delivery. And 50%-66.7% of the prenatal diagnosis in China are missed( 12 ). Thus, we analyzed the more available major confounders, the times of cesarean section and anterior placenta, and the AUC of the combined factors was 0.72(95%CI 0.62–0.82) and it was also with moderate performance. Weight was another independent risk factor and the definition of severe PPH considered individual tolerance in our study. It indicated that pregnant women with lower body weight have lower capacity and are more prone to severe postpartum hemorrhage and blood transfusion. The main limitation of our study was that it was a retrospective study in a single center with limited patient number. Secondly, some detailed imaging data were lacked for comparation. Future large-scale cohort researches should be performed. Abbreviations PPH: postpartum hemorrhage SPPH: severe postpartum hemorrhage CS: cesarean section aOR: Adjusted odds ratio CI: Confidence interval ROC: Receiver operating characteristic curve Declarations Ethics approval and consent to participate: Ethical approval for the study was obtained from the ethics committee of Peking Union Medical College Hospital (reference number, I-22PJ720). Written informed consent was waived due to the retrospective study. Consent for publication: Not applicable. Availability of Data and material: The data that support the findings of this study are available from the corresponding author upon reasonable request. Competing interests: The authors declare that they have no competing interests Funding: The study was supported by National Key Research and Development Program (2022YFC2704505) and Level Hospital Clinical Research Funding(2022-PUMCH-B-075). Author contributions Jinsong Gao, Huiying Hu, Liying Wang designed the study, participated in the operation, and drafted the manuscript. Liying Wang, Ziyi Chen, Xiaoxu Chen, Pingping Tang, Yifeng Zhong collected the clinical data and performed the statistical analysis. All authors read and approved the final manuscript. Acknowledgements: Not applicable. References Practice Bulletin No. 183: Postpartum Hemorrhage. Obstet Gynecol. 2017;130(4):e168-e86. Prevention and Management of Postpartum Haemorrhage: Green-top Guideline No. 52. Bjog. 2017;124(5):e106-e49. Creanga AA, Berg CJ, Syverson C, Seed K, Bruce FC, Callaghan WM. Pregnancy-related mortality in the United States, 2006-2010. Obstet Gynecol. 2015;125(1):5-12. 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Lee JY, Ahn EH, Kang S, Moon MJ, Jung SH, Chang SW, et al. Scoring model to predict massive post-partum bleeding in pregnancies with placenta previa: A retrospective cohort study. J Obstet Gynaecol Res. 2018;44(1):54-60. Obstetrics Subgroup CSoOaG, Chinese Medical Association. Guidelines for prevention and treatment of postpartum hemorrhage (2023). Chinese Journal of Obstetrics and Gynecology. 2023;58(06):401-9. Obstetrics Subgroup CSoOaG, Chinese Medical Association. Guidelines for the diagnosis and management of placenta previa (2020). Chinese Journal of Obstetrics and Gynecology. 2020;55(1):3-8. Obstetrics Subgroup CSoOaG, Chinese Medical Association. Guideline for diagnosis and treatment of placenta accreta spectrum disorders (2023). Chinese Journal of Perinatal Medicine. 2023;26(8):617-27. Corbetta-Rastelli CM, Friedman AM, Sobhani NC, Arditi B, Goffman D, Wen T. Postpartum Hemorrhage Trends and Outcomes in the United States, 2000-2019. Obstet Gynecol. 2023;141(1):152-61. 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Liu H, Zhang B, Wang W, Li H, Huang X, Wang J, et al. Effect of placenta location detected by ultrasound on the severity of placenta accreta spectrum in patients with placenta previa and placenta accreta spectrum. BMC Pregnancy Childbirth. 2023;23(1):406. Jing L, Wei G, Mengfan S, Yanyan H. Effect of site of placentation on pregnancy outcomes in patients with placenta previa. PLoS One. 2018;13(7):e0200252. Liu CN, Yu FB, Xu YZ, Li JS, Guan ZH, Sun MN, et al. Prevalence and risk factors of severe postpartum hemorrhage: a retrospective cohort study. BMC Pregnancy Childbirth. 2021;21(1):332. Silver RM, Landon MB, Rouse DJ, Leveno KJ, Spong CY, Thom EA, et al. Maternal morbidity associated with multiple repeat cesarean deliveries. Obstet Gynecol. 2006;107(6):1226-32. Cahill AG, Beigi R, Heine RP, Silver RM, Wax JR. Placenta Accreta Spectrum. Am J Obstet Gynecol. 2018;219(6):B2-b16. Jauniaux E, Alfirevic Z, Bhide AG, Belfort MA, Burton GJ, Collins SL, et al. Placenta Praevia and Placenta Accreta: Diagnosis and Management: Green-top Guideline No. 27a. Bjog. 2019;126(1):e1-e48. Additional Declarations No competing interests reported. Supplementary Files TableS1.docx Cite Share Download PDF Status: Published Journal Publication published 15 Oct, 2024 Read the published version in BMC Pregnancy and Childbirth → Version 1 posted Editorial decision: Revision requested 20 Sep, 2024 Reviews received at journal 09 Sep, 2024 Reviewers agreed at journal 02 Sep, 2024 Reviewers agreed at journal 01 Sep, 2024 Reviews received at journal 31 Aug, 2024 Reviewers agreed at journal 31 Aug, 2024 Reviewers invited by journal 29 Aug, 2024 Editor invited by journal 08 Aug, 2024 Editor assigned by journal 07 Aug, 2024 Submission checks completed at journal 07 Aug, 2024 First submitted to journal 07 Aug, 2024 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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Tang","email":"","orcid":"","institution":"Chinese Academy of Medical Sciences, National Clinical Research Center for Obstetric and Gynecologic Diseases","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Pingping","middleName":"","lastName":"Tang","suffix":""},{"id":348608248,"identity":"88784ca6-d4c1-47af-b651-0d618cdc4b2c","order_by":6,"name":"Yifeng Zhong","email":"","orcid":"","institution":"Chinese Academy of Medical Sciences, National Clinical Research Center for Obstetric and Gynecologic Diseases","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Yifeng","middleName":"","lastName":"Zhong","suffix":""}],"badges":[],"createdAt":"2024-08-07 14:47:13","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4875600/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4875600/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s12884-024-06876-3","type":"published","date":"2024-10-15T15:58:12+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":63852189,"identity":"5c20cf9d-b8cc-4b2a-bf0b-f9fd779b6346","added_by":"auto","created_at":"2024-09-03 04:28:14","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":173603,"visible":true,"origin":"","legend":"\u003cp\u003eROC for times of previous cesarean sections, type of placenta previa, main position of placenta, increta or percreta placenta, combination of times of cesarean sections and anterior placenta.\u003c/p\u003e","description":"","filename":"Figure1..png","url":"https://assets-eu.researchsquare.com/files/rs-4875600/v1/0a417b4e1a923cfe51864fee.png"},{"id":67149087,"identity":"8fbb0956-2da2-4ec7-acce-ccfc6b64a202","added_by":"auto","created_at":"2024-10-21 16:11:48","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":749166,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4875600/v1/dff72d33-762e-431d-93dc-fe9cf4e86c60.pdf"},{"id":63852187,"identity":"eb45fa4f-3955-405c-ae7f-7e9041b8993f","added_by":"auto","created_at":"2024-09-03 04:28:13","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":14875,"visible":true,"origin":"","legend":"","description":"","filename":"TableS1.docx","url":"https://assets-eu.researchsquare.com/files/rs-4875600/v1/a2617ce9be0b240e104bc5f9.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Risk factors of severe postpartum hemorrhage in pregnant women with placenta previa or low-lying placenta: a retrospective cohort study","fulltext":[{"header":"Background","content":"\u003cp\u003ePostpartum hemorrhage (PPH) is the leading cause of maternal morbidity and mortality globally(\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). Compared to normal postpartum hemorrhage, severe postpartum hemorrhage (SPPH) lead to both severe maternal and infant complications and death(\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e). Once severe postpartum hemorrhage is predicted accurately, prompt management may significantly improve the outcomes.\u003c/p\u003e \u003cp\u003eDespite all efforts, the severe postpartum hemorrhage rate is still increasing and the trend in related risk factors is changing(\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e). Placenta previa remains the high-risk factor for severe PPH. Several studies (\u003cspan additionalcitationids=\"CR7 CR8\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e)have investigated the prediction model for PPH in pregnancies with placenta previa or low-lying placenta. However, all studies are at high risk of bias due to the limited sample size(\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e). And the definition of severe PPH varied from 1000 to 2000 ml blood loss or from 4 to 8U red blood cells transfusion. Thus, there is still a lack of reliable prediction method for the SPPH. The aim of this study is to identify the risk factors for severe postpartum hemorrhage defined by the Chinese guideline(\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e) in women with placenta previa or low-lying placenta and enable planned intervention to decrease severe PPH.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eThe retrospective study was performed in women gave birth in the Peking Union Medical College Hospital from May 2018 to May 2023. The inclusive criteria were: maternal age of above 18 years, giving birth after 28 weeks of gestational, with placenta previa or low-lying placenta. Placenta previa is defined as when placenta adjacent to, reached or covered the cervical os according to the last obstetrical ultrasound assessment. It includes placenta previa (placenta completely or partially covering the cervix os) and low-lying placenta (placental edge measuring ＜\u0026thinsp;2\u0026thinsp;cm from the cervical os)(11).\u003c/p\u003e\n\u003cp\u003eThe outcome was severe postpartum hemorrhage defined as blood loss \u0026ge;1000\u0026thinsp;mL within 24\u0026thinsp;h of childbirth, or with signs or symptoms of low blood volume requiring transfusion of \u0026ge; 4U of red blood cells, regardless of the mode of delivery(10). Placenta accreta spectrum was suspected by the ultrasound or the magnetic resonance imaging, and diagnosed by the failure of placenta detachment during delivery. PAS was classified into accreta, increta, or percreta according to increasing depth of perceived invasion within the myometrium(12).\u003c/p\u003e\n\u003cp\u003eBased on previous relevant studies and medical files, the data of the maternal characteristics, obstetric-related factors, maternal and neonatal outcomes were collected.\u003c/p\u003e\n\u003cp\u003eThe maternal characteristics were: age, weight, height, gravidity, parity.\u003c/p\u003e\n\u003cp\u003eThe obstetric-related factors were: weight gain during pregnancy, method of conception, fetus number, hematology before delivery (hemoglobin, hematocrit, platelet count, weight blood cell), pregnant complications (hypertensive disorders of pregnancy, gestational diabetes mellitus), times of abortions, mode of abortion, gestational week of delivery, times of previous cesarean sections, type of placenta previa, main position of placenta, type of placenta accreta spectrum.\u003c/p\u003e\n\u003cp\u003eThe maternal and neonatal outcomes were: mode of delivery, uterine artery embolization or ligation, hysterectomy, length of hospital stay, maternal admission to the intensive care unit, premature birth, neonatal asphyxia, neonatal admission to the intensive care unit.\u003c/p\u003e\n\u003cp\u003eEthical approval for the study was obtained from the ethics committee of Peking Union Medical College Hospital (reference number, I-22PJ720). Written informed consent was waived due to the retrospective study.\u003c/p\u003e\n\u003cp\u003eMedians, interquartile ranges, and Mann\u0026ndash;Whitney U test were used for data description and comparision for continuous variables; numbers, percentages and \u0026chi;2 or Fisher\u0026rsquo;s exact test for categorical variables. The risk factors were analyzed by univariable and multivariable analysis.\u003c/p\u003e\n\u003cp\u003eStatistical software package SPSS 27.0 was used for data analyses.\u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eStudy population\u003c/h2\u003e \u003cp\u003eA total of 14964 women gave birth in Peking Union Medical College Hospital from May 2018 to May 2023. There are 201 (1.34%) women had placenta previa or low-lying placenta and the incidence of severe PPH (18.9%, 38/201) is much higher than the general population (1.3%). The characteristics and the relevant factors are summarized in Table\u0026nbsp;1. The median (IQR) maternal age was 35.5 (32.0\u0026ndash;38.0) years, median height was 162.0 (160.0-165.0) centimeters, median weight was 59.0(54.8\u0026ndash;62.0) kilograms, median gravidity was 2.0 (1.0\u0026ndash;3.0) times, median hemoglobin was 119.0( 111.0-127.0) g/L, median platelet count was 194.0(164.5\u0026ndash;228.0) *10\u003csup\u003e9\u003c/sup\u003e g/L; 120 (59.7%) were nulliparous, 82 (40.8%) were preterm birth, 137(68.2%) were with placenta previa and 64(31.8%) with low-lying placenta, 51 (25.4%) were with placenta accreta spectrum and of whom 33(16.4%) with increta or percreta placenta and 18(9.0%) with accreta placenta.\u003c/p\u003e \u003cp\u003eThe incidence of SPPH was 42.5% in women with previous cesarean sections in the context of the placenta previa or low-lying placenta, 33.9% in women with anterior-placenta, 54.5% in women with increta or percreta placenta, 73.3% in women with anterior-placenta and previous cesarean sections.\u003c/p\u003e \u003cp\u003eTabel 1. Characteristics of the women with placenta previa.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Taba\" border=\"1\"\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003enon-SPPH\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;163)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSPPH\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;38)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHeight(cm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e162(160\u0026ndash;165)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e161.8(158-164.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.067\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWeight(kg)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e59(55-62.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e58(51.5\u0026ndash;60)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.046\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMI(kg/m\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e21.9(20.5\u0026ndash;23.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e22.3(20.1\u0026ndash;23.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.594\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWeight gain during pregnancy(kg)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11.4(\u003cspan additionalcitationids=\"CR9 CR10 CR11 CR12 CR13\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11.7(\u003cspan additionalcitationids=\"CR10 CR11 CR12 CR13\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.541\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMaternal age\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026lt;35yares\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e80(49.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e13(34.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.098\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;35years\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e83(50.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e25(65.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGravidity\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2(\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3(\u003cspan additionalcitationids=\"CR3\" citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.010\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eParity\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e105(64.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e15(39.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.005\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e58(35.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e23(60.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGestational weeks at delivery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e28\u0026ndash;36\u0026thinsp;+\u0026thinsp;6 weeks\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e55(33.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e27(71.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;37 weeks\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e108(66.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11(28.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFetus number\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e155(95.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e34(89.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.349\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8(4.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4(10.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMethod of conception\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNatural\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e113(69.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e25(65.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.672\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIn vitro fertilization\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e50(30.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e13(34.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRegular prenatal visit\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e153(93.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e36(94.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10(6.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2(5.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFetal position\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHead presentation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e141(86.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e29(76.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.117\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNon-head presentation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e22(13.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9(23.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHematology before delivery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHemoglobin(g/L)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e119(112\u0026ndash;127)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e122(109.5-126.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.778\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eplatelet count\u003c/p\u003e \u003cp\u003e(*10\u003csup\u003e9\u003c/sup\u003e/L)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e197(167\u0026ndash;232)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e185(158.8-201.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.126\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHematocrit(%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e35.1(33\u0026ndash;37)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e35.1(34\u0026ndash;37)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.764\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ewhite blood cell\u003c/p\u003e \u003cp\u003e(*10\u003csup\u003e12\u003c/sup\u003e/L)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8.2(7-9.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8(6.9\u0026ndash;8.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.210\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePregnant complications\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHypertensive\u003c/p\u003e \u003cp\u003edisorders of pregnancy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3(1.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1(2.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.571\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGestational diabetes mellitus\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e33(20.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7(18.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.800\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTimes of abortions\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0(0\u0026ndash;1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1(0\u0026ndash;2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.028\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eType of abortion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSurgical abortion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e55(33.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18(47.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.116\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMedial abortion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14(8.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3(7.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNatural abortion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e32(19.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e13(34.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.052\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTimes of previous cesarean sections\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e0 time\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e140(85.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e21(55.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1 time\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e18(11.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10(26.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;2 times\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5(3.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7(18.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMain position of placenta\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAnterior-placenta\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e41(25.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e21(55.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNon-anterior placenta\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e122(74.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e17(44.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eType of placenta previa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLow-lying placenta\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e57(35)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7(18.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.049\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePlacenta previa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e106(65)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e31(81.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIncreta or percreta placenta\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15(9.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18(47.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAccreta placenta\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13(8.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5(13.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.489\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eRisk factors of severe PPH\u003c/h2\u003e \u003cp\u003eIn the univariate analysis, factors associated with a higher risk of SPPH were: weight, gravidity, parity, gestational week of delivery, times of abortion, times of previous cesarean sections, type of placenta previa, main position of placenta, increta or percreta placenta. In the multivariate analysis, the independent risk factors were increta or percreta placenta (aOR\u0026thinsp;=\u0026thinsp;7.93, 95%CI 2.53\u0026ndash;24.77) and weight (aOR\u0026thinsp;=\u0026thinsp;0.93, 95%CI 0.87\u0026ndash;0.99).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eRisk factors for severe postpartum hemorrhage: univariate and multivariate analysis.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003evariables\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eOR(95%CI)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eaOR(95%CI)*\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHeight\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.93(0.86-1.00)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.98(0.94\u0026ndash;1.01)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWeight\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.95(0.90\u0026ndash;0.99)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.93(0.87\u0026ndash;0.99)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGravidity\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.30(1.05\u0026ndash;1.60)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.50(0.21\u0026ndash;1.22)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eParity\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.78(1.34\u0026ndash;5.73)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.49(0.70\u0026ndash;8.85)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGestational weeks\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.21(0.10\u0026ndash;0.45)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.42(0.16\u0026ndash;1.12)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTimes of abortions\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.35(1.02\u0026ndash;1.78)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.37(0.88\u0026ndash;6.40)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTimes of previous cesarean sections\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.23(1.85\u0026ndash;5.62)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.58(0.83\u0026ndash;8.05)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHemoglobin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.99(0.96\u0026ndash;1.02)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.01(0.97\u0026ndash;1.05)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePlatelet count\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.00(0.99-1.00)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.00(0.99-1.00)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIncreta placenta\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.75(0.58\u0026ndash;5.24)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.73(0.67\u0026ndash;11.22)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIncreta or percreta placenta\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8.88(3.88\u0026ndash;20.35)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7.93(2.53\u0026ndash;24.77)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAnterior placenta\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.68(1.77\u0026ndash;7.63)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.63(0.59\u0026ndash;4.50)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePlacenta previa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.38(0.99\u0026ndash;5.75)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.39(0.45\u0026ndash;4.29)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"3\"\u003eaOR, adjusted odds ratio; OR, odds ratio\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e* Multivariate logistic regression model with multiple imputation including variables listed in the column.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eReceiver operating characteristic curves (ROC)\u003c/h2\u003e \u003cp\u003eThe ROC curves of different factors to predict SPPH were presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The area under the ROC curve was 0.66(95%CI 0.55\u0026ndash;0.77) for the times of previous cesarean sections, 0.58(95%CI 0.49\u0026ndash;0.68) for type of placenta previa, 0.65(95%CI 0.55\u0026ndash;0.75) for main position of placenta, 0.69(95%CI 0.59\u0026ndash;0.80) for increta or percreta placenta, and 0.72(95%CI 0.62\u0026ndash;0.82) for combination of times of cesarean sections and anterior placenta .\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eMaternal and neonatal outcomes\u003c/h2\u003e \u003cp\u003eMaternal and neonatal outcomes were showed in Table \u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e3\u003c/span\u003e and Table \u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e4\u003c/span\u003e. Women with severe PPH had higher rates of uterine artery embolization or ligation, hysterectomy, length of hospital stay and maternal admission to the intensive care unit; their babies had higher rates of premature birth, neonatal asphyxia and neonatal admission to the intensive care unit.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMaternal outcomes\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003enon-SPPH\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;163)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSPPH\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;38)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMode of delivery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVaginal delivery\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9(5.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1(2.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.746\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCesarean section\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e154(94.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e37(97.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUterine artery embolization or ligation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1(0.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3(7.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.022\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHysterectomy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0(0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2(5.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.035\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLength of hospital stay (day)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5(\u003cspan additionalcitationids=\"CR5 CR6\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e8(5-9.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.013\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAdmission to ICU\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2(1.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e12(31.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eNeonatal outcomes.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003enon-SPPH\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;171)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSPPH\u003c/p\u003e \u003cp\u003e(n\u0026thinsp;=\u0026thinsp;42)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBirth weight(gram)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2860(2570\u0026ndash;3150)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2575(2263.8-2912.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.012\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePremature birth\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e62(36.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e31(73.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1min Apgar score\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10(\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10(9.8\u0026ndash;10)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.411\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5min Apgar score\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10(\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10(\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.386\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNeonatal asphyxia\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2(1.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2(4.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.175\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAdmission to NICU\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e49(28.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e21(50)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.008\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe temporal most rapid increasing risk factors for severe PPH are the placenta-related problems(\u003cspan class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e13\u003c/span\u003e). Our study focused on the high-risk population, namely with placenta previa or low-lying placenta, and investigated the risk factors for severe PPH based on this context. Antenatal prediction of severe PPH in these population is highly desirable because outcomes are optimized when pregnancies are transferred and deliveries occur at high level maternal care facility.\u003c/p\u003e\n\u003cp\u003eThe rate and definition of severe PPH varied according to different nation guidelines. Given the varied individual tolerance, the definition of blood loss\u0026thinsp;\u0026ge;\u0026thinsp;1000 mL within 24 h of childbirth, or with signs or symptoms of low blood volume requiring transfusion of \u0026ge;\u0026thinsp;4U of red blood cells are more reliable in Chinese population. The rate of SPPH of our study is 18.9%, which is in accordance with the Asian data in the previous meta-analysis(\u003cspan class=\"CitationRef\"\u003e14\u003c/span\u003e).\u003c/p\u003e\n\u003cp\u003eWomen with placenta previa or low-lying placenta are at high risk of adverse outcomes, including PPH(\u003cspan class=\"CitationRef\"\u003e15\u003c/span\u003e). Compared with low-lying placenta, placenta previa have a higher risk of PPH(\u003cspan class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e17\u003c/span\u003e). In terms of severe PPH, whether low-lying placenta and placenta previa were statistically significant for severe PPH is not consistent(\u003cspan class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e18\u003c/span\u003e). Our study indicated that the severity of placenta previa is not the risk factor for severe PPH.\u003c/p\u003e\n\u003cp\u003eThe location of the placenta was studied and the anterior placenta was the risk factor for both severe PPH(\u003cspan class=\"CitationRef\"\u003e9\u003c/span\u003e) and placenta accreta spectrum(\u003cspan class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e20\u003c/span\u003e) in women with placenta previa. Our study demonstrated that the anterior placenta was risk factor in univariate analysis but not independent in multivariate analysis, which may imply that the anterior placenta may cause severe PPH through placenta accreta spectrum.\u003c/p\u003e\n\u003cp\u003eThe placenta accreta spectrum underwent the largest increasing change for PPH due to the increasing cesarean delivery rate in China and across the world(\u003cspan class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e22\u003c/span\u003e). Consistent to previous studies\u003csup\u003e6\u0026ndash;9\u003c/sup\u003e, our study showed that placenta accreta spectrum was the key independent risk factor for severe PPH in women with placenta previa. The risk factors for placenta accreta spectrum in our population were presented in Table S1. and further illustrate that the times of cesarean section and anterior placenta may cause severe PPH by increasing the rate of placenta accreta spectrum.\u003c/p\u003e\n\u003cp\u003eHowever, the prenatal diagnosis of placenta accreta spectrum and placental implantation degree is complex(\u003cspan class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e24\u003c/span\u003e) and the definite diagnosis was made after delivery. And 50%-66.7% of the prenatal diagnosis in China are missed(\u003cspan class=\"CitationRef\"\u003e12\u003c/span\u003e). Thus, we analyzed the more available major confounders, the times of cesarean section and anterior placenta, and the AUC of the combined factors was 0.72(95%CI 0.62\u0026ndash;0.82) and it was also with moderate performance.\u003c/p\u003e\n\u003cp\u003eWeight was another independent risk factor and the definition of severe PPH considered individual tolerance in our study. It indicated that pregnant women with lower body weight have lower capacity and are more prone to severe postpartum hemorrhage and blood transfusion.\u003c/p\u003e\n\u003cp\u003eThe main limitation of our study was that it was a retrospective study in a single center with limited patient number. Secondly, some detailed imaging data were lacked for comparation. Future large-scale cohort researches should be performed.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003e\u003cstrong\u003ePPH:\u0026nbsp;\u003c/strong\u003epostpartum hemorrhage\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSPPH:\u0026nbsp;\u003c/strong\u003esevere postpartum hemorrhage\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCS:\u0026nbsp;\u003c/strong\u003ecesarean section\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eaOR:\u0026nbsp;\u003c/strong\u003eAdjusted odds ratio\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCI:\u0026nbsp;\u003c/strong\u003eConfidence interval\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eROC:\u0026nbsp;\u003c/strong\u003eReceiver operating characteristic curve\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eEthical approval for the study was obtained from the ethics committee of Peking Union Medical College Hospital (reference number, I-22PJ720). Written informed consent was waived due to the retrospective study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of Data and material:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data that support the findings of this study are available from the corresponding author upon reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study was supported by National Key Research and Development Program (2022YFC2704505) and Level Hospital Clinical Research Funding(2022-PUMCH-B-075).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eJinsong Gao, Huiying Hu, Liying Wang designed the study, participated in the operation, and drafted the manuscript. Liying Wang, Ziyi Chen, Xiaoxu Chen, Pingping Tang, Yifeng Zhong\u003csup\u003e\u0026nbsp;\u003c/sup\u003ecollected the clinical data and performed the statistical analysis. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003ePractice Bulletin No. 183: Postpartum Hemorrhage. Obstet Gynecol. 2017;130(4):e168-e86.\u003c/li\u003e\n\u003cli\u003ePrevention and Management of Postpartum Haemorrhage: Green-top Guideline No. 52. Bjog. 2017;124(5):e106-e49.\u003c/li\u003e\n\u003cli\u003eCreanga AA, Berg CJ, Syverson C, Seed K, Bruce FC, Callaghan WM. Pregnancy-related mortality in the United States, 2006-2010. Obstet Gynecol. 2015;125(1):5-12.\u003c/li\u003e\n\u003cli\u003eTsamantioti E, Sandstr\u0026ouml;m A, Muraca GM, Joseph KS, Remaeus K, Razaz N. Severe maternal morbidity surveillance, temporal trends and regional variation: A population-based cohort study. Bjog. 2024;131(6):811-22.\u003c/li\u003e\n\u003cli\u003eNeary C, Naheed S, McLernon DJ, Black M. Predicting risk of postpartum haemorrhage: a systematic review. Bjog. 2021;128(1):46-53.\u003c/li\u003e\n\u003cli\u003eBaba Y, Ohkuchi A, Usui R, Suzuki H, Kuwata T, Matsubara S. Calculating probability of requiring allogeneic blood transfusion using three preoperative risk factors on cesarean section for placenta previa. Arch Gynecol Obstet. 2015;291(2):281-5.\u003c/li\u003e\n\u003cli\u003eChen C, Liu X, Chen D, Huang S, Yan X, Liu H, et al. A risk model to predict severe postpartum hemorrhage in patients with placenta previa: a single-center retrospective study. Ann Palliat Med. 2019;8(5):611-21.\u003c/li\u003e\n\u003cli\u003eKim JW, Lee YK, Chin JH, Kim SO, Lee MY, Won HS, et al. Development of a scoring system to predict massive postpartum transfusion in placenta previa totalis. J Anesth. 2017;31(4):593-600.\u003c/li\u003e\n\u003cli\u003eLee JY, Ahn EH, Kang S, Moon MJ, Jung SH, Chang SW, et al. Scoring model to predict massive post-partum bleeding in pregnancies with placenta previa: A retrospective cohort study. J Obstet Gynaecol Res. 2018;44(1):54-60.\u003c/li\u003e\n\u003cli\u003eObstetrics Subgroup CSoOaG, Chinese Medical Association. Guidelines for prevention and treatment of postpartum hemorrhage (2023). Chinese Journal of Obstetrics and Gynecology. 2023;58(06):401-9.\u003c/li\u003e\n\u003cli\u003eObstetrics Subgroup CSoOaG, Chinese Medical Association. Guidelines for the diagnosis and management of placenta previa (2020). Chinese Journal of Obstetrics and Gynecology. 2020;55(1):3-8.\u003c/li\u003e\n\u003cli\u003eObstetrics Subgroup CSoOaG, Chinese Medical Association. Guideline for diagnosis and treatment of placenta accreta spectrum disorders (2023). Chinese Journal of Perinatal Medicine. 2023;26(8):617-27.\u003c/li\u003e\n\u003cli\u003eCorbetta-Rastelli CM, Friedman AM, Sobhani NC, Arditi B, Goffman D, Wen T. Postpartum Hemorrhage Trends and Outcomes in the United States, 2000-2019. Obstet Gynecol. 2023;141(1):152-61.\u003c/li\u003e\n\u003cli\u003eFan D, Xia Q, Liu L, Wu S, Tian G, Wang W, et al. The Incidence of Postpartum Hemorrhage in Pregnant Women with Placenta Previa: A Systematic Review and Meta-Analysis. PLoS One. 2017;12(1):e0170194.\u003c/li\u003e\n\u003cli\u003eJain V, Bos H, Bujold E. Guideline No. 402: Diagnosis and Management of Placenta Previa. J Obstet Gynaecol Can. 2020;42(7):906-17.e1.\u003c/li\u003e\n\u003cli\u003eBhide A, Prefumo F, Moore J, Hollis B, Thilaganathan B. Placental edge to internal os distance in the late third trimester and mode of delivery in placenta praevia. Bjog. 2003;110(9):860-4.\u003c/li\u003e\n\u003cli\u003eBi S, Zhang L, Wang Z, Chen J, Tang J, Gong J, et al. Effect of types of placenta previa on maternal and neonatal outcomes: a 10-year retrospective cohort study. Arch Gynecol Obstet. 2021;304(1):65-72.\u003c/li\u003e\n\u003cli\u003eKayem G, Seco A, Vendittelli F, Crenn Hebert C, Dupont C, Branger B, et al. Risk factors for placenta accreta spectrum disorders in women with any prior cesarean and a placenta previa or low lying: a prospective population-based study. Sci Rep. 2024;14(1):6564.\u003c/li\u003e\n\u003cli\u003eLiu H, Zhang B, Wang W, Li H, Huang X, Wang J, et al. Effect of placenta location detected by ultrasound on the severity of placenta accreta spectrum in patients with placenta previa and placenta accreta spectrum. BMC Pregnancy Childbirth. 2023;23(1):406.\u003c/li\u003e\n\u003cli\u003eJing L, Wei G, Mengfan S, Yanyan H. Effect of site of placentation on pregnancy outcomes in patients with placenta previa. PLoS One. 2018;13(7):e0200252.\u003c/li\u003e\n\u003cli\u003eLiu CN, Yu FB, Xu YZ, Li JS, Guan ZH, Sun MN, et al. Prevalence and risk factors of severe postpartum hemorrhage: a retrospective cohort study. BMC Pregnancy Childbirth. 2021;21(1):332.\u003c/li\u003e\n\u003cli\u003eSilver RM, Landon MB, Rouse DJ, Leveno KJ, Spong CY, Thom EA, et al. Maternal morbidity associated with multiple repeat cesarean deliveries. Obstet Gynecol. 2006;107(6):1226-32.\u003c/li\u003e\n\u003cli\u003eCahill AG, Beigi R, Heine RP, Silver RM, Wax JR. Placenta Accreta Spectrum. Am J Obstet Gynecol. 2018;219(6):B2-b16.\u003c/li\u003e\n\u003cli\u003eJauniaux E, Alfirevic Z, Bhide AG, Belfort MA, Burton GJ, Collins SL, et al. Placenta Praevia and Placenta Accreta: Diagnosis and Management: Green-top Guideline No. 27a. Bjog. 2019;126(1):e1-e48.\u003c/li\u003e\n\u003c/ol\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":"bmc-pregnancy-and-childbirth","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"prch","sideBox":"Learn more about [BMC Pregnancy and Childbirth](http://bmcpregnancychildbirth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/prch/default.aspx","title":"BMC Pregnancy and Childbirth","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"placenta previa, low-lying placenta, severe postpartum hemorrhage, risk factors","lastPublishedDoi":"10.21203/rs.3.rs-4875600/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4875600/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eThe severe postpartum hemorrhage (SPPH) leads to dangerous maternal conditions, and its rate is still increasing and the trend in related risk factors is changing. Placenta-related problems remain the high-risk factor for SPPH. The object is to investigate the prevalence and the risk factors of the severe postpartum hemorrhage in pregnant women with placenta previa or low-lying placenta.\u003c/p\u003e\u003ch2\u003eMethod\u003c/h2\u003e \u003cp\u003eA retrospective analysis of pregnant women with placenta previa or low-lying placenta after 28 weeks gestation from May 2018 to May 2023 in the Peking Union Medical College Hospital was conducted. The primary outcome was severe postpartum hemorrhage defined as blood loss\u0026thinsp;\u0026ge;\u0026thinsp;1000 mL within 24 h of childbirth, or with signs or symptoms of low blood volume requiring transfusion of \u0026ge;\u0026thinsp;4U of red blood cells. Univariate and multivariate logistic regression was used to identify potential risk factors of severe postpartum hemorrhage and receiver operating curve to evaluate the prediction performance.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eOf the 14964 women, 201 met the inclusive criteria. Severe PPH rate was 1.3% overall and 18.9% in women with placenta previa or low-lying placenta. Weight (aOR\u0026thinsp;=\u0026thinsp;0.93, 95%CI 0.87\u0026ndash;0.99), increta or percreta placenta (aOR\u0026thinsp;=\u0026thinsp;7.93, 95%CI 2.53\u0026ndash;24.77) were the risk factors. The area under the ROC curve was 0.69(95%CI 0.59\u0026ndash;0.80) for increta or percreta placenta alone, and 0.72(95%CI 0.62\u0026ndash;0.82) for the combination of times of cesarean sections and anterior placenta.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003ePlacenta accreta spectrum was the key independent risk factor of SPPH in women with placenta previa or low-lying placenta. Antenatal risk assessment of severe PPH in these population is highly desirable and optimal intervention could be planned.\u003c/p\u003e","manuscriptTitle":"Risk factors of severe postpartum hemorrhage in pregnant women with placenta previa or low-lying placenta: a retrospective cohort study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-09-03 04:28:09","doi":"10.21203/rs.3.rs-4875600/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-09-20T11:17:38+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-09-09T12:11:16+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"158216174967209297027106569908565673237","date":"2024-09-02T22:20:15+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"222927041538486439363081564962140754429","date":"2024-09-01T10:41:21+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-08-31T21:07:14+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"83654655445600286258096304209068696888","date":"2024-08-31T19:45:39+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-08-29T11:25:43+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2024-08-08T08:03:38+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-08-08T00:42:39+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-08-08T00:41:51+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Pregnancy and Childbirth","date":"2024-08-07T14:45:33+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-pregnancy-and-childbirth","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"prch","sideBox":"Learn more about [BMC Pregnancy and Childbirth](http://bmcpregnancychildbirth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/prch/default.aspx","title":"BMC Pregnancy and Childbirth","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"87193e76-d11b-452f-a702-9072ce4f69a1","owner":[],"postedDate":"September 3rd, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-10-21T16:04:38+00:00","versionOfRecord":{"articleIdentity":"rs-4875600","link":"https://doi.org/10.1186/s12884-024-06876-3","journal":{"identity":"bmc-pregnancy-and-childbirth","isVorOnly":false,"title":"BMC Pregnancy and Childbirth"},"publishedOn":"2024-10-15 15:58:12","publishedOnDateReadable":"October 15th, 2024"},"versionCreatedAt":"2024-09-03 04:28:09","video":"","vorDoi":"10.1186/s12884-024-06876-3","vorDoiUrl":"https://doi.org/10.1186/s12884-024-06876-3","workflowStages":[]},"version":"v1","identity":"rs-4875600","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4875600","identity":"rs-4875600","version":["v1"]},"buildId":"GqpaHPwrfC8PjnIFayRh5","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}