http://informahealthcare.com/jmf ISSN: 1476-7058 (print), 1476-4954 (electronic) J Matern Fetal Neonatal Med, 2014; 27(16): 1661–1667 ! 2014 Informa UK Ltd. DOI: 10.3109/14767058.2013.872095

ORIGINAL ARTICLE

Prediction of postpartum blood transfusion – risk factors and recurrence Anne J. Wikkelsø1, Sofie Hjortøe2, Thomas A. Gerds3, Ann M. Møller1, and Jens Langhoff-Roos4 J Matern Fetal Neonatal Med Downloaded from informahealthcare.com by Washington University Library on 12/27/14 For personal use only.

1

Department of Anaesthesia and Intensive Care Medicine, University of Copenhagen, Herlev Hospital, Herlev, Denmark, 2Department of Obstetrics and Gynaecology, Roskilde Hospital, Roskilde, Denmark, 3Department of Biostatistics, University of Copenhagen, Copenhagen, Denmark, and 4 Department of Obstetrics, Juliane Marie Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark Abstract

Keywords

Objective: The aim was to find clinically useful risk factors for postpartum transfusion and to assess the joint predictive value in a population of women with a first and second delivery. Methods: All Danish women with a first and second delivery from January 2001 to September 2009 who gave birth in a hospital that reported transfusion of red blood cells to a national database: A total of 96 545 women were included. Results: Retained placental tissue explained more than all other risk factors in vaginal deliveries. Retained placental tissue at first delivery was associated with postpartum transfusion at a second vaginal delivery, and may also be used as an early predictor in parallel with a history of either placental abruption, postpartum transfusion or caesarean delivery. The positive predictive values of having more than one risk factor was low (2.2%–2.7%). Conclusions: Prediction of postpartum transfusion is difficult. Retained placental tissue is the strongest predictor of postpartum blood transfusion in vaginal deliveries. Retained placental tissue is usually diagnosed for the first time when the bleeding starts, which limits the clinical value of prediction. We need tools for an early diagnosis of retained placenta to intervene early before transfusion is needed.

Blood transfusion, postpartum haemorrhage, prediction, recurrence, retained placenta History Received 19 November 2013 Accepted 2 December 2013 Published online 13 January 2014

Introduction Postpartum haemorrhage may arise suddenly and unexpectedly [1,2] and blood transfusion may be needed in severe cases [3]. Numerous risk factors of postpartum haemorrhage have been identified. The clinical usefulness of these risk factors, however, should be quantified by their joint predictive ability including positive and negative predictive values. Women, who suffer from severe haemorrhage with transfusion at first delivery, may seek postpartum counselling regarding the risk of postpartum haemorrhage at the next delivery. The identification of high risk is important for the woman and for the planning of place of birth. A history of previous postpartum haemorrhage is a major independent risk factor of recurrence [1,4–7]. Other risk factors associated with a first delivery may also be associated with postpartum haemorrhage and transfusion at a second delivery. Knowledge of these risk factors is available to the obstetrician before the second pregnancy and delivery. The frequency and severity of risk factors are important as some are serious but very rare, and others are common but of less importance.

Address for correspondence: Anne Juul Wikkelsø, MD, Department of Anaesthesia and Intensive Care Medicine, University of Copenhagen, Herlev Hospital, Herlev, Denmark. Tel: þ45 22612152. E-mail: [email protected]

The objective of this register-based study was to describe the joint predictive value of risk factors of postpartum transfusion (PPT) in women with a first and second delivery, and to assess the risk of PPT by risk factors available at different clinical time points.

Materials and methods The cohort was based on nationwide register data obtained from the Danish medical birth registry (DMBR) and Danish transfusion database (DTDB). The DMBR contains information on all Danish deliveries including data on demography, previous reproductive history, and complications during pregnancy and delivery as well as in the neonatal period [8]. Data are registered by the midwife immediately after delivery and are evaluated by an obstetrician at discharge from hospital. The DTDB is a national database based on regional reports from the blood banks’ safety information system regarding the storage and transfusion of blood components. We merged data from DMBR and DTDB and included all parturients with a first and second delivery during the period of 1 January 2001–30 September 2009. We excluded parturients from delivery units not reporting to DTDB in that particular year. The cohort consisted of 96 545 women with information on the first and second delivery (Figure 1). We retrieved diagnoses (ICD-10) and interventions (Nordic Nomesco classification) in pregnancy and at

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delivery from the DMBR. The merge of registries was approved by the Danish National Data Protection Agency (nr. 2007-58-0015). Register studies in Denmark need no approval by ethical committees according to Danish law and practices. The National Danish Medical Birth registry 1.1.2001-30.9.2009

The Danish Transfusion Database

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n= 389,785 parturients (557,477 deliveries)

Excluded due to the centre of birth not reporting to The Danish Transfusion Database n= 44,464 parturients (71,046 deliveries)

Potential cohort of parturients n= 345,321 parturients (486,431 deliveries)

The outcome, PPT was defined by the transfusion of at least one unit of red blood cells (RBC) within 6 weeks postpartum [1,9–11]. PPT at first delivery was also assessed as a risk factor for PPT at the second delivery (previous PPT). Risk factors of PPT available from the register were: Previous PPT (RBC transfusion within 6 weeks postpartum of primipara delivery), maternal age (age at delivery 435 years), uterine distension (multiple gestations or macrosomia (birth weight 44.500 g) – if multiple gestation then macrosomia is missing), placenta previa, preeclampsia (preeclampsia, eclampsia and/or HELLP), placental abruption, preterm birth (gestational age 5273 days), caesarean section, induced labour, augmented labour, instrumental delivery (vacuum delivery, forceps cephalic delivery or forceps breech delivery), episiotomy, retained placenta/tissue (removal of retained products of conception after delivery or manual removal of placenta or placenta parts from delivered uterus). Statistical analysis

Parturients with no first delivery or only a first delivery during the period n= 248,776 parturients (293,341 deliveries)

Study cohort of parturients with a first and second delivery during the period n= 96,545 parturients (193,090 deliveries)

Figure 1. The dataflow of the established cohort. Maternal age >35 Macrosomia Multiple gestation Previa* Preeclampsia* Abruptio* Preterm CD* Induced Augmented Instrumental Episiotomy Retained*

The PPT risk assessments were analysed at five different time points of clinical relevance (‘‘During first pregnancy’’, ‘‘At first delivery’’, ‘‘Between pregnancies’’, ‘‘During second pregnancy’’ and ‘‘At second delivery’’) (Figure 2). Multiple logistic regression were used separately at each time point. PPT at caesarean and vaginal deliveries were analysed separately. Sensitivity, specificity, positive and negative predictive values were calculated for the crude measure of having no risk factors versus one or more risk factors for the prediction of PPT. Results from multiple logistic regression were summarised using counts and percentages, odds ratios (OR) and 95% confidence intervals (CI). The outcome of the Maternal age >35 Macrosomia Multiple gestation Previa Preeclampsia Abruptio Preterm CD Induced Augmented Instrumental Episiotomy Retained

PPT-1*

PPT-2 time

1. First pregnancy

2. First delivery

3. Between pregnancies

4. 5. Second Second pregnancy delivery

Figure 2. Conceptual model showing the five clinical time points for the analysis of included risk factors for postpartum transfusion at first and second delivery. *Indicates risk factors of first delivery included in second delivery analyses of transfusion risk. CD ¼ caesarean delivery, PPT-1 ¼ postpartum blood transfusion at first delivery, PPT-2 ¼ postpartum blood transfusion at second delivery, Retained ¼ retained placental tissue, Previa ¼ placenta previa, Abruptio ¼ placental abruption, Induced ¼ induced labour, Augmented ¼ augmented labour.

Prediction of postpartum blood transfusion

DOI: 10.3109/14767058.2013.872095

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Table 1. The percentage attributable risk (PAR) of PPT at first and second vaginal delivery. First vaginal delivery Factor Any Retained placental tissue Previous PPT Previous caesarean delivery Previous placental abruption

Second vaginal delivery

Frequency (%)

Odds ratio [95%CI]

PAR (%)

Frequency (%)

62.4 2.5 – – –

– 22.4 [19.8–25.3]*** – – –

51.9 28.8 – – –

45.1 1.8 1.8 9.4 0.4

Odds ratio [95%CI] 34.1 4.4 2.9 2.1

PAR (%)

– [29.0–39.9]*** [3.3–5.7]*** [2.5–3.5]*** [1.2–3.9]*

62.1 33.6 6.9 16.6 0.7

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‘‘Any’’ means all risk factors summarised in the ‘‘Methods’’ section. Odds ratio significance code: 0 – ‘***’; 0.01 – ‘*’.

logistic regression analyses were PPT at the first delivery for the analyses at the time points ‘‘During first pregnancy’’ and ‘‘At first delivery’’, and PPT at the second delivery for the remaining analyses. Risk factors with OR higher than 3 were termed as ‘‘major’’ and those with an incidence below 5% as ‘‘rare’’. The attributable risks were estimated for the single risk factor from the fitted logistic regression models. The statistical software package ‘‘R’’ (2012, Vienna, Austria) was used for all analyses.

Previous caesarean delivery was a significant risk factor of PPT, but only in vaginal deliveries, increasing the risk of PPT by OR 2.9–4.1 depending on the time of assessment (Appendix 1 and 2). Furthermore, previous CD was more prevalent among second caesarean deliveries (11 230, 60.6%) as compared to vaginal deliveries (7361, 9.4%). A history of previous placental abruption was independently associated with an increased risk of PPT at a second vaginal delivery, but the attributable risk was small (Appendix 1 and Table 1).

Results

Timed prediction

We included 96 545 women with a first and a second delivery. A total of 2076 (2.2%) women received RBC transfusion at the first delivery and 1421 (1.5%) at the second delivery.

Prediction during the first pregnancy, the first delivery and between deliveries

Retained placental tissue Retained placental tissue complicated 1963 (2.0%) first deliveries and 1450 (1.5%) second deliveries. Retained placental tissue was the strongest risk factor in second vaginal delivery (OR 34.12 [CI 29.0–39.9]) and more common in vaginal (1.8%) than caesarean deliveries (0.1%) (Appendix 1 and 2). The attributable risks of retained placental tissue at vaginal delivery were 28.8% at first and 33.6% at second delivery (Table 1). Including all risk factors we were able to explain PPT in 51.9% of first deliveries and in 62.1% of second deliveries. Thus, retained placental tissue explained more than half of PPT (Table 1). At a second caesarean delivery retained placental tissue also significantly increased the risk of PPT (Appendix 2). Prediction of a second PPT by risk factors identified at the first delivery PPT at second delivery was more frequent in women with Previous PPT compared to those without (7.6 versus 1.3%). A history of PPT was associated with a 4.5 times increased risk of PPT at all clinical time points in both vaginal and caesarean deliveries (Appendices 1–3) and holds an attributable risk of 6.9% (Table 1). Retained placenta at the first delivery was independently associated with PPT at the second vaginal delivery and increased the risk by 2.5 between pregnancies (Appendix 3) and by 3 during second pregnancy (Appendix 1). However, when retained placental tissue is diagnosed at the second delivery, information on a previous retained placenta was not of added value in the prediction of PPT (Appendix 1). Previous retained placental tissue was rare (1.6%) and not associated with PPT in women who had a caesarean section in their second pregnancy (Appendix 2).

At the first vaginal delivery placenta previa was the second most severe risk factor of PPT, at same delivery assessed both during pregnancy and at delivery increasing the risk 7–8 times (Appendix 3); however, this abnormal placentation was very rare. The most frequent risk factor was augmented labour with a prevalence of 42.7% in first vaginal deliveries, and associated with a slightly increased risk (OR 1.3 [CI 1.1– 1.4]) (Appendix 3). Multiple pregnancy was the most severe risk factor in first caesarean sections – both during pregnancy and delivery, with OR of 3.5–3.7. Also in first caesarean deliveries, augmented labour was the most common risk factor (36.3%, see Appendix 3). Between deliveries information on retained placental tissue and PPT were the only risk factors associated with increased risk (Appendix 3). In women with a second caesarean section only previous PPT was a significant risk factor assessed between deliveries (Appendix 3). Prediction during the second pregnancy and delivery The most severe risk factor identified among vaginal second delivery was retained placental tissue followed by placental abruption independently increasing the risk of PPT by 34 and 14 (Appendix 1). The most frequent risk factors were augmented labour (15.7%) and previous caesarean delivery (9.4%). In general, no risk factors were both common (incidence 45%) and major (OR43). Placenta previa was the most severe risk factor (OR 7.1 [CI 5.1–9.9]) at the second caesarean delivery and occurred in 1.8% (Appendix 2). Prediction of postpartum transfusion A total of 60 152 (62%) first deliveries and 50 390 (53%) second deliveries had at least one risk factor. Among women with no risk factors only few had PPT; 370 first deliveries (1.0%) and 185 second deliveries (0.4%). A total of 18% of the

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women with PPT at first delivery and 13% of the women with PPT at second delivery had no risk factors. The sensitivity and specificity of having none compared to at least one risk factor for PPT in a first vaginal delivery were 83.6% [CI 81.2–85.4] and 38.1% [CI 37.7–38.4]. At a second vaginal delivery, the sensitivity and specificity were 84.8% [CI 82.3–87.0] and 55.4% [CI 55.0–55.7]. This corresponds to positive and negative predictive values of 2.7% [CI 2.6–2.9] and 99.1% [CI 99.0–99.2] (first vaginal delivery) and 2.2% [CI 2.1–2.4] and 99.7% [CI 99.6–99.7] (second vaginal delivery), respectively.

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Discussion Retained placental tissue remains a severe and significant risk factor of postpartum haemorrhage and the need of blood transfusion [5,12–16]. Usually retained placental tissue is diagnosed in close timely relation to the bleeding, so using this factor to predict bleeding at same delivery is of limited clinical value. However, before a second delivery information on a history of retained placental tissue serves the same purpose. To some extent this might be caused by recurrence of retained tissue or scarring caused by interventions for retained tissue at the first delivery. Furthermore, the strong association between retained placental tissue and PPT is of such magnitude that when diagnosed, alertness is warranted and transfusion and other haemostatic measures should be available. The current focus on uterine atony [2] as the main cause of severe postpartum haemorrhage should be modified to include the diagnosis and treatment of abnormally invasive placenta [4]. Our results support this shift in paradigm since retained placental tissue holds the highest attributable risk in both first and second vaginal deliveries (Table 1). We confirmed previous findings on risk factors of severe postpartum haemorrhage [13,14,16–19] of which some were significantly associated with PPT at a vaginal or caesarean delivery, when adjusting for other risk factors (Appendices 1–3). However, all risk factors may not be known in a given clinical situation, and exploring the available risk factors at five different clinical times may result in more clinically useful prediction analyses. Obviously, the severity and frequency of risk factors are influenced by local guidelines of treatment and their implementation. Active management of the third stage of labour and the time limit prompting removal of a retained placenta before bleeding will influence the results of this study. Thus, regional differences in prophylaxis are important to consider when studies are compared. Previous studies conclude that the majority of women with postpartum haemorrhage are without any risk factors [15]. In contrast, we found that overall 82% of first delivery women with PPT and 87% of second deliveries had one or several risk factors present. Most risk factors were minor (OR53) and some were very common, so the ability to predict the probability of PPT at vaginal deliveries by having one or several of these risk factors were quite poor with positive predictive values of only 2.7 and 2.2%. However, this is also explained by the low prevalence of PPT in the total group of women giving birth by vaginal delivery (prevalence of PPT is 2.0% at first and 1.2% at second delivery). A history of postpartum haemorrhage has previously been identified as a major independent risk factor of the recurrence

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of haemorrhage with OR ranging between 2.2 and 8.4 [3,5,20–22]. Previous studies used estimated blood loss or drop in haemoglobin in the definition of postpartum haemorrhage, and our study confirms their findings using PPT as outcome. The adjusted OR of previous PPT was equal in size in vaginal and caesarean delivery possibly reflecting a cause, e.g. general bleeding tendency or vulnerability which might be independent of mode of delivery. A history of PPT has a prevalence of 1.8% and an attributable risk of 6.9% in second vaginal deliveries. Previous PPT is the fourth most important predictive factor only surpassed by retained placental tissue (33.6%), previous caesarean delivery (16.6%) and augmented labour (10.0%). Previous PPT is the only significant risk factor known after the first delivery in women with a second caesarean delivery. In vaginal deliveries, previous placental abruption and previous caesarean delivery also implies a significant risk. The risk of recurrent placental abruption is established [23], but the independent association of a previous placental abruption and PPT (adjusted for the effect of recurrence and previous PPT) might reflect the complexity of risk factors associated with placental abruption and antepartum haemorrhage [23] and the fact that many are identical to those of PPT. Furthermore, placental abruption is a difficult diagnosis and haemorrhage might be the only symptom present if it evolves just before delivery. A previous caesarean delivery increase the risk of PPT three to four times at a second vaginal delivery even if adjusted for retained placental tissue (as in previous studies [3,10,13,14,21]). The uterine scarring from a first caesarean section may impair uterine contraction after delivery and also increase the risk of local placenta accrete not coded or registered as retained placental tissue. A major strength of this study is the large populationbased cohort of women with a first and second delivery. Limitations related to the use of register data in terms of misclassification and under-reporting are presumably random and should not cause any systematic bias. Data on RBC transfusions are collected prospectively at the local blood banks enabling identification of donor and recipient and reporting of delivered blood products from the blood banks is regarded as complete. Ordered but unused blood products have been removed from the register [5]. Danish transfusion guidelines recommend RBC transfusion when haemoglobin falls below 4.5 mmol/L (7.2 g/dL) or with hypovolaemia/shock in case of rapid severe haemorrhage [24]. Antepartum bleeding and anaemia may increase the risk of postpartum transfusion and thereby affect the use of transfusion as an indicator of severe postpartum haemorrhage. However, the use of blood transfusion data seems to increase the sensitivity of reporting clinically relevant cases of severe postpartum haemorrhage [25]. The risk factors in this study are identical to the major well-established risk factors of postpartum haemorrhage, but we miss some such as prolongation of third stage of labour, smoking, ethnicity, body mass index, etc. If these were included also even fewer PPT cases would expectedly be without any risk factors. However, to improve bedside prediction of an acute event such as PPT only simple and easily assessable predictors should be included. Good predictive tools may facilitate clinical research on postpartum haemorrhage and

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DOI: 10.3109/14767058.2013.872095

transfusion by the selection of a relevant high risk population [6]. In conclusion, this large registry study identified retained placental tissue as the most severe and dominant risk factor of PPT. Most of women had one or several risk factors present, but the ability to predict PPT from these was low. We identified two first delivery risk factors (history of placental abruption and retained placental tissue) presumably relevant in the prediction of second vaginal delivery PPT. Women with no apparent risk factors still holds a risk of PPT. Early and timely identification of high risk patients may raise clinical alertness, appropriate use of uterotonics and timely removal of a retained placenta as well as blood transfusion when needed.

Acknowledgements Dr Jens Bartholdy, University of Copenhagen, Herlev Hospital, for assistance in the merge of databases, and Steen Rasmussen (Danish Medical Birth Registry) for extracting data and the Danish Transfusion Database.

Declaration of interest The authors report no declarations of interest.

References 1. Kominiarek MA, Kilpatrick SJ. Postpartum hemorrhage: a recurring pregnancy complication. Semin Perinatol 2007;31: 159–66. 2. Oyelese Y, Ananth CV. Postpartum hemorrhage: epidemiology, risk factors, and causes. Clin Obstet Gynecol 2010;53:147–56. 3. Jakobsson M, Gissler M, Tapper AM. Risk factors for blood transfusion at delivery in Finland. Acta Obstet Gynecol Scand 2013;92:414–20. 4. Dewhurst CJ, Dutton WA. Recurrent abnormalities of the third stage of labour. Lancet 1957;273:764–7. 5. Fullerton G, Danielian P, Bhattacharya S. Outcomes of pregnancy following postpartum haemorrhage. BJOG 2013;120:621–7. 6. Hall MH, Halliwell R, Carr-Hill R. Concomitant and repeated happenings of complications of the third stage of labour. Br J Obstet Gynaecol 1985;92:732–8. 7. Padmanabhan A, Schwartz J, Spitalnik SL. Transfusion therapy in postpartum hemorrhage. Semin Perinatol 2009;33:124–7. 8. Knudsen LB, Olsen J. The Danish Medical Birth Registry. Dan Med Bull 1998;45:320–3.

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9. Bais JM, Eskes M, Pel M, et al. Postpartum haemorrhage in nulliparous women: incidence and risk factors in low and high risk women. A Dutch population-based cohort study on standard (4 or ¼500 ml) and severe (4 or ¼1000 ml) postpartum haemorrhage. Eur J Obstet Gynecol Reprod Biol 2004;115:166–72. 10. Bateman BT, Berman MF, Riley LE, Leffert LR. The epidemiology of postpartum hemorrhage in a large, nationwide sample of deliveries. Anesth Analg 2010;110:1368–73. 11. Biguzzi E, Franchi F, Ambrogi F, et al. Risk factors for postpartum hemorrhage in a cohort of 6011 Italian women. Thromb Res 2012; 129:e1–7. 12. Langhoff-Roos J, Chantraine F, Geirsson RT. AIP (abnormally invasive placenta) – from a retained placenta to destruction of the uterine wall. Acta Obstet Gynecol Scand 2013;92:367–8. 13. Lu MC, Korst LM, Fridman M, et al. Identifying women most likely to benefit from prevention strategies for postpartum hemorrhage. J Perinatol 2009;29:422–7. 14. International Confederation of Midwives; International Federation of Gynaecologists and Obstetricians. Joint statement: management of the third stage of labour to prevent post-partum haemorrhage. J Midwifery Womens Health 2004;49:76–7. 15. Sosa CG, Althabe F, Belizan JM, Buekens P. Risk factors for postpartum hemorrhage in vaginal deliveries in a Latin-American population. Obstet Gynecol 2009;113:1313–19. 16. Kolas T, Oian P, Skjeldestad FE. Risks for peroperative excessive blood loss in cesarean delivery. Acta Obstet Gynecol Scand 2010; 89:658–63. 17. Combs CA, Murphy EL, Laros Jr RK. Factors associated with postpartum hemorrhage with vaginal birth. Obstet Gynecol 1991; 77:69–76. 18. Magann EF, Evans S, Hutchinson M, et al. Postpartum hemorrhage after vaginal birth: an analysis of risk factors. South Med J 2005;98: 419–22. 19. Naef III RW, Chauhan SP, Chevalier SP, et al. Prediction of hemorrhage at cesarean delivery. Obstet Gynecol 1994;83:923–6. 20. Danish transfusions database; 2013. Available from: http:// www.dtdb.dk/organisation/historie/ [last accessed 27 Feb 2013]. 21. Ford JB, Roberts CL, Bell JC, et al. Postpartum haemorrhage occurrence and recurrence: a population-based study. Med J Aust 2007;187:391–3. 22. Hoveyda F, MacKenzie IZ. Secondary postpartum haemorrhage: incidence, morbidity and current management. BJOG 2001;108: 927–30. 23. Tikkanen M. Placental abruption: epidemiology, risk factors and consequences. Acta Obstet Gynecol Scand 2011;90:140–9. 24. Danish health and medicines authority. Guidelines of Blood Transfusion (vejledning om blodtransfusion); 2007. Available from: http://www.sst.dk/publ/publ2007/EFT/blodtransfusion/vejl_ blodtransfusion.pdf [last accessed 1 Nov 2013]. 25. Lain SJ, Roberts CL, Hadfield RM, et al. How accurate is the reporting of obstetric haemorrhage in hospital discharge data? A validation study. Aust N Z J Obstet Gynaecol 2008;48:481–4.

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Appendix 1: Risk factors related to vaginal second deliveries predicting PPT at second delivery

Factor Total First delivery risk factors Placenta previa Preeclampsia Placental abruption Caesarean delivery Retained placental tissue PPT

n (%)

OR [CI.95]

OR [CI.95]

78 007 (100) 103 2134 325 7361 1658 1388

(0.1) (2.7) (0.4) (9.4) (2.1) (1.8)

During 0.82 0.92 1.95 4.10 3.00 4.71

second pregnancy [0.25–2.64] [0.66–1.30] [1.13–3.37]* [3.51–4.75]*** [2.27–3.97]*** [3.68–6.05]***

At second delivery 0.77 [0.22–2.67] 0.89 [0.61–1.28] 2.14 [1.19–3.87]* 2.94 [2.46–3.5]*** 1.12 [0.82–1.53] 4.35 [3.32–5.74]***

During 1.25 1.88 4.22 1.36 2.16 12.06

second pregnancy [1.04–1.49]* [1.44–2.44]*** [3.02–5.93]*** [0.18–10.15] [1.41–3.29]*** [6.53–22.17]*** – – – – – –

At second delivery 1.16 [0.96–1.41] 1.67 [1.25–2.21]*** 2.86 [1.95–4.23]*** 2.08 [0.28–15.53] 1.93 [1.21–3.06]** 14.44 [7.57–27.47]*** 1.19 [0.88–1.61] 1.42 [1.16–1.75]*** 1.55 [1.32–1.82]*** 1.49 [1.17–1.91]** 1.82 [1.42–2.34]*** 34.12 [28.97–39.88]***

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Second delivery risk factors Maternal age 435 years Macrosomia Multiple birth Placenta previa Preeclampsia Placental abruption Preterm delivery Induced labour Augmented labour Instrumental delivery Episiotomy Retained placental tissue

9512 3083 910 48 811 109 2379 6333 12 285 2967 2923 1425

(12.2) (4.0) (1.2) (0.1) (1.0) (0.1) (3.0) (8.1) (15.7) (3.8) (3.7) (1.8)

All factors are compared with the absence of that particular factor. Significance code: 0 – ‘***’; 0.001 – ‘**’; 0.01 – ‘*’; 0.05 –‘’; 0.1 –‘’.

Appendix 2: Risk factors related to caesarean second deliveries predicting PPT at second delivery

Factor Total First delivery risk factors Placenta previa Preeclampsia Placental abruption Caesarean delivery Retained placental tissue PPT Second delivery risk factors Maternal age 435 years Macrosomia Multiple birth Placenta previa Preeclampsia Placental abruption Preterm delivery Induced labour Augmented labour Instrumental delivery Episiotomy Retained placental tissue

n (%)

OR [CI.95]

OR [CI.95]

18 538 (100) 111 1101 231 11230 305 688

(0.6) (5.9) (1.2) (60.6) (1.6) (3.7)

During second pregnancy 1.40 [0.58–3.41] 1.03 [0.72–1.47] 0.54 [0.20–1.47] 1.09 [0.90–1.33] 0.98 [0.54–1.78] 4.22 [3.15–5.70]***

At second delivery 1.31 [0.54–3.17] 1.03 [0.72–1.47] 0.51 [0.19–1.40] 1.16 [0.96–1.42] 0.90 [0.50–1.65] 4.35 [3.21–5.85]***

3638 917 951 333 538 265 1898 1144 1916 197 7 25

(19.6) (4.9) (5.1) (1.8) (2.9) (1.4) (10.2) (6.2) (10.3) (1.1) (0.0) (0.1)

During second pregnancy 1.16 [0.93–1.44] 1.45 [0.98–2.15] 2.12 [1.53–2.91]*** 9.03 [6.58–12.36]*** 3.03 [2.09–4.37]*** 4.44 [2.89–6.75]*** – – – – – –

At second delivery 1.17 [0.95–1.47] 1.49 [1.00–2.22]* 1.60 [1.14–2.23]** 7.10 [5.09–9.88]*** 2.23 [1.52–3.27]*** 3.10 [1.99–4.79]*** 2.48 [1.95–3.16]*** 1.46 [1.04–2.07]* 1.42 [1.05–1.9]* 2.32 [1.21–4.43]* NA 5.37 [1.79-16.22]**

All factors are compared with the absence of that particular factor. Significance code: 0 – ‘***’; 0.001 – ‘**’; 0.01 – ‘*’; 0.05 –‘’; 0.1 –‘’. NA means too few cases to analyse.

(1.9) (0.5) (0.0) (2.4) (0.2) (5.2) (9.7) (42.7) (17.9) (16.1) (2.5)

3.71 3.82 7.03 2.51 2.94



[3.01–4.57]*** [2.63–5.60]*** [2.64–18.64]*** [2.01–3.11]*** [1.59–5.48]*** – – – – – –

During first pregnancy Outcome: PPT at first delivery 1.04 [0.8–1.35]

OR [CI.95]



3.46 [2.77–4.34]*** 3.32 [2.17–5.05]*** 8.17 [2.87–23.16]*** 2.03 [1.6–2.59]*** 2.44 [1.21–4.91]* 0.97 [0.78–1.22] 1.28 [1.10–1.49]** 1.26 [1.13–1.40]*** 1.72 [1.52–1.94]*** 1.3 [1.14–1.47]*** 22.42 [19.80–25.27]***

At first delivery Outcome: PPT at first delivery 0.77 [0.58–1.01].

OR [CI.95]

4.76 [3.72–6.05]***

– – NA 1.3 [0.90–1.86] 2.1 [0.84–5.17] – – – – – 2.53 [1.96–3.29]***

Between pregnancies Outcome: PPT at second delivery –

OR [CI.95]

(4.9) (2.3) (1.0) (7.3) (2.0) (11.1) (14.5) (36.3) (5.6) (0.3) (0.1)

493 (2.7)

909 433 181 1350 373 2065 2700 6748 1047 63 21

1256 (6.8)

18 591 (100)

n (%)

1.99 3.74 3.10 2.83 2.32



[1.42–2.78]*** [2.65–5.28]*** [1.73–5.52]*** [2.23–3.60]*** [1.49–3.58]*** – – – – – –

During first pregnancy Outcome: PPT at first delivery 0.91 [0.63–1.33]

OR [CI.95]



1.93 [1.37–2.71]*** 3.49 [2.44–5.02]*** 3.1 [1.72–5.57]*** 2.69 [2.09–3.49]*** 2.27 [1.45–3.55]*** 1.3 [0.99–1.69]. 1.07 [0.83–1.37] 1.23 [1.01–1.52]* 1.06 [0.71–1.61] 2.18 [0.74–6.40] 1.77 [0.23–13.49]

At first delivery Outcome: PPT at first delivery 0.92 [0.64–1.34]

OR [CI.95]

Caesarean first deliveries

All factors are compared with the absence of that particular factor. Significance code: 0 – ‘***’; 0.001 – ‘**’; 0.01 – ‘*’; 0.05 –‘’; 0.1 –; ‘’. NA means too few cases to analyse.

1583 (2.0)

1510 401 33 1885 183 4039 7580 33 300 13931 12 567 1942

2864 (3.7)

77 954 (100)

Total

Maternal age 435 years Macrosomia Multiple birth Placenta previa Preeclampsia Placental abruption Preterm delivery Induced labour Augmented labour Instrumental delivery Episiotomy Retained placental tissue PPT

n (%)

Factor

Vaginal first deliveries

Appendix 3: Risk factors related to vaginal and caesarean first deliveries

J Matern Fetal Neonatal Med Downloaded from informahealthcare.com by Washington University Library on 12/27/14 For personal use only.

4.44 [3.30–5.99]***

– – 1.57 [0.79–3.1] 1.12 [0.82–1.52] 1.16 [0.67–2.01] – – – – – NA

Between pregnancies Outcome: PPT at second delivery –

OR [CI.95]

DOI: 10.3109/14767058.2013.872095

Prediction of postpartum blood transfusion 1667

Prediction of postpartum blood transfusion--risk factors and recurrence.

The aim was to find clinically useful risk factors for postpartum transfusion and to assess the joint predictive value in a population of women with a...
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