***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background We aim ed to evaluate the incidence of undiagnosed abnormal postpartum blood loss ( UPPBL ) after vaginal delivery , identify the risk factors and compare them to those of postpartum haemorrhage ( PPH ) . Method The study population included women who participated in a r and omized controlled trial of women with singleton low-risk pregnancy who delivered vaginally after 35 weeks ’ gestation ( n = 3917 ) . Clinical PPH was defined as postpartum blood loss ≥ 500 mL measured by using a collector bag and UPPBL was defined by a peripartum change in haemoglobin ≥ 2 g/dL in the absence of clinical PPH . Risk factors were assessed by multivariate multinomial logistic regression . Results The incidence of UPPBL and PPH was 11.2 % and 11.0 % of vaginal deliveries , respectively . The median peripartum change in Hb level was comparable between UPPBL and PPH groups ( 2.5 g/dL interquartile range [ 2.2–3.0 ] and 2.4 g/dL IQR [ 1.5–3.3 ] ) . Risk factors specifically associated with UPPBL were Asian geographical origin ( adjusted OR [ aOR ] 2.3 , 95 % confidence interval [ CI ] 1.2–4.2 ; p = 0.009 ) , previous caesarean section ( aOR 3.4 , 2.1–5.5 ; p<0.001 ) and episiotomy ( aOR 2.6 , 1.8–3.6 ; p<0.001 ) . Risk factors for both UPPBL and PPH were primiparity , long duration of labour , instrumental delivery and retained placenta . Conclusion Undiagnosed abnormal postpartum blood loss is frequent among women giving birth vaginally and has specific risk factors . The clinical importance of this entity needs further confirmation , and the benefit of systematic or targeted prevention strategies needs to be assessed Objective The aim of the present study was to develop a toolkit combining various risk factors to predict the risk of developing a postpartum hemorrhage ( PPH ) during a cesarean delivery . Study Design A retrospective cohort study of 24,230 women who had cesarean delivery between January 2003 and December 2013 at a tertiary care teaching hospital within the United Kingdom serving a multiethnic population . Data were extracted from hospital data bases , and risk factors for PPH were identified . Hothorn et al recursive partitioning algorithm was used to infer a conditional decision tree . For each of the identified combinations of risk factors , two probabilities were calculated : the probability of a patient producing ≥1,000 and ≥ 2,000 mL blood loss . Results The Leicester PPH predict score was then tested on the r and omly selected remaining 25 % ( n = 6,095 ) of the data for internal validity . Reliability testing showed an intraclass correlation of 0.98 and mean absolute error of 239.8 mL with the actual outcome . Conclusion The proposed toolkit enables clinicians to predict the risk of postpartum hemorrhage . As a result , preventative measures for postpartum hemorrhage could be undertaken . Further external validation of the current toolkit is required Summary Background Post-partum haemorrhage is the leading cause of maternal death worldwide . Early administration of tranexamic acid reduces deaths due to bleeding in trauma patients . We aim ed to assess the effects of early administration of tranexamic acid on death , hysterectomy , and other relevant outcomes in women with post-partum haemorrhage . Methods In this r and omised , double-blind , placebo-controlled trial , we recruited women aged 16 years and older with a clinical diagnosis of post-partum haemorrhage after a vaginal birth or caesarean section from 193 hospitals in 21 countries . We r and omly assigned women to receive either 1 g intravenous tranexamic acid or matching placebo in addition to usual care . If bleeding continued after 30 min , or stopped and restarted within 24 h of the first dose , a second dose of 1 g of tranexamic acid or placebo could be given . Patients were assigned by selection of a numbered treatment pack from a box containing eight numbered packs that were identical apart from the pack number . Participants , care givers , and those assessing outcomes were masked to allocation . We originally planned to enrol 15 000 women with a composite primary endpoint of death from all-causes or hysterectomy within 42 days of giving birth . However , during the trial it became apparent that the decision to conduct a hysterectomy was often made at the same time as r and omisation . Although tranexamic acid could influence the risk of death in these cases , it could not affect the risk of hysterectomy . We therefore increased the sample size from 15 000 to 20 000 women in order to estimate the effect of tranexamic acid on the risk of death from post-partum haemorrhage . All analyses were done on an intention-to-treat basis . This trial is registered with IS RCT N76912190 ( Dec 8 , 2008 ) ; Clinical Trials.gov , number NCT00872469 ; and PACTR201007000192283 . Findings Between March , 2010 , and April , 2016 , 20 060 women were enrolled and r and omly assigned to receive tranexamic acid ( n=10 051 ) or placebo ( n=10 009 ) , of whom 10 036 and 9985 , respectively , were included in the analysis . Death due to bleeding was significantly reduced in women given tranexamic acid ( 155 [ 1·5 % ] of 10 036 patients vs 191 [ 1·9 % ] of 9985 in the placebo group , risk ratio [ RR ] 0·81 , 95 % CI 0·65–1·00 ; p=0·045 ) , especially in women given treatment within 3 h of giving birth ( 89 [ 1·2 % ] in the tranexamic acid group vs 127 [ 1·7 % ] in the placebo group , RR 0·69 , 95 % CI 0·52–0·91 ; p=0·008 ) . All other causes of death did not differ significantly by group . Hysterectomy was not reduced with tranexamic acid ( 358 [ 3·6 % ] patients in the tranexamic acid group vs 351 [ 3·5 % ] in the placebo group , RR 1·02 , 95 % CI 0·88–1·07 ; p=0·84 ) . The composite primary endpoint of death from all causes or hysterectomy was not reduced with tranexamic acid ( 534 [ 5·3 % ] deaths or hysterectomies in the tranexamic acid group vs 546 [ 5·5 % ] in the placebo group , RR 0·97 , 95 % CI 0·87 - 1·09 ; p=0·65 ) . Adverse events ( including thromboembolic events ) did not differ significantly in the tranexamic acid versus placebo group . Interpretation Tranexamic acid  reduces death due to bleeding in women with post-partum haemorrhage with no adverse effects . When used as a treatment for postpartum haemorrhage , tranexamic acid should be given as soon as possible after bleeding onset . Funding London School of Hygiene & Tropical Medicine , Pfizer , UK Department of Health , Wellcome Trust , and Bill & Melinda Gates Foundation Objective To investigate the effect of in situ simulation ( ISS ) versus off-site simulation ( OSS ) on knowledge , patient safety attitude , stress , motivation , perceptions of simulation , team performance and organisational impact . Design Investigator-initiated single-centre r and omised superiority educational trial . Setting Obstetrics and anaesthesiology departments , Rigshospitalet , University of Copenhagen , Denmark . Participants 100 participants in teams of 10 , comprising midwives , specialised midwives , auxiliary nurses , nurse anaesthetists , operating theatre nurses , and consultant doctors and trainees in obstetrics and anaesthesiology . Interventions Two multiprofessional simulations ( clinical management of an emergency caesarean section and a postpartum haemorrhage scenario ) were conducted in teams of 10 in the ISS versus the OSS setting . Primary outcome Knowledge assessed by a multiple choice question test . Exploratory outcomes Individual outcomes : scores on the Safety Attitudes Question naire , stress measurements ( State-Trait Anxiety Inventory , cognitive appraisal and salivary cortisol ) , Intrinsic Motivation Inventory and perceptions of simulations . Team outcome : video assessment of team performance . Organisational impact : suggestions for organisational changes . Results The trial was conducted from April to June 2013 . No differences between the two groups were found for the multiple choice question test , patient safety attitude , stress measurements , motivation or the evaluation of the simulations . The participants in the ISS group scored the authenticity of the simulation significantly higher than did the participants in the OSS group . Expert video assessment of team performance showed no differences between the ISS versus the OSS group . The ISS group provided more ideas and suggestions for changes at the organisational level . Conclusions In this r and omised trial , no significant differences were found regarding knowledge , patient safety attitude , motivation or stress measurements when comparing ISS versus OSS . Although participant perception of the authenticity of ISS versus OSS differed significantly , there were no differences in other outcomes between the groups except that the ISS group generated more suggestions for organisational changes . Trial registration number NCT01792674 Background In high-income countries , the incidence of severe postpartum hemorrhage ( PPH ) has increased . This has important public health relevance because severe PPH is a leading cause of major maternal morbidity . However , few studies have identified risk factors for severe PPH within a contemporary obstetric cohort . Methods We performed a case-control study to identify risk factors for severe PPH among a cohort of women who delivered at one of three hospitals in Norway between 2008 and 2011 . A case ( severe PPH ) was classified by an estimated blood loss ≥1500 mL or the need for blood transfusion for excessive postpartum bleeding . Using logistic regression , we applied a pragmatic strategy to identify independent risk factors for severe PPH . Results Among a total of 43,105 deliveries occurring between 2008 and 2011 , we identified 1064 cases and 2059 r and om controls . The frequency of severe PPH was 2.5 % ( 95 % confidence interval ( CI ) : 2.32–2.62 ) . The most common etiologies for severe PPH were uterine atony ( 60 % ) and placental complications ( 36 % ) . The strongest risk factors were a history of severe PPH ( adjusted OR ( aOR ) = 8.97 , 95 % CI : 5.25–15.33 ) , anticoagulant medication ( aOR = 4.79 , 95 % CI : 2.72–8.41 ) , anemia at booking ( aOR = 4.27 , 95 % CI : 2.79–6.54 ) , severe pre-eclampsia or HELLP syndrome ( aOR = 3.03 , 95 % CI : 1.74–5.27 ) , uterine fibromas ( aOR = 2.71 , 95 % CI : 1.69–4.35 ) , multiple pregnancy ( aOR = 2.11 , 95 % CI : 1.39–3.22 ) and assisted reproductive technologies ( aOR = 1.88 , 95 % CI : 1.33–2.65 ) . Conclusions Based on our findings , women with a history of severe PPH are at highest risk of severe PPH . As well as other established clinical risk factors for PPH , a history of severe PPH should be included as a risk factor in the development and validation of prediction models for PPH Objective Our main objective was to investigate the association between  duration of active labor  and  severe postpartum hemorrhage . We examined the effect of the total duration of active labor , the effect of each stage of active labor , and the gradient effect of duration of labor on severe postpartum hemorrhage . Methods A case-control study was generated from a source population of all women admitted for delivery at Oslo University Hospital and Drammen Hospital in Buskerud municipality during the time period January 1 , 2008 to December 31 , 2011 . The study population included all cases of severe postpartum hemorrhage ( n = 859 ) and a r and om sample of controls ( n = 1755 ) . Severe postpartum hemorrhage was defined as postpartum blood loss ≥1500 mL or need for blood transfusion . Prolonged labor was defined as duration of active labor > 12 hours according to the definition of the World Health Organization . We used logistic multivariable regression in the analysis . Results We observed a significantly longer mean duration of labor in women who experienced severe postpartum hemorrhage compared to controls ( 5.4 versus 3.8 hours , p<0.001 ) . Women with severe postpartum hemorrhage also had a longer duration of all stages of active labor compared to controls . The association between the duration of active labor and severe postpartum changed from a linear dose-response association to a threshold association after adjusting for augmentation with oxytocin , induction of labor , primiparity , and fever during labor . Compared to controls , women with severe postpartum hemorrhage were more likely to have a prolonged labor > 12 hours ( adjusted odds ratio = 2.44 , 95 % confidence interval : 1.69–3.53 , p < 0.001 ) . Conclusion Prolong 
    Output:
    
Maternal , pregnancy-associated , laborcorrelated and sociodemographic risk factors seem to be important predictors of EPH .
Interestingly , the majority of uterotonics seem to have a similar effect .
However , carbetocin seems to be the most effective in certain situations .