Oxytocin for preventing postpartum haemorrhage (PPH) in non-facility birth settings

Tranexamic acid versus oxytocin for primary postpartum Haemorrhage in the out-of-hospital setting: A systematic review with implications for rural practice

INTRODUCTION

Primary postpartum haemorrhage causes approximately 25% of global maternal deaths and accounts for significant maternal morbidity. While high certainty evidence demonstrates that tranexamic acid reduces comparative blood loss in postpartum haemorrhage in hospital settings, limited data exist on the specific pharmacological management of this condition in out-of-hospital settings, and the implications for rural communities.

OBJECTIVE

To determine the efficacy of oxytocin compared to tranexamic acid in women suffering postpartum haemorrhage in the out-of-hospital environment.

DESIGN

A systematic review comparing evidence containing patients with postpartum haemorrhage in the out-of-hospital and/or rural setting, in which oxytocin/tranexamic acid were used. Outcome measures were comparative blood loss/haemorrhagic shock, the need for further interventions and maternal/neonatal morbidity/mortality.

FINDINGS

No randomised control trials have been conducted in an out-of-hospital environment in relation to oxytocin/tranexamic acid. In this setting, there is no difference in outcome measures when using oxytocin compared to no intervention, or oxytocin compared to standard care. Data are lacking on the effect of tranexamic acid on the same outcome measures.

DISCUSSION

Rural and out-of-hospital management of postpartum haemorrhage is limited by resource availability and practitioner availability, capacity and experience. In-hospital evidence may lack transferability, therefore direct evidence on the efficacy of pharmacological management in these contexts is scant and requires redress.

CONCLUSION

There is no difference in blood loss, neonatal or maternal mortality or morbidity, or need for further interventions, when using oxytocin or TXA compared to no intervention, or compared to standard care, for PPH. Further studies are needed on the efficacy of these drugs, and alternate or co-drug therapies, for PPH in the out-of-hospital environment and rural clinical practice.

Systematic review of women's experiences of planning home birth in consultation with maternity care providers in middle to high-income countries

AIM

To synthesise findings from published studies, which reported on women's experiences of planning a home birth in consultation with maternity care providers.

DESIGN

Systematic Review DATA SOURCES: We searched seven bibliographic databases, (Ovid Medline, Embase, PsycInfo, CINAHL plus, Scopus, ProQuest and Cochrane (Central and Library), from January 2015 to 29th April 2022.

REVIEW METHODS

Primary studies were included if they investigated women's experiences of planning a home birth with maternity care providers, in upper-middle and high-income countries and written in English language. Studies were analysed using thematic synthesis. GRADE-CERQual was used to assess the quality, coherence, adequacy and relevance of data. The protocol is registered on PROSPERO registration ID: CRD 42018095042 (updated 28th September 2020) and published.

RESULTS

1274 articles were retrieved, and 410 duplicates removed. Following screening and quality appraisal, 20 eligible studies (19 qualitative and 1 survey) involving 2,145 women were included.

KEY CONCLUSIONS

Women's prior traumatic experience of hospital birth and a preference for physiological birth motivated their assertive decision to have a planned home birth despite criticisms and stigmatisation from their social circle and some maternity care providers. Midwives' competence and support enhanced women's confidence and positive experiences of planning a home birth.

IMPLICATIONS FOR PRACTICE

This review highlights the stigma that some women feel and the importance of support from health professionals, particularly midwives when planning a home birth. We recommend accessible evidence-based information for women and their families to support women's decision-making for planned home birth. The findings from this review can be used to inform woman-centred planned home birth services, particularly in the UK, (although evidence is drawn from papers in eight other countries, so findings are relevant elsewhere), which will impact positively on the experiences of women who are planning home birth.

Effects of Motherwort Injection Versus Intramuscular Oxytocin for Preventing Postpartum Hemorrhage Among Women Who Underwent Cesarean Section

Objectives: Subject to ethical constraints, real-world data are an important resource for evaluating treatment effects of medication use during pregnancy and the postpartum period. This study investigated whether motherwort injection, a traditional Chinese medicine preparation, was more effective than intramuscular (IM) oxytocin for preventing postpartum hemorrhage (PPH) in a real-world setting when intravenous (IV) oxytocin is administered.

Methods: We conducted an active-controlled, propensity-score matched cohort study using an established pregnancy registry database. Women who underwent cesarean section and received IV oxytocin at the third stage of labor were included. We used an active-comparator design to minimize indication bias, in which we compared IM motherwort injection in the uterus versus IM oxytocin, both on top of IV oxytocin use. We applied 1:1 propensity-score matching (PSM) to balance patient baseline characteristics and used a logistic regression model to estimate treatment effect (i.e., risk difference (RD) and odds ratio (OR)) by using the counterfactual framework. The outcomes of interest were blood loss over 500 ml within 2 h after delivery (PPH, primary) and blood loss over 1,000 ml (severe PPH, secondary). We conducted four sensitivity analyses to examine the robustness of the results.

Results: A total of 22,519 pregnant women underwent cesarean sections, among which 4,081 (18.12%) PPH and 480 (2.13%) severe PPH occurred. Among included women, 586 (2.60%) were administrated with IM motherwort injection, and 21,933 (97.40%) used IM oxytocin. After PSM, patient baseline characteristics were well balanced. Compared with IM oxytocin, the use of IM motherwort injection was associated with significantly lower risk of PPH (RD −25.26%, 95% CI −30.04% to −20.47%, p < 0.001; OR 0.25, 95% CI 0.18 to 0.32, p < 0.001) and severe PPH (RD −3.58%, 95% CI −5.87% to −1.30%, p < 0.001; OR 0.39, 95% CI 0.20 to 0.71, p < 0.002). Sensitivity analyses showed that the results were similar.

Conclusion: With the use of data from a real-world setting, the findings consistently showed that among women undergoing cesarean section who had received IV oxytocin, the additional use of IM motherwort injection could achieve a lower risk of PPH as compared to the additional use of IM oxytocin. Our study suggested a paradigm for investigating the treatment effect of Chinese herbal medicine in the real-world practice setting.

Mechanical and surgical interventions for treating primary postpartum haemorrhage

BACKGROUND

Primary postpartum haemorrhage (PPH) is commonly defined as bleeding from the genital tract of 500 mL or more within 24 hours of birth. It is one of the most common causes of maternal mortality worldwide and causes significant physical and psychological morbidity. An earlier Cochrane Review considering any treatments for the management of primary PPH, has been split into separate reviews. This review considers treatment with mechanical and surgical interventions.

OBJECTIVES

To determine the effectiveness and safety of mechanical and surgical interventions used for the treatment of primary PPH.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) (26 July 2019) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of mechanical/surgical methods for the treatment of primary PPH compared with standard care or another mechanical/surgical method. Interventions could include uterine packing, intrauterine balloon insertion, artery ligation/embolism, or uterine compression (either with sutures or manually). We included studies reported in abstract form if there was sufficient information to permit risk of bias assessment. Trials using a cluster-RCT design were eligible for inclusion, but quasi-RCTs or cross-over studies were not.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for inclusion and risk of bias, independently extracted data and checked data for accuracy. We used GRADE to assess the certainty of the evidence.

MAIN RESULTS

We included nine small trials (944 women) conducted in Pakistan, Turkey, Thailand, Egypt (four trials), Saudi Arabia, Benin and Mali. Overall, included trials were at an unclear risk of bias. Due to substantial differences between the studies, it was not possible to combine any trials in meta-analysis. Many of this review's important outcomes were not reported. GRADE assessments ranged from very low to low, with the majority of outcome results rated as very low certainty. Downgrading decisions were mainly based on study design limitations and imprecision; one study was also downgraded for indirectness. External uterine compression versus normal care (1 trial, 64 women) Very low-certainty evidence means that we are unclear about the effect on blood transfusion (risk ratio (RR) 2.33, 95% confidence interval (CI) 0.66 to 8.23). Uterine arterial embolisation versus surgical devascularisation plus B-Lynch (1 trial, 23 women) The available evidence for hysterectomy to control bleeding (RR 0.73, 95% CI 0.15 to 3.57) is unclear due to very low-certainty evidence. The available evidence for intervention side effects is also unclear because the evidence was very low certainty (RR 1.09; 95% CI 0.08 to 15.41). Intrauterine Tamponade Studies included various methods of intrauterine tamponade: the commercial Bakri balloon, a fluid-filled condom-loaded latex catheter ('condom catheter'), an air-filled latex balloon-loaded catheter ('latex balloon catheter'), or traditional packing with gauze. Balloon tamponade versus normal care (2 trials, 356 women) One study(116 women) used the condom catheter. This study found that it may increase blood loss of 1000 mL or more (RR 1.52, 95% CI 1.15 to 2.00; 113 women), very low-certainty evidence. For other outcomes the results are unclear and graded as very low-certainty evidence: mortality due to bleeding (RR 6.21, 95% CI 0.77 to 49.98); hysterectomy to control bleeding (RR 4.14, 95% CI 0.48 to 35.93); total blood transfusion (RR 1.49, 95% CI 0.88 to 2.51); and side effects. A second study of 240 women used the latex balloon catheter together with cervical cerclage. Very low-certainty evidence means we are unclear about the effect on hysterectomy (RR 0.14, 95% CI 0.01 to 2.74) and additional surgical interventions to control bleeding (RR 0.20, 95% CI 0.01 to 4.12). Bakri balloon tamponade versus haemostatic square suturing of the uterus (1 trial, 13 women) In this small trial there was no mortality due to bleeding, serious maternal morbidity or side effects of the intervention, and the results are unclear for blood transfusion (RR 0.57, 95% CI 0.14 to 2.36; very low certainty). Bakri balloon tamponade may reduce mean 'intraoperative' blood loss (mean difference (MD) -426 mL, 95% CI -631.28 to -220.72), very low-certainty evidence. Comparison of intrauterine tamponade methods (3 trials, 328 women) One study (66 women) compared the Bakri balloon and the condom catheter, but it was uncertain whether the Bakri balloon reduces the risk of hysterectomy to control bleeding due to very low-certainty evidence (RR 0.50, 95% CI 0.05 to 5.25). Very low-certainty evidence also means we are unclear about the results for the risk of blood transfusion (RR 0.97, 95% CI 0.88 to 1.06). A second study (50 women) compared Bakri balloon, with and without a traction stitch. Very low-certainty evidence means we are unclear about the results for hysterectomy to control bleeding (RR 0.20, 95% CI 0.01 to 3.97). A third study (212 women) compared the condom catheter to gauze packing and found that it may reduce fever (RR 0.47, 95% CI 0.38 to 0.59), but again the evidence was very low certainty. Modified B-Lynch compression suture versus standard B-Lynch compression suture (1 trial, 160 women) Low-certainty evidence suggests that a modified B-Lynch compression suture may reduce the risk of hysterectomy to control bleeding (RR 0.33, 95% CI 0.11 to 0.99) and postoperative blood loss (MD -244.00 mL, 95% CI -295.25 to -192.75).

AUTHORS' CONCLUSIONS

There is currently insufficient evidence from RCTs to determine the relative effectiveness and safety of mechanical and surgical interventions for treating primary PPH. High-quality randomised trials are urgently needed, and new emergency consent pathways should facilitate recruitment. The finding that intrauterine tamponade may increase total blood loss > 1000 mL suggests that introducing condom-balloon tamponade into low-resource settings on its own without multi-system quality improvement does not reduce PPH deaths or morbidity. The suggestion that modified B-Lynch suture may be superior to the original requires further research before the revised technique is adopted. In high-resource settings, uterine artery embolisation has become popular as the equipment and skills become more widely available. However, there is little randomised trial evidence regarding efficacy and this requires further research. We urge new trial authors to adopt PPH core outcomes to facilitate consistency between primary studies and subsequent meta-analysis.

Comparison of Blood Loss in Manual and Spontaneous Removal of Placenta in Caesarean Section

Background: Efforts should be made to minimize the blood loss at the time of cesarean section. The techniques used to reduce the blood loss include finger splitting versus scissor cutting of incision, in situ stitching versus exteriorization and stitching of uterus and finally spontaneous or manual removal of the placenta. Objective: The main objective of this study is to correlate the frequency of loss of blood between the placenta removed manually and spontaneously during cesarean section. Methods: Randomized controlled trial in the department of Obstetrics and Gynecology, Fauji Foundation Hospital, Rawalpindi. The sample is collected through Consecutive (non- probability) sampling. The study was conducted after approval from the hospital ethical and research committee. Informed written consent was taken from all the patients. The patients were divided into two groups, group A and group B randomly by using random table numbers. Group A had spontaneous placental delivery. Group B had manual placental delivery. Each patient was examined thoroughly and detailed history was taken. Data Analysis: Data was analyzed using SPSS 20 for windows. The frequency and percentage of blood loss were measured. A chi-square test was applied to correlate the blood loss between the two groups. p values <0.05 were considered statistically significant. Effect modifiers like age, gestational age, parity were controlled by stratification. Results: The blood loss was compared between both groups using the chi-square test not assuming null-hypothesis. The blood loss was comparatively high in-group in which the placenta was removed manually (p=0.007). Keywords: Caesarean Section, Placenta removal, Spontaneous, Manual, Blood loss.

Postpartum haemorrhage (PPH) rates in randomized trials of PPH prophylactic interventions and the effect of underlying participant PPH risk: a meta-analysis

Background

Postpartum haemorrhage (PPH) remains a leading cause of maternal mortality. Many trials assessing interventions to prevent PPH base their data on low risk women. It is important to consider the impact data collection methods may have on these results. This review aims to assess trials of PPH prophylaxis by grading trials according to the degree of risk status of the population enrolled in these trials and identify differences in the PPH rates of low risk and high risk populations.

Methods

Systematic review and meta-analysis using a random-effects model. Trials were identified through CENTRAL. Trials were assessed for eligibility then graded according to antenatal risk factors and method of birth into five grades. The main outcomes were overall trial rate of minor PPH (blood loss ≥500 ml) and major PPH (> 1000 ml) and method of determining blood loss (estimated/measured).

Results

There was no relationship between minor or major PPH rate and risk grade (Kruskal-Wallis: minor - T = 0.92, p = 0.82; major - T = 0.91, p = 0.92). There was no difference in minor or major PPH rates when comparing estimation or measurement methods (Mann-Whitney: minor - U = 67, p = 0.75; major - U = 35, p = 0.72). There was however a correlation between % operative births and minor PPH rate, but not major PPH (Spearman r = 0.32 v. Spearman r = 0.098).

Conclusions

Using data from trials using low risk women to generalise best practice guidelines might not be appropriate for all births, particularly complex births. Although complex births contribute disproportionately to PPH rates, this review showed they are often underrepresented in trials. Despite this, there was no difference in reported PPH rates between studies conducted in high and low risk groups. Method of birth was shown to be an important risk factor for minor PPH and may be a better predictor of PPH than antenatal risk factors. Women with operative births are often excluded from trials meaning a lack of data supporting interventions in these women. More focus on complex births is needed to ensure the evidence base is relevant to the target population.

Traditional Chinese Medicine Yimucao Injection Combined with Western Medicine for Preventing Postpartum Hemorrhage after Cesarean Section: A Systematic Review and Meta-Analysis

Objective

Yimucao injection combined with several contraction uterus drugs is in use for preventing postpartum hemorrhage after cesarean section. The present study is a meta-analysis comparing the efficacy and safety of these drugs.

Methods

PubMed, Cochrane Library, Embase, the China National Knowledge Infrastructure (CNKI), the Chinese Biomedical Database (CBM), VIP, and Wanfang database were searched until June 2018. We selected RCTs of Yimucao injection combined with western medicine for preventing postpartum hemorrhage and study quality was assessed using the revised Cochrane risk of bias tool. Forty-eight RCTs are comprised of 7,330 participants.

Results

The overall response rate of Yimucao injection combined with western medicine as a class (OR=4.19, 95%CI=2.83, 6.20, P<0.00001) was found to be significantly improved than western medicine alone. Yimucao injection combined with western medicine group could significantly reduce blood loss in intraoperative (SMD= -1.15, 95%CI= -1.43, -0.87, P<0.00001), compared with control group. The treatment group could significantly reduce postpartum blood loss within 2 hours (SMD= -1.73, 95%CI= -2.01, -1.46, P<0.00001) and had a significantly lower blood loss within 24 hours (SMD= -1.92, 95%CI= -2.21, -1.63, P<0.00001) than control group. Additionally, in terms of the safety, Yimucao injection group reduced the risk of adverse events in the course of prevention than the western medicine group.

Conclusions

This study demonstrated that Yimucao injection combined with western medicine may be more effective for preventing postpartum hemorrhage after cesarean section. However, high-quality and large multicenter randomized clinical trials will be needed to prove the consequence in the further.

Prophylactic oxytocin for the third stage of labour to prevent postpartum haemorrhage

BACKGROUND

Active management of the third stage of labour reduces the risk of postpartum blood loss (postpartum haemorrhage (PPH)), and is defined as administration of a prophylactic uterotonic, early umbilical cord clamping and controlled cord traction to facilitate placental delivery. The choice of uterotonic varies across the globe and may have an impact on maternal outcomes. This is an update of a review first published in 2001 and last updated in 2013.

OBJECTIVES

To determine the effectiveness of prophylactic oxytocin to prevent PPH and other adverse maternal outcomes in the third stage of labour.

SEARCH METHODS

For this update, we searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, WHO International Clinical Trials Registry Platform (ICTRP) (6 March 2019) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised, quasi- or cluster-randomised trials including women undergoing vaginal delivery who received prophylactic oxytocin during management of the third stage of labour. Primary outcomes were blood loss 500 mL or more after delivery, need for additional uterotonics, and maternal all-cause mortality.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion, extracted data, and assessed trial quality. Data were checked for accuracy. We assessed the quality of the evidence using the GRADE approach.

MAIN RESULTS

This review includes 24 trials, with 23 trials involving 10,018 women contributing data. Due to many trials assessed at high risk of bias, evidence grade ranged from very low to moderate quality.Prophylactic oxytocin versus no uterotonics or placebo (nine trials)Prophylactic oxytocin compared with no uterotonics or placebo may reduce the risk of blood loss of 500 mL after delivery (average risk ratio (RR) 0.51, 95% confidence interval (C) 0.37 to 0.72; 4162 women; 6 studies; Tau² = 0.10, I² = 75%; low-quality evidence), and blood loss 1000 mL after delivery (RR 0.59, 95% CI 0.42 to 0.83; 4123 women; 5 studies; low-quality evidence). Prophylactic oxytocin probably reduces the need for additional uterotonics (average RR 0.54, 95% CI 0.36 to 0.80; 3135 women; 4 studies; Tau² = 0.07, I² = 44%; moderate-quality evidence). There may be no difference in the risk of needing a blood transfusion in women receiving oxytocin compared to no uterotonics or placebo (RR 0.88, 95% CI 0.44 to 1.78; 3081 women; 3 studies; low-quality evidence). Oxytocin may be associated with an increased risk of a third stage greater than 30 minutes (RR 2.55, 95% CI 0.88 to 7.44; 1947 women; 1 study; moderate-quality evidence), however the confidence interval is wide and includes 1.0, indicating that there may be little or no difference.Prophylactic oxytocin versus ergot alkaloids (15 trials)It is uncertain whether oxytocin reduces the likelihood of blood loss 500 mL (average RR 0.84, 95% CI 0.56 to 1.25; 3082 women; 10 studies; Tau² = 0.14, I² = 49%; very low-quality evidence) or the need for additional uterotonics compared to ergot alkaloids (average RR 0.89, 95% CI 0.43 to 1.81; 2178 women; 8 studies; Tau² = 0.76, I² = 79%; very low-quality evidence), because the quality of this evidence is very low. The quality of evidence was very low for blood loss of 1000 mL (RR 1.13, 95% CI 0.63 to 2.01; 1577 women; 3 studies; very low-quality evidence), and need for blood transfusion (average RR 1.37, 95% CI 0.34 to 5.51; 1578 women; 7 studies; Tau² = 1.34, I² = 45%; very low-quality evidence), making benefit of oxytocin over ergot alkaloids uncertain. Oxytocin probably increases the risk of a prolonged third stage greater than 30 minutes (RR 4.69, 95% CI 1.63 to 13.45; 450 women; 2 studies; moderate-quality evidence), although it is uncertain if this translates into increased risk of manual placental removal (average RR 1.10, 95% CI 0.39 to 3.10; 3127 women; 8 studies; Tau² = 1.07, I² = 76%; very low-quality evidence). Oxytocin may make little or no difference to risk of diastolic blood pressure > 100 mm Hg (average RR 0.28, 95% CI 0.04 to 2.05; 960 women; 3 studies; Tau² = 1.23, I² = 50%; low-quality evidence), and is probably associated with a lower risk of vomiting (RR 0.09, 95% CI 0.05 to 0.14; 1991 women; 7 studies; moderate-quality evidence), although the impact of oxytocin on headaches is uncertain (average RR 0.19, 95% CI 0.03 to 1.02; 1543 women; 5 studies; Tau² = 2.54, I² = 72%; very low-quality evidence).Prophylactic oxytocin-ergometrine versus ergot alkaloids (four trials)Oxytocin-ergometrine may slightly reduce the risk of blood loss greater than 500 mL after delivery compared to ergot alkaloids (RR 0.44, 95% CI 0.20 to 0.94; 1168 women; 3 studies; low-quality evidence), based on outcomes from quasi-randomised trials with a high risk of bias. There were no maternal deaths reported in either treatment group in the one trial that reported this outcome (RR not estimable; 1 trial, 807 women; moderate-quality evidence). Need for additional uterotonics was not reported.No subgroup differences were observed between active or expectant management, or different routes or doses of oxytocin for any of our comparisons.

AUTHORS' CONCLUSIONS

Prophylactic oxytocin compared with no uterotonics may reduce blood loss and the need for additional uterotonics. The effect of oxytocin compared to ergot alkaloids is uncertain with regards to blood loss, need for additional uterotonics, and blood transfusion. Oxytocin may increase the risk of a prolonged third stage compared to ergot alkaloids, although whether this translates into increased risk of manual placental removal is uncertain. This potential risk must be weighed against the possible increased risk of side effects associated with ergot alkaloids. Oxytocin-ergometrine may reduce blood loss compared to ergot alkaloids, however the certainty of this conclusion is low. More high-quality trials are needed to assess optimal dosing and route of oxytocin administration, with inclusion of important outcomes such as maternal mortality, shock, and transfer to a higher level of care. A network meta-analysis of uterotonics for PPH prevention plans to address issues around optimal dosing and routes of oxytocin and other uterotonics.

Prophylactic management of postpartum haemorrhage in the third stage of labour: an overview of systematic reviews

BACKGROUND

Postpartum haemorrhage is a direct cause of maternal death worldwide and usually occurs during the third stage of labour. Most women receive some type of prophylactic management, which may include pharmacological or non-pharmacological interventions. The objective of this study was to summarize systematic reviews that assessed the effects of postpartum haemorrhage prophylactic management during the third stage of labour.

METHODS

We applied the guidelines for conducting an overview of reviews from the Cochrane Handbook for Systematic Reviews of Interventions. We searched MEDLINE, EMBASE, and the Cochrane Database of Systematic Reviews to identify all relevant systematic reviews of randomized controlled trials of prophylactic management of postpartum haemorrhage in the third stage of labour compared with no treatment, placebo, or another management technique. Two review authors independently extracted data and assessed methodological quality using a measurement tool to assess reviews and quality of evidence using the Grades of Recommendation, Assessment, Development, and Evaluation for primary outcomes, summarizing results narratively.

RESULTS

We identified 29 systematic reviews: 18 Cochrane and 11 non-Cochrane. Cochrane systematic reviews were high quality, while the quality of non-Cochrane systematic reviews varied. The following techniques suggested effective, third-stage interventions to reduce the incidence of severe postpartum haemorrhage: active management of the third stage of labour compared to physiological management, active management compared to expectant management, administration of oxytocin compared to placebo, and use of tranexamic acid compared to placebo. The following third-stage management approaches reduced the need for blood transfusion: active management compared to physiological management, active management compared to expectant management, oral misoprostol compared to placebo, and tranexamic acid compared to placebo.

CONCLUSIONS

No effective prophylactic management techniques were identified for maternal mortality. Most methods of effective prophylactic management of postpartum haemorrhage were supported by evidence; however, they were limited to low- or moderate-quality evidence, and high-quality studies are therefore needed. Outcome measures of the included systematic reviews varied. It is recommended that outcome measures in preventive postpartum haemorrhage intervention trials align with the World Health Organization guidelines.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO: CRD42016049220 .