Key messages

• The best time for women to begin receiving an allogeneic blood transfusion (where blood from a donor is injected into the woman's bloodstream through a vein) to reduce complications from excessive blood loss within 24 hours of birth (postpartum haemorrhage) is unknown.

• The effect of blood products (substances produced from whole blood) instead of, or in addition to, whole blood transfusion on reducing complications of postpartum haemorrhage is largely uncertain.

What is postpartum haemorrhage?

Postpartum haemorrhage is heavy bleeding after birth. It is commonly defined as a blood loss of 500 mL or more within 24 hours of birth. Worldwide, it is one of the leading causes of maternal death.

How is postpartum haemorrhage treated?

There are presently no guidelines on how postpartum haemorrhage should be treated, but transfusions of whole blood or parts of the blood (called blood products, such as fresh frozen plasma, which is made from the liquid part of the blood) can be used to manage postpartum haemorrhage and prevent complications among women who are actively bleeding.

What did we want to find out?

We wanted to find out the benefits and harms of different transfusion treatments for managing postpartum haemorrhage, which women should begin receiving a blood transfusion and when, and which blood products, alone or in combination, are best.

What did we do?

We searched for studies that evaluated the benefits and harms of blood transfusion for managing postpartum haemorrhage. We compared and summarised the results of the studies and rated our confidence in the evidence, based on factors such as study methods and sizes.

What did we find?

We found 12 studies with 17,868 women. We were able to use eight of these studies as four had problems with study design.

We found no certain evidence on when to start blood transfusion or on whether using blood products instead of, or in addition to, whole blood transfusion reduces complications of postpartum haemorrhage. Overall, we had very little confidence in the findings. Several factors affected this. Many studies did not randomly place women into the different treatment groups. This means that differences between the groups could have been due to differences between women rather than between the treatments. While some studies did randomly place women into the treatment groups, we had concerns about how this was done. A few studies were small and the results varied.

What are the limitations of the evidence?

We could not draw any conclusions on the benefits and harms of blood transfusions for postpartum haemorrhage management with any certainty because the studies produced findings in which we have very little overall confidence.

How up to date is the evidence?

The evidence is up to date to 18 July 2024.