PPH is a leading global cause of maternal deaths during pregnancy. Treatment must be given quickly and delays in recognizing the condition cost lives. Doctors worldwide currently use a threshold of 500 mL or more of blood loss to diagnose PPH, however, this threshold is not based on strong evidence.

This study analyzed data from more than 300,000 women from 23 countries, to assess the sensitivity and specificity of using different warning signs to predict complications from PPH. Their study found:

• The conventional 500 mL threshold measure of blood loss predicted severe life-threatening complications with 76% sensitivity and 81% specificity
• The lower threshold of 300 mL with no additional measures had 84% sensitivity and 55% specificity
• The lower threshold of 300 mL plus high heart rate or low blood pressure or vital signs suggestive of shock; or measured blood loss threshold of at least 500 mL (whichever occurs first) had 88% sensitivity and 67% specificity