Categories of postpartum haemorrhage
Physical reaction of the woman
A postpartum haemorrhage can be classified into how severe the haemorrhage is, based on the actual amount of blood lost. A caregiver can also take into the consideration the physical reaction of the woman and how much help or intervention she required after the bleed, when assessing how severe it was.
Different countries will define a postpartum haemorrhage with different estimate amounts for the blood loss. Some will state 500mls or more, others (like Australia) 600 mls or more. A few caregivers have suggested the limit of 1000mls as being more appropriate, as it will normally take a blood loss of this amount to produce any noticeable problems for most women.
The fact that an 'estimated blood loss' can be 35 to 50% out and it is possible that the estimate can be on the conservative side (or an 'underestimation'), as well as the fact that many women will normally lose about 500 mls after the birth, the definition of 600 mls has become the Australian benchmark.
Categories of postpartum haemorrhage
A postpartum haemorrhage can be classified into grades of severity, relating to the amount of blood actually lost by the woman. The severity reflects the percentage of blood lost from the woman's total blood volume.
The blood volume of a pregnant woman increases by up to 50% during pregnancy, peaking by about 32 weeks of pregnancy to around 6000 mls (or 6 litres) or more. It stays at this level until after the baby is born. The increase involves the plasma part of the blood, or the clear fluid that all the blood cells float in. This 'dilutes' the blood in a sense.
Some of this blood is lost at the birth, normally 200 to 400 mls or up to 550 mls (being 3 to 10 % of the total blood volume). The remainder is naturally depleted back to non-pregnant blood volume levels through the mother passing large amounts of urine in the first few days after the birth, as her body readjusts.