Anemia is associated with postpartum hemorrhage-- but why? For the non-clinical elements among us, we seek to break down this issue a little further. 45% of women worldwide are anemic, roughly half of them due to iron-deficiency anemia caused by inadequate iron in the diet. Pregnancy puts a high demand on iron stores, and women who have had multiple pregnancies and perhaps began in a slightly anemic state are further depleted with each pregnancy. Thus a woman facing labor in a moderately or severely anemic state may be at [greater risk from excessive blood loss. Jorge Tolosa uses a succinct analogy, "A woman with severe anemia is already running low on fuel, running on empty" he states.
Anemia, in a layperson's terms, means that there is [less hemoglobin in the blood --fewer red blood cells carrying oxygen]. This means that less oxygen can be carried to vital organs-- in childbirth, this means less oxygen to the [uterus, fetus and placenta] and at a cellular level, the mechanisms that work to contract the necessary muscles are impaired.
If we recall that the main reason for postpartum hemorrhage is uterine atony (failure of the uterus to contract properly), then the link between anemia and postpartum hemorrhage becomes more clear. Lower hemoglobin, less oxygen carrying capacity, less capacity to contract the uterus, higher postpartum hemorrhage. Severe anemia (normally defined as hemoglobin [Hb] < 70 g/l) can result in circulatory decompensation and increased cardiac output at rest. The added stress of labor and blood loss, whether normal or excessive, can lead to circulatory shock and death.
There is also evidence to suggest that anemia is associated with prolonged labor, lower wound-healing capacity and greater likelihood of having sepsis--another key cause of maternal mortality.
The question of how to prevent and treat anemia in pregnancy proves to be a fairly difficult one-- which we will examine in a later post. For iron deficiency anemia, iron and folate supplementation is the usual recommended intervention. In the meantime, however, knowing the anemia status of a woman in the early stages of labor seems important. Is it important to know that a woman is severely anemic? What is the cutoff for blood loss if a woman is severely anemic and 10 miles from a health facility? There are so many questions that are not yet answered.
It is also important to note there are associations between severe anemia and postpartum hemorrhage, prolonged labor and possibly sepsis as well. We'll continue to follow the research, though it is surprising how little research there is on maternal outcomes.