What is physiologic anemia during pregnancy primarily caused by?

Physiologic anemia during pregnancy is primarily caused by increased blood volume. During pregnancy, a woman's body undergoes significant changes to support the growing fetus, one of which includes an increase in plasma volume. This increase in volume is more pronounced than the increase in red blood cell mass, leading to a dilution effect—often referred to as 'hemodilution.' As a result, despite an overall increase in red blood cells, the concentration per volume decreases, which is what is classified as physiologic anemia.

Given that physiological anemia reflects a normal adaptation to pregnancy rather than an iron deficiency or pathological condition, the increased blood volume is a key factor. It allows for improved blood flow and nutrient delivery to the placenta and supports the expanding needs of both the mother and the fetus. This adaptation is vital for ensuring adequate perfusion and oxygen delivery throughout the pregnancy.