It goes up consistently from 6-8 weeks gestation and to the highest point of maximum of ~150% pre-pregnancy level, around 32-34 weeks. Facilitates maternal/fetal exchange of: respiratory gases, nutrients, and metabolites, and reduces impact of maternal blood loss at delivery.
- Red cell mass increases by 20-30%. Smaller than the ~50% increase in plasma volume. Net reduction in hemoglobin occurs.