How does fetal hemoglobin enhance oxygen transfer across placenta?

Fetal hemoglobin (HbF) has a higher affinity for oxygen compared to maternal hemoglobin (HbA), allowing it to effectively extract oxygen from the maternal blood in the placenta. This enhanced affinity is primarily due to HbF's reduced ability to bind 2,3-bisphosphoglycerate, which stabilizes the deoxygenated form of hemoglobin. As a result, HbF can capture more oxygen even at lower partial pressures, facilitating efficient oxygen transfer during fetal development. This mechanism ensures that the developing fetus receives adequate oxygen for growth and metabolic needs.