Which combination of factors contributes to a rightward shift of the oxygen dissociation curve in neonates?

• A. Increased DPG with Higher HbA Proportion
• B. Increased DPG Only
• C. Increased HbF Only
• D. Decreased DPG and HbA

Answer: (A)

Rightward shifts in the oxygen dissociation curve mean hemoglobin has a lower affinity for oxygen, so it releases O2 more readily to tissues. In neonates, two factors shape this shift: the type of hemoglobin present and the level of 2,3-DPG in red cells. HbF (fetal hemoglobin) binds oxygen more tightly and carries little 2,3-DPG, which tends to keep the curve to the left. After birth, HbA becomes more prevalent and 2,3-DPG levels rise; 2,3-DPG binds to deoxygenated HbA and stabilizes the T-state, lowering O2 affinity and shifting the curve to the right. Therefore, having more HbA and higher DPG produces the strongest rightward shift, enhancing O2 unloading to tissues. If HbF remains high or DPG does not rise, the shift toward the right would be less pronounced.