Which statement about fetal hemoglobin is correct?

Fetal hemoglobin, also known as hemoglobin F, plays a crucial role in pregnancy by enabling effective oxygen transfer from the mother to the fetus. Its structural differences compared to adult hemoglobin (hemoglobin A) result in a higher affinity for oxygen. This property ensures that fetal hemoglobin can effectively extract oxygen from maternal blood, even when oxygen levels are low.

Fundamentally, this high affinity is vital because the fetal circulatory system relies on this mechanism to receive adequate oxygen supply, which is critical for proper development and growth. The presence of fetal hemoglobin is predominantly in the developing fetus and gradually decreases after birth as adult hemoglobin levels rise.

In contrast, other statements do not accurately reflect the functional characteristics and significance of fetal hemoglobin. The decreased affinity for oxygen is inconsistent with its primary role; fetal hemoglobin being found in adults usually refers to only small amounts present, and it is not less effective than adult hemoglobin but rather optimized for the fetal environment.