Neonatal hemoglobin typically declines to a nadir around which age?

Neonatal hemoglobin typically declines to a nadir around which age?

• A. At birth
• B. 1 month
• C. 2-3 months
• D. 9 months

Answer: (C)

After birth, healthy term infants experience a normal dip in hemoglobin known as physiologic anemia of infancy. This drop happens because the transition from fetal to adult hemoglobin, along with hemodilution from rapid plasma volume expansion and a relative decrease in erythropoietin as oxygenation improves, reduces red cell mass for a short period. The lowest point of this curve typically occurs around two to three months of age, when hemoglobin is often in the 9–11 g/dL range for term infants. After this nadir, hemoglobin gradually rises toward the normal range over the next several months as erythropoiesis increases and fetal hemoglobin is replaced by adult hemoglobin. So the nadir around 2–3 months best fits the pattern. At birth the hemoglobin is higher due to fetal Hb; by one month the level has already begun to fall but is not yet at its lowest; by nine months it is typically rising again, not at the nadir.

After birth, healthy term infants experience a normal dip in hemoglobin known as physiologic anemia of infancy. This drop happens because the transition from fetal to adult hemoglobin, along with hemodilution from rapid plasma volume expansion and a relative decrease in erythropoietin as oxygenation improves, reduces red cell mass for a short period. The lowest point of this curve typically occurs around two to three months of age, when hemoglobin is often in the 9–11 g/dL range for term infants. After this nadir, hemoglobin gradually rises toward the normal range over the next several months as erythropoiesis increases and fetal hemoglobin is replaced by adult hemoglobin. So the nadir around 2–3 months best fits the pattern. At birth the hemoglobin is higher due to fetal Hb; by one month the level has already begun to fall but is not yet at its lowest; by nine months it is typically rising again, not at the nadir.