Fetal hemoglobin (Hemoglobin F), Alkali-resistant hemoglobin, HBF (or Hb F), is the major hemoglobin component in the bloodstream of the fetus. After birth, it decreases rapidly until only traces are found in normal.

Greater than 2% of total hemoglobin is abnormal.

Fetal hemoglobin has a pair of gamma-globin molecules in place of the typical beta-globins of adult hemoglobin

This test requires a blood sample. The patient is not required to be in a fasting state (nothing to eat or drink for a period of hours before the test).

Reference values vary from laboratory to laboratory but are generally found within the following ranges: six months to adult: up to 2% of the total hemoglobin, newborn to six months: up to 75% of the total hemoglobin.