Use of the minor hemoglobin ratio for the determination of gestational age.

Maternal and cord blood hemoglobin A1c were quantitated at the time of delivery by radioimmunoassay. Other cord blood hemoglobins were quantitated by column chromatography using Bio-Rex 70. The minor hemoglobin ratio : formula: (see text),showed an excellent linear correlation (r2 = 0.88) with gestational age. Therefore, the ratio of : formula: (see text), could be a useful test to determine gestational age in the third trimester.