The concentration of hemoglobin in the plasma of normal human subjects has recently been reexamined in our laboratory, employing modified methods for blood sampling and for hemoglobin measurement.1,2 Study of 25 ambulatory adults revealed a mean value for plasma hemoglobin concentration (PHgbC) of 0.31 mg. per 100 ml., with a range of 0.16 to 0.58 mg. per 100 ml.As part of a broad study of PHgbC in normal subjects, preliminary observations were made on blood samples obtained from 6 women at the time of parturition and from the placental segment of the umbilical vein immediately after separation of the newborn infants. Although PHgbC was within the normal range for the 6 maternal samples, all of the umbilical vein samples yielded elevated values, half of them in the range 10 to 20 times the mean value for normal adults. Since to our knowledge this phenomenon had not been previously described, a detailed investigation was undertaken: (a) in order to confirm the preliminary findings and (b) to attempt to correlate the elevated values in umbilical vein samples with the infants' hématologie status at birth and any pertinent features of the pregnancy, labor, and delivery.The present report summarizes clinical, hématologie, and blood chemical studies on 30 normal infants and their mothers.
Materials and MethodsThe subjects were private or ward patients con¬ fined at the St. Louis Maternity Hospital, affiliated with the Barnes Hospital Group. Two-thirds of the patients were white ; one-third were Negro.Collection of Blood Samples.-The technique of blood collection has been detailed in a previous publication.1Umbilical Vein Blood.-Sterile equipment was employed, and the investigators followed the routine scrub, gown, mask, and glove procedures recom¬ mended for the attending obstetricians. As soon as the infant had been delivered, 2 clamps were placed across the cord within 12 in. of the umbilicus, and the cord was cut between the clamps. A 15-gauge needle attached to a 14 in. length of polyvinyl tubing was immediately inserted cleanly into the umbilical vein on the placental segment of cord projecting from the introitus. The first 5 ml. of blood to flow by gravity was collected in a heparinized tube to be used for subsequent determination of hemoglobin, hematocrit, differential nucleated cell count, ABO blood group, Rh type, and direct Coombs test. Eight to 10 ml. was then collected with great care in each of 2 siliconized centrifuge tubes whose inner walls were coated with a fine mist of heparin solution. The tubes were promptly capped and centrifuged, and the supernatant plasma was separated and recentri fuged, as previously described.1 The plasma was used for determination of plasma hemoglobin