Chemical analyses of blood from the umbilical cord of the newborn: relation to fetal maturity and perinatal distress

The oxygen saturation of the blood in the umbilical vein is significantly higher when the initial gasp occurs prior to clamping. Presumably an increment of oxygen is added by this respiration so that the oxygen saturation at the moment of sampling no longer represents the oxygenation status of the fetus by means of the placenta. In the evaluation of any data on oxygen saturation in the blood of the umbilical cord, serious consideration must be given to this time relationship. In general where the clinical status of babies is poor at birth, the oxygen saturation is significantly lower than in babies without distress, when sampled before respiration. More specifically, there seems to be a direct relationship between lower oxygen saturation and clinical evidence of difficulty in initiating respiration. Premature infants sampled before initiation of respiration have lower values for oxygen saturation than mature or postmature infants. This difference is not explained solely by the less favorable neonatal clinical status of some premature infants. The oxygen saturation of postmature infants sampled before respiration is not lower than that of mature infants. The oxygen saturation of infants delivered by cesarean section is lower than those delivered by other means.