Umbilical cord blood gas analysis

The prognostic value of measuring umbilical cord blood pH at birth is examined in a recent meta-analysis study. Cord blood acidosis (usually defined as cord blood pH <7.0) is considered evidence that the newborn baby was deprived of oxygen during labor, and in some maternity units cord blood pH is used in the assessment of a small proportion of neonates believed to be at high risk of neonatal asphyxia.

The study sought to establish if the test has wider application in the prognostic assessment of neonates. The authors of this study examined the results of 51 relevant studies. In total this database provided the outcome (both during the perinatal period and in some cases up to 5 years after birth) of close to half a million babies whose cord blood pH at birth was known.

In summary the study found that low arterial cord blood pH was significantly associated with neonatal mortality, morbidity and cerebral palsy. Particular morbidities (apart from cerebral palsy) found to be strongly associated with low cord blood pH were: hypoxic ischemic encephalopathy, seizures and intraventricular hemorrhage.

The study provides evidence that cord blood pH might have much wider clinical application than is currently the case.