The merit of routine cord blood pH measurement at birth.

We searched the literature for mean values of arterial cord blood pH at birth and their lower limits of statistical normality. An arterial cord blood pH, correctly sampled, measured, validated, and interpreted, provides the most objective and sensitive index for fetal hypoxemia during labor. We advise to sample both artery and vein from a clamped segment of the cord within 30 minutes after birth. In accordance with physiological and statistical evidence, it is proposed to classify arterial cord blood pH in three categories: normal (when > 7.11), abnormal (when < 6.99), and borderline (7.00-7.11). An abnormal pH indicates that the fetus was in a state of biochemical decompensation at birth. Disadvantages of routine measurement include extra work load and the lack of a universally agreed definition of normal or abnormal pH. The major advantage of routine measurement is to provide care-givers with immediate feedback on their care during childbirth and an opportunity to learn from that feedback.