Outcome of fetuses with lactic acidemia

Umbilical arterial lactate, pH, PO2, PCO2, and base deficit were measured at delivery of 468 live-born infants. The correlation between the 1-minute Apgar score and lactate (r = -0.34) was comparable to that between the 1-minute Apgar score and pH (r = 0.30). The multiple correlation coefficient between the 1-minute Apgar score and all five parameters combined (lactate, pH, PO2, PCO2, and base deficit) was 0.36. This was not significantly higher than the simple correlation coefficient for pH alone (0.30). Similar correlation coefficients were noted for the 5-minute Apgar score. The dividing point between normal and pathologic lactate levels was 3.70 mmol/L. A pH less than 7.20 and a lactate level greater than or equal to 3.70 mmol/L had the same sensitivity, specificity, and positive and negative predictive values for low Apgar scores (less than 7). While pH and lactate are equally correlated with fetal outcome, their combination with each other and with other blood gas parameters does not predict outcome better than either pH or lactate alone.