Correlation between the foetal acid-base status and the Apgar score.

The foetal pH values of eighty-eight cases delivered within 30 min after foetal blood sampling were correlated with the 1-min Apgar score. With a pH of 7.20 or above the error of prediction was 1'3%o. The error in cases with pH below 7.20 was 54'5/. Significantly higher pH and lower A base deficit were present in the low foetal pH group in vigorous, as opposed to depressed infants, suggesting that infusion acidosis was present in infants with a high Apgar score. The degree of correlation between the foetal pH and the Apgar score was not significantly influenced by shortening the sampling-delivery interval to 15 min or lengthening it to 3 hr. The most significant factor affecting the degree of correlation in the present study was the setting of the critical pH. If the criterion of the critical pH was taken as 7-13 there would have been no false positive results and the error of prediction in cases delivered within 30 min of foetal blood sampling would be reduced to 1.1%.