The actual pH of the blood obtained from the fetal scalp, the fetal heart rate by auscultation, and expulsion of meconium in vertex presentations before delivery of the fetus were determined in the second stage of labor in 100 deliveries. The neonates were evaluated by means of the Apgar score at one and five minutes after birth. It was found that fetuses with a blood pH higher than 7.25 showed alterations of the FHR in 39.28% of the cases, and meconium expulsion in 12.50%. One-third of the fetuses with a pH lower than 7.20 showed a normal FHR, and most of them did not pass meconium before delivery. A highly significant relationship was found between the pH of the fetal blood and the value of the Apgar score at one and five minutes; there was no relationship between the Apgar score at one minute, and the FHR and the presence of meconium. © 1969 S. Karger AG, Basel.