Quantitative relationships between slowing of the fetal heart rate and changes in base-excess in the second stage of labor.

Abstract

The partial pressure of oxygen in the blood of the scalp and that of the umbilical artery of the fetus is lowered during the first and second stage xpJE labor, if there is a slowing of the heart rate in conjunction with uterine contractions (CALDEYRO-BARCIA et al. [2]; KUNZEL [4]). In animal experiments the reduction of uterine blood flow was shown to be a cause of this deceleration (JUNGE, KUNZEL, KLOCK [3]). Since the duration of the reduced blood flow corresponds well to the duration of the deceleration and hypoxia, it might be assumed that the dip area is an indication of the hypoxia and the resulting metabolic acidosis. This is even more probable since TIPTON and SHELLEY [6] have shown a definite relationship between the dip area and clinical Parameters. We have attempted to find out whether there is a quantitative relationship between the dip areas measured before birth and the metabolic changes in the blood of the fetus so that an increase in the deficit in the fetal blood can be estimated more precisely. The examinations showed a good relationship between such a dip area and the increased base excess in the fetal blood.