Dip area in fetal heart rate and its relationship to acid-base-observations of fetus and mother during labor.

The relationship between dip area (DA) of fetal heart rate (FHR) and the acid base status of fetus and mother during the first and second stage of labor were studied on 39 women at term. The observations reveal a significant correlation between the fall in fetal base excess (BE) and the measured DA: deltaBE = 0.01 - 0.143 DA (2alpha less than 0.01). There is no difference in the correlation of these parameters between the first and the second stage of labor despite the fact of a greater fall in BE and a greater DA per time compared to the first:BE meq/1/10min. 0.14 (SD 0.26) and 0.76 (SD 0.62); DA cm2/10 min. 0.99 (SD 1.19) and 4.28 (SD 3.06), respectively. With increasing DA the variance of the fall of fetal BE (S2BE) rose also: DA of 0-5 cm2: S2BE 0.66; DA greater than 15.1cm2:S2BE 3.76. With the fall in fetal BE there was also a fall in maternal BE, more pronounced during the second stage of labor:-BEF=0.38.DELTA BEM-0.70(2alphaless than 0.01). The fraction of the fall in fetal BE per DA increased with the fall in maternal BE (2alpha less than 0.05). This correlation reveals that there might be a slight influence of maternal BE on fetal BE. The present observation shows that measuring DA serves only as an approach to predict fetal condition during labor. It therefore should be combined with fetal scalp blood sampling. The influence of maternal BE on fetal BE seems to be only of less importance.