[Fetal heart rate, dip area and acid base observations in breech and vertex deliveries (author's transl)].

Fetal heart rate (FHR), dip area (DA) and the acid base status (AB) were investigated in breech deliveries (BD) (N= 167) and in group of spontaneously delivered vertex presentations (VP) (NFHR, DA=50; NAB=109). 90 minutes prior to delivery fetal heart rate and dip area were in both groups not significantly different. However as labor progressed the fetal heart rate as well as dip area increased in breech deliveries much more (FHR 163 (SD 16.2) beats/min, DA 1,07 (SD 0,80) cm2/min) than in VP (FHR 136 (SD 14,8) beats/min, DA 0,65 (SD 0,39) cm2/min) (2p less than 0,001). The base excess of the umbilical arterial blood was correlated to the DA measured from 10 minutes prior to birth till the delivery of the baby: BE = -8,2 --0,3 (DA) (2alpha less than 0,01). The frequency of acidotic babies was more in vaginally delivered breech presentations (pH less than 7,20 = 30, 2%, BE greater than -10 meq/l = 43,7%) than in breech deliveries by caesarean section (pH less than 7,20 = 19,1%, BE greater than -10 meq/l = 24,4%) and vertex presentations (pH less than 7,20 - 5,5%, BE greater than -10 meq/l = 14,6%), respectively. The distance between the vertex and the umbilicus was 28 cm and between the breech and the umbilicus 9,4 cm. From this anatomical observation it is concluded that umbilical cord compression, preferentially umbilicai vein occlusion takes place in breech presentation at an earlier point on than in vertex presentation. The rise of fetal heart rate and the increase in dip area are showing in addition that the fetal buffer base in breech presentation will be reduced during the last time course of the second stage of labor.