By means of 149 fetal microblood samplings (FBA) from the breech in deliveries in breech presentation and by means of 64 cardiotocograms the validity of biochemical parameters and biophysical ones of fetal monitoring will be investigated. It takes an increased number of suspect or pathologic CTG into account in cases of breech presentation. By means of FBA it is possible to exclude or to confirm the supposed acidoses. By this the rate of operations during delivery can be reduced or the operation will be indicated respectively. A normal fetal pH resulting from the general biochemical monitoring does enlarge the obstetricians license when the fetus presents himself in advanced parturition in pelvic floor (hold back of breech during assisted spontaneous delivery). A pH less than 7.15 demands an immediate delivery. A prognosis of fetal outcome by means of FBA and CTG is not possible due to difficulties in calculation of the final stage of breech presentation. The difference between fetal pH measured in pelvic floor and pH in umbilical artery must be kept as small as possible and it might be regarded as criterion of the management of the delivery in breech presentation.