Intrapartum monitoring and umbilical arterial blood pH study were carried out in 103 cases of normal pregnancy from March 1987 to December 1987. A stepwise linear regression analysis was done on 23 factors concerning the status of the newborns and 5 significant umbilical arterial blood pH, related ones that is fetal scalp blood pH, duration of the second stage of labour. Maternal blood PCO2, BB and M/F delta BDHb5. It is considered that Fischer's FHR-monitoring scoring system M/F delta pH and status of amniotic fluid etc, bear no relation to umbilical arterial blood pH. From these 5 significant factors, a regression equation was obtained so that the acid-base status of newborns can be predicted.