Umbilical cord blood gas analysis of umbilical vein and umbilical artery in this study was similar to the results of previous studies . The partial oxygen pressure (PO2) of the arterial blood gas in the umbilical vein was not significantly affected to the oxygen supply of the newborn infants. On the other hand, the umbilical arterial blood gas was the most reliable indicator of the oxygenation index and acid-base status of the fetus. Previous studies have indicated that the relationship between hydrogen ion concentration(PH), base excess（BE） and neonatal asphyxia was relatively large, and it was positively related to growth.