1National Instiute of child health and humana Develotment Research planning worhshop. Electronic fetal heart rate monitoring;research guidelines for interpretation,Am J obstet Gynecol,1997, 177(6): 1385- 1390.
3Salam Alekis E,Bakas P,Saloum I,et al. Severe variable decelerations and fetal pulse oximetry during the second stage of labor.Fetal Diagn Ther, 2005,20(1):31-34.