A RISK MODEL APPROACH TO THE PREDICTION OR FETAL ACIDEMIA

Known risk factors for adverse perinatal outcome were related to sever e fetal acidemia during labor and at birth. Severe fetal acidemia was defined as a fetal scalp or umbilical artery pH > 3 SD below the mean for normal pregnancy. pH values were available for 1,524 singleton bir ths without congenital anomalies. Of these births, 83 (5.4%) had at le ast one pH value > 3 SD below the reference mean. Known risk factors i n the group with severe acidemia were compared with those in a random sample of the remaining 94.6% births. The strongest predictor of sever e fetal acidemia was an abnormal cardiotocogram with a Hammacher score > 8. Risk factors shown to lower pH values significantly were combine d in a prediction model based on multiple regression analysis. Back-va lidation of the model showed that half of all cases of severe fetal ac idemia could not be adequately predicted. It is concluded that such pr ediction models do not contribute to a more effective detection of sev ere fetal acidemia.