[Factors influencing the accuracy of fetal-weight computation]

Parameters which have influence on the accuracy of the calculation of fetal weight. We estimated about 1500 cases in which we within three days before birth carried out an ultrasonic measurement. Most of the differences between the calculated prenatal and the scaled postnatal weight are caused by errors of measurement and abnormalities of the fetal development in pathologic pregnancy. In severe intrauterine retardation the actual fetal weight will be calculated about 600 g to heavy. In fetopathia diabetica with fetal hypertrophy the weight will be calculated about 400 g to small. Opposite to these sources of error the biologic variation and the inaccuracy involved by the mathematical regression model are small. The regression formula should be adapted by 1000 cases.