Estimation of fetal weight during labor.

Fetal weight was estimated clinically and by two ultrasonographic methods in 62 patients in labor at term. Maternal obesity precluded clinical estimation of fetal weight in eight patients (12.9%) and a combination of maternal obesity, anterior placentation, and oligohydramnios prevented ultrasonographic fetal measurement in four patients (6.5%). In 43 patients, in whom all three methods of estimate were obtainable, a regression equation using ultrasonically measured fetal abdominal circumference provided the greatest accuracy. However, significant interpatient variability affecting the accuracy of all three methods of estimating fetal weight may limit the clinical application of these measurement techniques.