The estimation of fetal weight by computer-assisted analysis.

The need for a quick and easy method for estimating fetal weight in utero has been clearly established. Estimates by abdominal palpation and fetal hormone production have proved to be of limited value. Eight-five patients, ranging from 17 to 41 weeks' gestation, were ultrasonically scanned within 48 hours of delivery. Statistical analysis and multiple multivariant linear regressions were performed employing the BMD statistical packages. Our results show that birth weight is a logarithmic function of fetal body parameters and that the abdominal circumference has the single best correlation with the log10 birth weight. Our best linear regression with the use of two fetal dimensions (abdominal circumference and biparietal diameter) had a standard deviation of 106 grams per kilogram fetal weight. Since this derived formula is very cumbersome to manipulate, tables have been prepared with computer assistance to read the estimated fetal weight directly. Prospective estimates in 32 cases of both normal and pathologic gestations have proved to be within our expected accuracy.