PREDICTING BIRTH-WEIGHT BY FETAL UPPER-ARM VOLUME WITH USE OF 3-DIMENSIONAL ULTRASONOGRAPHY

OBJECTIVE: Our purpose was to determine the usefulness and accuracy of the three-dimensional ultrasonography assessed fetal upper-arm volume in predicting birth weight. STUDY DESIGN: From June 1996 to October 1 996, we performed a prospective study of ultrasonography on 105 pregna nt women without fetal structural anomaly or aneuploidy. Both the trad itional two-dimensional ultrasonographic parameters and three-dimensio nal ultrasonography for fetal upper arm volume were measured within 48 hours of delivery. RESULTS: The upper arm volume correlated well with birth weight (r = 0.92, n = 105, p < 0.0001), With use of linear and polynomial regression, we obtained a best-fit new formula, Birth weigh t = 1088.60 + 36.024 x Upper-arm volume. The accuracy of this new form ula is compared with that of two Chinese equations predicting fetal we ight reported before and other formulas commonly used in the world as well. Our formula is more accurate in predicting birth weight than all the other formulas by traditional two-dimensional ultrasonography, ei ther in error, percentage error, or absolute error. Another group by p rospective validation further proved this finding. CONCLUSION: The upp er-arm volume assessed by three-dimensional ultrasonography can accura tely predict birth weight, and its accuracy is superior to the previou s formulas. Our study has at least validated the application of upper- arm volume by three-dimensional ultrasonography in estimating fetal we ight. Further larger series are needed to confirm our findings.