ESTIMATE OF BIRTH WEIGHT USING TWO- AND THREE-DIMENSIONAL ULTRASONOGRAPHY

ESTIMATE OF BIRTH WEIGHT USING TWO- AND THREE-DIMENSIONAL ULTRASONOGRAPHY OBJECTIVE. Assess and compare accuracy of birth weight prediction using a combination of two-dimensional (abdominal circumference - AC and femur length - FL) and three-dimensional parameters (fetal arm -VolArm and thigh -VolTh volumes). METHODS. A cross sectional study was carried out involving 78 singleton, live, euploid fetuses without structural malformations born within 48 hours after ultrasonography. VolArm and VolTh were obtained by three-dimensional ultrasound using the multiplanar mode at 5 mm intervals. AC and FL were measured by two-dimensional ultrasound. Linear and polynomial regressions were calculated to determine the best formula to predict birth weight using VolArm, VolTh, CA and FL. ANOVA was used to compare errors in birth weight prediction using this formula and those obtained using the Shepard and Hadlock formulae. RESULTS. The best formula for prediction of birth weight was a simple linear regression (Weight = -1486.1 + 60.5AC + 140.57FL + 16.6 VolArm + 4.8VolTh), R2= 0.932. The error (E), absolute error (AE), percent error (PE) and absolute percent error (APE) for this new formula were 0 g, 0.2%, 112.2 g and 3.7%. This new formula had smaller E, AE, PE and APE than the Shepard formula and smaller AE and APE than Hadlock 's formula. CONCLUSION. A formula using VolArm, VolTh, AC and FL was more accurate for prediction of birth weight than formulae using only two-dimensional parameters. [Rev Assoc Med Bras 2010; 56(2): 204-8]