[Studies on individual fetal weight estimation by ultrasonography in multiple pregnancies]

Fetal weight estimation was tried in each fetus in 16 cases of twins and 2 cases of triplets using the formula derived from the regression analysis of fetal biometric data and actual neonatal weights in 26 cases of singleton pregnancies. The fetal biometric data used were biparietal diameter (BPD), abdominal antero-posterior diameter (APD), abdominal transverse diameter (TD), abdominal circumference (AC) and fetal femur length (FFL). The correlation between the estimated and actual weight was significant (r = 0.926) and the estimation error in neonates smaller than 2,500 g was less than 10% of the birth weight. Estimated weight differences in 16 pairs of twin pregnancies correlated well with the actual weight differences (r = 0.678). A sensitivity of 70% and specificity of 100% were revealed in the diagnosis of IUGR using the estimation formula and the intrauterine fetal growth curve. These results showed how the estimation formula derived from ultrasonically measured fetal biometric parameters, can be applied clinically but two kinds of formula with or without BPD are necessary for fetal weight estimation in multiple pregnancies as only 53% of BPD were available for fetal weight estimation.