Prediction of neonatal crown-heel length in normal singletons, twins, and triplets using individualized growth assessment.

In groups of normally growing singletons (20), twins (20), and triplets (13), predicted femur diaphysis length (FDL) values at birth were obtained using Rossavik growth models specified from second-trimester ultrasound studies of fetal growth. Six previously published functions were utilized to obtain predicted crown-heel length (CHL) values from predicted FDL values. These values were compared to the actual CHL values and the percent differences calculated. Based on their systematic (mean percent difference) and random (standard deviation of percent difference) prediction errors, the functions of Vintzileos (singletons), Hadlock (twins), and Brown (triplets) were found to give optimal results (no systematic error; random error: +/- 6%). Using predicted CHL values obtained with these optimal functions, growth potential realization index values for CHL (GPRICHL) were determined for singletons, twins, and triplets. In all three groups, the mean GPRICHL value was 100% with a range of approximately 95% to 105%. These results indicate that the CHL can be predicted from second-trimester growth patterns and evaluated using individualized growth assessment methods.