Ultrasonographic ear length measurement in normal second-and third-trimester fetuses

OBJECTIVE: We sought to develop a nomogram for fetal ear length measurement s from a large population of healthy second- and third-trimester fetuses an d to investigate the correlation of fetal ear length with other standard fe tal biometry measurements, as follows: biparietal diameter, head circumfere nce, abdominal circumference, femur length, and humerus length. STUDY DESIGN: Ear length measurement was obtained prospectively in 4240 sin gleton fetuses between 15 and 40 weeks' gestational age. Either complete da ta for normal karyotype on amniocentesis or normal infant examination at bi rth or both were available in 2583 cases. These constituted the final study population. RESULTS: A nomogram was developed by linearly regressing ear length on gest ational age (Ear length [in millimeters] = 1.076 x Gestational age [in week s] - 7.308). There was a high correlation between ear length and gestationa l age (r = 0.96; P = .0001). CONCLUSION: The results of this study provide normative data on growth of f etal ear length from 15 to 40 weeks' gestation. Good correlation was also o bserved between ear length and other fetal biometric measurements (bipariet al diameter, head circumference, abdominal circumference, femur length, and humerus length).