Use of Femur Length as a Means of Assessing M‐Mode Ventricular Dimensions During Second and Third Trimesters of Pregnancy in Normal Fetus

Eighty‐two normal fetuses were scanned from 18 to 41 weeks of gestation. The following M‐mode measurements were correlated with the femur length: end‐diastolic right ventricular (r = 0.93), left ventricular (r = 0.92), biventricular outer (r = 0.94), and biventricular inner (r = 0.94) dimensions; tricuspid (r = 0.93) and mitral (r = 0.92) valve opening excursion; right (r = 0.76) and left (r = 0.70) ventricular wall thickness; and interventricular septal thickness (r = 0.75). Polynomial regression demonstrated that linear regression best described the data from which the mean and 5% and 95% confidence limits for predicted M‐mode measurements were computed for the femur length.