Evaluation of fetal femur length for prediction of gestational age in a racially mixed obstetric population.

In a retrospective study, a group of 314 patients between 19 and 32 completed weeks' gestation were evaluated for differences in sonographic measurement of femur length vs. gestational age between the following racial categories: Hispanic, black, Oriental, and Caucasian. Selection criteria included known last menstrual period, singleton gestation, and a historic absence of maternal diabetes, hypertension, or renal disease or fetal anomalies. The gestational age against which the femur length was judged was determined from the last normal menstrual period, provided that this date differed by less than 2 weeks from age determined by fetal biparietal diameter and evaluation of the newborn. No statistically significant difference in femur length vs. gestational age was noted between the various racial categories.