Fetal radius length: a critical evaluation of race as a factor in gestational age assessment

Growth of the fetal radius was examined ultrasonographically in a prospective cross-sectional study of 290 white and 63 black patients between 12 and 43 weeks' gestation. The mean of radius length and 95% predictive intervals were calculated for each week. The most efficient description of the data was given by a simple log-linear model. The slopes for the white and black study groups estimated were distinctly different. Consequently, a single equation was estimated that considers race when assessing gestational age from radius length.