Decreased birth weight and femur length in fetuses of patients with the sickle-cell trait.

The mean birth weight in women with the sickle-cell trait (Hb-AS) was less than in a matched population (Hb-AA), and the difference was statistically significant. Ultrasonic fetal biparietal diameter measurements in 30 patients with Hb-AS fell within normal limits, but mean femur lengths were found to be reduced at each gestational period when compared with similar measurements in patients with normal hemoglobin.