Sonographic determination of fetal sex from twelve weeks of gestation.

Fetal sex was sonographically determined in 1879 pregnant women between 12 and 40 weeks of gestation by obtaining transverse, frontal, and sagittal sections of the fetal lower pelvic region. The success rates of producing echoimages that were sufficient to determine fetal sex were 97.1% for both sexes (7783 correct diagnoses out of 8010 sonograms), 97.1% for males (3986/4103), and 97.1% for females (3797/3907). Postnatal confirmation of the sex of 1886 newborn infants delivered of 1879 pregnant women revealed that the rate of correct diagnosis before delivery was 99.9% (1885/1886)-100% for males (957/957) and 99.8% for females (928/929). The method of ultrasonic examination of the fetal sex reported here appears to be feasible in obstetric practice with consistent reproducibility and a high incidence of correct determinations at 12 weeks of gestation and thereafter.