[Prediction of fetal sex by ultrasonography]

Five hundred thirteen echographic reports are analyzed in order to predict fetal sex between 17 and 39 weeks of pregnancy. The diagnostic certainty was of 98.06%. The error was of 1.48% for masculine sex and 2.49% for feminine sex. Podalic presentation and early and late pregnancy influenced negatively in the prediction of the fetal sex. The amniotic fluid, placental localization, and any abnormality of the fetal anatomy, have no influence in the prediction of the sex. The best moment for sex prediction was between 28 and 36 weeks of pregnancy.