[Fetal biometry: review and application of sex determination].

Diagnostic ultrasound was introduced in the practice of obstetrics through its ability to measure accurately the biparietal (DBP) diameter of the foetus. The development of bidimensional and grey tone images expanded the possibility of fetal biometry. One of its most important uses is the estimation of gestational age.

[Value and indications for ultrasonographic determination of fetal sex].

From the end of the first trimester of pregnancy it is possible to recognize the sex of the fetus. The percentage with which this can be done rises progressively with the age of the fetus (from 29% at 18 weeks to 72% at 24 weeks), and with the experience of the operator. Errors are few; about between 1 and 2%.

Fetal biometric data obtained in a sole population with emphasis to sex differences.

Several biometrical parameters have been studied on an homogeneous population sample of 7548 fetuses. The measurement of numerous body and organ sizes on a sole population of fetuses is the only method of considering fetal biometry as a whole and allowing study of the clinical value of some ratios, indices and products of dimensions (not discussed here). The possibility of referring to separate norms for male and female fetuses increases the discriminant power of biometry in detecting fetal growth.