[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%. The number of errors in the ability to decide the sex is independent of which sex the fetus is. The body measurements show a difference between the made and the female fetuses which is statistically significant from the 20th week onwards. Growth tables which are specific for each sex can be made.