Fetal nasal bone length in euploid and aneuploid fetuses between 11 and 20 weeks' gestation: a prospective study.

Objective: To develop normative data for nasal bone length between 11 and 20 weeks' gestation and to assess the utility of nasal bone hypoplasia in the detection of fetal aneuploidy in the second trimester.

Methods: Well-dated, nonanomalous fetuses were examined between 11 and 20.9 weeks' gestation.