Fetal breasts in normal and down syndrome fetuses

To assess the validity of fetal breast size measurement as a sonographic marker in fetuses with Down syndrome. Methods: Fetal breasts were studied in 26 fetuses with trisomy 21 and 78 fetuses with normal chromosomes. Breasts were identified and measured in a cross-sectional plane of the fetal chest at the level of the four-chamber view of the heart. Normal fetuses had a mean breast size of 3.8 mm ± 1.1 mm. Fetuses with Down syndrome had a mean breast size of 1.9 mm ± 0.7 mm (p ≤ 0.0001). Diminished breast size measured by ultrasound in the second trimester may be helpful in identifying fetuses with Down syndrome.