
Keywords: Trisomy 21; Histopathology; Umbilical artery Doppler; Maternal vascular malperfusion; Fetal vascular malperfusion; Placenta; T21; Trisomy 21; UAD; Umbilical Artery Doppler; PI; Pulsatility Index; AEDF; Absent End Diastolic Flow; REDF; Reversed End Diastol