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Table 1 Characteristics of the study population

From: Utility of fetal facial markers on a second trimester genetic sonogram in screening for Down syndrome in a high-risk Thai population

Parameter Euploid fetuses
(n = 340)
Fetuses with Down syndrome (n = 11) P value
Maternal age
(median, years)
35 (32,37.25) 39 (34.5,39.5) 0.0788
Gestational age at ultrasound
(median, weeks)
17 (16,20) 18 (18,20) 0.0887
PT (mm)
median (min,max)
2.73 (2.33,3.3) 4.8 (4.1,5.2)  < 0.001
NBL (mm)
median (min,max)
5.4 (5,6.1) 1.4 (1.07,1.8)  < 0.001
PT/NBL ratio
median (min,max)
0.5 (0.46,0.55) 3 (2.65,4.7)  < 0.001
NBL/PT ratio
median (min,max)
2 (1.81,2.18) 0.33 (0.2,0.38)  < 0.001
  1. Min Minimum, Max Maximum, PT Prenasal thickness, NBL Nasal bone length