Marker

Standard Deviation

Healthy Population

Alpha-Fetoprotein

0.13 a 0.18

Total hCG

0.2 a 0.4

2nd Trimester Beta hCG Libre

0.22 a 0.27

1st Trimester Beta hCG Free

0.25 a 0.29

Unconjugated Estriol

0.11 a 0.14

PAPP-A

0.23 a 0.29

Inhibin-A

0.19 a 0.23

Nucal Translucency

0.12