Normal Values:

Values are mean (10th - 90th percentiles):

Oyer et al Firpo et al.
RV Wall: 
IVS: ~
LV Wall: 

References

Reference Values for Valve Circumferences and Ventricular Wall Thicknesses of Fetal and Neonatal Hearts
Oyer CE, Sung CJ, Friedman R, Hansen K, Paepe MD, Pinar H, Singer DB.
Pediatr Dev Pathol. 2004 Sep-Oct;7(5):499-505. Epub 2004 Jul 30.
Erratum in: Pediatr Dev Pathol. 2005 Jan-Feb;8(1):139-40.
Evaluation of fetal heart dimensions from 12 weeks to term.
Firpo C, Hoffman JI, Silverman NH.
Am J Cardiol. 2001 Mar 1;87(5):594-600.