How to construct 'normal ranges' for fetal variables

Ultrasound Obstet Gynecol. 1998 Jan;11(1):30-8. doi: 10.1046/j.1469-0705.1998.11010030.x.


A method to estimate reference intervals which depend on gestational age is described. The approach is based on standard statistical techniques, so implementation should be straightforward with most statistical packages. The reference limits are defined by simple formulae which may be plotted as smooth curves. The method is illustrated with analyses of three real datasets arising from different aspects of fetal monitoring.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cephalometry
  • Fetus / anatomy & histology*
  • Gestational Age
  • Hemoglobins / analysis
  • Humans
  • Kidney / embryology
  • Models, Statistical*
  • Normal Distribution
  • Reference Values
  • Regression Analysis
  • Ultrasonography, Prenatal*


  • Hemoglobins