Accuracy of different equations for estimating fetal weight

Gynecol Obstet Invest. 2011;72(4):264-8. doi: 10.1159/000328693. Epub 2011 Oct 11.


Objective: To evaluate the accuracy of ten equations based on ultrasound parameters for estimating fetal weight (FW).

Study design: A cross-sectional study was performed in 250 healthy women with normal singleton pregnancies between 34 and 41 weeks of gestation. FW estimations calculated according to ten different equations were compared against birth weight (BW) which was determined within 72 h after FW estimation. Estimated error rate, intraclass correlation coefficient, and agreement between BW and FW calculated by each formula were analyzed.

Results: Most of the formulas were inaccurate in predicting BW, only 2 formulas showed less than 10% of the measurements lying within the 10% of estimated error. Four formulas tended to overestimate, while six tended to underestimate FW.

Conclusions: Appropriate equations for estimating FW in all populations should be developed. However, where there are no local growth curves, the accuracy of the available fetal growth equations should be tested.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Birth Weight
  • Body Weights and Measures / methods
  • Cross-Sectional Studies
  • Female
  • Fetal Weight*
  • Humans
  • Infant, Newborn
  • Pregnancy
  • Reproducibility of Results*
  • Ultrasonography, Prenatal*
  • Young Adult