title: Evaluation of Fetal Weight Estimation Formulas in Assessing Small-for-Gestational-Age Fetuses.
abstract: OBJECTIVE
  The aim of this study was to compare the accuracy of multiple sonographic fetal weight estimation models in assessing small-for-gestational-age (SGA) fetuses.
  
  
  METHODS
  The cohort included all singleton pregnancies recorded at a single medical center from January 2004 to September 2011, with a minimum of 24 weeks of gestation. SGA was defined as a fetal weight of less than the 10th percentile. We used birth weight (BW) distribution curves for our population, matched according to fetal gender and gestational age. Predicted birth weights were calculated using 26 sonographic fetal weight estimation models, including targeted formulas for SGA fetuses.
  
  
  RESULTS
  1218 cases of SGA fetuses that underwent sonographic fetal weight estimation within one week prior to delivery were found. Prediction of fetal weight was significantly less accurate in SGA fetuses than in the general population. The random error for SGA fetuses ranged from 7.2 % to 13.9 % in different models, while the systematic error ranged from -12.8 % to 26 %. Most non-targeted formulas showed a specificity of over 90 % but a sensitivity of only 20 - 35 % in the detection of SGA fetuses, while most targeted formulas had a low specificity but a high sensitivity. The model by Scott et al. was found to be the most accurate in assessing SGA fetuses in our population.
  
  
  CONCLUSIONS
  Estimation of fetal weight in SGA fetuses is less accurate than in the general population. Some formulas which are designed for SGA are more accurate than others and their use might increase the sensitivity in identifying SGA fetuses, with only a small decline in specificity.
authors: O
authors: O
authors: Barel
authors: R
authors: R
authors: Maymon
authors: M
authors: M
authors: Elovits
authors: N
authors: N
authors: Smorgick
authors: J
authors: J
authors: Tovbin
authors: Z
authors: Z
authors: Vaknin
mesh_terms: D000293:Adolescent; D000328:Adult; D001724:Birth Weight; D015331:Cohort Studies; D005260:Female; D020567:Fetal Weight; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D007557:Israel; D008297:Male; D008875:Middle Aged; D011247:Pregnancy; D012016:Reference Values; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D016216:Ultrasonography, Prenatal / Q000379:methods*; D055815:Young Adult