Estimation of birth weight by use of ultrasonographic formulas targeted to large-, appropriate-, and small-for-gestational-age fetuses

Ruby E. Sabbagha*, John Minogue, Ralph K. Tamura, Sue A. Hungerford

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

96 Scopus citations


This report sought to determine whether estimates of fetal weight are enhanced by using ultrasonographic formulas targeted to the large-, appropriate-, and small-for-gestational-age fetus in both preterm and term pregnancies. Ultrasonographic fetal measurements from 575 singleton pregnancies were obtained within 7 days of delivery. The first 194 fetuses were classified into three groups on the basis of the growth percentile rank of the abdominal circumference (≥90%, >5% and <90%, and ≤5%). Regression analyses were performed to generate three formulas for estimating fetal weight on the basis of the following: Gestational age (weeks) + Head circumference (cm) +2 × Abdominal circumference (cm) + Femur length (cm). This mathematic model allowed formulation of accurate and concise tables relating the sum of these measurements to estimated birth weight. The accuracy of these formulas was then prospectively compared, first, with the formula published by Hadlock et al. (in 32 large-, 279 appropriate-, and 70 small-for-gestational-age fetuses) and second, with the formula of Weiner et al. (in 82 preterm fetuses). The difference between actual and estimated birth weight generated by the three study formulas had no systemic error (f test, p > 0.05). Cumulatively, there was a statistically significant reduction of random error in the birth weight estimates by use of the three study formulas versus the best single formulas of Hadlock et al. (2 SD reduced from 21.6% to 19.8% and absolute 2 SD reduced from 15.6% to 12.2%). Additionally, the three study formulas resulted in a statistically significant reduction in the absolute 2 SD error compared with the best formula by Weiner et al. in fetuses ≤34 weeks' gestation (2 SD reduced from 19.1% to 13.6%).

Original languageEnglish (US)
Pages (from-to)854-862
Number of pages9
JournalAmerican journal of obstetrics and gynecology
Issue number4
StatePublished - Apr 1989


  • Fetal weight by growth status
  • abdominal circumference
  • femur length
  • head circumferences

ASJC Scopus subject areas

  • Obstetrics and Gynecology


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