Ultrasonic prediction of birth weight in preterm fetuses: Which formula is best?

Bruce W. Pielet*, Rudy E. Sabbagha, Scott N. MacGregor, Ralph K. Tamura, Seth L. Feigenbaum

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


Data from previous studies have suggested that birth weight prediction was enhanced by using formulas specifically derived from preterm fetuses. However, no prospective comparison of different formulas was performed. We obtained ultrasonic data on 61 pregnancies at risk for preterm delivery with a gestational age of 29.0 ± 3.0 weeks (mean ± SD). In all women birth weight was predicted within 7 days of delivery. Of the 61 pregnancies, 49 (80%), 41 (67%), 30 (49%), and 17 (28%) weighed < 1750, and 1000 gm, respectively; 14 published formulas were compared for accuracy in predicting birth weight in these four categories. The formulas with the smallest absolute mean percent errors incorporated head and abdominal circumferences and femur length. The formula of Weiner et al., derived from low birth weight infants, produced the smallest absolute mean percent error and SD, 10.9% ± 7.9%; this error was further reduced to 7.7% ± 6.5% in infants weighing <750 gm. These findings suggest that birth weight in the preterm fetus is best predicted by a formula targeted to such a population.

Original languageEnglish (US)
Pages (from-to)1411-1414
Number of pages4
JournalAmerican journal of obstetrics and gynecology
Issue number6
StatePublished - 1987


  • Accuracy
  • low birth weight
  • targeted formula

ASJC Scopus subject areas

  • Obstetrics and Gynecology


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