Ultrasonic prediction of term birth weight in Hispanic women. Accuracy in an outpatient clinic.
OBJECTIVE
To investigate the accuracy of ultrasonic fetal biometric algorithms for estimating term fetal weight.


METHODS
Ultrasonographic fetal biometric assessments were made in 74 Hispanic women who delivered at 37-42 weeks of gestation. Measurements were taken of the fetal biparietal diameter, head circumference, abdominal circumference and femur length. Twenty-seven standard fetal biometric algorithms were assessed for their accuracy in predicting fetal weight. Results were compared to those obtained by merely guessing the mean term birth weight in each case.


RESULTS
The correlation between ultrasonically predicted and actual birth weights ranged from 0.52 to 0.79. The different ultrasonic algorithms estimated fetal weight to within +/- 8.6-15.0% (+/- 295-520 g) of actual birth weight as compared with +/- 13.6% (+/- 449 g) for guessing the mean birth weight in each case (mean +/- SD). The mean absolute prediction errors for 17 of the ultrasonic equations (63%) were superior to those obtained by guessing the mean birth weight by 3.2-5.0% (96-154 g) (P < .05). Fourteen algorithms (52%) were more accurate for predicting fetal weight to within +/- 15%, and 20 algorithms (74%) were more accurate for predicting fetal weight to within +/- 10% of actual birth weight than simply guessing the mean birth weight (P < .05). Ten ultrasonic equations (37%) showed significant utility for predicting fetal weight > 4,000 g (likelihood ratio > 5.0).


CONCLUSIONS
Term fetal weight predictions using the majority of sonographic fetal biometric equations are more accurate, by up to 154 g and 5%, than simply guessing the population-specific mean birth weight.
Nahum
Gerard G
GG
Department of Obstetrics and Gynecology, Duke University Medical Center, Durham, North Carolina, USA. nahum001@mc.duke.edu
Pham
Krystle Q
KQ
McHugh
John P
JP
D000328:Adult; D000465:Algorithms; D000554:Ambulatory Care Facilities; D001724:Birth Weight / Q000502:physiology*; D015331:Cohort Studies; D005260:Female; D020567:Fetal Weight / Q000208:ethnology* / Q000502:physiology*; D005865:Gestational Age; D006630:Hispanic or Latino; D006801:Humans; D007231:Infant, Newborn; D007745:Labor Onset; D011237:Predictive Value of Tests; D011247:Pregnancy; D011295:Prenatal Care; D012680:Sensitivity and Specificity; D016216:Ultrasonography, Prenatal / Q000379:methods*