PREDICTION OF FETAL MACROSOMIA USING HUMERAL SOFT-TISSUE THICKNESS

Objective: To determine the usefulness of an objective assessment of h umeral soft tissue thickness in estimating birth weight in a populatio n at risk for macrosomia. Methods: Shortly before delivery, ultrasound examinations were performed on 95 women at risk of having macrosomic infants. In each case, the fetal humeral soft tissue thickness (the di stance between the outer edge of the humerus to the skin surface on tr ansverse views of the upper arm) was measured three times, and an aver age was taken. Results: The humeral soft tissue thickness correlated s ignificantly with birth weight (R(2) = 0.40, P < .001) and ponderal in dex (R(2) = 0.20, P = .02). The humeral soft tissue thickness was sign ificantly higher in macrosomic infants (P < .001), in those with an ab normally high ponderal index (P = .02), and in infants whose deliverie s were complicated by shoulder dystocia (P = .05). There was no appare nt effect of maternal diabetes on the humeral soft tissue thickness. T he humeral soft tissue thickness was more sensitive in predicting macr osomia than was the ultrasound-estimated fetal weight (88 versus 71%), but less specific (75 versus 91%). Conclusion: The humeral soft tissu e thickness correlates with birth weight. However, its clinical use co mpared with other predictors remains to be defined.