INTRAPARTUM ASSESSMENT OF BIRTH-WEIGHT AT TERM - CLINICAL VERSUS SONOGRAPHIC MODELS USING FROM ONE TO 4 FETAL PARAMETERS

Objective: To determine, among term patients in early labor at a commu nity hospital, the relative accuracy of estimating birth weight clinic ally vs sonographically using four fetal parameters (biparietal diamet er, head/abdominal circumference, and femur length). Methods: Prospect ively, 92 laboring women underwent clinical estimation of birth weight and concurrent sonographic measurements of four fetal parameters. At the completion of the study, the clinical estimates were compared with sonographic mensuration using four different models which employ from one (abdominal circumference alone) to four (biparietal diameter, fem ur length, head, and abdominal circumference) fetal parameters to deri ve the estimated birth weight. The data were analyzed using analysis o f variance followed by the Student Newman-Keuls test and chisquare ana lysis. Results: Among 92 parturients, the mean birth weight was 3553 /-: 426 g and the incidence of macrosomia was 13% (12/92). The mean st andardized error for clinical estimates of birth weight was 91 +/- 76 g/kg, significantly lower than estimates derived using from one to fou r fetal parameters (P < 0.0001). The lowest mean standardized error so nographically was 121 g/kg (SD +/- 76 g/kg) with the model using abdom inal circumference and femur length. The highest mean standardized err or (141 +/- 93 g/kg) was with the sonographic model based on femur len gth, and abdominal and head circumference. Clinical estimates were wit hin +/- 10% of the actual birth weight (69.5%) significantly more ofte n than any of the estimates derived sonographically (P < 0.0001). Conc lusions: In a community hospital, clinical estimate of birth weight, a mong laboring patients at term, is superior to that derived sonographi cally using from one to four fetal parameters.