Intrapartum prediction of birth weight: clinical versus sonographic estimation based on femur length alone.

Abstract

To determine the relative accuracy of predicting birth weight by clinical estimate versus sonographic mensuration of femur length (FL) alone. Two hundred pregnant women at term and in early labor had the weight of their fetuses estimated by clinical and sonographic methods. Clinical assessment of birth weight had a significantly lower mean standardized absolute error (90.6 g/kg) than sonographic estimate based on FL alone (106.7 g/kg) (P < .05). Clinical estimates were significantly more often within 5% (35%) of actual birth weight than were those derived sonographically (29%) (P = .005). Using FL alone to predict birth weight has no advantage over a clinical estimate among term patients in labor.