Objective: To determine the relative accuracy of predicting birth weight by clinical estimate versus sonographic mensuration of femur length (FL) alone.
Methods: Two hundred pregnant women at term and in early labor had the weight of their fetuses estimated by clinical and sonographic methods.
Results: 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).
Conclusion: Using FL alone to predict birth weight has no advantage over a clinical estimate among term patients in labor.