Estimation of fetal weight by ultrasonic measurement of several fetal growth parameters.

Fetal biparietal diameter (BPD) and head, chest and abdominal circumferences (HC, CC, AC) were measured by means of real-time B-scan echography. The study population consisted of 198 patients who were hospitalized at Tohoku University Hospital. All live-born infants were delivered within 48 hr after ultrasonic examination. This study was intended to establish criteria for diagnosis of fetuses weighing more than 2,500 g by means of a single ultrasonic measurement of several different fetal growth parameters. When estimated diameter of BPD exceeded 9.0 cm, 96.1% of the infants weighed more than 2,500 g. In all cases in which HC, CC, and AC exceeded 30 cm, the infants weighed more than 2,500 g. Finally, a multiple regression equation was constructed for estimation of birth weight by the values of fetal BPD, HC, CC and AC. The prediction error between prospective birth weight given by this formula and actual birth weight was +/- 200 g. The present method for estimation of fetal weight is simple and useful in obstetrical clinic.