Estimation of fetal weight near term: comparison between ultrasound and symphysis-fundus evaluation by Johnson's rule.

Introduction: The fetal weight estimation is commonly performed by ultrasound but the manual method is also applied in developing countries due to the lack of scan availability and in western countries for the management of low-risk pregnancy managed autonomously by the midwives. The most applied method to estimate fetal weight measures the longitudinal diameter of the symphysis-fundus according to Johnson's rule. The aim of the present study is to evaluate the reliability of the symphysis-fundus method with respect to the ultrasound to estimate fetal weight in low risk pregnancies according to the classification of adequate, small and large for gestational age.