New formulas for fetal weight prediction by sonography: A comparison of their effectivenss with Hadlock and Shepard method

Abstract Background: Prediction of fetal weight by anthropometric measurements through sonography has been considered by many researchers. Objective: To compare the predicted weights by Hadlock and shepard formulas to observed weights and recommend new formulas. Methods: 99 pregnant women underwent sonography at the last week of their pregnancy to measure biparietal diameter, femoral length and abdominal circum ference .Their fetal weights were measured immediately after delivery .The predicted weights were calculated by Hadlock , Shepard and first and second Afshinnia- Hekmatnia formulas based on the three variables .The estimated weights were compard to the observed ones.The formulas were determined by multiple regression line analysis. Findings: In women with normal amniotic volume or polyhydroamnious, Hadlock and Shepard formulas showed Significant to observed weights and lacked appropriate predictive power .Only E2 in oligohydroamnious worked effectively. The first Afshinnia _ Hekmatnia formula predicted weights in normal and oligohydroamnious mothers with the error of 0.3_%and 3.6% respectively. Similarly, the second Afshinnia- Hekmatnia formula predicted weights in polyhydroamnious mothers with no error. Conclusion: None of Hadlock and shepard formulas except E2 in oligohydoamniotic mothers can predict fetal weights effectively due to Iranian anthropometric features.