RESUMO
Objective: Large number of fetal weight formulae derived using different populations suggest that there is no fetal weight formula which is acceptable worldwide. Ethnicity and gender of the fetus are the well reported and recognized causes of inaccuracies in these fetal weight formulae. The aim of this study was to compare the accuracies of Schild's gender specific formula with Hadlock's, Shepard's and Aoki's formulae in Pakistani population
Study Design: Cross sectional study
Place and Duration of Study: This study was conducted at Ziauddin University Hospital, from May 2014 to May 2015
Material and Methods: This cross sectional study recruited 150 primary gravida with singleton pregnancy. Patients with hypertension, diabetes and smoking were excluded. Sonographic evaluation for fetal parameters was done during 36.39 +/- 0.684 weeks of gestation. Mean fetal weight was estimated from these formulae. Mean error, mean percentage error and the limit of agreement by Bland -Altman plot was determined. Anova was applied to compare the means of estimated fetal weight, error and percentage error. Gender and weight was noted after birth
Results: No significant difference was found between the means of estimated fetal weightobtained by these formulae. Statistically significant difference was found between mean error of these formulae [p -value = 0.012] ranging between -217.24 gram to - 310.93 gram. Insignificant difference in mean percentage errors was noted which was between - 6.74% to - 9.37%. The narrowest and widest limit of agreement was found with Schild's formula and Hadlock's formula respectively
Conclusion:In our population,for pregnancies with in normal range of fetal weight, Hadlock's, Shepard's, Aoki's and Schild's fetal weight formulae, all showed low values of mean errors and mean percentage errors which were within acceptable range