RESUMEN
Objectives: To investigate the factors which might influence the sonographic fetal weight estimation [SFWE] accuracy
Methods: This prospective study was conducted among 949 singleton term pregnant women who delivered at a tertiary center, from January 2017 to December 2017. All participants' maternal [i.e. parity, age, body mass index and gestational weight gain during pregnancy], fetal sonographic [i.e. fetal presentation, amniotic fluid index, localization of placenta and estimated fetal weight] and neonatal [birth weight and gender] characteristics were recorded. A p<0.05 was considered significant
Results: The mean absolute percent error [APE] values of SFWE was 8.2+/-6.5 percent, and overall failure ratio [APE >10%] was 33%. In failure group, primiparous woman and cephalic presentation fetus were significantly more common compared to accuracy group [55.9% vs.44.8%; p=0.001 and 98% vs. 95.2%; p=0.03, respectively]. In contrast, the mean neonatal birth weight [NBW] value was significantly lower in failure group compared to success group [3250+/-565 gr vs. 3404+/-410 gr; p=0.001]. The correlation between SFWE and NBW was linear, however negative, and significant [p=0.001]. Logistic regression analysis revealed that primiparous woman, cephalic presentation fetus and <3300 gr NBW were independent risk factors for the SFWE failure [relative risks were 1.6, 2.8 and 2.4 respectively, p<0.05]
Conclusion: SFWE has a high correlation with NBW, however it's accuracy is still unsatisfactory, and depend on many unpredictable and inconsistent factors