Clinical accuracy of estimated fetal weight in term pregnancies in a teaching hospital

Objective: To evaluate whether clinical characteristics alter the accuracy of clinical estimation of fetal weight (EFW) in term pregnancies in a teaching hospital. Methods: Secondary analysis of a retrospective cohort study of patients presenting for labor at term. Clinical EFW was performed using Leopold maneuvers. A Spearman's rank correlation coefficient (r) was used to evaluate the linear relationship between clinical EFW and actual birth weight (BW). Body mass index (BMI), gestational age, fetal station, and admission diagnosis were evaluated with respect to their impact on clinical EFW. The primary outcome was an absolute error between clinical EFW and actual BW >500g. Results: Of 3797 patients, 941 (24.8%) had an absolute error in clinical EFW exceeding 500g. The overall correlation between clinical EFW and actual BW was weak (r=0.4). There was a significant trend of improved accuracy of clinical EFW with increasing gestational age; however, BMI, fetal station, and admission diagnosis did not have significant effects. Of 221 cases of macrosomia (>4000 g), 181 (81.9%) were undetected by clinical EFW. Conclusion: The correlation between clinical EFW and actual BW is overall weak, particularly in patients with macrosomic fetuses; however, BMI, admission diagnosis, and fetal station do not have a significant impact.