Overestimation of fetal weight by ultrasound: does it influence the likelihood of cesarean delivery for labor arrest?

Am J Obstet Gynecol. 2009 Mar;200(3):340.e1-3. doi: 10.1016/j.ajog.2008.12.043.


Objective: We sought to determine whether the overestimation of ultrasound-derived estimated fetal weight (EFW) is associated with increased diagnosis of labor arrest.

Study design: This is a historical cohort study of nulliparous women with term pregnancies who underwent bedside ultrasound examination for EFW before labor induction. Labor outcomes of women with EFW overestimation > 15% the actual birthweight were compared with those with EFW not overestimated.

Results: Overestimation of EFW occurred in 9.5% of cases (23/241). The rate of cesarean delivery (CD) for labor arrest was higher for those with EFW overestimation (34.8% vs 13.3%; P = .01) even though there were no differences in length of the induction duration. After adjusting for confounding factors, EFW overestimation remained associated with CD for labor arrest (odds ratio, 4.8; 95% confidence interval, 1.5-15.2).

Conclusion: Our finding suggests that an overestimation of EFW may be associated with a lower threshold for CD for labor arrest.

MeSH terms

  • Adolescent
  • Adult
  • Cesarean Section / statistics & numerical data*
  • Cohort Studies
  • Diagnostic Errors
  • Female
  • Fetal Macrosomia / diagnostic imaging*
  • Fetal Weight*
  • Humans
  • Labor, Induced
  • Obstetric Labor Complications / diagnostic imaging
  • Parity
  • Pregnancy
  • Ultrasonography, Prenatal / standards
  • Ultrasonography, Prenatal / statistics & numerical data*
  • Young Adult