Accuracy of Clinically Estimated Fetal Weight in Pregnancies Complicated by Diabetes Mellitus and Obesity

Abstract

Objective To determine the accuracy of clinically estimated fetal weight (CEFW) in patients with gestational diabetes (GDM), pregestational diabetes (DM), and obesity.

Study Design This is a retrospective analysis of Consortium of Safe Labor data. Subjects were classified into six groups: DM, DM and obese, GDM, GDM and obese, nondiabetic obese, and controls. The mean difference between birth weight (BW) and CEFW, the percent of accurate CEFW (defined as < 10% difference), and the sensitivity for identifying BW > 4,000 g and > 4,500 g were calculated for each group.

Results The accuracy of CEFW in our population was 54.3 to 64.4% and was significantly lower in patients with DM and obesity and patients with obesity but not diabetes. When CEFW was analyzed in the >4,000-g and > 4,500-g groups, its accuracy was 20 to 51% and 14 to 40%, respectively. CEFW overestimated BW more commonly in GDM, obese GDM, and obese groups. The sensitivity of CEFW for diagnosing BW > 4,000 g or > 4,500 g was 19.6% and 9.6%, respectively, and it improved in pregnancies complicated by diabetes.

Conclusion CEFW is a poor predictor of macrosomia in pregnancies complicated by obesity and diabetes.

Keywords

clinically estimated fetal weight - accuracy - gestational diabetes - obesity

Note

This research was presented at the Annual Meeting of the Diabetes in Pregnancy Study Group of North America in Washington, DC, on April 1, 2011.

• References

• 1 ACOG Committee on Practice Bulletins. The American College of Obstetricians and Gynecologists. Fetal macrosomia. ACOG Practice Bulletin No. 22. Obstet Gynecol 2000; 96: 5
• 2 ACOG Committee on Practice Bulletins. The American College of Obstetricians and Gynecologists. Shoulder Dystocia. ACOG Practice Bulletin Number 40. Obstet Gynecol 2002; 100: 1045-1050
• 3 Dudley NJ. A systematic review of the ultrasound estimation of fetal weight. Ultrasound Obstet Gynecol 2005; 25: 80-89
• 4 Alsulyman OM, Ouzounian JG, Kjos SL. The accuracy of intrapartum ultrasonographic fetal weight estimation in diabetic pregnancies. Am J Obstet Gynecol 1997; 177: 503-506
• 5 Shamley KT, Landon MB. Accuracy and modifying factors for ultrasonographic determination of fetal weight at term. Obstet Gynecol 1994; 84: 926-930
• 6 Raman S, Urquhart R, Yusof M. Clinical versus ultrasound estimation of fetal weight. Aust N Z J Obstet Gynaecol 1992; 32: 196-199
• 7 Bernstein IM, Catalano PM. Influence of fetal fat on the ultrasound estimation of fetal weight in diabetic mothers. Obstet Gynecol 1992; 79: 561-563
• 8 Insler V, Bernstein D, Rikover M, Segal T. Estimation of fetal weight in utero by simple external palpation. Am J Obstet Gynecol 1967; 98: 292-293
• 9 Farrell T, Holmes R, Stone P. The effect of body mass index on three methods of fetal weight estimation. BJOG 2002; 109: 651-657
• 10 Sherman DJ, Arieli S, Tovbin J, Siegel G, Caspi E, Bukovsky I. A comparison of clinical and ultrasonic estimation of fetal weight. Obstet Gynecol 1998; 91: 212-217
• 11 Delpapa EH, Mueller-Heubach E. Pregnancy outcome following ultrasound diagnosis of macrosomia. Obstet Gynecol 1991; 78 (3 Pt 1) 340-343
• 12 Stetzer BP, Thomas A, Amini SB, Catalano PM. Neonatal anthropometric measurements to predict birth weight by ultrasound. J Perinatol 2002; 22: 397-402
• 13 Mehta SH, Blackwell SC, Hendler I , et al. Accuracy of estimated fetal weight in shoulder dystocia and neonatal birth injury. Am J Obstet Gynecol 2005; 192: 1877-1880 , discussion 1880–1881
• 14 Blackwell SC, Refuerzo J, Chadha R, Carreno CA. Overestimation of fetal weight by ultrasound: does it influence the likelihood of cesarean delivery for labor arrest?. Am J Obstet Gynecol 2009; 200: e1-e3
• 15 Zhang J, Troendle J, Reddy UM , et al; Consortium on Safe Labor. Contemporary cesarean delivery practice in the United States. Am J Obstet Gynecol 2010; 203: e1 , e10