Clinical and Sonographic Estimates of Birth Weight Among Diabetic Parturients.

Objective: To determine the relative accuracy of clinical and sonographic estimates of fetal weight (EFW) among parturients with diabetes requiring insulin (White's classifications A2 and higher).Methods: In early labor, clinical EFW was followed by sonographic mensuration of fetal parts. At the completion of the study, sonographic EFW was calculated using abdominal circumference and femur length. Student's t test, Wilcoxan test, and chi square test were used to assess the relative accuracy of the two methods of assessing birth weight.Results: Among 94 parturients with various classifications of diabetes, the clinical estimate of birth weight has a significantly higher simple error (-180.3 + 419.5 g) but not a significantly higher mean standardized absolute error (130.7 +/- 130.1 g/kg) than sonographic prediction (-139.3 +/- 447.1 g, 115.6 +/- 90.8 g/kg, respectively). Analysis of the data, according to gestational age, indicates that clinical EFW is more accurate than sonographic EFW among term (n = 67) parturients with diabetes, but both methods are comparable in preterm (n = 27) parturients. However, when the data are analyzed according to birth weight, EFW by Leopold maneuvers is significantly more accurate than those obtained sonographically in infants weighing 2500-3999 g (n = 66) and >4000 g (n = 12).Conclusion: In term gestations of diabetic mothers and those infants with a birth weight of 2500 g or more, the clinical estimate of birth weight is more accurate; however, in preterm diabetic pregnancies, clinical and sonographic estimates are equal.