Two sonograms enough to predict gestational diabetes mellitus macrosomia

Two serial sonographic abdominal circumference measurements are enough to reliably predict the absence of fetal overgrowth in women with gestational diabetes mellitus (GDM), according to the findings of a recent study from Germany. Moreover, the predictive ability of 2 scans is enhanced when a woman has no risk factors for GDM.

Researchers from Berlin performed 4,478 sonograms on 1,914 women with GDM. Of 518 women with fetal abdominal circumference measurements greater than the 90th percentile, the first sonogram diagnosed macrosomia in 73.9% of cases. The second ultrasound caught another 13.1% of cases.

When fetal abdominal circumference was less than the 90th percentile at 24-27 weeks and 28-32 weeks, 85.9% and 86.9% of the fetuses were born non-large-for-gestational-age (LGA), and when the first 2 sonographic measurements of abdominal circumference were less than the 90th percentile, 88.0% of the infants were born non-LGA. In women without risk factors for macrosomia (ie, body mass index greater than 30 kg/m², a history of macrosomia, and fasting glucose greater than 100 mg/dL), the accuracy of the scans in terms of predicting a non-LGA neonate was as high as 95.2%. Predictive ability did not improve with additional scans beyond 2 normal ones.

Following the protocol suggested by the study findings provides a way to detect virtually all fetuses with a tendency for fetal overgrowth while keeping costs associated with such scans to a minimum.

Schaefer-Graf UM, Wendt L, Sacks DA, et al. How many sonograms are needed to reliably predict the absence of fetal overgrowth in gestational diabetes mellitus pregnancies? Diabetes Care. 2011;34(1):39-43.