Predictive Performance Of Race/Ethnicity Based Growth Velocities In Pregnancies Complicated By Diabetes

Recently, the NICHD published a race/ethnicity-based fetal growth velocity percentile calculator derived from a cohort of low-risk pregnancies. Fetal growth velocity is accelerated in pregnancies affected by diabetes. However, use of growth velocity percentiles are untested in this population. We sought to determine the test performance of growth velocity percentiles in pregnancies with diabetes. Retrospective cohort study of all women with pregestational and gestational diabetes with ultrasound data at two third trimester time points (28w0d-31w6d and 32w0d-35w6d) between 2009-2019 at a single academic institution. Self-reported race/ethnicity and fetal biometry were used to calculate abdominal circumference (AC) and estimated fetal weight (EFW) velocities between time points. Traditional AC and EFW percentiles were recorded for the second ultrasound for comparison. ROC curves and areas under the curve (AUC) were compared between parameters for prediction of composite neonatal outcome and LGA. Test statistics were calculated and compared at optimal cut points identified by the Youden J statistic. There were 1,093 pregnancies included in the analysis with 599 (54.8%) and 297 (27%) complicated by adverse composite outcome or LGA birthweight. No differences in AUCs for neonatal composite outcome were found (p=.234; Figure 1). Traditional EFW and AC biometric percentiles were significantly better predictors of LGA birthweight than either velocity parameter (Figure 2). The optimal cut point for EFW velocity (51%) had poor overall performance with a sensitivity 65.7% (CI 60.0%-71.0%) and positive predictive value (PPV) of 35.6% (CI 31.6-39.8%) for LGA. Results were similar for AC velocity (cut point 57%) with a sensitivity of 57.6% (CI 51.7%-63.3%) and PPV of 36.9% (CI 32.5%-41.4%). Neither traditional ultrasound biometry nor race/ethnicity-based growth velocity accurately predicted adverse neonatal outcomes in pregnancies complicated by diabetes. However, traditional ultrasound biometry was superior to both EFW and AC growth velocities for prediction of LGA birth weight.View Large Image Figure ViewerDownload Hi-res image Download (PPT)