Prediction of late-onset fetal growth restriction by umbilical artery velocities at 37 weeks' gestation

Objectives: To explore the predictive capacity of the umbilical artery velocities at 37 weeks’ gestation in identifying fetal growth restriction (FGR), small-for-gestational-age (SGA) neonates and adverse perinatal outcome (APO). Methods: We retrospectively recruited FGR and SGA with normal umbilical artery Doppler at 37 weeks, and adequate-for-gestational age (AGA) controls in a tertiary referral center. All the parameters of the umbilical artery velocities were measured at about 37 weeks’ gestation, including the umbilical artery end-diastolic velocity (UA-EDV), umbilical artery peak systolic velocity (UA-PSV), umbilical artery mean diastolic velocity (UA-MDV) and umbilical artery time-averaged maximum velocity (UA-TAMXV). Results: A total of 569 cases were included in the study and divided into three groups: FGR group, SGA group and AGA group. Of these, 39 (6.9%) were identified as FGR, 57 (10.0%) were SGA and 473 (83.1%) were AGA. Among the three groups, the UA-MDV, UA-TAMXV, UA-PSV, and UA-EDV were decreased with the severity of growth restriction. Multivariate logistic regression analyses showed that the UA-TAMXV was independent predicting factor of FGR. It had a moderate predictive value for FGR, with an area under the ROC curve of 0.821 [95% confidence interval (CI): 0.785-0.853]. Conclusions: The UA velocities were decreased with the severity of growth restriction and the UA-TAMXV was independently predictive of FGR. The results suggest that UA-TAMXV might be a new parameter to predict FGR.