The role of umbilical vein flow rate and foetal growth velocity in predicting iatrogenic preterm birth and adverse perinatal outcomes in a population of small foetuses

Objective. Delphi consensus criteria for foetal growth restriction (FGR) definition have proven to be more accurate in predicting adverse perinatal outcomes (APO) compared to the definition based on estimated foetal weight (EFW) or abdominal circumference (AC) < 10^th percentile. However, this definition still shows a suboptimal performance as a proportion of FGR remains undiagnosed. The aim of this study was to evaluate the capacity of umbilical vein blood flow (UVF) and foetal growth velocity (FGV) in predicting APO and iatrogenic preterm birth in a population of small foetuses, regardless of Delphi consensus criteria.
Materials and Methods. In this prospective multicentric observational study we enrolled women with a diagnosis of small for gestational age (SGA) or FGR. Foetal biometry and Doppler assessment, including UVF measurement, were collected at the time of diagnosis. The FGV was derived from the difference between the EFW calculated in two consecutive sonographic evaluations. Multiple logistic regression models were estimated using UVF and FGV to predict APO and iatrogenic preterm birth.
Results. The study involved 57 SGA and 57 FGR. The multivariable logistic regression analyses showed that, after adjusting for diagnosis of FGR, UVF ≤ 0.65 MoM (aOR 3.5; 95%CI 1.0-11.8) and FGV ≤ 0.63 MoM (aOR 3.0, 95%CI 1.2-7.9) were associated with APO. Moreover, UVF ≤ 0.60 MoM (aOR 5.2, 95%CI 1.7-15.9), and FGV ≤ 0.63 MoM (aOR 3.6, 95%CI 1.1-12.6) were significant predictors of iatrogenic preterm birth.
Conclusions. UVF and FGV are independent predictors of iatrogenic preterm birth and APO in a population of small foetuses, regardless of the Delphi consensus criteria.