Fetal Growth Restriction (FGR): Delphi Criteria, Doppler Staging, and Timing of Delivery

Delphi Consensus in Defining FGR

The consensus definition of fetal growth restriction was obtained through the Delphi procedure (Gordijn SJ, Beune IM, Thilaganathan B, et al. Consensus definition of fetal growth restriction: a Delphi procedure. Ultrasound Obstet Gynecol. 2016;48(3):333-339). Validation of the Delphi criteria was conducted in separate studies (Molina LCG et al.), confirming their applicability in clinical practice.

According to the excerpts, the key components of the Delphi criteria for diagnosing FGR are: Doppler of the uterine arteries, cerebroplacental ratio (CPR), longitudinal assessment of fetal growth, and third-trimester combined screening. It is noted that in isolation, these parameters may not significantly improve the prediction of SGA/FGR compared to a single determination of EFW, but they form the basis of the Delphi criteria.

Early and Late FGR

The literature distinguishes between early-onset and late-onset FGR. Late FGR, as defined by the Delphi consensus, is associated with impaired growth of the fetal midline and cortical brain structures compared to SGA and AGA fetuses (Ultrasound Obstet Gynecol, Vol. 64, No. 2, 2024). Placental pathology differs between early and late FGR (Mifsud W, Sebire NJ. Placental pathology in early-onset and late-onset fetal growth restriction. Fetal Diagn Ther).

Perinatal morbidity and mortality in early FGR were studied in the TRUFFLE study (Lees C, Marlow N, Arabin B, et al. Ultrasound Obstet Gynecol. 2013;42(4):400-408), which uses a Doppler approach to monitoring.

Doppler Staging

Staging is conducted based on Doppler status; in the cited studies, FGR analysis was stratified according to Doppler status. Specific stages and their threshold values (pulsatility indices, ductus venosus changes, etc.) are not provided in the excerpts [clarify]. The use of Doppler in obstetrics is regulated by separate ISUOG practice guidelines (Bhide A, Acharya G, Bilardo CM, et al.).

Screening and Timing

Screening for SGA/FGR in the general population is more accurate when conducted at 36 weeks rather than at 32 weeks of pregnancy (GRADE recommendations: B). Fetal Doppler assessment in some protocols begins earlier than the third trimester — between 26 and 28 weeks of gestation.

Timing of Delivery

Specific timing and criteria for delivery at various stages of FGR are not detailed in the provided excerpts [clarify]. For clinical decision-making, it is recommended to refer to the full text of ISUOG practice guidelines on the diagnosis and management of SGA/FGR (2020).