Standardizing research definitions and clinical triaging for growth abnormalities globally
The Paradigm Shift
Historically, any fetus <10th percentile was labeled FGR. The Delphi consensus establishes that FGR is a trajectory/functional issue. A fetus dropping dramatically from the 70th to 15th percentile may be highly restricted, while a genetically healthy 8th percentile fetus is merely SGA.
Section 2
Formula & Logic
Early FGR (< 32 Weeks) - Needs ONE of the following:
AC or EFW < 3rd percentile
Absent End-Diastolic Flow (AEDF) in Umbilical Artery (UA)
AC or EFW < 10th percentile PLUS UA-PI > 95th percentile AND/OR MCA-PI < 5th percentile
Late FGR (≥ 32 Weeks) - Needs ONE isolated, OR TWO contributory:
Isolated Criteria: AC or EFW < 3rd percentile
Contributory (need ≥2): AC or EFW < 10th percentile
Contributory (need ≥2): AC or EFW crossing percentiles by > 2 quartiles (>50 percentile drop) on growth chart
Contributory (need ≥2): Cerebroplacental ratio (CPR) < 5th percentile OR UA-PI > 95th percentile
Section 3
Pearls/Pitfalls
Vital Nuance: Cerebroplacental Ratio (CPR)
CPR is MCA-PI divided by UA-PI.
A low index (< 5th percentile) strongly implies "brain-sparing" hemodynamics (vasodilation of fetal brain). In late FGR, CPR is often the ONLY abnormal Doppler metric before decompensation.
Section 4
Next Steps
Management via TRUFFLE/ACOG Guidelines
01
Fetus meets SGA but not FGR (e.g., normal Doppler, steady growth): Reassure, schedule 2-3 weekly growth scans.
02
Fetus meets FGR Criteria: Initiate intensive surveillance. Non-Stress Tests (NST), Biophysical Profile (BPP), and Doppler indices (UA, MCA, ductus venosus) 1-2 times weekly depending on severity.
03
Absent end-diastolic flow (AEDF): Highly concerning. Accelerate surveillance. Consider delivery between 33+0 to 34+0 weeks after corticosteroids for lung maturation.
04
Reversed end-diastolic flow (REDF) or Ductus Venosus abnormal A-wave: Critical hypoxia. Highly imminent risk of fetal demise. Immediate delivery if viability parameters allow (frequently 30-32 weeks).
Section 5
Evidence Appraisal
The Delphi Consensus
Consensus definition of fetal growth restriction: a Delphi procedure.
Gordijn SJ et al. • Ultrasound Obstet Gynecol.. 2016;Global panel of maternal-fetal medicine experts voted iteratively to separate true placental insufficiency (FGR) from demographic smallness.
Section 6
Literature
Need for Clarity
Prior to 2016, there were over 100 different clinical definitions of FGR/IUGR published in medical literature. The Gordijn/ISUOG Delphi process was the first successful attempt to unify global Fetal Medicine societies under a single, pathophysiologically-driven definition.
