Fetal Growth Restriction Diagnosis and Implications

Diagnostic Criteria

The American College of Obstetricians and Gynecologists defines fetal growth restriction (FGR) as an estimated fetal weight (EFW) or abdominal circumference (AC) below the 10th percentile for gestational age 1, 2, 3
Severe FGR is defined as EFW below the 3rd percentile, representing the most critical category with stillbirth rates up to 2.5% 1, 2, 3

Fetuses below the 10th percentile face doubled stillbirth risk (approximately 1.5% compared to 0.7% in normally growing fetuses), along with increased risks of severe acidosis, low Apgar scores, and NICU admissions 1, 3
Below the 5th percentile, stillbirth rates increase to 2.5% 3, 1
Below the 3rd percentile (severe FGR), stillbirth rates reach up to 2.5% regardless of other findings 3
Preterm FGR compounds risk with 2- to 5-fold increased perinatal death rates compared to term FGR 1

Abnormal umbilical artery Doppler, such as elevated pulsatility index, resistance index, or absent/reversed end-diastolic velocity, confirms placental insufficiency 2, 3
Reduced growth velocity, such as AC change <5mm over 14 days or >30% reduction in growth velocity, indicates progressive pathology 2, 3
Oligohydramnios suggests chronic placental dysfunction 3
Abnormal middle cerebral artery Doppler or cerebroplacental ratio indicates fetal brain-sparing redistribution 3

Early-onset FGR, diagnosed at <32 weeks gestation, is often associated with more severe placental insufficiency and may warrant genetic testing 1, 2
Late-onset FGR is diagnosed at ≥32 weeks gestation 2

The American College of Obstetricians and Gynecologists acknowledges that IUGR is linked with lifelong health consequences beyond the perinatal period, including impaired intellectual performance in childhood and adult diseases such as hypertension, obesity, and cardiovascular disease 4