What is the management plan for a pregnant woman with suspected fetal growth restriction?

Management of Fetal Growth Restriction

The management of suspected fetal growth restriction centers on immediate umbilical artery Doppler assessment to stratify risk, followed by a surveillance protocol and delivery timing algorithm that balances prematurity risks against stillbirth risk, with delivery timing ranging from 30-32 weeks for reversed end-diastolic velocity to 37-39 weeks for milder forms. 1

Initial Diagnostic Confirmation and Risk Stratification

• Confirm FGR diagnosis with ultrasound showing estimated fetal weight or abdominal circumference below the 10th percentile using population-based growth references 1
• Obtain umbilical artery Doppler immediately upon FGR diagnosis, as this is the single most important prognostic tool that will guide all subsequent management decisions 2
• Perform detailed anatomical ultrasound when FGR is diagnosed before 32 weeks gestation, as early-onset cases carry substantially higher morbidity and mortality risk 2
• Assess amniotic fluid volume, as oligohydramnios combined with FGR significantly worsens prognosis and indicates severe placental dysfunction 2, 3

Genetic and Infectious Workup

• Offer chromosomal microarray analysis when FGR occurs with fetal malformations, polyhydramnios, or when isolated FGR is diagnosed before 32 weeks gestation, as these scenarios have higher rates of chromosomal abnormalities 2
• Do not routinely screen for toxoplasmosis, rubella, or herpes in FGR pregnancies without other risk factors, as these tests have low yield 2
• Perform PCR testing for cytomegalovirus only in women with unexplained FGR who elect diagnostic amniocentesis, as CMV is the most common infectious cause worth investigating 2

Surveillance Protocol Based on Doppler Findings

The surveillance intensity must be adjusted based on umbilical artery Doppler findings, which reflect the severity of placental dysfunction:

Normal or Decreased End-Diastolic Velocity

• Perform weekly umbilical artery Doppler evaluation when end-diastolic velocity is decreased or when severe FGR (estimated fetal weight <3rd percentile) is present 1, 2
• Conduct weekly cardiotocography testing after viability 1
• Monitor for development of maternal hypertensive disorders, which are present in 50-70% of early-onset FGR cases and independently worsen outcomes 1

Absent End-Diastolic Velocity

• Increase Doppler assessment frequency to 2-3 times per week, as this indicates significant placental dysfunction requiring heightened surveillance 2
• Increase cardiotocography frequency beyond weekly testing 1
• Prepare for delivery at 33-34 weeks gestation 1

Reversed End-Diastolic Velocity

• Hospitalize immediately upon detection, as this represents severe placental failure with imminent risk of fetal demise 2
• Plan for delivery at 30-32 weeks gestation 1

Critical Pitfall to Avoid

Do not use middle cerebral artery, ductus venosus, or uterine artery Doppler for routine clinical management decisions in FGR, as only umbilical artery Doppler has Level I evidence demonstrating improved outcomes 1

Delivery Timing Algorithm

The timing of delivery must balance prematurity risks against ongoing placental insufficiency, guided primarily by umbilical artery Doppler findings and severity of growth restriction. 1, 2

Reversed End-Diastolic Velocity

• Deliver at 30-32 weeks gestation, as this represents the highest-risk category requiring earliest intervention 1, 2

Absent End-Diastolic Velocity

• Deliver at 33-34 weeks gestation, as waiting beyond this gestational age increases stillbirth risk without meaningful reduction in neonatal morbidity 1, 2

Decreased Diastolic Flow or Severe FGR (<3rd percentile)

• Deliver at 37 weeks gestation, as this balances the risks of prematurity and ongoing placental insufficiency 1, 2

Mild FGR (3rd-10th percentile) with Normal Doppler

• Deliver at 38-39 weeks gestation, as these fetuses have lower risk but still warrant earlier delivery than uncomplicated pregnancies 1

FGR with Oligohydramnios at ≥35 Weeks

• Proceed with immediate delivery after corticosteroid administration, as the risks of expectant management outweigh any benefits of continued gestation at this point 3

Mode of Delivery Considerations

• Consider cesarean delivery for FGR complicated by absent or reversed end-diastolic velocity based on the entire clinical scenario, as these fetuses have limited physiologic reserve and may not tolerate labor well 1, 2
• Continuous electronic fetal heart rate monitoring is mandatory during labor for all FGR cases 4

Antenatal Corticosteroids and Neuroprotection

• Administer antenatal corticosteroids if delivery is anticipated before 33 6/7 weeks gestation, as this is critical for reducing neonatal respiratory morbidity and mortality 1, 2
• Consider corticosteroids for pregnancies between 34 0/7 and 36 6/7 weeks in women at risk of preterm delivery within 7 days who have not received a prior course 1
• Administer intrapartum magnesium sulfate for fetal neuroprotection when delivery is anticipated before 32 weeks gestation, as this reduces the risk of cerebral palsy in surviving infants 1, 2

What NOT to Do: Ineffective Interventions

The evidence is clear that several interventions should be avoided:

• Do not use low-molecular-weight heparin solely for prevention or treatment of FGR, as evidence does not support this intervention 1, 2
• Do not prescribe sildenafil for in utero treatment of FGR, as this intervention is ineffective and potentially harmful 1, 2
• Do not recommend activity restriction or bed rest, as there is no consistent evidence this prevents FGR or improves outcomes 1
• Do not use low-dose aspirin solely for FGR prevention in otherwise low-risk women, as evidence is conflicting and ACOG recommends against this indication 1

Key Clinical Pearls

• The single most important prognostic factor in preterm fetuses with growth restriction is the gestational age at delivery, with a 1-2% increase in intact survival for every additional day spent in utero up until 32 weeks 1
• Standardized protocols for diagnosis and management are associated with more favorable outcomes compared to discretionary management 1
• Do not delay delivery beyond recommended gestational ages based on Doppler findings, as this increases stillbirth risk 2
• Do not rely on biophysical profile or nonstress testing alone without Doppler assessment in diagnosed FGR, as Doppler provides superior prognostic information about placental function 2