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

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 1

Reversed End-Diastolic Velocity

• Hospitalize immediately upon detection, as this represents severe placental failure with imminent risk of fetal demise 2
• Perform daily or more frequent monitoring 1

Critical Delivery Timing Algorithm

Delivery timing 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 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 prematurity and ongoing placental insufficiency risks 1, 2

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

• Deliver at 38-39 weeks gestation 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 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
• The decision should account for gestational age, estimated fetal weight, cervical status, and presence of other comorbidities 1

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

Interventions to Avoid

The evidence is clear that several interventions lack efficacy and should not be used:

• Do not use low-molecular-weight heparin solely for prevention of recurrent FGR, as evidence does not support this intervention 1, 2
• Do not prescribe sildenafil or recommend activity restriction for in utero treatment of FGR, as these interventions are ineffective and potentially harmful 1, 2
• Do not use low-dose aspirin for the sole indication of FGR prevention in otherwise low-risk women, as evidence is conflicting 1

Critical Pitfalls to Avoid

• Do not delay delivery beyond recommended gestational ages based on Doppler findings, as this increases stillbirth risk without benefit 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
• Do not use middle cerebral artery, ductus venosus, or uterine artery Doppler for routine clinical management decisions in place of umbilical artery Doppler 1
• Recognize that maternal hypertensive disease is common in early-onset FGR (present in 50-70% of cases) and is an important independent determinant of poor outcomes requiring close monitoring 1

Long-Term Considerations

• Understand that FGR has implications beyond the perinatal period, with associations to metabolic syndrome, cardiovascular disease, and endocrine disorders in adulthood 1, 4
• The single most important prognostic factor in preterm fetuses with growth restriction is gestational age at delivery, with a 1-2% increase in intact survival for every additional day in utero up until 32 weeks 1
• Coordinate with neonatology for optimal resuscitation planning, particularly in cases of severe FGR or early delivery 3