What is the recommended treatment for fetal growth restriction in a pregnant patient?

Treatment for Fetal Growth Restriction

The primary treatment for fetal growth restriction is timely delivery based on umbilical artery Doppler findings, combined with intensive fetal surveillance and supportive interventions—there is no effective in-utero therapy to reverse placental insufficiency. 1

Prevention Strategies

Low-dose aspirin (100-150 mg daily) started before 16 weeks of gestation reduces the risk of FGR in high-risk women, including those with prior preeclampsia, prior FGR, or multiple risk factors. 1

• Smoking cessation at any stage of pregnancy is the only other modifiable intervention with proven benefit. 1
• No evidence supports bed rest, dietary modifications, or other lifestyle interventions for preventing or treating FGR. 1

Surveillance Protocol After FGR Diagnosis

Umbilical Artery Doppler Assessment

Umbilical artery Doppler is the only surveillance modality with Level I evidence showing a 29% reduction in perinatal mortality (RR 0.71,95% CI 0.52-0.98) and must be initiated immediately upon FGR diagnosis. 2

• Every 2 weeks when umbilical artery Doppler is normal 1
• Weekly when decreased end-diastolic velocity or severe FGR (EFW <3rd percentile) is present 1, 2
• 2-3 times per week when absent end-diastolic velocity (AEDV) is detected 1, 3, 2
• Daily with hospitalization when reversed end-diastolic velocity (REDV) is present 3, 2

Cardiotocography (NST/BPP)

Weekly cardiotocography testing after viability for FGR without absent/reversed end-diastolic velocity, increasing frequency when Doppler abnormalities develop. 1, 2

• Do not use cardiotocography or biophysical profile as the sole surveillance method—normal fetal heart rate testing does not exclude worsening FGR. 1, 2
• Increase to twice-weekly or more frequent testing when AEDV or REDV is present. 1

Additional Doppler Studies

The Society for Maternal-Fetal Medicine recommends against using middle cerebral artery, ductus venosus, or uterine artery Doppler for routine clinical management of FGR. 1

• While some international guidelines suggest middle cerebral artery Doppler or cerebroplacental ratio monitoring, the highest quality U.S. guideline does not support their routine use. 1

Timing of Delivery: The Critical Decision

Delivery timing is determined by umbilical artery Doppler findings and severity of growth restriction, not by fetal heart rate patterns alone. 1, 3

Normal Umbilical Artery Doppler

• Deliver at 38-39 weeks when EFW is between 3rd-10th percentile with normal Doppler 1, 3, 2
• Continue weekly Doppler and weekly cardiotocography until delivery 2

Decreased Diastolic Flow (but not absent)

• Deliver at 37 weeks when umbilical artery shows decreased diastolic flow or when severe FGR with EFW <3rd percentile 1, 3, 2
• Maintain weekly Doppler surveillance until delivery 1

Absent End-Diastolic Velocity (AEDV)

• Deliver at 33-34 weeks as neonatal morbidity/mortality with AEDV exceeds complications of prematurity at this gestational age 1, 3, 4
• Increase Doppler to 2-3 times weekly and cardiotocography to at least twice weekly 1, 3, 2
• AEDV indicates obliteration of approximately 70% of placental tertiary villi arteries and represents severe placental insufficiency 4

Reversed End-Diastolic Velocity (REDV)

• Deliver at 30-32 weeks due to severe placental dysfunction with high risk of fetal demise 1, 3, 2
• Hospitalize immediately with cardiotocography 1-2 times daily 3, 2
• REDV represents the most severe form of placental failure requiring urgent intervention 3

Pre-Delivery Interventions

Antenatal Corticosteroids

Administer betamethasone or dexamethasone if delivery is anticipated before 33 6/7 weeks or between 34 0/7 and 36 6/7 weeks in women at risk of delivery within 7 days. 1, 3, 2

• This is a GRADE 1A recommendation with the highest level of evidence. 1
• Corticosteroids reduce neonatal respiratory distress syndrome, intraventricular hemorrhage, and necrotizing enterocolitis. 3

Magnesium Sulfate for Neuroprotection

Administer intrapartum magnesium sulfate for fetal and neonatal neuroprotection when delivery is anticipated at <32 weeks of gestation. 1, 3, 2

• This is a GRADE 1A recommendation supported by multiple randomized trials. 1

Mode of Delivery Considerations

For FGR complicated by AEDV or REDV, cesarean delivery should be strongly considered based on the complete clinical scenario. 1, 3, 4

• Studies report 75-95% of FGR pregnancies with AEDV/REDV require cesarean delivery for intrapartum fetal heart rate abnormalities, even when antepartum testing was reassuring. 3, 2
• FGR fetuses with abnormal Dopplers are at increased risk for intrapartum decelerations, emergency cesarean delivery, and metabolic acidemia. 3
• Vaginal delivery may be attempted in FGR with normal or decreased (but not absent) diastolic flow, with continuous electronic fetal monitoring. 3

Diagnostic Workup

Genetic Testing

Chromosomal microarray analysis is recommended when unexplained isolated FGR is diagnosed before 32 weeks of gestation. 2

• Chromosomal disorders and congenital malformations account for approximately 20% of FGR cases. 1

Infectious Workup

Do not routinely screen for toxoplasmosis, rubella, or herpes in the absence of other risk factors. 2

• Consider PCR for cytomegalovirus in women with unexplained FGR who choose diagnostic testing with amniocentesis. 2

Common Pitfalls and Caveats

Normal fetal heart rate testing does not exclude worsening FGR—heart rate changes occur late in the deterioration sequence, typically after significant Doppler abnormalities are already present. 2

• Early or compensated FGR maintains normal heart rate patterns, normal variability, and reactive NSTs while the fetus adapts to chronic hypoxemia through blood flow redistribution. 2
• Doppler abnormalities progress in a predictable sequence: increased umbilical artery resistance → absent end-diastolic flow → reversed end-diastolic flow → venous Doppler changes → finally, abnormal heart rate patterns. 2

Do not delay delivery beyond the recommended gestational age based on Doppler findings, even if fetal heart rate testing remains reassuring. 3, 4

• At 35 weeks with AEDV, delivery should not be delayed since the recommended delivery timing is 33-34 weeks. 4
• No antenatal test can predict stillbirth from acute events such as placental abruption or cord accidents. 2

Fetal growth evaluation should be performed at intervals of no less than 2 weeks, with 3-4 week intervals being more reliable due to inherent error in fetal biometry. 2

FGR remains widely underdiagnosed—up to 50% of cases are missed antenatally, often due to failure to measure symphysis-fundal height or failure to order ultrasound when fundal height is abnormal. 5

Coordination of Care

For delivery before 26 weeks or at estimated fetal weight <500g, coordinate care between maternal-fetal medicine and neonatology services. 3

• Neonatal survival increases from 13% at 24 weeks to 43% at 25 weeks and 58-76% at 26 weeks. 3
• Prepare for potential neonatal complications including respiratory distress syndrome, necrotizing enterocolitis, and intraventricular hemorrhage. 4