Management of Intrauterine Growth Restriction (IUGR)
The management of IUGR requires a structured approach with umbilical artery Doppler assessment as the cornerstone of surveillance, followed by timely delivery based on Doppler findings and gestational age to reduce perinatal mortality and morbidity. 1
Diagnosis and Initial Assessment
- IUGR is defined as an ultrasonographic estimated fetal weight (EFW) or abdominal circumference (AC) below the 10th percentile for gestational age 1
- Population-based fetal growth references (such as Hadlock) should be used to determine fetal weight percentiles 1
- When early-onset IUGR (<32 weeks) is identified, a detailed obstetrical ultrasound examination should be performed as up to 20% of cases are associated with fetal or chromosomal abnormalities 1
- Diagnostic testing with chromosomal microarray analysis (CMA) should be offered when IUGR is detected with fetal malformation or polyhydramnios, or when unexplained isolated IUGR is diagnosed at <32 weeks 1
Surveillance Protocol
- Antepartum surveillance of a viable fetus with suspected IUGR should include Doppler of the umbilical artery, as its use is associated with a significant decrease in perinatal mortality (Level A recommendation) 1
- Weekly umbilical artery Doppler assessment should be performed in conjunction with other antepartum testing 1
- Weekly cardiotocography testing after viability is recommended for IUGR without absent/reversed end-diastolic velocity 1
- Frequency of testing should be increased when IUGR is complicated by absent/reversed end-diastolic velocity or other comorbidities 1
- For cases with absent or reversed flow, nonstress tests and/or biophysical profiles should be performed twice weekly or more often 1
- Hospitalization may be considered when fetal testing more than 3 times per week is necessary 1
Timing of Delivery Based on Doppler Findings
Normal Umbilical Artery Doppler
- Consider delivery at 38-39 weeks of gestation when EFW is between the 3rd and 10th percentile 1
- Surveillance can be extended to less frequent intervals if findings remain normal 1
Abnormal Umbilical Artery Doppler
- Decreased diastolic flow: Recommend delivery at 37 weeks of gestation or for severe IUGR with EFW less than the 3rd percentile 1
- Absent end-diastolic flow: Recommend delivery at 33-34 weeks of gestation as long as fetal surveillance remains reassuring 1
- Reversed end-diastolic flow: Recommend delivery at 30-32 weeks of gestation as long as fetal surveillance remains reassuring 1
Antenatal Interventions
- Antenatal corticosteroids should be administered if absent or reversed end-diastolic flow is noted at <34 weeks (Level A recommendation) 1
- Close observation for 48-72 hours after corticosteroid administration is reasonable, as there may be transient return of end-diastolic flow in about two-thirds of cases 1
- Intrapartum magnesium sulfate for fetal and neonatal neuroprotection is recommended for women with pregnancies <32 weeks of gestation 1
- Low-molecular-weight heparin, sildenafil, or activity restriction are not recommended for in utero treatment of IUGR 1
Mode of Delivery
- For pregnancies with IUGR complicated by absent/reversed end-diastolic velocity, cesarean delivery should be considered based on the entire clinical scenario 1
- Careful monitoring during labor is crucial as the IUGR fetus can quickly decompensate once uterine contractions begin 2
Special Considerations
- Women with early-onset IUGR should be closely monitored for the development of hypertensive disorders of pregnancy, as maternal hypertension is present in up to 70% of these cases at delivery 1
- The single most important prognostic factor in preterm fetuses with growth restriction is the gestational age at delivery, with an increase of 1%-2% in intact survival for every additional day spent in utero up until 32 weeks of gestation 1
- Delivery of IUGR fetuses should take place in centers where appropriate neonatal assistance can be provided 2