Management of a Newborn Suspected with Intrauterine Growth Retardation
For a newborn suspected of IUGR, immediately initiate umbilical artery Doppler assessment as the cornerstone of surveillance, combined with weekly cardiotocography testing, and plan delivery timing based on Doppler findings: 38-39 weeks for normal Doppler, 37 weeks for decreased diastolic flow or severe IUGR (<3rd percentile), 33-34 weeks for absent end-diastolic flow, and 30-32 weeks for reversed end-diastolic flow. 1, 2
Initial Diagnostic Confirmation
Confirm IUGR diagnosis by documenting estimated fetal weight or abdominal circumference below the 10th percentile for gestational age using population-based fetal growth references. 1, 2 This distinguishes true IUGR from constitutionally small but healthy fetuses.
Perform detailed anatomic ultrasound examination when IUGR is identified, particularly if early-onset (before 32 weeks), as up to 20% of cases are associated with fetal or chromosomal abnormalities. 1
Offer chromosomal microarray analysis when IUGR is detected with fetal malformation, polyhydramnios, or when unexplained isolated IUGR is diagnosed before 32 weeks of gestation. 1, 2
Surveillance Protocol: The Doppler-Driven Approach
Primary Surveillance Tool
Initiate weekly umbilical artery Doppler studies immediately upon IUGR diagnosis, as this 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). 3, 1, 2 This is superior to all other monitoring methods and should guide all management decisions.
Complementary Monitoring
Add weekly cardiotocography testing (nonstress test or biophysical profile) after viability for IUGR without absent or reversed end-diastolic velocity. 3, 1, 2 The combination of ultrasound and cardiotographic surveillance improves outcomes compared to either alone. 3, 4
Critical caveat: Normal fetal heart rate testing does NOT exclude IUGR and should never be used as the sole surveillance method. 2, 4 Heart rate abnormalities appear late in the deterioration sequence, only after significant vascular changes are already present on Doppler. 2
Frequency Adjustments Based on Severity
Increase Doppler surveillance to 2-3 times per week when IUGR is complicated by oligohydramnios, absent end-diastolic flow, or reversed end-diastolic flow. 3, 2
Perform serial growth ultrasounds every 2-4 weeks to monitor progression, as evaluations at intervals less than 2 weeks are unreliable due to inherent measurement error. 2, 4
Delivery Timing Algorithm: Doppler-Based Decision Tree
Normal Umbilical Artery Doppler
Deliver at 38-39 weeks of gestation when estimated fetal weight is between the 3rd and 10th percentile with normal Doppler findings. 3, 1 Continue weekly Doppler and weekly cardiotocography until delivery. 3
Decreased Diastolic Flow (but forward flow present)
Deliver at 37 weeks of gestation or when severe IUGR is present (estimated fetal weight less than the 3rd percentile). 3, 1, 2 Maintain weekly Doppler surveillance and increase cardiotocography frequency. 3, 2
Absent End-Diastolic Flow
Deliver at 33-34 weeks of gestation as long as fetal surveillance remains reassuring. 3, 1, 2 Increase Doppler surveillance to 2-3 times weekly and perform cardiotocography twice weekly or more often. 3, 2
Reversed End-Diastolic Flow
Deliver at 30-32 weeks of gestation as long as fetal surveillance remains reassuring. 3, 1, 2 Consider hospitalization, perform cardiotocography at least 1-2 times daily, and intensify Doppler surveillance. 2
Antenatal Interventions Before Delivery
Corticosteroid Administration
Administer antenatal corticosteroids if absent or reversed end-diastolic flow is noted at less than 34 weeks (Level A recommendation). 3, 1, 2 This applies even though the original Liggins and Howie trial showed excess fetal deaths in IUGR cases, as overall published evidence supports their use. 3
Provide close observation for 48-72 hours after corticosteroid administration, as transient return of end-diastolic flow occurs in approximately two-thirds of cases due to altered placental vascular tone. 3, 1
Also administer corticosteroids if delivery is anticipated between 34 0/7 and 36 6/7 weeks in women at risk of delivery within 7 days who haven't received a prior course. 1, 2
Neuroprotection
Administer intrapartum magnesium sulfate for fetal and neonatal neuroprotection for pregnancies less than 32 weeks of gestation (GRADE 1A recommendation). 1, 2
Mode of Delivery Considerations
Consider cesarean delivery for pregnancies with IUGR complicated by absent or reversed end-diastolic velocity, based on the complete clinical scenario. 1, 2 Studies report 75-95% of IUGR pregnancies with absent/reversed end-diastolic flow require cesarean delivery for intrapartum heart rate abnormalities, even when antepartum testing was reassuring. 2
Require continuous electronic fetal monitoring during labor for all IUGR fetuses, regardless of normal antepartum heart rate patterns. 2
Special Clinical Considerations
Monitor closely for development of hypertensive disorders of pregnancy, as maternal hypertension is present in up to 70% of early-onset IUGR cases at delivery. 1
Recognize that gestational age at delivery is the single most important prognostic factor in preterm fetuses with growth restriction, with an increase of 1-2% in intact survival for every additional day spent in utero up until 32 weeks of gestation. 1 This supports expectant management with intensive surveillance when Doppler findings permit.
What NOT to Do
Do not use low-molecular-weight heparin for prevention of recurrent IUGR (GRADE 1B recommendation). 1
Do not use sildenafil for in utero treatment of IUGR (GRADE 1B recommendation). 1
Do not prescribe activity restriction or bed rest for treatment of IUGR (GRADE 1B recommendation). 1
Do not use Doppler of any vessel as a screening tool for identifying pregnancies that will subsequently be complicated by IUGR, as standards are lacking for study technique, gestational age at testing, and criteria for abnormal results. 3