Provider education · MCDA / selective FGR
A decision for both twins. A delivery window that changes with the clinical picture.
Identify selective fetal growth restriction and its Doppler phenotype.
Integrate trajectory, fetal testing, and neonatal prognosis.
Specify timing, location, and the findings that would prompt earlier birth.
OpenMFM · Dr. Chukwuma Onyeije · September 2026
Learning objectives
By the end, you should be able to explain why today’s plan is appropriate.
Distinguish uncomplicated MCDA twins, Type I, Type II, and Type III sFGR.
Choose continued surveillance, urgent reassessment, fetal-center counseling, or delivery.
The handoff should answer: When are we planning birth, and what would move it earlier?
Guideline baseline
Complicated pregnancies need a separate timing decision.
NICE recommends planned birth at 36 weeks for uncomplicated MCDA twins.
Ultrasound every 2 weeks from 16 weeks screens for monochorionic complications.
Growth restriction, TTTS, TAPS, fetal compromise, or maternal disease changes the plan.
Diagnosis
Delphi consensus criteria distinguish a growth disorder from discordance alone.
Estimated fetal weight (EFW) below the 3rd percentile in one twin.
EFW <10th; abdominal circumference <10th; EFW discordance ≥25%; smaller-twin UA pulsatility index >95th percentile.
Differential diagnosis
A Doppler type does not replace the rest of the assessment.
Evaluate amniotic fluid and bladder findings; growth discordance is not required for TTTS.
Assess MCA peak systolic velocity (PSV) in both twins for an anemia–polycythemia pattern.
Review anatomy and discuss diagnostic testing when indicated.
Confirm labels, dating, biometry, and trends before interpreting apparent change.
Pathophysiology
Placental territory and vascular connections influence both growth and risk.
If one twin decompensates or dies, acute transfusion and hypotension can injure the co-twin.
Counsel about risks to both twins. Avoid presenting one pooled percentage as an individualized prognosis.
Gratacós classification
Classify the umbilical artery (UA) end-diastolic flow pattern.
Type II schematic shows absent flow; persistent reversed flow also qualifies. Type III requires enough observation to capture intermittency.
Conceptual waveforms; dashed line = zero flow. Classification can change over time.
Expert opinion · conditional range
Preserved forward flow supports expectant care when the rest of the assessment is reassuring.
Review-based planning range for stable Type I sFGR.
Check interval growth and the complete fetal assessment.
New compromise or a changed Doppler phenotype requires a new plan.
Discussion: What would change your proposed date? Ask for specific findings rather than “worsening growth” alone.
Expert opinion · conditional range
Persistent absent flow and persistent reversed flow carry different clinical implications.
A review-based range, individualized to UA pattern, venous Doppler, and fetal condition.
30–32 weeks may be selected for more severe disease. The upper end is not a target to reach despite deterioration.
Do not transfer singleton FGR delivery thresholds directly to MCDA sFGR. Consider the shared circulation and risks of prematurity for both infants.
Expert opinion + observational evidence
Reassuring surveillance cannot eliminate sudden events.
Review-based planning range, with individualized earlier delivery.
Intermittent flow reflects the shared circulation and may be followed by sudden deterioration.
Additional gestation can reduce neonatal morbidity; cohort selection limits certainty.
Fictional discussion prompt: At 31 weeks with stable Type III findings, explain why a normal test today does not guarantee safety to the planned date.
Delivery planning at a glance
All ranges assume that ongoing assessment supports continued pregnancy.
Uncomplicated timing: guideline recommendation. sFGR bands: expert-review ranges, not validated universal deadlines.
Bands are schematic. Earlier delivery may be indicated for fetal or maternal deterioration.
Surveillance
The minimum schedule is a starting point, not a ceiling.
Assess fetal growth.
Assess UA and MCA Dopplers.
Add ductus venosus (DV) assessment.
Increase monitoring with severity; add gestation-appropriate fetal heart-rate testing and biophysical assessment. Decide outpatient versus inpatient care individually.
A written plan should identify the responsible team, access to urgent reassessment, and delivery capability. Local testing frequency is not a universal type-specific mandate.
Escalation
Ask whether continued pregnancy still benefits both fetuses.
Absent/reversed DV a-wave, recurrent decelerations, or nonreassuring biophysical findings.
Gestation, trend, maternal status, neonatal prognosis, and goals of care determine urgency.
Do not wait for every test to become abnormal. An isolated MCA change is not a universal immediate-delivery rule.
If compromise is sustained and neonatal resuscitation is planned, expedite delivery as clinically indicated. Computerized CTG may inform assessment where available; singleton short-term-variation thresholds are not validated MCDA rules.
Early severe sFGR
Viability depends on gestation, fetal size, neonatal capabilities, and family goals.
Attempt to gain gestation while accepting ongoing fetal risks.
Separate placental vascular connections in selected cases; technical feasibility and outcomes vary.
Sacrifice the compromised twin’s circulation to protect the co-twin in selected severe cases.
These options have different goals. Refer to a tertiary fetal therapy center; 26 weeks is not a universal viability cutoff.
Perinatal preparation
Preparation should not postpone a delivery that is already indicated.
For anticipated early-preterm birth, aim for administration within 7 days of delivery; use the applicable gestational-age protocol.
Give neuroprotection when birth before 32 weeks is likely, according to local protocol.
Counsel for both infants and arrange the required neonatal capability before deterioration when possible.
Specify the provisional date, escalation criteria, treatment status, and delivery site in the handoff.
Guidance versus new evidence
A newer trial informs counseling; it does not establish an MCDA sFGR delivery date.
SMFM #58 bases its strong late-preterm recommendation on ALPS-eligible singleton pregnancies. Ongoing twins require separate consideration.
Severe respiratory morbidity: 4.8% vs 7.5% (betamethasone vs placebo). Hypoglycemia: 15.6% vs 11.7%; an exploratory outcome.
812 pregnancies; most were dichorionic. Apply the findings cautiously to MCDA sFGR and discuss benefits, harms, and local practice.
The trial included 1,620 neonates. Respiratory RR 0.64 (95% CI 0.42–0.98). It was not a trial of sFGR delivery timing. Do not delay indicated birth to complete steroids.
Delivery route
Chorionicity or the Type I label alone does not decide the route.
Evaluate presenting-twin position, gestation, size discordance, fetal status, and obstetric factors; ensure experienced staff and emergency access.
Severe Doppler abnormalities and limited fetal reserve often favor cesarean; individualize the decision.
The evidence supporting planned vaginal birth in uncomplicated twins should not be assumed to apply to severe sFGR.
Single-twin demise
Urgent specialist assessment is essential; reflex preterm delivery may add harm.
Evaluate fetal status and MCA-PSV for anemia; involve fetal medicine and neonatology.
Arrange targeted brain imaging and ongoing surveillance with the fetal center.
Immediate birth cannot reverse an injury sustained at the time of demise. Deliver for the current clinical situation, not demise alone.
This principle does not justify delay when the survivor has persistent acute compromise. Counseling should acknowledge that apparently reassuring early imaging does not exclude later-detected injury.
Apply the evidence
Fictional case · smaller twin EFW 5th percentile; discordance 28%; forward UA flow; reassuring testing.
What is your provisional delivery window? What surveillance continues?
Name two findings that would prompt earlier reassessment or birth.
A 34–36-week review-based window is reasonable if stability persists. Continue the sFGR surveillance plan. A new abnormal Doppler phenotype, nonreassuring testing, or maternal indication changes the decision. Discordance alone does not dictate immediate birth.
Apply the evidence
Fictional case · persistent reversed UA flow, new reversed DV a-wave, and recurrent fetal heart-rate decelerations.
Should the team wait until the planned 30–32-week window?
Urgent MFM assessment, neonatal counseling, delivery preparation, and neuroprotection when feasible.
The planned window no longer governs. Confirm and manage sustained compromise urgently. If active neonatal care is intended, these combined findings strongly favor expedited delivery. Do not postpone necessary birth for a complete steroid course.
Clinical pearls
Seven habits make a delivery plan usable.
Type III counseling prompt: “We are planning birth at 32–34 weeks if findings permit, while recognizing that earlier birth may become appropriate.”
Evidence & controversies
Evidence & controversies · cohort practice varies widely.
Discordance and SGA raise absolute risk; growth-disorder meta-analysis does not resolve timing in severe abnormal-Doppler sFGR.
Compare management prospectively and measure long-term neurodevelopment. A 2026 cohort suggests the Doppler class alone incompletely predicts outcome.
Experts differ most on stable Types II/III and fetal intervention. Observational studies are affected by referral patterns, severity, intervention, and clinician-driven delivery. The 2026 study does not validate new delivery thresholds.
References · 1 of 2
Guidelines, expert reviews, and observational evidence have different roles.
References · 2 of 2
Sources checked September 22, 2026.
Educational discussion for clinicians. Apply current local protocols and individualized assessment. All cases are fictional; all diagrams are original schematics.
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