Outcome of monochorionic diamniotic twin pregnancy with selective fetal growth restriction and continuous or intermittent absent or reversed end-diastolic umbilical artery flow: international multicenter cohort study.

objectivesMonochorionic diamniotic (MCDA) twins with selective fetal growth restriction (sFGR) and either continuous (cAREDF) or intermittent (iAREDF) absent or reversed end-diastolic flow in the umbilical artery face significant fetal and neonatal risks. This study evaluated fetal and neonatal outcomes in these cases and compared outcomes for the larger twin following selective reduction (SR) vs expectant management (EM).

methodsThis was an international retrospective cohort study of MCDA twin pregnancies with sFGR and cAREDF or iAREDF from five fetal medicine centers over 7 years (2016-2022). Patients were included based on an estimated fetal weight (EFW) discordance of ≥ 20% combined with cAREDF or iAREDF. We collected demographic and antenatal characteristics, longitudinal ultrasound and management data, and key perinatal outcomes, including gestational age (GA) at birth, survival rate and severe neonatal morbidity. Outcomes for the larger twin following SR vs EM were compared using logistic regression with standardization, inverse probability weighting and augmented inverse probability weighting to adjust for confounders. Average treatment effects (risk differences) were calculated for three composite outcomes (live birth at ≥ 32 weeks; live birth at ≥ 32 weeks and absence of severe neonatal morbidity; and live birth without a GA limit and absence of severe neonatal morbidity) and overall live birth.

resultsData were analyzed from 363 MCDA twin pregnancies (726 fetuses) with sFGR, which were diagnosed initially as having either cAREDF (n = 124) or iAREDF (n = 239). The umbilical artery flow pattern changed in 59% of pregnancies during gestation. Smaller twins with cAREDF at the final ultrasound scan before demise, delivery or intervention had a 70% survival rate, with 29% of survivors experiencing severe neonatal morbidity. In contrast, larger twins in this group had an 87% survival rate and a 26% risk of severe neonatal morbidity among survivors. For smaller twins with iAREDF at the final ultrasound scan, the survival rate was 83% and 22% of survivors were affected by severe neonatal morbidity, whereas larger twins had an 87% survival rate and a 13% risk of severe neonatal morbidity among survivors. The combined risk of adverse outcomes (fetal or neonatal demise or severe neonatal morbidity) was 52% for smaller twins with cAREDF and 37% for those with iAREDF. Among 37 cases of spontaneous fetal demise, 24 (65%) were double demise. Severe cerebral injury following single fetal demise occurred in approximately 30% of survivors. SR was associated with a 32-34% higher probability of the larger twin being liveborn ≥ 32 weeks compared with EM. This benefit seemed to align with later GA at birth and reduced rate of severe neonatal morbidity, despite similar rates of live birth.

conclusionsMCDA twins with sFGR and cAREDF or iAREDF are at high risk for demise and severe morbidity, particularly the smaller twin with cAREDF. Compared with EM, SR significantly improves the chance of the larger twin being born at ≥ 32 weeks and surviving without severe morbidity, which may be influenced by increased GA at birth. These data should inform patient counseling and management decisions. © 2025 The Author(s). Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.