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Objective: Monochorionic diamniotic twin pregnancies complicated by Type-III selective fetal growth restriction (sFGR) are at high risk of fetal death. The aim of this study was to identify predictors of fetal death in these pregnancies. Methods: This was an international multicenter retrospective cohort study. Type-III sFGR was defined as fetal estimated fetal weight (EFW) of one twin below the 10th percentile and intertwin EFW discordance of ≥ 25% in combination with intermittent absent or reversed end-diastolic flow in the umbilical artery of the smaller fetus. Predictors of fetal death were recorded longitudinally throughout gestation and assessed in univariable and multivariable logistic regression models. The classification and regression trees (CART) method was used to construct a prediction model of fetal death using significant predictors derived from the univariable analysis.Results: A total of 308 twin pregnancies (616 fetuses) were included in the analysis. In 273 (88.6%) pregnancies, both twins were liveborn, whereas 35 pregnancies had single (n = 19 (6.2%)) or double (n = 16 (5.2%)) fetal death. On univariable analysis, earlier gestational age at diagnosis of Type-III sFGR, oligohydramnios in the smaller twin and deterioration in umbilical artery Doppler flow were associated with an increased risk of fetal death, as was larger fetal EFW discordance, particularly between 24 and 32 weeks' gestation. None of the parameters identified on univariable analysis maintained statistical significance on multivariable analysis. The CART model allowed us to identify three risk groups: a low-risk group (6.8% risk of fetal death), in which umbilical artery Doppler did not deteriorate; an intermediate-risk group (16.3% risk of fetal death), in which umbilical artery Doppler deteriorated but the diagnosis of sFGR was made at or after 16 + 5 weeks' gestation; and a high-risk group (58.3% risk of fetal death), in which umbilical artery Doppler deteriorated and gestational age at diagnosis was < 16 + 5 weeks' gestation. Conclusions: Type-III sFGR is associated with a high risk of fetal death. A prediction algorithm can help to identify the highest-risk group, which is characterized by Doppler deterioration and early referral. Further studies should investigate the potential benefit of fetal surveillance and intervention in this cohort.

OBJECTIVE Type III selective intrauterine growth restriction (sIUGR) is associated with a high and unpredictable risk of fetal death and fetal brain injury. Our objective was to describe the prospective risk of fetal death and the risk of adverse neonatal outcomes in a contemporary cohort. METHODS We retrospectively reviewed all monochorionic diamniotic twin pregnancies complicated by type III sIUGR managed at nine fetal centers over a 12-year time period. Higher order multiples, major fetal anomalies or other monochorionicity related complications at initial presentation were excluded. Fetal and neonatal outcomes were collected and management strategies were reviewed. Composite adverse neonatal outcome was defined as neonatal death, invasive ventilation beyond the resuscitation period, culture proven sepsis, necrotizing enterocolitis (NEC) requiring treatment, intraventricular hemorrhage (IVH) >grade I, retinopathy of prematurity (ROP) >stage II or periventricular leukomalacia (PVL). The prospective risk of fetal death and the risk of neonatal complications at each gestational age were evaluated. RESULTS We collected data on 328 pregnancies (656 fetuses). After exclusion of pregnancies which underwent selective reduction (n=18, 5.5%), there were 51 (8.3%) non-iatrogenic fetal deaths in 35 pregnancies (11.3%). Single deaths occurred in 19 (5.8%) pregnancies and double deaths in 16 (4.9%) pregnancies. The prospective risk of non-iatrogenic fetal death per fetus declined from 8.1% (95% CI 5.95-10.26) at 16 weeks, to less than 2% (95% CI 0.59-2.79) after 28.4 weeks and to less than 1% (95% CI -0.30-1.89) beyond 32.6 weeks. In otherwise uncomplicated type III sIUGR, delivery was generally planned at 32 weeks, at which time the risk of composite adverse neonatal outcomes was 29% (31/107 neonates). For twin pregnancies that continued to 34 weeks there was a very low risk of fetal demise (0.7%) and a low risk of adverse outcomes (11%). CONCLUSIONS In this contemporary cohort from tertiary fetal centers, the risk of fetal death in type III sIUGR was lower than previously reported. Further efforts should be directed at identifying predictors of fetal death and optimal antenatal surveillance strategies to select a cohort of pregnancies that can safely continue beyond 33 weeks of gestation. This article is protected by copyright. All rights reserved.

OBJECTIVE Little is known regarding fetal growth patterns of monochorionic twins complicated by type 3 selective fetal growth restriction (sFGR). We aimed to assess fetal growth and Doppler patterns in type 3 sFGR across gestation and evaluate the effect of changing Doppler flow patterns on growth and intertwin weight discordance. METHODS We retrospectively reviewed all type 3 sFGR pregnancies managed at nine fetal centers over a 12-year time period. Higher-order multiples, major fetal anomalies, or other monochorionicity-related complications at initial presentation were excluded. Estimated fetal weights (EFW) for each twin pair in each of five gestational age blocks (16-20, 21-24, 25-28, 29-32 and above 32���weeks' gestation) were reviewed and compared to singleton growth as well as uncomplicated monochorionic twin growth. EFW and intertwin growth discordance were compared between pregnancies with normalization of umbilical artery Dopplers of the smaller twin and those with persistently abnormal Dopplers . RESULTS 328 pregnancies (656 fetuses) met the study criteria. In type 3 sFGR, the smaller twin was smaller than the average singleton fetus (z-score ranging from -1.52 at 16���weeks to -2.7 at 36���weeks) and the average monochorionic twin (z-score ranging from -1.73 at 16���weeks to -1.49 at 36���weeks), throughout the entire pregnancy, while the larger twin was larger than an average singleton fetus until 22���weeks' gestation and similar in weight to an average monochorionic twin throughout gestation. As pregnancy advanced, both twin's growth velocities decreased with the larger twin remaining appropriately grown and the smaller twin becoming more growth restricted. Intertwin growth discordance remained stable throughout gestation. In multivariable longitudinal modelling, normalization of fetal Dopplers was associated with better growth of the smaller twin (p=0.002) but not the larger twin (p=0.1), without affecting the intertwin growth discordance (p=0.08). CONCLUSION Abnormal fetal growth of the smaller twin in type 3 sFGR was evident from early in pregnancy, while the larger twin's growth remained normal throughout gestation. Normalization of Dopplers resulted in improved fetal growth of the smaller twin. This article is protected by copyright. All rights reserved.