Selective fetal growth restriction in dichorionic diamniotic twin pregnancies: systematic review and meta‐analysis of maternal and perinatal outcomes

Most of the published literature has focused on selective fetal growth restriction (sFGR) in monochorionic twin pregnancies. National and international guidelines have proposed that the management of sFGR in dichorionic twin pregnancies should be similar to that of singletons ignoring the inherent differences between multiple and singleton pregnancies and the added complexity of, as well as the impact of iatrogenic prematurity on the normally growing co-twin. The aim of this systematic review was to report the outcomes of dichorionic diamniotic (DCDA) twin pregnancies complicated by sFGR.Medline, Embase and Cochrane databases were searched. The inclusion criteria were DCDA twin pregnancies complicated by sFGR. The outcomes explored were intra-uterine (IUD), neonatal (NND), and perinatal death (PND), survival of at least one and both twins, preterm birth (PTB) birth (either spontaneous or iatrogenic) prior to 37, 34, 32 and 28 weeks of gestation, pre-eclampsia (PE), a composite score of perinatal morbidity, neurological, respiratory, infectious, morbidity, Apgar score <7 at 5 minutes, necrotizing enterocolitis, retinopathy of prematurity, admission to neonatal intensive care unit (NICU). Random effect meta-analyses of proportion and risk were used to analyse the data. PND death was computed only in studies reporting both IUD and NND. Furthermore, we planned sub-group analyses according to gestational age at diagnosis and Doppler status.Thirteen studies (1339 pregnancies complicated and 6316 non complicated by sFGR) were included. IUD occurred in 2.6% (95% CI 1.1-4.7) of DCDA pregnancies with and in 0.58% (95% CI 0.3-9.7) of those non complicated by sFGR, while the corresponding figures for PND were 5.2% (95% CI 3.5-7.3) and 1.7% (95% CI 0.1-5.7). PTB< 37 weeks, either spontaneous or iatrogenic, complicated 84.1% (95% CI 55.6-99.2) of pregnancies with and 69.1% (95% CI 45.4-88.4) without sFGR, while the corresponding figures for PTB <34, <32 and <28 were 18.4% (95% CI 4.4-38.9), 13.0% (95% CI 9.5-17.1) and 1.5% (95% CI 0.6-2.3) in pregnancies complicated and 10.2% (95% CI 3.1-20.7), 7.8% (95% CI 6.8-8.9) and 1.8% (95% CI 1.3-2.4) in those non-complicated by sFGR. PE complicated 19.9% (95% CI 12.4-28.6) of pregnancies with and 12.8% (95% CI 10.4-15.4) of those with no sFGR. Composite morbidity occurred in 28.2% (95% CI 7.8-55,1) of twins with and 13.9% (95% 6.5-23.5) of those without sFGR. When stratifying the risk of morbidity according to the sFGR status within a twin pair, this occurred in 39.0% (95% CI 11.1-71.5) and in 29.9% (95% CI 3.5-65.0) with an OR of 1.91 (95% CI 1.7-3.1). At risk analysis, DCDA pregnancies complicated by sFGR had a significantly higher risk of IUD (OR: 5.23, 95% CI 3.2-8.6) and composite morbidity or admission to NICU compared to those not affected (OR of 3.22, 95% CI 1.85-5.60), while there was no difference in the risk of PTB <34 weeks of gestation (p=0.220) and PE (p=0.465).DCDA twin pregnancies complicated by sFGR are at high risk of perinatal mortality and morbidity. The findings are pertinent in the counselling and management of complicated twin pregnancies, where twin-specific, rather than singletons, outcome data should be used. This article is protected by copyright. All rights reserved.