Management of Monochorionic Twin Pregnancies Complicated by Selective Fetal Growth Restriction: Retrospective Single-Center 12-Year Experience

<b>Objectives:</b> To describe the perinatal outcomes of a series of monochorionic diamniotic (MCDA) twin pregnancies complicated by selective fetal growth restriction (sFGR), classified according to the umbilical artery (UA) Doppler flow pattern of the smaller twin, and managed in a single centre over a 12-year period. <b>Methods:</b> Retrospective cohort study involving MCDA twin pregnancies followed up at the Twin Pregnancy Care Unit of Sant'Anna Hospital, Turin, Italy, between January 2010 and May 2023. We compared perinatal outcomes of MCDA pregnancies classified based on the UA Doppler flow pattern of the smaller twin. <b>Results:</b> The percentage of sFGR in our sample was 14.8%. A total of 103 MCDA pregnancies with sFGR were included. In 34.9% cases, the UA flow pattern changed throughout pregnancy. At last examination, 58.3% cases were classified as type I, 25.2% as type II and 16.5% as type III. The perinatal survival rate of both twins in type I and III was 100%, in type II 88.5%. Type II sFGR had the highest perinatal mortality rate (7.7%). Type III twins were more likely to have malformations compared to type II and type I; compared to type I sFGR babies, they were more likely to develop RDS and to be admitted to NICU, where the length of stay was longer. <b>Conclusions:</b> Although the UA flow pattern correlates with perinatal outcome, it can change throughout pregnancy. Type III sFGR may have lower risk of fetal demise than traditionally thought. The main challenge remains finding the optimal balance between adverse outcomes and premature birth.