RESUMEN
BACKGROUND: Because selective termination (ST) for discordant dichorionic twin anomalies carries a risk of pregnancy loss, deferring the procedure until the third trimester can be considered in settings where it is legal. OBJECTIVE: To determine whether perinatal outcomes were more favorable following deferred rather than immediate ST. STUDY DESIGN: A French multicenter retrospective study from 2012 to 2023 on dichorionic twin pregnancies with ST for fetal conditions which were diagnosed before 24 WG. Pregnancies with additional risk factors for late miscarriage were excluded. We defined two groups according to the intention to perform ST within 2 weeks after the diagnosis of the severe fetal anomaly was established (immediate ST) or to wait until the third trimester (deferred ST). The primary outcome was perinatal survival at 28 days of life. Secondary outcomes were pregnancy losses before 24 WG and preterm delivery. RESULTS: Of 390 pregnancies, 258 were in the immediate ST group and 132 in deferred ST group. Baseline characteristics were similar in both groups. Overall survival of the healthy co-twin was 93.8% (242/258) in the immediate ST group vs 100% (132/132) in the deferred ST group (p<0.01). Preterm birth < 37 weeks' gestation was lower in the immediate than in the deferred ST group (66.7% vs 20.2%, p<0.01); preterm birth < 28 WG and < 32 WG did not differ significantly (respectively 1.7% vs 0.8%, p=0.66 and 8.26% vs 11.4%, p=0.36). In the deferred ST group, an emergency procedure was performed in 11.3% (15/132) because of threatened preterm labor, of which 3.7% (5/132) for imminent delivery. CONCLUSION: Overall survival after ST was high regardless of the gestational age at which the procedure was performed. Postponing ST until the third trimester seems to improve survival, while immediate ST reduces the risk of preterm delivery. Furthermore, deferred ST requires an expert center capable of performing the ST procedure on an emergency basis if required.
