Perinatal Outcome of Early‐ and Late‐Onset Selective Fetal Growth Restriction in Monochorionic Diamniotic Twin Pregnancies

OBJECTIVE: To compare clinical differences and growth velocity patterns between early- and late-onset selective fetal growth restriction (sFGR) in monochorionic diamniotic (MC) twins. METHODS: A retrospective cohort study analyzed 394 MC twin pregnancies with sFGR (2017-2024). Early-onset (≤ 24 weeks) and late-onset (> 24 weeks) groups were compared for fetal growth velocity (serial EFW measurements) and perinatal outcomes (composite morbidity/mortality). RESULTS: Before 28 weeks, the larger twin's EFW growth was similar in both groups. The smaller twin in late-onset sFGR grew faster than in early-onset sFGR until 32.9 weeks. Early-onset sFGR is associated with higher rates of Type II/III sFGR (31.7% vs. 9.8% in late-onset). Perinatal mortality was similar (5.8% vs. 4.7%), but adverse outcomes were higher in early-onset (69.5% vs. 48.6%). Median delivery GA was earlier in early-onset (32.7 vs. 34.3 weeks). CONCLUSIONS: In MCDA twin pregnancies, early-onset sFGR leads to more adverse perinatal outcomes than late-onset cases, despite similar perinatal mortality rates. Early-onset sFGR is more often associated with Type II and III sFGR. This information can help clinicians offer better counseling on perinatal outcomes and management strategies.