How to deal with first trimester anomalies in biventricular twin fetuses?　　[Expert opinion or recommendation] In the case of first trimester anomalies in dichorionic twins (including structural and chromosomal anomalies), the severity of the fetal anomaly, the impact on the mother and the healthy fetus, the risk of reduction surgery, and the patient’s wishes, ethical and social factors should be taken into consideration to develop an individualized treatment plan. For severe fetal anomalies, fetal reduction is feasible. Shalev et al. and Hern suggest that for severe non-fatal fetal anomalies (e.g., trisomy 21) in one of the twin chorionic twins detected in the middle of pregnancy, the fetus may be observed until late in pregnancy to improve the live birth rate of healthy fetuses, but after 28 weeks of gestation in the perinatal period, there are medical and ethical questions whether reduction can be performed. However, after 28 weeks of gestation, when the perinatal period is reached, there are medical ethical issues that need to be discussed and decided by the relevant ethics committee.