辅助生殖后中孕期多胎妊娠减胎相关问题

辅助生育技术增加多胎妊娠，通过限制胚胎移植数目及取消卵巢高反应周期，高数目多胎妊娠的风险在减少。因多胎妊娠母儿风险增加，有些情况下选择性中期妊娠减胎术是必要的。减胎术一般保留至2个胎儿，减胎后妊娠成功率随初始胎儿数的增加而降低。绒毛膜性的确定对于围产期管理至关重要。中期妊娠减胎术的手术方法根据绒毛膜性不同而选择药物注射或脐带血管闭塞法。辅助生殖技术也增加单绒毛膜双胎的发生。当单绒毛膜双胎发生血管吻合异常和胎盘共享不均时，可能导致不良结局，为复杂性双胎。多胎妊娠减胎可优化孕妇和留存胎儿的健康状况，但少数可能发生整个妊娠丢失。应正确把握减胎指征，尊重孕妇和家属的知情选择。

Issues related to the reduction of multiple pregnancies after assisted reproduction

The incidence of multifetal pregnancies has risen owing to wide application of assisted reproductive techniques. However, the risk of multifetal pregnancies has recently decreased by limiting the number of embryos to be transferred or by canceling ovarian hyper-response cycle. Multifetal pregnancies increase maternal and perinatal risk. Thus, selective fetal reduction in the second trimester is necessary in some cases. Fetal reduction is usually reserved for two fetuses. The success rate of pregnancy after birth reduction decreases with the increase in the number of initial fetuses. The determination of chorionicity is critical for perinatal management. According to the different chorionicity, surgical methods the drug injection or umbilical vascular occlusion are selected for the mid-term pregnancy reduction. Assisted reproductive technology also increases the rate of monochorionic diamniotic twin pregnancies. Abnormal vascular anastomosis and unequal placental sharing may lead to adverse pregnancy outcomes in monochorionic diamniotic twin pregnancies. And that is complex twins. Fetal reduction in multiple pregnancy can benefit health of pregnant women and remained fetuses. However, pregnancy loss may occur in a small number of pregnancies. So, we should get the indications for fetal reduction right and respect the informed choices of the pregnant women and their families.