Monochorionic twin amniocentesis means that the two fetuses share a placenta and have two amniotic sacs separated by two layers of amniotic membrane. A difference of 1-2 weeks between the two fetuses is usually normal. Generally, the development of twins is not synchronized, and a difference of 1-2 weeks is normal, but you need to be alert to the possibility of growth restriction in the small fetus. If the difference between the two fetuses is relatively large, it is necessary to be alert to the twin fetal transfusion syndrome, whose main pathogenesis is based on the existence of arteriovenous anastomosis between the placentas of the two fetuses, resulting in an imbalance in the exchange of blood flow between the fetuses, so that one of the fetuses becomes a blood donor, the volume of blood continues to decrease; and the other fetus becomes a recipient of blood, the volume of blood continues to increase, which is a more serious complication. Therefore, if the difference between the two fetuses of monochorionic twin sheep twin fetuses is large, it is recommended to consult a doctor in time, under the guidance of the doctor, complete the relevant examinations, clarify the cause of the disease and treat the symptoms.