Abstract: Objective To analyze the risk of severe anemia and blood transfusion in perinatal M antigen-positive fetuses and neonates caused by maternal plasma anti-M antibodies during pregnancy, and to explore the effect of anti-M antibodies on the apoptosis rate of M antigen-positive red blood cells. Methods Serological methods were used to identify the ABO, RhD, MN blood types of umbilical cord blood of pregnant mothers and fetuses, as well as the Coombs test of newborns. Experimental group: The plasma of three mothers containing anti-M antibodies was respectively compared with the MN-type red blood cells of blood donors with the same ABO type; Control group: AB-type plasma with negative irregular antibody identification and MN-type red blood cells from AB-type blood donors. In vitro culture was carried out by simulating the in vivo environment of the human body to monitor the apoptosis rate of M antigen-positive red blood cells at 24 hours, 48 hours and 72 hours. Results Anti-M antibodies were present in the plasma of all three mothers, which led to severe anemia in the fetus in utero or after the birth of the newborn. The apoptosis rates of M antigen-positive red blood cells at 24 hours, 48 hours and 72 hours were monitored by simulating the in vivo environment of the human body. In the control group: 1.46%, 3.35%, 29.7%; Plasma of mothers in the experimental group: 3.17%, 42.8%, 73.9%; Mother's plasma 2:4.68%, 32.1%, 59.2%; Mother 3 plasma: 4.15%, 33.7%, 69.3%. Compared with the control group, the plasma anti-M antibody of pregnant mothers can induce the accelerated apoptosis of M antigen-positive red blood cells within 72 hours. The higher the titer of the anti-M antibody, the faster the apoptosis rate of M antigen-positive red blood cells. Conclusion Anti-M antibodies in the plasma of pregnant mothers can cause severe anemia in fetuses and newborns, and have the ability to accelerate the apoptosis of M antigen-positive red blood cells. Select M antigen-negative red blood cells for blood transfusion to avoid the harm of adverse blood transfusion reactions.

Key words: Isoimmunity, Fetal and neonatal anemia, Anti-M antibody, Erythrocyte apoptosis rate