A case report published in Transfusion and Apheresis Science highlighted the need for serial monitoring in pregnancies complicated by maternal red blood cell alloimmunizationAlloimmunization When a person’s immune system develops antibodies against foreign antigens from the same species—such as when an Rh-negative mother’s body forms antibodies against her baby’s Rh-positive red blood cells..
Researchers monitored the alloantibodies anti-D, anti-C, anti-Fya, and anti-M in an RhD-negative woman carrying an RHD-positive fetus. These maternal red blood cell alloantibodies can cause hemolytic disease of the fetus and newborn (HDFN).
The antibodyAntibody A protein made by the immune system that recognizes and attacks foreign substances, such as bacteria, or in HDFN, fetal red blood cells carrying incompatible antigens. levels remained stable until the third trimester, when anti-D and anti-C titers rose sharply at 31 to 32 weeks. The increase occurred around the time the woman received routine maternal vaccines against influenza, pertussis, and RSV. However, the researchers could not establish a causal relationship. “Our observation should therefore be interpreted cautiously – as a hypothesis-generating clinical observation rather than proof of causation,” they wrote.
At that point, fetal monitoring showed evidence of anemiaAnemia A condition that occurs when the body doesn’t have enough healthy red blood cells to carry oxygen to its tissues. In HDFN, anemia occurs when maternal antibodies destroy fetal red blood cells., and two intrauterine transfusions were performed. The patient delivered at 37 weeks, and the neonate required phototherapyPhototherapy A treatment that uses special blue light to help newborns break down bilirubin and prevent kernicterus., IVIGIntravenous immunoglobulin A therapy made from donated antibodies that may help reduce the mother’s immune response and protect the fetus. and transfusion support but had a good outcome.
Read more about HDFN testing and diagnosis
The team detected the antibodiesAntibody A protein made by the immune system that recognizes and attacks foreign substances, such as bacteria, or in HDFN, fetal red blood cells carrying incompatible antigens. at 10 weeks. Anti-D and anti-C started with low titers (eight and two) and remained stable until 30 weeks. Anti-Fya and anti-M were initially non-titerable. At 31 weeks, anti-D and anti-C rose to 16 and eight, respectively. By 32 weeks, they had increased to 128 and 64. Meanwhile, anti-M became reactive, while anti-Fya remained non-titerable.
The authors suggested that the rapid rise could be related to immune activation after vaccination, which may have boosted the body’s antibody response. However, they also noted that the increase could simply reflect the natural course of the condition, as fetal red blood cells can enter the mother’s circulation during pregnancy and stimulate the production of antibodies over time.
Researchers also monitored middle cerebral artery peak systolic velocity (MCA-PSVDoppler ultrasound A non-invasive scan that measures blood flow speed in the fetus' brain to diagnose anemia. Specifically, it checks the middle cerebral artery peak systolic velocity (MCA-PSV).) to assess fetal anemia. This measure rose from 1.3 to 1.7 MoM, supporting the indication for intrauterine transfusionIntrauterine transfusion A procedure that delivers donor red blood cells to the fetus through the umbilical vein to treat severe anemia caused by HDFN..
Multiple maternal alloantibodies complicated transfusion planning, since donor red blood cells used for intrauterine transfusion had to be negative for all corresponding antigensAntibody A protein made by the immune system that recognizes and attacks foreign substances, such as bacteria, or in HDFN, fetal red blood cells carrying incompatible antigens.. Finding suitable blood was challenging, highlighting the logistical difficulties of managing pregnancies with multiple alloantibodies.
The findings support the importance of close monitoring in pregnancies complicated by maternal red blood cell alloimmunization, since titers can change quickly.
