Autoimmune hemolytic anemia in pregnancy: a challenge for maternal and fetal follow-up.

Background: Autoimmune hemolytic anemia (AIHA) is a rare entity during pregnancy. The fetal risk is determined primarily by the ability of autoantibodies to cross the placental barrier. Currently, the establishment of a standardized antenatal care in cases with AIHA remains as a pending issue.
Cases: Firstly, we describe a case of a 17-week pregnant woman that was diagnosed with cold agglutinin mediated (C3 and IgM) AIHA. Treatment was started with prednisone, showing initial improvement, but requiring intravenous gammaglobulins at 27 weeks. During the fetal follow-up, all studies showed normal results. In the third trimester, when there was a clinic and analytic maternal improvement, an unexpected fetal death occurred. Secondly, we present a case of a 30-week pregnant woman, diagnosed with warm antibody (IgG) AIHA. Despite the ability of IgG to cross the placental barrier, the serial measurements of the Middle Cerebral Artery (MCA) peak systolic velocity were always normal and childbirth occurred at term without any adverse perinatal outcome.
Conclusion: During pregnancy, identification of the type antibodies in AIHA is crucial to estimate the potential maternal and fetal risks and to establish the follow-up. The interaction of the complement cascade with the coagulation cascade could be an explanation for a perinatal adverse outcome despite the inability of the IgM to cross the placental barrier.