Alloimmunization in pregnancy during the years 1992-2005 in the central west region of Sweden

Objectives. To study the incidence of red cell immunization and to evaluate the use of low-risk invasive procedures in the management of alloimmunized during pregnancy. Design. A 14-year retrospective study of all immunized mothers and their newborns. Population. All reported alloimmunizations between the years 1992 and 2005 in our catchment area were examined. Methods. Background factors, maternal antibody classification, antibody titers, anti-D quantitation, procedures and maternal treatments instituted during pregnancy, fetal outcome and treatment of the newborn were evaluated. Results. There were 78,145 deliveries in the region. Alloimmunization during pregnancy was detected in 0.4% of all pregnancies, excluding ABO immunizations. A significant alloimmunization (titer level 8) was detected in 0.16%. Anti-D immunizations were responsible for 60% of significant immunizations followed by anti-Fya in 10%, anti-c in 7% and anti-K in 4%. Maternal plasma exchange and high-dose intravenous immunoglobulin were used as low-risk invasive treatments in 12 cases. Delivery was in 38 weeks in 93% of cases. Twenty-nine newborns were treated with exchange transfusions (ETs) after delivery, whereof 21/29 were due to anti-D, seven due to anti-c and anti-E and in one case anti-Fya. No deaths occurred due to severe alloimmunization. Conclusion. Anti-D still accounts for the most severe immunizations and for most of the cases where ET was necessary. Low-risk invasive techniques to evaluate and treat pregnancies complicated by alloimmunization seem possible and accurate, avoiding invasive procedures that may exacerbate the immunization during pregnancy.