(P-TS-101) The Clinical Significance of Warm Autoantibody during Pregnancy

There is little or no information in the literature concerning the significance of warm autoantibodies during pregnancy. Therefore, warm autoimmune hemolytic anemia (WAIHA) is rare during pregnancy. The risk to the fetus is determined by the IgG autoantibody’s ability to cross the placental barrier. Currently, there is no established protocol for antenatal care in cases with WAIHA and each case is treated if there is clinical symptoms or severity of the anemia in the mother and or the fetus. The objective of the current study is to determine the clinical significance of warm autoantibody detected in patients during pregnancy.

Study

Design/Methods:

Existing data of all obstetrics patients who had a positive antibody screen with a warm autoantibody diagnosis at first presentation in the last 7 years from August 1^st, 2016, to October 31, 2023, were reviewed. If positive, a direct antiglobulin test and an eluate was performed. Our aim is to compare the results of positive warm autoantibody with evidence of clinical hemolysis in the mother or hemolytic disease of the fetus and newborn during pregnancy.

Results/Findings:

Between August 2016 and October 2023, 23,510 pregnant patients had blood type and antibody screen completed at our institution. A total of 812 (3.5%) patients had a positive antibody screen. Only 16 (< 2.0%) patients (6 Caucasian and 6 African American) with median age of 26.3 years had a positive DAT and eluate confirmation of a warm autoantibody. Other antibodies detected were alloantibodies including anti-D, anti-E, anti-c, and anti-K. All the sixteen patients with confirmed warm autoantibody were all Rh positive (16/123), even though many of the patients with a positive antibody screen were Rh negative (0/689). All the 16 patients had no previous history of warm autoantibody. Our study did not show a clinical significance between the patients who were positive for warm autoantibody and development of hemolytic disease of the fetus and newborn.

Conclusions:

Although pregnancy-induced warm autoantibody appears to be harmless for both the mother and the baby, unlike alloantibodies, the serological finding is evident in our cases. The detection of warm autoantibody in pregnancy initially reflects a risk for both the mother and child. However, on follow up there was no evidence of hemolytic anemia in the mother or hemolytic disease of the fetus and newborn during the pregnancy and after delivery.