The Clinical Significance of Warm Autoantibodies during Pregnancy.

Objectives: The objective of the current study is to determine the clinical significance of a warm autoantibody detected in patients during pregnancy.

Background: There are few published studies concerning the clinical significance of warm autoantibodies during pregnancy. The risk to the fetus is determined by the IgG autoantibody's ability to cross the placental barrier.

Materials and methods: Existing data of all obstetric patients who had a positive antibody screen with a warm autoantibody diagnosis during their pregnancy in the last 7 years from August 2016 to October 2023 were reviewed. If positive, a direct antiglobulin test (DAT) and an eluate were performed. Statistical analysis was performed to determine the clinical significance of warm autoantibody in pregnant patients. Data collected included blood type, race, age, BMI, the most recent hemoglobin before delivery, and gestation in weeks.

Results: 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 had a positive DAT and eluate confirmation of a warm autoantibody. None of the 16 patients had a previous history of warm autoantibody. 14/16 mothers did not experience an AIHA or HDFN in the newborns.

Conclusion: Pregnancy-induced warm autoantibody appears to be harmless for most mothers and their babies. The detection of a warm autoantibody in pregnancy may reflect a potential risk for both the mother and the child; however, on follow up, there were no clinical complications associated with warm autoantibodies in our patient cohort.