Pregnancy-related warm autoantibodies, which some have said may be connected to hemolytic disease of the fetus and newborn (HDFN), appeared not to harm mothers or babies, according to a new study published recently in Transfusion Medicine.
The research found no cases of HDFN or autoimmune hemolytic anemia (AIHA) in women or their children despite the presence of these antibodies.
“[O]ur study did not show evidence of AIHA or HDFN in any of the mothers,” the study authors wrote. “Even though the maternal autoantibody may cross the placenta, the clinical significance of a warm autoantibody in pregnancy remains unknown; our study demonstrates that a warm autoantibody is rare in pregnancy and the autoantibody detected may not be clinically significant.”
Investigators reviewed data from 23,510 pregnant patients screened for blood type and antibodies between August 2016 and October 2023. Of those, 812 patients (3.5 percent) had a positive antibody screen. Just 16 women, or fewer than 2 percent of those positive, had a confirmed warm autoantibody. Every one of these women was RhD positive, and none had a prior history of such antibodies.
Read more about the causes and risk factors for HDFN
Among the 16 cases, two patients were lost to follow-up. Of the 14 newborns with complete outcomes, none showed signs of HDFN such as jaundice, cyanosis, or need for phototherapy. One baby showed an ABO blood type difference with the mother, but even in that case no illness developed. All infants were discharged in good health.
This study also found that age and body mass index were predictors for the presence of a warm autoantibody. However, neither factor translated into adverse pregnancy outcomes. Logistic regression analysis showed younger age and lower BMI were more strongly associated with positive antibody screens, but these remained statistical findings without clinical consequences.
Every warm autoantibody in the cohort appeared during pregnancy and not before the first prenatal screen. None of the women developed AIHA, and Doppler studies of the umbilical artery in some cases showed only minimal risk for anemia. Overall, birth occurred at an average of 37 weeks with normal physical findings in the newborns.
Although warm autoantibodies are uncommon and can cross the placenta, this study showed that in this population, they did not lead to HDFN. Clinicians may continue to monitor for antibodies in pregnancy, but the presence of a warm autoantibody alone should not create unnecessary fear for expectant mothers.
Sign up here to get the latest news, perspectives, and information about HDFN sent directly to your inbox. Registration is free and only takes a minute.
