Patients who have several antibodies known to cause hemolytic disease of the fetus and newborn (HDFN) are more likely to experience complications during pregnancy, according to a poster presentation at the 2025 Society for Maternal-Fetal Medicine Meeting.
The retrospective study included 166 pregnant individuals presenting to a center with at least one antibody that can cause HDFN between 2018 and 2023. The authors investigated several outcomes, including antibody titers, frequency and timing of intrauterine transfusions (IUT), need for middle cerebral artery (MCA) Doppler ultrasound and incidence of preterm birth.
Read more about HDFN testing and diagnosis
While 80% of participants with multiple antibodies underwent IUT, only 34.3% of those with one antibody required the procedure (P = 0.005). Additionally, patients with more than one antibody tended to require multiple IUTs that began earlier in gestation.
The authors also found that 20% of individuals with multiple antibodies required IUT during a prior pregnancy compared to 0.8% of those with one antibody (P < 0.001).
Furthermore, average antibody titers were higher among patients with multiple antibodies when comparing samples taken at approximately the same gestational age. These patients also experienced a higher maximum titer of 381.6 as compared to 40.56 in individuals with one antibody. Patients with several alloantibodies were also more likely to have anti-D antibodies, the most common cause of HDFN.
MCA Doppler ultrasounds assess fetal blood flow and can be used to identify signs of anemia or hypoxia. While 93.3% of patients with multiple antibodies underwent MCA Doppler, 59.8% of those with one antibody required the procedure.
The average gestational age of children born to mothers with multiple antibodies was 34.7 weeks, slightly lower than that of 36.7 weeks in children born to mothers with just one antibody.
“Patients with alloimmunization involving multiple antibodies rather than a single antibody are more likely to have critical antibody titers, require early MCA Dopplers, develop HDFN requiring IUT procedures that were more commonly early and multiple, and deliver at an earlier gestational age,” the authors concluded.
