When hemolytic disease of the fetus and newborn (HDFN) begins before 20 to 22 weeks of pregnancy, outcomes can be serious, but new tools and treatments are improving the chances for affected babies, according to an article published recently in Best Practice and Research Clinical Obstetrics and Gynaecology.
This early form of HDFN, caused when a mother’s immune system attacks her baby’s red blood cells, can lead to fetal anemia, swelling known as hydrops fetalis or even fetal death if untreated. Doctors now define early-onset HDFN by the presence of these signs before 20 to 22 weeks and have found ways to detect and manage it much earlier than in the past.
One of the most important advances is the use of cell-free fetal DNA testing between 10 and 12 weeks of pregnancy. This simple blood test can identify whether the baby has red cell antigens that may trigger a maternal immune response. If a previous pregnancy was affected by HDFN, early DNA testing gives a clear picture of whether the current pregnancy is at risk. Weekly ultrasounds of the baby’s brain blood flow, starting as early as 15 weeks, help identify early signs of anemia.
“Early confirmation of the fetal antigen status followed by immunomodulation should be considered,” explained the author of this article, continuing, “MCA-PSV Dopplers can be performed as early at 15 weeks’ gestation and intraperitoneal intrauterine transfusions used as a bridging therapy until an intravascular approach for IUT can be achieved. In the future, immunomodulation through FcRN blockade may negative the need for invasive therapy.”
Read more about HDFN treatment and care
In high-risk cases, immune therapies can start before any transfusions are needed. Giving intravenous immune globulin at 10 to 12 weeks may reduce the mother’s harmful antibodies or block their transfer to the baby. If needed, doctors can perform a blood transfusion through the baby’s abdomen—a safer method at early gestational ages—until the baby is large enough for a direct transfusion through the umbilical cord.
Although intravascular transfusions remain the standard, they carry greater risk before 20 weeks. Reports show a perinatal loss rate of 20% when transfusions are done this early. However, with advances such as intravenous immune globulin, plasmapheresis and close fetal monitoring, some babies avoid transfusions altogether. In some studies, 14% of high-risk pregnancies with the same father did not need transfusions, despite the baby having the at-risk blood type.
In the future, treatments that block the maternal antibody transport system, such as Fc receptor blockers, may reduce or eliminate the need for invasive transfusions altogether. Until then, early diagnosis, close monitoring and a stepwise approach to treatment are key to giving these babies the best possible chance.
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