Having a pregnancy affected by hemolytic disease of the fetus and newborn (HDFN) significantly increases the risk of the condition in future pregnancies.
If you were at risk of or diagnosed with HDFN in a previous pregnancy, you may be wondering if that risk still exists if your next pregnancy occurs with a different partner. The answer depends on both your immune history and the new partner’s blood type.
What affects the risk of HDFN?
HDFN develops when a mother lacks a certain red blood cell antigen, such as RhD, c, E or Kell, but has developed antibodies against it. This can happen through exposure in a prior pregnancy, transfusion or needle drug use.
Learn more about HDFN testing and diagnosis
If her baby inherits that antigen from the father, the mother’s antibodies can cross the placenta and destroy the baby’s red blood cells. This can result in fetal complications, such as anemia, jaundice or in severe cases, hydrops fetalis (a condition characterized by fluid build up in the fetus).
HDFN risk with a new partner
Once a woman develops red blood cell antibodies, they stay in her bloodstream forever and do not disappear if she changes partners. Her immune system retains the “memory” of that antigen, and if a future baby inherits the same antigen from a new father, HDFN risk remains.
However, the level of risk depends on the genetic makeup of the new partner. If the new partner does not carry the antigen that triggered the mother’s antibodies, the baby cannot inherit it, and therefore HDFN risk is eliminated for that specific antibody.
Genetic testing of the father can sometimes provide reassurance early in pregnancy.
What families should know
For women who have previously had a pregnancy affected by HDFN, changing partners may alter the level of risk, but by no means guarantees protection. The safest approach is early and ongoing communication with obstetricians and maternal-fetal medicine specialists.
With proper monitoring, ultrasound surveillance and treatments such as intrauterine transfusions, most HDFN affected pregnancies today result in healthy outcomes.
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