In at least some unborn babies, a shortage of red blood cells (fetal anemia) may raise the risk of brain injury even when their overall blood circulation appears stable, according to a recent study published in the journal Prenatal Diagnosis.
Fetal anemia is a rare but serious condition that can develop during pregnancy for several reasons, including hemolytic disease of the fetus and newborn (HDFN), bleeding from the baby into the mother’s bloodstream, viral infections like parvovirus B19 or cytomegalovirus, inherited blood disorders or sometimes no identifiable cause at all. It can lead to dangerous fluid buildup (hydrops fetalis), brain damage or death before birth. While treatments like blood transfusions given directly to the fetus in the womb have improved survival rates, babies who survive can still go on to have developmental problems.
In this study, researchers examined 93 fetuses diagnosed with anemia and treated with intrauterine blood transfusions. They found that just over half — 48 of them — showed signs of brain injury. The most common sign of injury was bleeding within the skull, which was present in nearly half of cases. This was followed by reduced blood flow to brain tissue (present in 21% of cases) and other non-specific injuries (present in 25% of cases). Additionally, 6% of cases had a combination of both bleeding and reduced blood flow.
One important finding was that male fetuses with anemia were roughly five times more likely to have brain injuries compared to female fetuses.
Meanwhile, the severity of the anemia itself, the presence of hydrops, heart problems or how far along the pregnancy was at diagnosis did not appear to predict brain injury.
Read more about HDFN symptoms and risks
“This study represents the largest cohort to date describing brain injuries in foetuses with anaemia diagnosed via FBS [fetal blood sampling] and treated with IUT [intrauterine transfusions],” the researchers said.
These findings highlight the need for future studies that follow patients over a long period of time, they added. This would allow doctors to better understand the real level of risk and pinpoint which babies would benefit most from closer monitoring.
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