Doctors can now accurately determine a baby’s blood group during pregnancy using a simple blood test from the mother, without putting the baby at risk, according to a recent study published in the Journal of Clinical Medicine.
Knowing a baby’s blood group early is important for preventing complications like hemolytic disease of the fetus and newborn (HDFN) or fetal and neonatal alloimmune thrombocytopenia (FNAIT). These conditions can happen when a mother’s immune system reacts to the baby’s blood cells, producing proetins called antibodies that attack the baby’s blood cells.
Traditionally, doctors use procedures like amniocentesis (a process in which amniotic fluid is sampled using a hollow needle inserted into the uterus) to find out a baby’s blood type. While generally safe, these procedures carry small risks for both mother and baby.
The new blood test avoids those risks by looking at tiny fragments of the baby’s DNA that naturally circulate in the mother’s blood. This approach uses advanced technology called next-generation sequencing (NGS), which can detect even very small amounts of fetal DNA and accurately determine the baby’s blood group.
Read more about treatment and care for FNAIT
In the study, researchers tested blood samples from 21 pregnant women. In 15 cases where newborn blood was available for comparison, the results from the non-invasive blood test matched the baby’s actual blood type perfectly.
On average, the baby’s DNA made up about 11% of the mother’s blood sample. The test was carefully validated to detect fetal DNA fractions as low as 2%, ensuring it is reliable even when only a small amount of fetal DNA is present.
“For pregnant women with a history of fetal and neonatal alloimmune thrombocytopenia (FNAIT) or hemolytic disease of the fetus and newborn (HDFN), prenatal intervention in subsequent pregnancies may be necessary to prevent complications for the fetus,” the researchers said. The new test is a non-invasive and accurate way to determine a baby’s blood group, they said.
