How Fetal Anemia Is Diagnosed and Monitored

Anemia, a condition in which you don’t have enough healthy red blood cells to carry oxygen throughout the body, can be dangerous for anybody. However, it is particularly problematic when it occurs during pregnancy.

With fetal anemia, the amount of circulating red blood cells and hemoglobin falls below normal levels in the fetus. Hemoglobin is the protein inside red blood cells that carries oxygen to the body’s tissues. If the fetus’s heart does not receive enough oxygen, there is a danger of heart failure.

Fetal anemia can be caused by multiple factors, including an incompatibility between the blood types of the pregnant person and their fetus, says Mert Ozan Bahtiyar, MD, director of the Yale Fetal Care Center.

At Yale, fetal anemia can be diagnosed and monitored noninvasively with something called middle cerebral artery (MCA) doppler, which measures the speed of blood flow in the MCA, a major artery in the brain.

“If we see that the anemia is in the severe range, then we can do a blood transfusion,” Dr. Bahtiyar says. “When anemia is suspected very early in pregnancy, we can give the blood into the abdominal cavity of the baby, where it gets slowly absorbed into the fetal system. However, after about 16 or 17 weeks, the size of the placenta gets large enough that we can insert a needle reliably and repeatedly, and sample and deliver the blood as much as is needed.”

After birth, anemia generally resolves, Dr. Bahtiyar says. What sets Yale apart, he adds, is the personal care and attention he and his colleagues give to each patient. “We spend time and effort with each patient throughout their journey,” he says.

Dr. Bahtiyar talks more about fetal anemia in the video above.