MCA Peak Systolic Velocity Calculator

What the MCA Doppler Calculator Is

If you’ve been told your baby might be at risk for anemia during pregnancy because of red blood cell antibodies (like anti-D or others), your doctors may be doing regular MCA Doppler ultrasounds. These ultrasounds are safe and painless, and they measure how fast blood is flowing through one of the arteries in your baby’s brain. That artery is called the middle cerebral artery, or MCA.

When a baby becomes anemic, their blood gets thinner and flows faster than normal. By measuring that blood flow, doctors can often tell how anemic your baby might be without needing to do anything invasive.

The Website Doctors Use to Help Track This

Your care team might use either of these sites:
https://perinatology.com/calculators/MCA.htm

https://fetalmedicinebarcelona.org/calc/

Here is what the tool does:

They enter how far along you are in your pregnancy
They enter the MCA blood flow speed from your ultrasound (measured in cm per second)
The calculator gives a result called the MoM which stands for “multiples of the median”

This number helps the doctor understand whether the blood flow is normal or faster than expected, which may mean your baby needs treatment for anemia.

What the Numbers Mean

Here is a general guide to how doctors interpret the result:

MoM less than 1.29 — This is considered normal. There are no signs of anemia.
MoM between 1.29 and 1.49 — This is a gray zone. Doctors usually repeat the ultrasound soon to watch for changes.
MoM of 1.5 or higher — This suggests that your baby may have moderate to severe anemia. Your doctor may recommend treatment, which can include a transfusion while the baby is still in the womb.

Your doctor will also consider how far along you are, the baby’s condition, and other test results before deciding what to do.

What You Can Do as a Parent

Keep going to all your ultrasounds and appointments. These scans help keep your baby safe and give your doctors the information they need.
Ask questions. You can say things like, “Can you explain the MCA result to me?” or “What does this number mean for my baby?”
Speak up if anything feels confusing or stressful. You are your baby’s biggest advocate, and your voice matters.