What Does It Mean If My Baby Is Coombs Positive? (2025)

It's a thrilling moment to welcome your baby into the world. Once your infant arrives, several tests need to be conducted to ensure their health, a Coombs test is one of them. A Coombs test is conducted to see if your newborn is Coombs-positive which means that they have foreign antibodies in their blood.

Hearing that your baby is Coombs-positive can be confusing and upsetting. However, it is usually a mild and passing condition that does not impact your newborn’s current or future quality of life. A Coombs-positive lab result does require that your baby receive medical monitoring in the form of more frequent testing of bilirubin level.

Let's take a closer look to understand what it means for a newborn to be Coombs positive, what causes the condition, and how it's treated.

What Is a Coombs-Positive Newborn?

When a baby is Coombs positive, it means their blood and their birth parent’s blood aredifferent types and have mixedduring pregnancy ordelivery. It is determined by a Coombs test or direct antibody test (DAT), usually done on blood from the newborn’s umbilical cord.

This combination of blood types can become a problem for the baby, causing jaundice and anemia, conditions that require extra care. While most Coombs-positive newborns go home from the hospital at the usual time, they need additional evaluation and possibly treatment, such as phototherapy—exposing the baby to a special kind of light.

Typically, Coombs-positive babies do not have any long-term problems. Because the parent's blood and baby’s blood don’t mix after delivery, the reaction in the baby’s bloodstream slowly resolves. "The newborn naturally makes more new red blood cells, eliminating the issue," explains Kelly L. Ross, MD, associate professor at Washington University School of Medicine, St. Louis Children's Hospital.

What Causes a Newborn to Be Coombs-Positive?

A Coombs-positive test result occurs due to a reaction in the newborn's bloodstream. It's not uncommon for babies to have a different blood type than their gestational parent's.

During pregnancy and birth, the blood of the pregnant person and the baby can mix.When their blood groups or types are different and not compatible, the pregnant person’s immune system may recognize the baby’s red blood cells as foreign and produce antibodies.

"These antibodies can cross over to the baby during pregnancy and birth and damage the baby’s red blood cells," explainsAthis Arunachalam, MD, assistant professor of pediatrics at Baylor College of Medicine in Houston. "When the baby’s red blood cells are damaged and broken down, bilirubin (a yellow pigment) is produced in excessive amounts. That's called jaundice and needs to be treated if severe."

One way of preventing a scenario in which a baby is Coombs-positive is to offer a medication called RhoGAM to RH-negative mothers It's also important for health care providers to routinely test your Rh factor during pregnancy.

Symptoms of Coombs-Positive Newborns

When a baby is Coombs positive, their blood cells break down at a higher-than-usual rate due to the interaction of the two different blood types. This can cause jaundice and also anemia.

Jaundice

Jaundice causes the skin and whites of the eyes to appear yellow. This is a sign of too much bilirubin (the orange-yellow pigment that occurs as red blood cells break down) in the bloodstream. It gets deposited under the skin and is responsible for the yellow tone.

Many newborns develop mild jaundice. It usually gets better or goes away on its own. Coombs-positive babies are at higher risk for jaundice, though, and this can become a serious issue if it’s a severe, untreated case. As a result, vigilance is important.

Anemia

Anemic babies have a deficiency of red blood cells, which carry oxygen. Newborns with anemia may have the following symptoms:

• Pale skin
• Feed poorly
• Very sleepy to the point of lethargy
• Increased breathing and heart rates

While most Coombs-positive babies do not become anemic, there is an elevated risk of this condition.

Diagnosing Coombs-Positive Babies

This condition is diagnosed by a blood test that you may hear referred to as either a Coombs test or direct antibody test (DAT). Dr. Arunachalam says that a Coombs test is routinely done on newborns who have different blood types than their gestational parent's. A positive test means that the baby’s red blood cells have their parent's antibodies attached to them, putting them at high risk of developing moderate to severe jaundice after birth.

How the test is done

Usually, the blood is taken from the baby’s umbilical cord while it is still attached to the placenta following delivery, explains Dr. Ross. Sometimes, it is taken directly from the baby.

False positives

Note that a Coombs test can yield a false-positive result, typically when a pregnant person has been treated for havingRh-negative bloodduring a routine prenatal screening, says Dr. Ross. If their blood is Rh negative (Rh-), they may receive an injection known as Rho(D) immune globulin or RhoGAM during pregnancy. This shotis designed to prevent them from making antibodies against their baby’s blood. This protective procedure can, in some cases, cause the results of a Coombs test to be positive for a baby.

"Newborns who are Coombs positive for this reason do not develop either jaundice or anemia," says Dr. Ross. Your medical records will reflect whether you have had this treatment. If your baby tests as Coombs-positive, your healthcare providers will know that this prenatal shot is responsible for the test result.

Treatment for Coombs-Positive Newborns

When your baby is diagnosed as Coombs positive, they will need a bit of extra monitoring to ensure they thrive. Medical staff will evaluate your baby to see what degree of jaundice and anemia may occur. These conditions can be determined by physical exams, a special instrument called a bilimeter—this device has a sensor that is pressed against the baby's forehead to determine the degree of jaundice—and blood tests as needed.

Phototherapy

A significant level of jaundice will be treated with phototherapy. Also known as light therapy, this is a non-invasive medical treatment in which a light source (often from fluorescent, LED, or halogen bulbs) is used to help the baby’s body break down bilirubin. When that happens, the bilirubin can be naturally eliminated from the body.

Other interventions

In rare cases, babies need more extensive interventions (such as IV treatments like transfusions or medications) for jaundice or anemia. Your health care providers will explain exactly what is needed for your baby if that occurs.

When Can Coombs-Positive Newborns Go Home?

Most babies who are Coombs positive go home at the usual time. It is possible, however, that jaundice or anemia may recur once your baby is home. For this reason, your baby will need to be seen again within a few days of going home. Your infant's progress will be carefully assessed to ensure they are in good health.

Contact a health care provider if you notice any symptoms that could indicate Coombs-related jaundice or anemia. These include:

• Pale skin tone
• Increasing yellowness of the skin and the whites of the eyes
• Poor feeding
• Fast breathing or trouble breathing
• Enlarged liver or spleen
• Full-body swelling
• Excessive sleepiness