A negative Rhesus (Rh) test can have certain implications for a pregnancy. However, with the right medical care, people and their babies with Rh incompatibility can experience a healthy pregnancy and delivery.

The Rh factor is an inherited protein that may appear on the surface of red blood cells.

Testing negative for Rh protein is not a problem in itself, but in some cases, a pregnant individual may have a different Rh status from their baby. Without suitable care, this incompatibility could cause medical problems during and after pregnancy.

This article discusses testing Rh-negative during pregnancy, results, risks, and follow-ups.

A baby sleeping on its side and holding onto a person's fingerShare on Pinterest
©fitopardo/Getty Images

Rh-positive is the most common blood type, which means that a person’s red blood cells have this protein. The remainder of the population is Rh-negative.

A person who is Rh-negative will not experience health issues from their blood type. However, there may be complications if they become pregnant with a partner who is Rh-positive. In this scenario, the fetus may inherit Rh-positive blood.

During pregnancy, blood from the fetus can cross the placenta and enter the parent’s blood. With Rh incompatibility, this can cause a harmful immune response to the fetus or newborn. The parent’s immune system may recognize this blood as foreign material and produce antibodies against the Rh-positive blood.

Proper testing and care drastically reduce any risk to parent and child who have different Rh factors.

Medical professionals recommend Rh testing at the beginning of every pregnancy. Being aware of Rh incompatibility is crucial for minimizing potential risks.

Other recommended tests and screenings may include:

  • having regular antibody screening throughout pregnancy
  • testing the other parent’s Rh status
  • determining the fetus’s Rh status through amniocentesis

Research has shown that Rh incompatibility is less problematic during a first pregnancy. In such cases, doctors may choose to rely on regular antibody screening tests. These can show whether a pregnant person is producing too many antibodies.

Rh screening and antibody testing involve simple blood tests. These are typically quick and painless for both parents.

In certain cases, a fetus may be at risk for anemia. Doctors can check for this condition using advanced ultrasound imaging. If a fetus shows signs of anemia, doctors can induce an early delivery or provide blood transfusions to the fetus.

Read more about Rh factor screening here.

When tests reveal Rh incompatibility, this can lead to a number of risks for the developing fetus.

Some most common risks after birth include:

If a pregnant person experiences Rh incompatibility, their immune system may attack the fetus’s blood. This can cause anemia if the fetus loses more blood cells than they can produce.

Since red blood cells carry oxygen through the body, this fetus may not get enough oxygen. This could lead to newborn jaundice. It could also cause fluids to build up inside the fetus, which could cause further problems.

The presence of Rh incompatibility does not necessarily mean that a fetus will experience complications. There are many testing and treatment options to prevent serious health issues from occurring.

Parental antibodies can be prevented early in pregnancy. If antibodies cannot develop, then they cannot impact the health of the growing fetus.

Doctors may suggest the following during pregnancy to prevent antibodies:


The most common way to stop these antibodies is through Rh immunoglobulin. Doctors administer this medication as an injection, and it prevents antibodies from developing in the pregnant person. This treatment program can prevent a fetus from developing anemia.

Research has shown that the earlier doctors provide this treatment, the better the outcome. Early testing to identify Rh incompatibility is crucial for starting this treatment process.

Avoiding fluid buildup

Researchers found that 24% of fetuses had fluid buildup without immunoglobulin treatment. This happened in only 4% of treated pregnancies.

Regular antibody screening is essential during Rh-incompatible pregnancies. Each pregnancy is unique, so individuals should consult a medical team to determine the right treatment for them.

Before delivery, immunoglobulin treatment may reduce symptoms of Rh incompatibility. In cases where this does not occur, a medical professional may recommend some of the following options:

Early delivery

An early delivery may be the best option for certain cases of Rh incompatibility. Once a fetus’s lungs have developed, a medical professional may recommend inducing labor. This can help protect the baby from any further risks while still inside the uterus.

Exchange transfusion

After delivery, doctors could recommend exchange transfusion. This process replaces a newborn’s blood with healthy donor blood. Exchange transfusion is particularly useful for babies who are born with jaundice.


This treatment can also help treat jaundice in newborns. Phototherapy exposes the baby to as much light as possible. This helps lower the levels of bilirubin in a newborn’s blood.

There is no treatment that will be suitable for all Rh-incompatible pregnancies. Regular tests and check-ins with a doctor can help determine the most effective course of action for each parent and newborn.

Rh incompatibility is relatively rare during pregnancy. However, doctors recommend that all pregnant people go through screenings and tests early in their pregnancy.

For people who experience Rh incompatibility, there are many testing and treatment options available. Regular antibody screenings can be an especially important part of preventing problems for both the parent and baby.

With regular treatment, pregnant people with Rh incompatibility can experience a healthy pregnancy and delivery.