A positive rubella IgG test indicates immunity to rubella, meaning that the pregnant person and the fetus cannot contract this virus.

If a person contracts rubella, also known as German measles, during pregnancy, it can have severe consequences for the unborn child. The primary concern is congenital rubella syndrome (CRS), which can lead to a wide range of serious developmental issues in the fetus. Rubella infection during pregnancy also increases the risk of miscarriage or stillbirth.

However, a positive IgG test generally indicates immunity to rubella, which is good news for people who are pregnant. Those who have a positive IgG test result are immune to the virus and cannot pass it to their babies.

This article explores what a positive IgG test means, its importance, and its impact on pregnancy.

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A positive rubella IgG test indicates the presence of IgG antibodies specific to the rubella virus in a person’s blood. These antibodies signal that the immune system has previously encountered the rubella virus, either through infection or, more commonly, through vaccination.

The presence of these antibodies confirms immunity to rubella, which is particularly important for pregnant people. Being immune means the body can fight off the rubella virus, preventing its transmission to the fetus.

For anyone who is pregnant or planning to become pregnant, a positive result on this test offers reassurance that they and their developing baby have protection from the risks of a rubella infection.

What is rubella?

Rubella is a contagious viral infection that causes a distinctive red rash, which starts on the face and may affect the rest of the body. The virus spreads through airborne droplets when people with the infection cough or sneeze.

While the infection typically causes mild symptoms in children and adults, such as a low grade fever, sore throat, and rash, it is far more severe if a person contracts it during pregnancy.

When a pregnant person contracts rubella, especially during the first trimester, the virus can cross the placenta and infect the fetus. This can lead to congenital rubella syndrome (CRS), a serious condition that may cause issues such as heart abnormalities, hearing loss, and eye problems. Infants with CRS may also experience developmental delays and slow growth.

Learn more about rubella.

Symptoms of rubella are typically mild, and up to half of people with the condition have no symptoms. People who have symptoms may experience:

However, the primary concern for a pregnant person is not the symptoms but the impact on fetal health.

Learn more about rubella rash.

A pregnant person should contact a healthcare professional if they:

  • are unsure of their rubella immunity status
  • suspect they have had an exposure to rubella
  • develop symptoms suggestive of rubella

Rubella comes from the rubella virus, which spreads through airborne droplets when people with the infection sneeze or cough. Pregnant people who are not immune can contract the virus and potentially transmit it to their developing fetus.

Doctors diagnose rubella through blood tests that detect the rubella-specific antibodies IgM and IgG.

IgM antibodies in the blood typically indicate a recent rubella infection. These antibodies are the first to respond to an infection and are usually detectable within a few days after the onset of the rash. IgM levels rise rapidly and are most helpful in diagnosing a current or recent infection.

In contrast, IgG antibodies indicate past infection or immunity to the virus. These antibodies develop later but remain in the body for life, providing long-term immunity. Detection of IgG antibodies can help determine whether a person is immune to rubella, either through previous infection or vaccination.

Alongside blood test results, doctors consider clinical signs and symptoms of rubella, particularly when potentially diagnosing the condition in those who have not yet had a blood test or when test results are pending.

Rubella generally resolves by itself without needing specific antiviral or other treatments. Since the infection is typically mild and self-limiting, management focuses on symptom relief, including:

  • Rest: A person should rest to help the immune system fight off the infection.
  • Hydration: Staying hydrated is crucial, especially if fever is present.
  • Fever reducers and pain relievers: Over-the-counter medications such as acetaminophen and ibuprofen can alleviate fever, aches, and discomfort associated with rubella.

To reduce the spread of the virus, particularly to pregnant people or those who are not immune, people who have rubella should stay home and avoid close contact with others during the period when they may be able to transmit the virus.

The outlook for people with rubella is excellent. However, if a pregnant person contracts rubella, there are varying outlooks for the fetus.

If a person has rubella in early pregnancy, there is up to a 90% chance that their baby will be born with CRS. Around 1 in 3 babies born with CRS die before their first birthday.

Effective rubella prevention is crucial to reduce the spread of the virus and avoid the severe risks it poses during pregnancy.

Everyone — especially people of reproductive age — should receive the MMR (measles, mumps, and rubella) vaccine. It is crucial that people who are planning a pregnancy wait at least 4 weeks after vaccination before trying to become pregnant.

People who are unsure of their vaccination status should ask a doctor about booster vaccination or antibody testing.

Furthermore, people should avoid close contact with anyone who has rubella or has symptoms such as a rash and fever. This is especially important for people who are pregnant or trying to conceive.

Rubella is a viral infection that poses significant risks to fetuses, increasing the risk of congenital anomalies and stillbirth. However, vaccination is highly effective in preventing infections.

A positive rubella IgG test during pregnancy is beneficial because it indicates immunity to rubella. This immunity protects the pregnant person and their unborn child from the risks of a rubella infection.