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Group B Strep and Pregnancy

What Is Group B Strep?

Group B Streptococcus (group B strep, GBS) is a type of bacteria often found in the urinary tract, digestive system, and reproductive tracts. The bacteria come and go from our bodies, so most people who have it don't know that they do. GBS usually doesn't cause health problems.

What Problems Can Group B Strep Cause?

Health problems from GBS are not common. But it can cause illness in some people, such as the elderly and those with some medical conditions. GBS can cause infections in such areas of the body as the blood, lungs, skin, or bones.

About 1 out of every 4 women have GBS. In pregnant women, GBS can cause infection of the urinary tract, placenta, womb, and amniotic fluid.

Even if they haven't had any symptoms of infection, pregnant women can pass the infection to their babies during labor and delivery.

How Does Group B Strep Affect Babies?

When women with GBS are treated with antibiotics during labor, most of their babies do not have any problems. But some babies can become very sick from GBS. Premature babies are more likely to be infected with GBS than full-term babies because their bodies and immune systems are less developed.

The two types of GBS disease in babies are:

  1. Early-onset infections, which happen during the first week of life. Babies often have symptoms within 24 hours of birth.
  2. Late-onset infections, which develop weeks to months after birth. This type of GBS disease is not well understood.

What Are the Signs & Symptoms of GBS Disease?

Newborns and infants with GBS disease might show these signs:

  • a fever
  • feeding problems
  • breathing problems
  • irritability or fussiness
  • inactivity or limpness
  • trouble keeping a healthy body temperature

Babies with GBS disease can develop serious problems, such as:

  • pneumonia
  • sepsis
  • meningitis (infection of the fluid and lining around the brain). Meningitis is more common with late-onset GBS disease and, in some cases, can lead to hearing loss, vision loss, learning disabilities, seizures, and even death.

How Is Group B Strep Diagnosed?

Pregnant women are routinely tested for GBS late in the pregnancy, usually between weeks 35 and 37. The test is simple, inexpensive, and painless. Called a culture, it involves using a large cotton swab to collect samples from the vagina and rectum. These samples are tested in a lab to check for GBS. The results are usually available in 1 to 3 days.

If a test finds GBS, the woman is said to be "GBS-positive." This means only that she has the bacteria in her body — not that she or her baby will become sick from it.

GBS infection in babies is diagnosed by testing a sample of blood or spinal fluid. But not all babies born to GBS-positive mothers need testing. Most healthy babies are simply watched to see if they have signs of infection.

How Is Group B Strep Treated?

Doctors will test a pregnant woman to see if she has GBS. If she does, she will get intravenous (IV) antibiotics during labor to kill the bacteria. Doctors usually use penicillin, but can give other medicines if a woman is allergic to it.

It's best for a woman to get antibiotics for at least 4 hours before delivery. This simple step greatly helps to prevent the spread of GBS to the baby.

Doctors also might give antibiotics during labor to a pregnant woman if she:

  • goes into labor prematurely, before being tested for GBS
  • hasn't been tested for GBS and her water breaks 18 or more hours before delivery
  • hasn't been tested for GBS and has a fever during labor
  • had a GBS bladder infection during the pregnancy
  • had a baby before with GBS disease

Giving antibiotics during labor helps to prevent early-onset GBS disease only. The cause of late-onset disease isn't known, so no method has yet been found to prevent it. Researchers are working to develop a vaccine to prevent GBS infection.

Babies who get GBS disease are treated with antibiotics. These are started as soon as possible to help prevent problems. These babies also may need other treatments, like breathing help and IV fluids.

How Can I Help Prevent Group B Strep Infection?

Because GBS comes and goes from the body, a woman should be tested for it during each pregnancy. Women who are GBS-positive and get antibiotics at the right time during labor do well, and most don't pass the infection to their babies.

If you are GBS-positive and begin to go into labor, go to the hospital rather than laboring at home. By getting IV antibiotics for at least 4 hours before delivery, you can help protect your baby against early-onset GBS disease.

Reviewed by: Thinh Phu Nguyen, MD
Date Reviewed: Jul 22, 2022

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