St. Mark's Hospital - April 25, 2019

Group B streptococcus (GBS) can cause serious illness or death in a newborn. If you are pregnant or thinking of getting pregnant, a simple screening test and antibiotic treatment can protect you and your baby.

What is group B streptococcus?

GBS is a bacterium that is commonly found in vaginal and/or rectal areas. GBS can sometimes cause illness in newborn babies, pregnant women, elderly adults or adults with chronic medical conditions like diabetes, liver disease and cancer.

Fortunately, most babies who are exposed to the bacteria will not become infected.

However, for those that are infected, it can lead to life-threatening infections, such as sepsis (blood infection) or, less commonly, meningitis (infection of the fluid and lining surrounding the brain).

Babies who have had meningitis can develop long-term problems, such as hearing and/or vision loss or learning disabilities and may even die if the infection is left untreated.

Newborn babies become infected with GBS in three ways:

  • Before birth: Bacteria in the vagina can spread up the birth canal into the uterus and infect the amniotic fluid surrounding the baby. The baby becomes infected by inhaling the infected fluid into the lungs.
  • During birth: The baby can come in contact with the bacteria in the birth canal.
  • After birth: The baby can come in contact with the bacteria through close physical contact with the mother.

How do I know if I’m at risk? 

GBS is present in about 25 percent of all healthy adult women. Not all women with the bacteria will pass it on. Factors that may increase your risk of passing GBS bacteria to your baby include:

  • A previous baby with GBS
  • GBS bacteria present in urine during any trimester of the current pregnancy
  • Positive GBS screening culture in third trimester of current pregnancy
  • Unknown GBS status and:
    • Labor or rupture of the membranes (water breaking) before 37 weeks gestation
    • A rupture of the membranes 18 hours or more before delivery
    • A fever during labor

What are the symptoms of GBS?

Usually, the pregnant woman has no symptoms of GBS. In pregnant women, GBS infections can cause infection of the uterine lining or amniotic fluid and can lead to a miscarriage. Two forms of infection occur in newborns:

  • Early-onset GBS: This produces illness soon after birth, usually within the first 24-48 hours, but may be up to seven days. Problems can include sepsis, pneumonia and meningitis.
  • Late-onset GBS: This usually occurs one week to three months after birth. Medical problems associated with late-onset disease may include sepsis and meningitis.

Symptoms for both early and late onset include:

  • Trouble breathing
  • Temperature instability (high and/or low)
  • Poor feeding
  • Irritability
  • Lethargy
  • Vomiting and diarrhea

If you notice any of these symptoms in your baby (especially if you have tested positive for GBS), call your pediatrician right away.

Getting screened

Screening for GBS bacteria is simple. A swab of the vagina and rectum will be taken about one month before the baby is due. The sample will be sent to a lab to test for the presence of the bacteria. Test results are usually available in 24–48 hours.

What to expect if your test comes back positive

The most common treatment is to give IV antibiotics during labor, hopefully at least four hours prior to delivery. If your baby is diagnosed with GBS, IV antibiotics will also be given. In some cases, your baby may be given antibiotics as a preventive measure.

Using what you know 

The first thing you can do is make sure your doctor screens you for GBS before your delivery date at 35-37 weeks. If you have been identified as a GBS carrier, make sure to tell your doctor of your status when your water breaks or you arrive at the hospital in labor.

By getting screened and treated during labor (if you have GBS), you can reduce the risk of your child developing GBS.