Group B Strep

What is Group B Strep (Beta Strep or GBS)?

Group B streptococcus (GBS) is a type of bacteria.  20-25% of pregnant women carry GBS in the rectum or vagina.  Although it is possible for GBS to cause illness in the mother (especially urinary tract infections or infections inside the uterus), most women who carry GBS in their bodies do not become ill or have any symptoms at all.  These people are considered to be “carriers.”  People who carry GBS typically do so temporarily; that is, they do not become lifelong carriers of the bacteria.

Why should I care about GBS?

A fetus may come in contact with GBS before or during birth if the mother carries GBS in the rectum or vagina, and unfortunately, they can become gravely ill because of it.  In fact, GBS is the most common cause of life-threatening infections in newborns, resulting in sepsis (blood infection), meningitis (infection of the fluid and lining surrounding the brain), or pneumonia.

Approximately one of every 100 to 200 babies whose mothers carry GBS (0.5%-1%) develop GBS disease. Three-fourths of the cases of GBS disease among newborns occur in the first week of life (“early-onset disease”), and most of these cases are apparent a few hours after birth.  GBS disease may also develop in infants one week to several months after birth (“late-onset disease”).  Meningitis is more common with late-onset GBS disease.  Only about half of late-onset GBS disease among newborns comes from a mother who is a GBS carrier; the source of infection for others with late-onset GBS disease is unknown.  Late-onset disease is very rare.

There are other factors besides GBS carrier status that increase the chances that a baby will be affected by GBS disease.  They are:

  • fever during labor
  • rupture of membranes (water breaking) 18 hours or more before delivery
  • labor or rupture of membranes before 37 weeks
  • black race
  • Hispanic ethnicity
  • previous baby with GBS disease
  • urinary tract infection due to GBS

Babies who get sick with GBS disease will likely spend a minimum of 10 days in the newborn intensive care unit on IV antibiotics.  One of every 20 babies with GBS disease (5%) dies from infection.  Premature babies are more susceptible to GBS infection and are more likely to die from it than full-term babies.  Babies that survive, particularly those who have meningitis, may have long-term problems, such as hearing or vision loss or learning disabilities.

What are the symptoms of GBS disease?

The symptoms of GS disease in babies can vary widely, making it hard to distinguish GBS disease from other problems.  Generally, however, the symptoms are:

  • difficulty breathing or periods of not breathing
  • lethargy (baby is difficult to rouse or does not respond normally)
  • seizures
  • temperature too low or too high
  • cyanosis (blue hue to skin, particularly around the mouth and gums, or all over dusky color. Blue hands and feet are NOT cyanosis.)
  • poor feeding

How is GBS disease diagnosed and treated in the baby?

GBS disease is diagnosed when the bacterium is grown from cultures of sterile body fluids, such as blood or spinal fluid.  Cultures take a few days to complete.  GBS infections in newborns are usually treated with antibiotics (e.g., penicillin or ampicillin) given through a vein.

Can I be tested for GBS?

GBS carriage can be detected during pregnancy by taking a swab of both the vagina and rectum for special culture.  These cultures should be done in late pregnancy (35-37 weeks gestation); cultures collected earlier do not accurately predict whether a mother will have GBS at delivery.

A positive culture result means that the mother carries GBS–not that she or her baby will definitely become ill.  A negative result means that the mother does not carry GBS.

Can GBS disease among newborns be prevented?

Most, but not all, cases of GBS disease can be prevented.  The Centers for Disease Control (CDC) recommends that antibiotics (usually penicillin or ampicillin) be given intravenously (through a vein) in labor to mothers who carry GBS.  Additionally, they recommend any pregnant women who previously had a baby with GBS disease or who has a urinary tract infection caused by GBS should receive antibiotics during labor.  The CDC protocol of IV antibiotics reduces the chance of GBS disease n the newborn from 1 in 200 to 1 in 4000.

The CDC does not recommend injectable antibiotics because IV administration achieves a higher concentration of antibiotic inside the uterus.  Oral antibiotics before labor are not recommended because antibiotic treatment prior to labor does not prevent GBS disease in newborns.  An exception to this is when GBS is identified in urine during pregnancy.  GBS in the urine should be treated at the time it is diagnosed.

Another option that has been investigated for preventing GBS disease in the infant is a chlorhexadine (Hibiclens®) wash.  Under this protocol, the vagina is rinsed with a 0.2% solution of chlorhexadine every 6 hours during labor.  The appeal of this method is that neither needles nor antibiotics are involved.  However, in its recent statement on GBS, the CDC has declared that there is no evidence chlorhexadine washes are effective.

None of these treatments is 100% effective at preventing GBS disease.  Each of them carries its own risks. Because women who carry GBS but do not develop additional risk factors have a relatively low risk of delivering an infant with GBS disease, the CDD recommends that the decision to receive antibiotics during labor should balance these risks and benefits.

What are the risks of the treatments?

The risks of antibiotics are:

  • 1 in 10 chance of experiencing a mild allergic reaction (such as rash)
  • 1 in 10,000 chance of developing a severe allergic reaction–anaphylaxis–to penicillin. Anaphylaxis requires emergency treatment and can be life-threatening, especially in an out-of-hospital setting.
  • May cause resistance in the GBS bacteria making subsequent illness more difficult to treat
  • May produce other side effects (such as diarrhea or yeast infections such as thrush)
  • May allow other bacteria in the mother or baby to become resistant (especially E. Coli) and cause other complications which, in the rare worst case, can be life-threatening

The risks of chlorhexidine are:

  • May cause a burning sensation
  • Not an approved CDC protocol, may be less effective than IV antibiotics or not effective at all

What should I do?

Now that you know about GBS, you need to make some choices.  First, choose whether you want to be tested for GBS.  Then, choose how (or whether) you want to be treated if your test comes out positive.


The information in this document was taken from the CDC’s patient information brochure on Group B Strep, written and published by the Respiratory Disease Branch, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA.

In addition, information regarding the chlorhexidine wash alternative to antibiotic prophylaxis was obtained from the following sources:

J Matern Fetal Med 2002 Feb;11(2):84-8. Chlorhexidine vaginal flushings versus systemic ampicillin in the prevention of vertical transmission of neonatal group B streptococcus, at term. Facchinetti F, Piccinini, Mordini B, Volpe A. “In this carefully screened target population, intrapartum vaginal flushings with chlorhexidine in colonized mothers displayed the same efficacy as ampicillin in preventing vertical transmission of group B streptococcus. Moreover, the rate of neonatal E. Coli colonization was reduced by chorhexidine.”

Lancet 1992 Jul 11;340(8811):659. Prevention of excess neonatal morbidity associated with group B streptococci by vaginal chlorhexidine disinfection during labour. The Swedish Chorhexidine Study Group, Burman LG, Christensen P, Christensen K, Fryklund B, Helgesson AM, Svenningsen NW, Tullus K. “Chlorhexidine reduced the admission rate for infants born of carrier mothers to 2.8% [from 5.4%]...Maternal S agalactiae colonisation is associated with excess early neonatal morbidity, apparently related to aspiration of the organism, that can be reduced with chlorhexidine disinfection of the vagina during labour.”

Int J Antimicrob Agents 1999 Aug;12(3);245-51. Vaginal disinfection with chlorhexidine during childbirth. Stray-Pedersen B, Bergan T, Hafstad A, Normann E, Grogaard J, Vangdal M. “This prospective controlled trial demonstrated that vaginal douching with 0.2% chlorhexidine during labour can significantly reduce both maternal and early neonatal infectious morbidity.”

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Group B what?