What is GBS?

Group B strep (streptococcus) is a type of bacteria that can cause serious illness and death in newborns. Until recent prevention efforts, hundreds of babies died from group B strep every year. This type of bacteria can also cause illness in adults, especially the elderly, but it is most common in newborns.

Among babies, there are 2 main types of group B strep disease:

  • Early-onset disease — occurs during the first week of life.
  • Late-onset disease — occurs from the first week through three months of life.

Early-onset disease used to be the most common type of disease in babies. Today, because of effective early-onset disease prevention, early and late-onset disease occur at similar low rates.

For early-onset disease, group B strep most commonly causes sepsis (infection of the blood), pneumonia (infection in the lungs), and sometimes meningitis (infection of the fluid and lining around the brain). Similar illnesses are associated with late-onset group B strep disease. Meningitis is more common with late-onset group B strep disease than with early-onset group B strep disease.

For both early and late-onset group B strep disease, and particularly for babies who had meningitis, there may be long-term consequences of the group B strep infection such as deafness and developmental disabilities. Care for sick babies has improved a lot and in the U.S., only 4-6% of babies with group B strep infections die.

On average, about 1,200 babies in the U.S. less than one week old get early-onset group B strep disease each year, with rates of group B strep disease higher among blacks. Group B strep can also cause some miscarriages, stillbirths and preterm deliveries.


A pregnant woman who tests positive for group B strep and gets antibiotics during labor can feel confident knowing that she has only a 1 in 4,000 chance of delivering a baby with group B strep disease. If a pregnant woman who tests positive for group B strep does not get antibiotics at the time of labor, her baby has a 1 in 200 chance of developing group B strep disease. This means that those infants whose mothers are group B strep positive and do not get antibiotics have over 20 times the risk of developing disease than those who do receive preventive antibiotics.

Information from CDC.gov