The group B strep test is done during pregnancy to identify women who carry this common bacterium.

Group B strep is usually harmless in adults. Rarely, however, group B strep can cause health problems during pregnancy, including:

  • Urinary tract infection
  • Infection of the placenta and amniotic fluid (chorioamnionitis)
  • Pneumonia
  • Bacteria in the blood (bacteremia)
  • Life-threatening infection in the blood (sepsis)

Rarely, group B strep can contribute to inflammation and infection of the membrane lining the uterus (endometritis) after delivery. Group B strep also increases the risk of wound infection after a C-section.

The primary concern with group B strep, however, is the risk to the baby.

Group B strep can spread to the baby during a vaginal delivery if the baby is exposed to fluids containing the bacterium. While only a few babies who are exposed to group B step develop an infection, those who are infected could develop life-threatening complications — often shortly after birth, but sometimes days or even months later.

Complications for the baby could include:

  • Inflammation of the lungs (pneumonia)
  • Inflammation of the membranes and fluid surrounding the brain and spinal cord (meningitis)
  • Bacteria in the blood (bacteremia)
  • Life-threatening infection in the blood (sepsis)

If you have group B strep, treatment with antibiotics during labor will be recommended to destroy bacteria in the birth canal and reduce your baby's risk of developing an infection. Taking antibiotics before labor doesn't help since the bacteria can grow back quickly.

If you previously gave birth to a baby who had a group B strep infection or you had a urinary tract infection caused by group B strep during your current pregnancy, you're at higher risk of spreading group B strep to your baby. As a result, you'll automatically be treated with antibiotics during labor — making a group B strep test unnecessary.

Antibiotics aren't necessary if you're having a planned C-section, as long as labor hasn't begun and the amniotic sac — the fluid-filled membrane that surrounds and cushions your baby during pregnancy — is intact. Testing is still important, however, since labor could begin naturally before the scheduled C-section.

April 01, 2015