Group B Streptococcal Infection

Group B Streptococcal Infection



Group B streptococcal (GBS) infection is rare illness in newborns. It is caused by a bacteria that is often passed to the baby in the birth canal.


GBS is a specific bacteria. It is common to find this bacteria on the skin along with other bacteria. GBS may pass to newborns in the birth canal during delivery. They may also pick up the bacteria after birth when they come in contact with someone who has the bacteria on their skin.

Bacteria Spreading to Fetus

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Risk Factors

Things that may raise a baby's risk of GBS infection include:

  • An infected mother who doesn’t get treated before birth
  • Mother had a prior baby with GBS infection
  • Mother has a urinary tract infection due to GBS
  • Labor or water breaking before 37 weeks
  • Water breaking for 18 hours or more before birth
  • Mother has a fever during labor
  • Frequent pelvic exams during labor
  • Use of tools that check the fetus


The newborn with GBS infection may have:

  • Fever
  • Breathing problems
  • Not eating well
  • Crying a lot
  • Problems waking

A pregnant woman will rarely have symptoms.


Pregnant women are tested for the presence of GBS about 5 weeks before delivery date. It is part of normal prenatal care. A cotton swab will be swiped over the vagina and rectum. A lab will test the sample for GBS. If GBS is found, the mother is said to be colonized.

A baby born to a mother with GBS will not always be ill. Tests to confirm GBS infection in the baby may include:

  • Blood tests
  • Urine tests
  • Lumbar puncture—to collect fluid around the spine


For the Mother

A mother can be colonized with GBS and not be sick. Treatment may be done to decrease the risk of passing GBS to the baby. Antibiotics will be given through IV during labor. Treatment must be given at least four hours before birth.

For the Baby

A newborn with a GBS infection may be need extra days of medical care. Antibiotics will be given.


The risk of a GBS infection in newborns may be decreased by:

  • Good prenatal care—includes screening for GBS at 35 to 37 weeks gestation
  • Taking antibiotics during birth if you have not been tested but are at risk


The American Congress of Obstetricians and Gynecologists
Group B Strep Association


The Society of Obstetricians and Gynaecologists of Canada
Women's Health Matters


Group B strep (GBS). Centers for Disease Control and Prevention website. Available at:
...(Click grey area to select URL)
Updated May 29, 2018. Accessed September 27, 2019.
Group B strep infection: GBS. American Pregnancy Association website. Available at:
...(Click grey area to select URL)
Updated March 2, 2017. Accessed September 27, 2019.
Group B streptococcal infection in infants less than 3 months old. EBSCO DynaMed website. Available at: https://www.dyname... . Updated September 19, 2019. Accessed September 27, 2019.
Last reviewed September 2019 by EBSCO Medical Review Board Kathleen A. Barry, MD
Last Updated: 9/27/2019

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This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

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