Understanding Group B Strep, Testing and Management Options, and Risks to Your Newborn
- Loree Siermachesky
- Feb 23
- 7 min read
What is Group B Strep?
Group B Streptococcus (GBS) is a bacterium that can exist in the gastrointestinal tract, urinary tract, and reproductive tract in 10 to 30% of healthy people at any given time (ACOG 2021). GBS often does not cause harm in adults. It is not a sexually transmitted disease, and it is not the same bacteria that causes strep throat. GBS can potentially be transmitted from pregnant women to their babies during vaginal birth and can cause sepsis, meningitis, or pneumonia in 1-2% of all full-term newborns (ACOG, 2021). Risks triple in preterm infants (ACOG, 2021).
How is GBS Diagnosed?
Pregnant people are routinely tested for GBS in late pregnancy, usually between 35- and 36 weeks gestation. This test can be self-administered or done by your provider. Group B Strep testing consists of collecting a sample from the vagina and rectum with a large cotton swab. This sample is then cultured in the lab to check for GBS bacteria. The procedure is painless and straightforward. The results are available within 48-72 hours and stand for five weeks (ACOG, 2021). If the test finds GBS, the pregnant person is said to be 'positive', which means that the bacteria is present, not that they will infect the baby at birth. This test identifies 84% of GBS-positive cases, but 16% of birthers at the time of labour become GBS-negative (AOM, 2010).
Group B Strep Infection in Your Newborn
Two kinds of GBS infections can happen in newborn babies. All newborns are observed for infectious symptoms, particularly when the mother was GBS-positive in labour. Babies who show signs of a GBS infection after birth will be treated with antibiotics in the neonatal intensive care unit (NICU) (ACOG, 2021). However, even with NICU, approximately one in 16 infected newborns will die from their GBS infection including about 5% of newborns with early-onset GBS disease and around 8% of infants with a late-onset GBS infection (GBSS, 2025).
The most common type is called early-onset disease. This occurs within the first week of life. Most GBS infections will show signs of a problem within 12 hours of birth (ACOG, 2021). In early-onset infections, babies are almost always exposed during vaginal birth because GBS is in the birth canal. This type of GBS infection makes up half of all cases and is the most serious (ACOG, 2021).
The second type is called late-onset disease. In this case, infants will not show signs of a GBS infection until they are between one week and three months of age (ACOG, 2021). About half of these babies were also infected during their birth (ACOG, 2021). The other half became infected after the birth by being in contact with their GBS-positive mother, or another person who is a carrier of the disease (ACOG, 2021).
Group B Strep Testing and Management Options
Universal Approach
The current "gold standard" of practice is to test all pregnant people and treat everyone who is GBS-positive during labour with prophylactic intravenous penicillin antibiotics every four hours (AOM, 2010). It is 89% effective if given 4 hours before birth but only 47% effective if given less than 2 hours before birth (Fairlie et al., 2013). Mothers can receive intravenous antibiotic treatment in either a hospital or homebirth setting. For patients with penicillin anaphylaxis, clindamycin every four hours is recommended but is only 22% effective if given 4 hours before birth (AOM, 2010; Fairlie et al., 2013). Mothers can receive this intravenous antibiotic treatment in either a hospital or homebirth setting, too. If GBS is resistant to clindamycin, intravenous vancomycin every eight hours is suggested (AOM, 2010). There are no clinical trials for this antibiotic for the prevention of GBS infection to determine its effectiveness and it is a drug of last resort (AOM, 2010). This intravenous antibiotic must be administered in a hospital setting.
Risk-based Approach
A risk-based approach is an alternative therapy that does not universally screen all pregnant people and only necessitates the administration of IV antibiotics if the following risk factors exist:
Labor starts before 37 weeks gestation (AOM, 2010).
GBS bacteria are found in the urine during pregnancy (AOM, 2010).
There is a preterm premature rupture of membranes (PPROM) (AOM, 2010).
A pregnant woman has an 'unknown' GBS status (AOM, 2010).
A full-term neonate is expected but the amniotic membranes have been ruptured for 18 hours or longer before the baby's birth (AOM, 2010).
An unexplained, mild fever (100°F or 38°C) develops in the mother during labour (AOM, 2010).
There are more than 6 vaginal exams performed after membranes have ruptured (AOM, 2010).
There is a history of a previous baby who had a GBS infection (AOM, 2010).
The mother has (or had) a prior infection caused by GBS bacteria during pregnancy (AOM, 2010).
Risks of IV Antibiotics in Labour
GBS IV therapy treatments may cause adverse effects on the parent or the infant during pregnancy, delivery, and breastfeeding. These can include:
Intravenous therapy for GBS during labour is not 100% effective (ACOG, 2021).
An intravenous apparatus can be uncomfortable and cumbersome during labour (AOM, 2010).
Intravenous antibiotics may temporarily impact the infant microbiome at birth (Azad et al., 2015).
Antibiotic exposure may increase the incidence of childhood eczema and asthma (Azad et al., 2015).
Overuse of antibiotics may cause future antibiotic resistance (Fairlie et al., 2013).
Intravenous antibiotics during labour will not prevent all GBS infections in newborns (Fairlie et al., 2013).
Intravenous antibiotics may cause vaginal yeast infection (AOM, 2010).
Intravenous antibiotics may cause yeast-infected diaper rash (Azad et al., 2015).
Intravenous antibiotics may cause diarrhea (ACOG, 2021).
Intravenous antibiotics may cause ductal thrush and decrease milk supply due to nipple pain (Azad et al., 2015).
Intravenous antibiotics may cause neonatal thrush leading to breast rejection due to oral pain (Azad et al., 2015).
Alternative Approaches
Universally test all pregnant women but try alternative suggestions for patients who prefer not to have IV antibiotics in labour. The following therapies are:
Using chlorhexidine gluconate vaginal wash, or Hibiclens, throughout the last weeks of pregnancy and every 4 hours during labour. Inconsistent research shows no statistical difference in preventing GBS infection rates (Ohlsson et al., 2016). However, it may reduce sepsis rates in newborns (Goldenberg et al., 2006).
Raw garlic cloves ingested orally or inserted as a vaginal suppository during pregnancy. Garlic is known for its antibacterial properties, but current evidence lacks the long-term effectiveness of reducing GBS colonization rates (Romm, 2021).
Colloidal silver application during pregnancy. Although known for its antibacterial properties, there are no studies of its safety in pregnancy (Room, 2021).
Ingesting oral probiotics containing L. rhamnosus and L. reuteri throughout pregnancy. According to a small study, probiotics can be 43% effective in reducing GBS colonization, but more research is needed (Ho et al., 2016).
Minimizing vaginal examinations during birth. Digital exams can reintroduce GBS bacteria into the vagina, cervix, and uterus leading to infection (AOM, 2010).
Delaying or avoiding artificial rupturing of the membranes during birth. Limiting the time frame between rupture and birth can significantly reduce colonization of the newborn (ACOG, 2021).
Waterbirth can be an effective tool for reducing GBS transmission rates to the newborn (Cohain, 2010).
Risks of Alternative Therapies
Alternative treatments may cause adverse effects for the parent or the infant during pregnancy, delivery, and breastfeeding. These can include:
Chlorhexidine gluconate douching may alter vaginal flora during pregnancy and delivery and affect the infant microbiome at birth (Goldenberg et al., 2006).
The FDA does not recommend colloidal silver for treating any condition (Romm, 2021).
Homeopathic therapies using douches or suppositories may cause an increase in vaginal infections (Romm, 2021).
Homeopathic therapies may provide a false sense of security with short-term benefits (Romm, 2021).
Probiotic therapies may cause gastrointestinal upset (Ho et al., 2016).
Quality evidence-based research is absent in supporting or rejecting alternative therapies to prevent GBS transmission to the neonate at birth (Romm, 2021).
Do Nothing Approach
Do not test, diagnose, or treat after an informed discussion with your healthcare provider about the pros and cons of declining any or all options.
Risk of Doing Nothing
Up to 50% of newborns will be colonized with GBS from GBS-positive mothers. About 1 to 2% will become severely ill with sepsis, pneumonia, or meningitis. The mortality rate ranges from 2% to 3% in these neonates (ACOG, 2021).
There may be an increased risk of severe long-term health issues, such as developmental problems, cerebral palsy, paralysis, seizure disorders, or hearing and vision loss (ACOG, 2021).
Parent Resources:
References:
American College of Obstetricians and Gynecologists (ACOG). (2021). Group B strep and pregnancy. Retrieved from https://www.acog.org/womens-health/faqs/group-b-strep-and-pregnancy
Azad, M., Konya, T., Persaud, R., Guttman, D., Chari, R., Field, C., Sears, M., Mandhane, P., Turvey, S., Subbarao, P., Becker, A., Scott, J., & Kozyrskyj, A. (2015). Impact of maternal intrapartum antibiotics, method of birth and breastfeeding on gut microbiota during the first year of life: a prospective cohort study. BJOG: An International Journal of Obstetrics & Gynaecology, 123(6), 983–993. https://doi.org/10.1111/1471-0528.13601
Association of Ontario Midwives (AOM). (2010, January 20). Group B streptococcus: Prevention and management in labour. Retrieved from https://www.ontariomidwives.ca/sites/default/files/CPG-GBS-Prevention-and-management-in-labour-PUB.pdf
Cohain, J. S. (2010, December). Waterbirth and GBS. PubMed. Retrieved from https://pubmed.ncbi.nlm.nih.gov/21322437/
Fairlie, T., Zell, E. R., & Schrag, S. (2013). Effectiveness of intrapartum antibiotic prophylaxis for prevention of early-onset group B streptococcal disease. Obstetrics & Gynecology, 121(3), 570–577. https://doi.org/10.1097/aog.0b013e318280d4f6
Goldenberg, R. L., McClure, E. M., Saleem, S., Rouse, D., & Vermund, S. (2006). Use of vaginally administered chlorhexidine during labor to improve pregnancy outcomes. Obstetrics & Gynecology, 107(5), 1139–1146.
Group B Strep Support (GBSS). (2025). Group B strep support: Treating GBS in babies. Retrieved from https://gbss.org.uk/info-support/group-b-strep-infection/treatment/
Ho, M., Chang, Y. Y., Chang, W. C., Lin, H. C., Wang, M. H., Lin, W. C., & Chiu, T. H. (2016). Oral lactobacillus rhamnosus GR-1 and lactobacillus reuteri RC-14 to reduce group B streptococcus colonization in pregnant women: A randomized controlled trial. Taiwanese Journal of Obstetrics and Gynecology, 55(4), 515–518. https://doi.org/10.1016/j.tjog.2016.06.003
Ohlsson, A., Shah, V. S., & Stade, B. C. (2014). Vaginal chlorhexidine during labour to prevent early-onset neonatal group B streptococcal infection. The Cochrane database of systematic reviews, (12). https://doi.org/10.1002/14651858.CD003520.pub3
Romm, A. (2021, March 5). Group B strep (GBS) in pregnancy and birth: What’s a mom to do? Aviva Romm MD. Retrieved from https://avivaromm.com/group-b-strep-gbs-in-pregnancy-whats-a-mom-to-do/
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