group b strep gbs

G is for Group B Strep

Group B Streptococcus (GBS) is a bacteria that is indigenous to the gastrointestinal tract and vagina; it can normally be found in ~25% of healthy adult women. A positive culture (done via vaginal and rectal swabbing) indicates colonization, whereas the presence of Group B Strep in your urine are indicative of an infection. Testing for GBS between weeks 35 and 37 of pregnancy has become a standard part of prenatal care in this country as testing within five weeks of delivery appears to be the best predictor of GBS status at birth.

What is Group B Strep?

Group B Strep is not a sexually transmitted disease and it is not the same as the bacteria that causes strep throat (that is Group A Strep). It is part of the normal gut flora of roughly 1/4 of women. GBS is usually harmless in adults and the majority of those who are colonized by it are asymptomatic. However, GBS can cause serious complications in newborns.

Why is Group B Strep a concern during my pregnancy and for my baby?

If a woman is colonized with Group B Strep, there is a chance she can pass on the bacteria to her baby if the baby is delivered vaginally or via C section after the rupturing of membranes. A baby is at a higher risk of developing a GBS infection if the mother is colonized with the bacteria and:

  • her membranes rupture or she goes into labor before 37 weeks
  • her membranes have been ruptured for >18 hours before delivery
  • she develops a fever >100.4°F during labor
  • she had a urinary tract infection (UTI) caused by GBS during her pregnancy
  • she had previously birthed a baby who developed a GBS infection
  • she has an infection of the placental tissues or amniotic fluid (chorioamnionitis)

If you have tested positive for Group B Strep colonization and are not at high risk (none of the previously listed factors), your chances of delivering a baby with a GBS infection are 1 in 200. This drops to 1 in 4,000 if you receive antibiotic treatment during labor.

Preventing Transmission

Because Group B Strep naturally inhabits the gastrointestinal (GI) tracts of colonized individuals, oral antibiotics given prior to delivery will not prevent the transmission of GBS from mother to baby; the bacteria can come back. For this reason it is important to test for GBS colonization towards the end of each of your pregnancies, as your status from an earlier swab may have changed.

IV antibiotics given every four hours during labor can best prevent the likelihood of GBS transmission. Penicillin is the most commonly administered antibiotic for GBS and appropriate substitutes are available in the case of allergy.

In the event of a C section, antibiotics may not be required by your provider if: labor has not yet started and your water has not broken. You will, however, still be given antibiotics to prevent an infection from the C section incision if that is your provider’s standard practice. If labor has begun or your water has broken and you will be delivering by C section your provider may still advise you to receive antibiotics for the GBS.

Positive GBS status and treatment during labor do not effect the amount of time that you or your baby must stay in the hospital before going home, but an infection will.

What are the risks of GBS infection to my baby?

Nobody likes to see someone they love sick. If your baby contracts a Group B Strep infection it can lead to: sepsis (a blood infection), pneumonia, meningitis, breathing problems, heart rate and blood pressure instability, and GI and kidney problems. These infections can be early onset (symptoms appear within 24-48 hours of delivery) or late onset (with symptoms appearing >6 days after delivery).

With early onset GBS the symptoms usually appear within 12 hours of birth with the majority of infections detected within the first hour, strongly suggesting that the infection began before delivery. How can this happen? When your water breaks the bacteria can travel up the vagina into the uterus. If the baby swallows some of this contaminated fluid, an infection can ensue. Early onset GBS infections have a death rate of 2-3% for full-term babies (the rate is much higher for babies born before 33 weeks gestation). Though the mortality rate is low, early onset GBS infections usually lead to expensive stays in the NICU. A 2012 study suggests that up to 44% of infants who survive a GBS infection have long-term health problems, including but not limited to: developmental delays, paralysis, seizure disorder, and hearing and vision loss.

Late onset infections can occur due to vaginal delivery in a mother who has GBS and has not been treated or through contact with someone colonized by GBS.

If you are GBS+ and have your placenta encapsulated, request that your placenta is steamed before dehydration (this is standard procedure for all of our encapsulation clients) and make sure to wash your hands after handling your capsules to further minimize the risk of transmission to your baby or others with whom you come in contact.



The information contained in this blog is not intended to be used as medical advice and should not serve as a substitute for consultation with a physician. As with any and all medical concerns, we strongly suggest you speak with your OB/GYN or midwife to determine the best course for you and your baby.

Leave a Reply

Your email address will not be published. Required fields are marked *