GBS: Group B Streptococcus in Pregnancy

GBS: Group B Streptococcus in Pregnancy

At your last prenatal visit, your doctor or midwife informed you that they’d test for GBS on your upcoming visit. Now you’re wondering what in the world GBS is, what the test is like, and if you should worry about it. Today we’re going to learn all about Group B Streptococcus in pregnancy.

Estimated reading time: 4 minutes

What is GBS?

GBS, or Group B Streptococcus, is a bacteria.  It is not the same bacteria that causes strep throat.  It’s commonly found in the digestive and reproductive tracts of healthy men, women, and children and is typically nothing to worry about.  In fact, about 25% of pregnant women carry it in their rectum or vagina (1).

Is GBS dangerous?

Group B Streptococcus is not usually harmful to someone who’s colonized with it.  They likely won’t feel sick or have any symptoms.  However, the bacteria can be very harmful to a newborn.  In fact, it’s one of the major causes of meningitis and sepsis – a blood infection – in a newborn’s first week of life (1).

Most babies who are colonized with GBS will remain healthy (2).  However, if left untreated, 1:200 babies born to a GBS positive mom will develop Group B Streptococcus infection, which can be life threatening (1).

How does a baby contract GBS?

As baby passes through the birth canal, his skin comes in contact with mom’s vaginal flora.  This introduces the risk that he can become colonized with Group B Streptococcus.  The bacteria can also travel up the vagina and into the amniotic fluid after the water breaks, exposure to GBS can even happen during labor (2).

Who is tested for GBS during pregnancy?

Every pregnant woman should be tested for Group B Streptococcus when she’s between 35-37 weeks pregnant.  Your doctor will use a sterile q-tip to swab the rectum and vagina, and send it off for testing.

What treatment can I expect if I am GBS positive?

If you test positive for Group B Streptococcus during pregnancy, your doctor will likely encourage you to receive IV antibiotics during labor.  Typically, IV penicillin is given every 4 hours with the goal of starting it more than 4 hours before baby is born.  It takes about 15 to 30 minutes for the antibiotic to run in through the IV, so you will be temporarily hooked up to the IV tubing during this time.

How important is it that I take the antibiotics for GBS?

A woman receives penicillin treatment decreases the risk of her baby developing a Group B Streptococcus infection from a 1:200 chance all the way down to a 1:4,000 chance.

With that said, some women have concerns about the use of antibiotics during labor.  While the CDC strongly recommends the use of IV penicillin, it is true that most babies colonized with GBS will remain healthy.  If this is a concern for you, discuss the pros and cons of antibiotics with your doctor or midwife.

Group B Streptococcus is a common, yet potentially harmful bacteria to your baby.  Learn more about Group B Strep treatment and other common interventions offered during labor by participating in a high-quality natural childbirth class.  As you prepare yourself with evidence-based knowledge, you’ll be ready to make the best decisions for you and your baby.

Kopa Birth’s online birthing classes allow you to prepare for natural childbirth in the comfort of your own home, 24/7. Enroll today in our free online childbirth class to learn more about preparing for natural childbirth. 


  1. Centers for Disease Control and Prevention.  (2014).  Group B Strep:  Fast acts.  Retrieved from
  2. Centers for Disease Control and Prevention.  (2010).  Prevention of Perinatal Group B Streptococcal Disease:  Revised Guidelines from CDC, 2010.  Retrieved from
  3. Gardner, S.E., Yow, M.D., Leeds, L.J., Thompson, P.K., Mason, E.O. Jr., Clark, D.J.   (1979).  Failure of penicillin to eradicate group B streptococcal colonization in the pregnant woman. A couple study.  Am J Obstet Gynecol 135(8): 1062-1065.

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Meet Katie Griffin

I’m a registered nurse, Lamaze certified childbirth educator, and the mother of 7. I help women realize their dream of a natural, intimate, and empowering hospital birth.

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At your last prenatal visit, your doctor or midwife informed you that they’d test for GBS on your upcoming visit. Now you’re wondering what in the world GBS is, what