Group B Streptococcal (GBS) Infection in Pregnancy

If you are pregnant or have been pregnant you may have already heard of the term ‘GBS’. This bacteria, formally called Group B Streptococcus, is a common inhabitant of the genitourinary tract. Meaning, it can be found anywhere from the gastrointestinal tract to the urinary tract to the vagina. It is the culprit behind up to 5% of all UTIs (urinary tract infections) in pregnancy. It can also cause infections during labor (chorioamnionitis), after birth (endometritis) and wound infections after cesarean births. In most adults, GBS is harmless but in pregnancy it can cause serious harm to the mother and baby if left untreated. 

Before we all throw up our hands in despair, there is good news. In the United States, we test for GBS during pregnancy so we can appropriately treat those soon to be moms who require antibiotics. Prior to this universal screening, GBS was linked to an increased risk of chorioamnionitis and also still birth in the 3rd trimester.  

A UTI caused by GBS can cause very mild symptoms. For those women who do have symptoms they may include: pain or bleeding with urination and frequent need for urination. If left untreated, these UTIs can also cause kidney infections that may require hospitalization and prolonged use of antibiotics for the duration of the pregnancy.  

During the first few visits for a new pregnancy, your obstetrician/health care provider will usually test your urine to determine if you have GBS in your urine.  If you do have GBS in your urine, you may or may not be treated with antibiotics. If the amount of bacteria is low you may not require antibiotics while pregnant. In either scenario, whether you are treated with antibiotics in pregnancy or not, you will be given antibiotics while in labor. The reason to treat GBS in labor is to prevent an infection from impacting the baby. 

If your urine does not show signs of GBS, then you will be screened for GBS closer to 35-37 weeks of pregnancy. This is performed by your health care provider during a routine visit. A soft swab is used to collect a specimen near the vagina and anus. If this swab is positive for GBS then you will require antibiotics in labor. You will not need to be treated prior to labor unless you show signs/symptoms of an infection.  

When a mom with evidence of GBS in her urine or in a GBS swab arrives for labor, she will usually be given penicillin through her IV. If there is an allergy to penicillin, then alternate antiboitics are used.  

In labor, an infection of the amniotic fluid, placenta or membranes (‘bag of water’) can be diagnosed when there are signs and symptoms such as fever, uterine tenderness or a fast heart beat (tachycardia) for mom or baby. Whether you are a carrier of GBS or not, you will require antibiotics for an infection diagnosed during labor (chorioamnionitis).  

Some women develop signs and symptoms of infection after delivery (endometritis). GBS is responsible for 2-14% of these infections. This type of infection is also treated with antibiotics and can require hospitalization.  

So, given all the risks associated with GBS infection why wouldn’t we treat GBS the moment it is diagnosed in pregnancy? Research suggests that even if GBS is treated the moment it is diagnosed it does not treat and remove all GBS from the body.  At the time of delivery GBS may still be present and mom and baby will still be at risk of infection.  

Make sure you are aware of your GBS status near delivery and ask your provider if this information is routinely shared with the labor and delivery staff. You can also request a copy of your GBS results to carry with you.

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