What You Need to Know about Group B Strep (GBS) in Pregnancy

Strep GBS Pregnancy

Group B streptococcus, also known as group B strep or GBS, is a type of bacteria that can naturally live on your body and in your reproductive, urinary, and digestive systems. It is different from group A strep, the bacteria that causes strep throat, and like most bacteria that live in your body, it typically does not cause any trouble for adults. [1] But GBS can be passed to newborns during delivery, so what follows is an overview of what you need to know about GBS testing, treatment, and symptoms to watch for in your baby.

What happens during a GBS test?

Sometime between weeks 35 and 37 of pregnancy, your care provider will most likely run a test to see if you have GBS. During the simple test, your provider (or you, if they tell you how to do so) will use a long, sterile Q-tip to gently swab your vagina and your rectum. [2] Then, a lab analyzes the collected sample for the presence of GBS bacteria, and you will find out within a week if you are GBS positive or negative. If you’re negative, then you probably don’t need to think about GBS for the rest of your pregnancy.

What if I’m GBS positive?

If your results come back GBS positive, which just means that the bacteria is living on your body—not that you are sick, your care provider will let you know and also talk to you about what it means. To help prevent your baby from becoming colonized during his or her birth, your provider will recommend that you receive antibiotics—most commonly penicillin or ampicillin—intravenously during your labor. Antibiotics work best when you receive them at least four hours before baby is born, so keep that in mind when you go into labor and remind the hospital or birth center staff. Another thing to keep in mind is that GBS can rarely present problems for you after birth—such as uterine infection, abdominal pain, and increased heart rate. [3]

If you are GBS positive, you have about a one to two percent chance of passing the bacteria to your baby, but there are other things that can increase this chance:

If you experience any of these things, you don’t need to be alarmed, but you will want to make sure you receive your antibiotics, and you might want to keep a close eye on baby for the signs discussed in the next section. If you receive your antibiotics at least four hours before baby is born, it is unlikely that baby will develop an infection.

Dealing with GBS Infection in Newborns

Call your pediatrician immediately and let them know you were GBS positive during pregnancy, if you notice that your baby has symptoms such as:

  • trouble breathing (this blog post gives great guidelines for checking on baby’s breathing),
  • difficulty feeding,
  • fever,
  • lethargy (is extremely difficult to wake),
  • irritability, or
  • blueish skin color.

A baby who develops these signs within the first week after birth could have early-onset GBS infection. If baby develops any of these symptoms from age one week to three months, they could have late-onset GBS infection. [2]

If your doctor determines that baby has a GBS infection, they will give baby intravenous antibiotics and other supportive care as needed. It is important to have baby treated as soon as possible to prevent possible complications of GBS infections, which can include pneumonia, an infection of the lungs, an infection of the blood called sepsis, and meningitis, where the fluid around baby’s brain and spine becomes infected. [3]

While all of this information may feel overwhelming, it is important to remember that, even if you are GBS positive, it is very rare for your baby to become infected, especially if you receive antibiotics during labor. And you might also be glad to know that, if you want to, it is still safe to breastfeed your baby, even if you tested positive for GBS during pregnancy. [4]


  1. American College of Obstetricians and Gynecologists, Group B Strep and Pregnancy
  2. Centers for Disease Control, Group B Strep in Newborns
  3. March of Dimes, Group B Strep Infection
Abby Olena
Dr. Abby Olena has a PhD in Biological Sciences from Vanderbilt University. She lives with her husband and daughter in North Carolina, where she writes about science and parenting, produces a conversational podcast, and teaches prenatal yoga.

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