January 3, 2022

What To Know About Vaginal Strep If You’re Pregnant

Adults are often asymptomatic, but this bacteria can seriously harm newborns

Pregnant woman lying on couch

When you hear “strep,” you probably think of strep throat, that painful throat and tonsil infection that nearly every child and many unlucky adults have suffered through at some point or another. Strep throat is the most common of a number of Group A streptococcal (GAS) infections.


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But there’s another type of strep, too — Group B Streptococcus (GBS), sometimes called vaginal strep, which can be deadly to newborn babies.

Ob/Gyn Edward Chien, MD, MBA, explains what people who are pregnant and hopeful future parents should know about Group B strep, including how it’s detected and treated.

What is Group B strep?

Group B strep is a germ that lives in an estimated 10% to 30% of people who are pregnant — though that in itself is not too alarming. “As humans, we have all sorts of bacteria living inside us,” Dr. Chien explains. “About a third of women are colonized with group B strep. It commonly lives in the colon and can then colonize the vagina.”

Group B strep is usually pretty unproblematic in healthy adults — but if it’s passed to your newborn baby during vaginal birth, it can cause them very serious health problems, including:

“Babies’ immune systems haven’t been exposed to lots of bacteria, so their bodies aren’t as good at fighting it off or living with it,” Dr. Chien explains. “If a baby passes through the birth canal, where Group B strep is present, that baby may be susceptible to infection.”


He continues, “Most full-term babies have a strong enough immune system to fight it off or prevent it from causing a problem, but a small percentage won’t have a strong enough immune system. In that case, it can become severe in a very short period of time.”

What are symptoms of Group B strep?

In healthy adults, Group B strep is a bit of a lurker — that is to say, it doesn’t often cause symptoms or complications in people who have it. If you have GBS but don’t exhibit any symptoms, you’re called a carrier.

“Typically, people just live with it, and it doesn’t cause a problem,” Dr. Chien says.

Group B strep symptoms in babies

Most babies who have GBS will start showing signs of it within 24 hours after birth, before they’ve even left the hospital. Those signs include:

  • Breathing problems.
  • Difficulty feeding.
  • Fever.
  • Irritability and/or jitteriness.
  • Jaundice.
  • Low body temperature.
  • Rash.
  • Seizures.
  • Sluggishness.

Babies who test positive for Group B strep may need to be treated in the newborn intensive care unit (NICU), where they’ll receive antibiotics. “If your newborn starts to experience any of these symptoms after you’ve left the hospital, call your pediatrician right away,” Dr. Chien advises.


Can you get rid of Group B Strep?

Good news: Your pregnancy care team will screen you for Group B strep near the end of your pregnancy — around 36 to 37 weeks. If you test positive, you’ll be given IV antibiotics (typically penicillin, unless you’re allergic) when you go into labor. This quickly reduces the amount of transmissible GBS in your body to the point that you’re unlikely to pass it on to your newborn.

“Group B strep is an organism that’s very sensitive to penicillin, so when we give penicillin to a pregnant patient, it reduces the bacteria within one to two hours,” Dr. Chien says. “That way, even if a baby passes through the birth canal, it’s not likely to get sick.”

If you go into labor before you’ve been tested for group B strep, doctors will typically give you penicillin if you are still preterm regardless, just to be on the safe side. “Premature babies are more susceptible to Group B strep, so unless they recently tested negative for it, patients who go into early labor are automatically treated for it when they come in.”

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