If your provider has mentioned group B strep during your pregnancy, or your newborn is being watched for it after delivery, it’s normal to feel a little uneasy. The good news is that this is one of the most closely monitored issues in newborn care, and screening and treatment have made serious infection far less common than it used to be.
Here’s what group B strep is, how it’s screened for and treated, and what to watch for once you’re home.
What is Group B Strep?
Group B streptococcus, or GBS, is an ordinary strep B bacterium that lives in the gastrointestinal and genital tracts of most people, including a large share of healthy adults. Most of the time, it lives in balance with the rest of the body’s microbiome and causes no problems at all. Occasionally, though, GBS ends up somewhere it doesn’t belong, and that’s when it can cause an infection.
How common is GBS in newborns?
Newborns, especially those born before 37 weeks, are among the people most susceptible to GBS infection, along with older adults, pregnant people, and those with weakened immune systems.
This is a great example of medicine getting safer over time. In 1993, the risk of newborn GBS infection was about 0.17 percent, or roughly 1 in every 590 live births. By 2023, that number had dropped to about 0.02 percent, or 1 in 500. That’s nearly a tenfold improvement in three decades, largely thanks to routine screening and preventive antibiotics.
How GBS Passes From Parent to Baby
Pregnant parents pass on a lot to their babies: half of their genetic code, nutrients, a preliminary immune system, and yes, some bacteria too. Most of that bacteria is helpful and shapes your baby’s own microbiome, but GBS is one of the exceptions that can cause problems if it reaches the wrong place.
Newborns who develop GBS in the first week of life are almost always exposed during birth, since the bacteria live in the vagina and rectum and can transfer as your baby moves through the birth canal. Less often, it can pass to the baby during pregnancy itself, which is more likely if your water breaks more than 18 hours before delivery.
GBS Screening During Pregnancy: What the Test Involves
Every pregnant person is recommended to be screened for GBS in late pregnancy, usually around week 36 or 37. Because bacteria levels naturally shift over time, testing close to your due date gives the most accurate picture. A negative result earlier in pregnancy doesn’t guarantee you’ll still be negative at delivery, which is why the timing matters.
Screening is simple and painless. Your provider will use a sterile swab on the vagina and rectum and send the sample to a lab, and you’ll likely be screened even if you’re planning a Cesarean delivery. Your provider may also test your urine.
GBS is common. Roughly 1 in 4 pregnant people test positive during routine screening, and most don’t have any symptoms or feel sick at all. If you test positive, you’ll receive IV antibiotics during labor, which is far more effective at protecting your baby than taking antibiotics in advance. Without treatment, a newborn’s risk of developing GBS disease is about 1 in 200. With antibiotics during delivery, that risk drops to about 1 in 4,000. Be sure to let your provider know if you have a penicillin allergy so they can plan accordingly.
Early-Onset vs. Late-Onset Group B Strep Disease
GBS disease shows up in two general timeframes, and each looks a little different.
- Early-onset GBS develops during the first week of life, most often within the first 24 hours. It most commonly causes sepsis (the body’s extreme response to infection) and pneumonia, and less often meningitis.
- Late-onset GBS develops between 7 and 89 days of age. It most often shows up as bacteremia (bacteria in the bloodstream) or meningitis, and can also cause sepsis or pneumonia.
Signs of Group B Strep in Infants
Symptoms depend on where the infection is in the body. Keep an eye out for:
- Fever
- Difficulty breathing or unusually rapid breathing
- Lethargy or unusual irritability
- Difficulty feeding
- Bluish-colored skin
- Chills or a cough
- Skin that’s red, swollen, or warm to the touch, with pus or drainage
- Stiffness or swelling in the limbs or joints
How GBS is Treated
Because GBS disease can show up in different ways, treatment starts with confirming what’s going on. Your baby’s provider may order blood tests, spinal fluid tests, urine tests, or a chest X-ray to check for pneumonia.
GBS disease is treated with antibiotics, and rapid treatment matters because it can help prevent longer-term complications like hearing loss or developmental delays, particularly when meningitis is involved. In rare cases where GBS causes a soft tissue or bone infection, surgery may be needed alongside antibiotics.
Is there a Group B Strep vaccine?
Not yet, but researchers are working on one. A maternal GBS vaccine would let a birthing parent’s immune system pass antibodies to the baby during pregnancy, offering protection before birth even happens. The World Health Organization expects a vaccine could be available by around 2030.
When to Call Your Provider
Most babies with GBS show symptoms within the first day of life and are treated before they ever go home, which is one of the reasons hospital monitoring matters so much in those first hours. Once you’re home, it’s still worth knowing the signs of late-onset GBS disease, which can include:
- Decreased movement of an arm or leg
- Pain when moving a limb
- Difficulty breathing
- Fever
- Unusual redness on the face or body
If your baby shows any of these signs after you’ve gone home, contact your care team right away. GBS disease is treatable and catching it early makes a real difference.
You don’t have to navigate any of this alone. If you have questions about your GBS screening results, your delivery plan, or symptoms you’re noticing in your newborn, reach out to your care team at Families First Pediatrics. We’re here to help, day or night.
Sources:
Mayo Clinic, Group B strep disease
CDC, About Group B Strep Disease
World Health Organization, Group B Streptococcus (GBS
Department of Health & Human Services, Streptococcal infections (Group B)
CDC, Preventing Group B Strep Disease in Newborns
CDC, Screening for Group B Strep Bacteria
UCLA Health, Group B Strep Screening
