Group B Strep (GBS) in Pregnancy: What Chicago Parents Need to Know
You may have heard your provider mention Group B Streptococcus (GBS) screening around the end of pregnancy. It’s a routine part of prenatal care, but many families aren’t exactly sure what it means or why it matters.
Let’s walk through it together.
What Is Group B Strep?
Group B Streptococcus is a type of bacteria that normally lives in the body, most often in the lower intestinal tract and the vaginal or rectovaginal area. In fact, about 10–30% of pregnant people have GBS colonization at any given time.
Being “colonized” simply means the bacteria are present. It does not mean you’re sick. It does not mean you have done something wrong.
Most people with GBS have:
No symptoms
No signs of infection
No health problems from it
For healthy adults, it’s usually harmless. We talk about it during pregnancy because of vertical transmission, meaning the bacteria can pass from parent to baby during birth.
Why Does GBS Matter for Babies?
While GBS is typically mild for adults, it can cause serious infection in newborns if transmitted during labor. Routine care after birth helps monitor your baby’s transition in the first days. Nurses and pediatricians are looking for early symptoms like:
Severe or unusual crying
Poor feeding
Low blood sugar
Low blood pressure
Fever or temperature instability
Breathing difficulty
Early-onset GBS Disease occurs within the first 12–48 hours after birth, and up to the first week of life.
It can cause:
Early-onset neonatal sepsis
Pneumonia
GBS meningitis
Blood infection (septicemia)
The good news? Since universal screening and intrapartum antibiotic prophylaxis (IAP) became standard practice, the incidence of early-onset GBS has dropped dramatically.
How Is GBS Testing Done?
Around 36–37 weeks of pregnancy, you’ll be offered a rectovaginal swab. (Yes, both areas. This improves accuracy.)
The swab is:
Quick
Painless
Usually self-collected
The sample is sent for culture testing, which is considered the gold standard. Some hospitals are also studying rapid PCR testing for use during labor.
Testing at this specific timing matters. Earlier testing can lead to false negatives because colonization can change.
What Happens If You Test Positive?
If your culture shows GBS colonization, it won’t be treated during pregnancy. Treating it early doesn’t reduce the risk to newborns because the bacteria often return.
Instead, it is recommended to use intrapartum antibiotic prophylaxis (IAP), meaning antibiotics given during labor.
The standard treatment is:
Penicillin G (first-line)
Ampicillin (alternative)
Cefazolin for certain penicillin allergies
Clindamycin only if the strain is confirmed sensitive (due to resistance concerns)
To be most effective, antibiotics are ideally started at least 4 hours before birth.
The goal isn’t to eliminate GBS completely; it’s to lower the bacterial load enough to reduce transmission risk.
What If I’m Planning a Cesarean?
If you’re having a planned cesarean birth before labor begins and before your water breaks, antibiotics specifically for GBS are generally not needed, even if you tested positive.
However, if labor starts or membranes rupture before surgery, antibiotics are recommended. There are alternatives to antibiotics, but at this time, research and evidence-based reviews show there is insufficient evidence that these methods prevent newborn GBS disease as effectively as antibiotics during labor.
If you are curious about your options, make a plan to discuss this with your provider, along with the results of your GBS test.
How Common Is Serious GBS Disease?
Thanks to screening and antibiotics, early-onset GBS now affects roughly 0.2–0.3 per 1,000 live births in many high-income countries, thanks to universal screening protocols.
While severe outcomes are rare, early treatment in newborns (sometimes requiring NICU care) has dramatically improved survival rates.
In Short…
GBS is common and usually harmless for adults.
It can be serious for newborns.
A simple rectovaginal swab at 36–37 weeks helps guide care.
Antibiotics during labor significantly reduce the risk of early-onset infection.
If you test positive, it’s not a reflection of hygiene, lifestyle, or anything you did wrong. It’s simply part of your body’s natural flora.
And if GBS does come up in your pregnancy, know that your care team is prepared and experienced in managing it safely.
GBS and Your Doula
It can be helpful for your doula to know your GBS status because it allows us to better prepare and support you both emotionally and practically during labor. If you test positive for Group B Streptococcus, you may have questions or worries about what that means for your baby. You don’t have to navigate the what-ifs alone.
When your doula is aware ahead of time, we can help you process anxiety, normalize how common GBS colonization is, and support you in having informed conversations with your provider. We can also help you think through logistics, such as timing your arrival to the hospital if antibiotics are recommended, preparing to move and labor comfortably with an IV, and understanding what newborn monitoring may look like after birth.
If labor progresses quickly and you do not receive the full recommended course of antibiotics, your doula can provide reassurance and help you stay grounded during any additional observation of your baby. Ultimately, knowing your GBS status allows your doula to anticipate potential scenarios, reduce surprises, and focus on keeping you calm, confident, and supported throughout your birth experience.
Doulas can help navigate the emotional landscape more effectively if you keep us up to date as you move through your pregnancy.
Follow link if you would like to listen to the Evidence Based Birth Podcast episode on GBS.
Feminist Midwife has a wonderful post on self swabs for GBS, if you are interested in further reading.