Group B Strep in Pregnancy: Risks, Antibiotics, and What to Know Before You Decide
If you’re in your third trimester, chances are your provider has mentioned Group B Strep—or GBS—testing.
And if you’ve already gotten a positive result?
You might be wondering:
What does GBS positive actually mean?
How big is the risk to my baby?
Do I really need antibiotics during labor?
Those are good questions.
Because hearing “You tested positive for bacteria that could affect your baby” can sound scary.
But a positive GBS test doesn’t mean your baby is sick.
And it doesn’t mean something has gone wrong with your pregnancy.
So before fear takes over, let’s slow this down and look at:
what GBS actually is
what the risks are
why antibiotics are recommended
what questions to ask before you make decisions
Because this isn’t about automatically saying yes—or no.
It’s about understanding enough to make an informed decision.
What Is Group B Strep in Pregnancy?
Group B Streptococcus (GBS) is a common type of bacteria that can live in the gastrointestinal and genital tracts.
GBS colonization is common, usually causes no symptoms, and can come and go over time.
Being GBS positive is not a sexually transmitted infection.
And it doesn’t mean you’re dirty, unhealthy, or that you did something wrong.
The reason we care about it during pregnancy is different:
GBS can sometimes pass from mother to baby around the time of birth and cause serious infection in a newborn.
That’s why routine screening is recommended late in pregnancy.
How Big Is the Risk if You’re GBS Positive?
This is where I want to slow things down.
Because risk deserves context.
A positive GBS test does not mean your baby is infected.
And it does not mean your baby will become sick.
GBS colonization is a risk factor for early-onset GBS disease, an infection that can develop during the first days of a baby’s life.
Other factors can also affect your baby’s risk, including:
being born prematurely
how long your water has been broken
signs of infection during labor
whether antibiotics were given during labor
Early-onset GBS disease is uncommon.
But when it happens, it can be serious.
That’s why antibiotics during labor are recommended for many people who test positive.
Here’s the distinction I want you to remember:
Exposure to GBS is not the same thing as developing GBS disease.
And understanding that difference can help you look at your options without immediately jumping to fear.
What Can Happen if a Baby Develops GBS Disease?
Most babies exposed to GBS do not develop invasive disease.
But when early-onset GBS disease occurs, it can cause serious illness, including:
sepsis
pneumonia
meningitis
respiratory problems
Premature babies are particularly vulnerable.
So even though the absolute risk for an individual baby may be relatively low, the potential severity of the infection is why prevention is taken seriously.
Low probability doesn’t mean no risk.
And a serious possibility doesn’t mean panic.
It means we look at the information clearly.
Why Are Antibiotics Recommended for GBS During Labor?
If you test positive for GBS, the standard recommendation is IV antibiotics during labor.
And there’s a reason for that.
The goal isn’t necessarily to eliminate GBS from your body weeks before birth.
It’s to reduce the amount of bacteria around the time your baby is being born and lower the chance of early-onset infection.
Penicillin is typically the preferred antibiotic, with other options available depending on your allergy history and individual circumstances.
And antibiotics during labor have been shown to significantly reduce the risk of early-onset GBS disease.
That’s a meaningful benefit.
One important distinction:
Antibiotics during labor help prevent early-onset GBS disease. They do not prevent late-onset GBS disease, which can occur later in infancy.
GBS Antibiotics During Labor: Benefits and Trade-Offs
This is where informed decision-making matters.
Because the conversation doesn’t need to be:
“Antibiotics are good.”
or
“Antibiotics are bad.”
A better question is:
What benefit are we trying to achieve—and what are the trade-offs?
The Benefit
The biggest benefit is clear:
Antibiotics during labor significantly reduce the risk of early-onset GBS disease.
For many parents, that benefit weighs heavily in their decision.
The Considerations
Antibiotics aren’t completely consequence-free either.
Potential considerations include:
allergic reactions, which are uncommon but possible
changes in maternal and newborn bacterial colonization
temporary changes in baby’s developing gut microbiome
Research has found differences in the infant gut microbiome after antibiotic exposure during labor.
But here’s where nuance matters:
We don’t yet fully understand what those changes mean for long-term health.
So how does one come to a decision?
Look at what we know.
Look at what we don’t know.
Then look at your situation.
Your Individual Risk Matters Too
A positive test isn’t the only piece of information that matters.
Your care team may also consider factors such as:
your gestational age
how long your membranes have been ruptured
signs of infection during labor
your baby’s condition after birth
whether and how long you received appropriate antibiotics
Those factors can change how your baby’s risk is assessed.
And this is exactly why birth decisions don’t always fit neatly into:
“Yes or no?”
Context matters.
Questions to Ask if You’re GBS Positive
If you opt-in for the test and test positive, save these questions for your next appointment:
1. What does being GBS positive mean for my specific pregnancy?
2. Which antibiotic do you recommend—and why?
3. What happens if my labor moves too quickly to receive the planned antibiotics?
4. What are my options if I’m allergic to penicillin?
5. How will my baby be evaluated after birth?
And here’s one of my favorite questions for almost any birth decision:
“What would change your recommendation?”
That question helps you understand what information actually matters.
Because you don’t need to memorize every statistic.
You need to know how to ask good questions.
Your Partner Should Understand This Too
You shouldn’t have to carry all of this information into labor by yourself.
Talk through GBS with your partner before birth.
Make sure they understand:
what your test result means
what you’ve discussed with your provider
what you’ve decided
what questions matter to you
Then, if circumstances change during labor, your partner can help ask:
“What has changed?”
“How does that change the risk?”
“What are our options now?”
Your partner isn’t there to fight your medical team.
They’re there to help you stay informed, supported, and involved—especially when you’re busy doing the work of labor.
This is also why we prepare couples together inside Our BirthRoom Academy.
Birth decisions shouldn’t fall entirely on you—especially while you’re laboring.
When your partner understands the options, knows what questions to ask, and knows how to support you through the decision-making process, you become a team.
That’s the kind of preparation that changes birth.
And it means you don't have to carry the mental load of birth alone.
This Isn’t About Finding the “Perfect” Decision
Birth advocacy doesn’t mean choosing the least medical option every time.
And it doesn’t mean automatically agreeing to every recommendation either.
It means understanding:
What’s the risk?
What’s the benefit?
What are the trade-offs?
What applies to my situation?
Then making an informed decision with your care team.
Sometimes informed decision-making leads you toward less intervention.
Sometimes it leads you toward using an intervention because the benefit makes sense to you.
Both can be informed birth.
Want to Feel More Confident Making Birth Decisions?
GBS is just one decision.
Induction.
Fetal monitoring.
Breaking your water.
Pain medication.
Cesarean birth.
There may be several moments during pregnancy and labor when someone recommends something and you suddenly have to decide:
“Is this right for us?”
And those decisions feel very different when you already have a framework for navigating them.
That’s why I created the Birth Advocate Blueprint™.
Inside, you and your partner will learn how to:
ask the right questions
understand risks, benefits, and alternatives
communicate clearly with your care team
slow down non-emergency decisions
use simple advocacy scripts when you’re unsure what to say
Because you don’t need a medical degree to advocate for yourself.
You need a framework for making informed decisions.
👉Explore the Birth Advocate Blueprint™ here
A positive GBS test isn’t something you need to panic about.
Final Thought
But it is information worth understanding.
Know what the result means.
Understand why antibiotics are recommended.
Ask about the benefits and trade-offs.
And make your decision based on your actual clinical situation—not fear or pressure.
Birth advocacy isn’t about avoiding every intervention.
It’s about knowing why you’re saying yes—or no.
And when you understand your options?
You stop feeling like birth decisions are simply being made for you.
You become part of the conversation.
Continue Preparing for Your Birth
If this helped you feel more informed, here’s where to go next:
• 39 Week Induction: Pros, Cons & What to Know Before You Decide
• Electronic Fetal Monitoring in Labor: Pros and Cons (What the Research Really Says)
• Do Birth Plans Actually Matter? (And What Most People Get Wrong)
