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 already mentioned Group B Strep (GBS) testing.
And for many parents, this is where things start to feel… unclear.
You might be wondering:
• What is GBS—and how common is it?
• What are the actual risks for my baby?
• Do I really need antibiotics during labor?
If that’s you—
You’re not alone.
Because this is one of those decisions where you’re often told what to do…
But not always given the full picture.
So instead of rushing through it—
Let’s slow it down and look at what actually matters.
What Is Group B Strep?
Group B strep is a naturally occurring bacteria.
It lives in the intestines, rectum, and sometimes the vagina.
About 1 in 4 pregnant women (25%) carry it at any given time.
Most people never know they have it—
Because outside of pregnancy, it usually doesn’t cause problems.
During birth, however, GBS can sometimes be passed to the baby.
What Are the Risks for Newborns?
This is where clarity really matters.
Let’s walk through it step by step:
• About 25% of pregnant women carry GBS
• If positive, about 50% of babies will also carry the bacteria
But here’s the part that often gets lost:
Only 1–2 out of 100 of those babies develop a serious infection without antibiotics
So when you zoom out:
About 1 in 200–400 babies born to GBS-positive mothers develop infection without antibiotics
Across all births:
That’s about 1–2 cases per 1,000 babies
Why This Feels Like a Hard Decision
Because you’re weighing:
a low probability
against a potentially serious outcome
And no one really teaches you how to think through that.
So instead, it can feel like:
pressure
urgency
“just do this”
When what you actually need is clarity.
What Happens With Antibiotics in Labor?
If you receive IV antibiotics during labor:
The risk drops to about 1 in 5,000 babies
That’s a meaningful reduction.
And for many parents, that alone helps them feel confident in their decision.
What Can Happen if a Baby Develops GBS Disease?
Most babies who develop GBS infection recover fully.
But in rare cases, it can lead to:
• sepsis (blood infection)
• pneumonia
• meningitis
Mortality rates are low today:
around 2% for full-term babies
higher for preterm infants
Antibiotics in Labor: Benefits and Trade-Offs
If you test positive, antibiotics are the standard recommendation.
And like any intervention—
there are benefits and considerations.
Benefits
• Significantly lowers risk of newborn infection
Considerations
• Alters mom and baby’s microbiome
• May increase risk of yeast imbalance
• Rare (but possible) allergic reactions
This Isn’t About “Right” or “Wrong”
This is where we shift the conversation.
Because the question isn’t:
“What should I do?”
It’s:
“What matters most to me in this situation?”
A Simple Way to Think About It
You’re weighing:
With antibiotics: ~1 in 5,000 risk
Without antibiotics: ~1 in 200–400 risk
Neither option is zero risk.
But one may feel more aligned with your values, your comfort level, and your approach to birth.
The Part Most Parents Aren’t Given
Information is one thing.
But confidence?
comes from knowing how to think through decisions like this and how to talk about them with your provider.
Because in the moment, it’s easy to feel:
unsure
rushed
like you should just say yes
Want to Feel This Clear About All Your Birth Decisions?
Group B strep is just one example.
There will be other moments in pregnancy and labor where decisions come up.
And the goal isn’t to memorize everything—
it’s to feel prepared when it matters.
Free Class: 10 Steps to a Calm and Confident Birth—Together
Inside, you’ll learn:
✨ A clear framework for birth preparation
✨ How to navigate common interventions (like this one)
✨ How to stay calm when labor gets intense
✨ How your partner can support you in real time
So instead of feeling pressured—
you feel confident.
Group B strep isn’t just a test result.
It’s a decision point.
And when you understand:
the numbers
the risks
the trade-offs
Something shifts.
You stop feeling like decisions are being made for you—
and start making them with intention.
Continue Preparing for Your Birth
If this helped you feel more informed, here’s where to go next:
• Thinking about induction? Read this first
• Electronic Fetal Monitoring in Labor: What the Research Really Says
• Do Birth Plans Actually Matter? (And What Most People Get Wrong)
• How to Work With Contractions (Instead of Fighting Them)
