The GBS Test

As of today, I’m officially on maternity leave!  In California, you can start it at 36 weeks, but I decided to work into my 36th week.  I’m glad to be done now, especially because for the last few days, I’ve been waking up at 5 am for no good reason.  Maybe I’m mildly uncomfortable, but there doesn’t seem to be a reason like needing to pee that wakes me up.  I just find myself more awake with a very active mind.  Not so great going into a full workday without a good night’s rest, but I guess I’ll be dealing with that when I head back to work postpartum.  I’m hoping for at least a couple of weeks of some chill time to relax and take care of things before Little Willie arrives.  As my husband puts it, it’s the last vacation…of my life.

Last week, I had my GBS test done.  GBS, or group B streptococcus, is a bacteria that commonly colonizes our bodies.  According to my go-to resource UpToDate, 15-40% of pregnant women are colonized with GBS.  In my experience, I wouldn’t say 40% of my patients test positive, but since we test everyone, I see it frequently.  We perform GBS screening for all pregnant patients at 35-37 weeks’ gestation with a swab of the vagina and rectum.  Anyone who screens positive automatically gets penicillin (or another antibiotic if allergic) in their IV when they are in active labor or break their water.  This is done to help prevent GBS infection in the babies, and is done routinely nationwide, per CDC recommendations.

Some women are found to have the GBS bacteria in their urine on a routine urine exam with their initial prenatal labs.  They are considered to be colonized, so they will automatically be treated on Labor & Delivery.  If a patient had a previous baby who became sick due to GBS, then we will automatically treat them with antibiotics.  Also, since preterm babies are more susceptible to illness due to GBS, we automatically give antibiotics to patients in preterm labor to help prevent it, since most of these patients haven’t had the swab done yet.

Initially, when this was getting started, they were treating the pregnant women based on risk factors.  But in the end, they found that testing everyone and treating the positive women (unless they were having a scheduled C-section) significantly reduced illness due to GBS in the babies.  In the early 1990s, before this was implemented, the rate of early-onset GBS was 1.5 per 1000 live births according to the CDC.  By 2010, after universal screening and treatment were implemented, the rate fell to 0.24 per 1000 live births.  There is also late-onset GBS infection that occurs 7+ days after birth, and antibiotics in labor unfortunately haven’t decreased those rates.

So what happens if a baby gets sick with GBS?  They can get sepsis, which means they can have a generalized infection throughout their bodies.  The severity can range, but they can develop septic shock and have long-term consequences.  They can also develop pneumonia or meningitis due to GBS.  Bottom line is that it can be very bad.

With that said, during the pregnancy I’d been thinking about this.  Yes, I know that GBS infection is bad and I certainly wouldn’t want that to occur to my baby (or anyone else’s).  And I tell all of my patients about why we screen and the importance of getting the antibiotics in labor if they are positive.  But the fact is that it’s still rare.  Back in 1981 when I was born, my mom wasn’t tested, and most of us did just fine.  What I’ve been more concerned about is that there’s probably a lot we still don’t know about the effects of all of these antibiotics in labor.

Those of us in the Paleo community are probably more aware than the average American about this issue.  Our natural flora- the normal bacteria that occur in our bodies, mostly our digestive tracts, play an important role in our health.  Taking antibiotics and throwing off that normal bacterial balance likely has negative implications.  Problem is, that research is still developing and isn’t as robust as the data above on GBS infection.  Mark Sisson has discussed it previously on his Mark’s Daily Apple site:

As an OB/Gyn, I see this a lot with vaginal yeast infections.  Women take antibiotics for a urinary tract infection (UTI) or the like, which then kills the bacteria in the urine, but also the normal bacteria in the vagina.  That causes the yeast to grow, causing the vaginal yeast infection.  Antibiotics are necessary and good when one really has an infection.  The issue is that many times people take antibiotics that end up not being needed- like maybe they thought they had a UTI, but in the end they didn’t.  I have some patients who are really frustrated with recurrent vaginal yeast infections, and often we are not able to pinpoint why they keep getting them.  I can’t help but wonder if their eating habits are to blame, but I can’t just tell everyone to go Paleo.  And that might not even work.  I do encourage them to reduce sugar and junk food, and to consider probiotics in the case that they keep getting infections and don’t otherwise have any explanation.

So back to the GBS- the rates of GBS infection was 1.5 out of 1000 live births before the days of universal screening.  It’s very bad when it occurs, but it’s rare.  And if 15-40% of pregnant women are testing positive, that’s a lot of women who are getting prophylactic antibiotics that they don’t need.  The problem is that we don’t know who is who.  We don’t have a good way of predicting which of those positive moms are going to have sick babies, so that’s why we treat everyone.

My concern if I tested positive and got the prophylactic antibiotics was that it would change my normal flora, as well as my baby’s.  And that could have potential negative consequences.  I thought about declining the prophylactic antibiotics in case I was positive.  That would have raised some eyebrows amongst the staff I work with.  And of course, I’d be gambling and taking the risk that my baby might develop a GBS infection- not something my husband and I take lightly.  In the end, I’m not sure what I would’ve done.  I was relieved to test negative and not have to make that decision.


2 thoughts on “The GBS Test

  1. breana May 8, 2017 / 6:25 am

    I was GBS positive and at the time I wasn’t sure what to do. I knew what I knew about antibiotics but the risks of my baby getting sepsis weren’t readily available for me and my doctors weren’t willing to review them with me. They all said we do antibiotics, its just what we do. Any links you can post to help me learn more about this. I did end up getting the antibiotics, luckily I was only on them for a few hours as my labor was fast! But I feel guilty for not looking into this more and guilty that I may have messed up my sons gut flora upon birth! 😦


    • Paleo OB May 14, 2017 / 8:32 pm

      Please don’t feel guilty at all. Any obstetrician would be out of their mind not to tell you to get antibiotics for a positive GBS test. It’s well-established as standard of care, and I myself do the same with my patients. The only way a patient wouldn’t get antibiotics is if she refused it, and acknowledged that is it against medical advice, and that she accepted the risks of GBS sepsis for her newborn.

      Ultimately the data on GBS sepsis is well-established. The best information that I have is in my post in terms of the numbers. 1.5 per 1000 live births was the rate before testing and treatment was established. So that would be the baseline rate. Now, it’s estimated that 15-40% of women carry GBS. So if you test positive, I’m not sure exactly how that affects the numbers, but with a known positive test, the risk of GBS sepsis would then be well above the 1.5 per 1000 risk. And it’s definitely established that GBS sepsis, if it occurs, is very bad.

      On the other hand, while we are getting more and more information about the importance of the microbiome on health, we still don’t have tons of data on it. In other words, we have bits and pieces of info. Taking antibiotics affects the microbiome. And alterations in the microbiome can have health consequences. But the exact cause-and-effect of taking antibiotics for GBS causing particular health conditions in the baby are not known. Tons of women have been getting antibiotics in labor for a positive GBS since routine screening and testing were implemented. But it’s not like we’re clearly seeing that all of those children are having overt consequences. Same thing with C-sections- it is now standard to give antibiotics prior to C-sections to prevent wound infections in the mother. Not like all children who are born via C-section end up with particular health issues.

      So bottom line is, don’t worry about your son. There are many things that affect his microbiome, so breastfeeding, the foods he eats, his home environment, the time he spends in the dirt- those are all of the things you have control over. And ultimately, we all just have to do what we think is best for our children at the time. In the future, we might find out different information. But hey, my parents fed us sugary snacks throughout childhood, and I think I turned out just fine. 🙂


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