Group Beta Strep (GBS): What to know about your microbiome & your baby’s options
Blog Overview:
This 2-part blog series takes a balanced, confidence-building approach to understanding Group Beta Strep (GBS) during your pregnancy. You’ll learn how GBS relates to your body's natural microbiome, the birth process, and your natural birth plan. Let’s dive into part 1!
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Not sure what to think about GBS in pregnancy? Let’s look closer.
First, let’s begin this blog by pressing pause on fear or stress, and let’s prepare your heart for confidence. When it comes to GBS, or Group Beta Streptococcus (Group B Strep), it’s easy to find information that creates fear and concern, and perhaps even tunnel vision about your options.
Before pregnancy, you may not have heard of GBS or how it relates to your body’s natural microbial balance (aka, your microbiome). But in pregnancy, GBS does become important to understand.
To make confident, rather than fear-based, decisions about GBS in pregnancy, you’ll want to have a deeper understanding of how GBS relates to your normal physiology and the natural birth process for you and your baby.
You deserve the opportunity to weigh the big-picture pros and cons of GBS-related risks, testing, and care options so you can make informed choices that align with your birth philosophy, values, and personal comfort level. You have more options than just routine protocols.
So in this 2-part blog series, we will help you have an upstream view of why GBS matters in pregnancy, what your options are related to GBS decisions, how those options could affect your natural birth plan, and what you can consider to make the most optimal choices for you and your baby. Part 1 starts here with where GBS comes from and what options you’ll want to weigh for your baby.
What is Group Beta Strep (GBS), and how did it show up in my pregnancy?
Let’s start by describing your physiological microbiome.
Your body has a microbiome — a whole world of microbes including bacteria, fungi, protozoa, and even viruses that live in our bodies on a regular basis. Some of these microbes are beneficial, helping in processes like digestion and absorption in our gut, maintaining pH balance in various places in our bodies, and even brain activity.
However, we often notice when there's an imbalance of microbes in our bodies or when less friendly microbes are present because we experience symptoms of illness, like the flu virus for example. So our bodies are consistently working to have a healthy microbiome balance for all the health functions and benefits it provides.
Your microbiome is connected to your baby’s microbiome development.
The foundation of your baby's microbiome begins even before birth, as they also begin to swallow tiny amounts of your gut bacteria while in your womb. This process of transferring your microbiome to your baby (called “seeding”) continues during birth, which is made easier for babies born vaginally, as they come into contact with beneficial bacteria from the mother's vaginal tissue.
After birth, breastfeeding plays a crucial role in supporting the baby's microbiome development, with human milk containing prebiotics that feed beneficial gut bacteria and boost the baby's immune system.
The infant microbiome remains highly variable in the early years of life, not stabilizing until around age 3. The early establishment of a diverse and balanced microbiome can have long-lasting effects on a child's health, potentially influencing immune function, metabolism, and even brain development.
This underscores the importance of supporting healthy microbiome development from pregnancy through the early years of life.
Group Beta Strep (GBS) can be a normal microbiome resident.
In our bodies, both for men and women, Group Beta Streptococcus, or GBS for short, can be a normal microbial neighbor, often living in our intestines and gut areas. Because it's commonly a normal neighbor in our gut, it can also often be found in our rectum area since our intestines fully extend there.
GBS is considered a hemolytic bacteria, meaning that it destroys any red blood cells that surround it when it sets up a colony. This usually does not cause significant challenges for your body as part of your overall microbiome community.
We can get GBS as early as day 1 of our lives from our mother's microbiome and have it well into older age, with studies showing adults as old as 80 years old having GBS in their microbiome.
GBS is not an ‘infection,’ per se, nor a sexually transmitted disease.
On the regular, GBS should not be considered an infection. It is also not a sexually transmitted disease because men and women who are not sexually active can also have GBS.
However, because GBS can be in places where men and women are intimate through touch, partners can also share GBS between their microbiomes, which is a normal part of how microbiomes can change based on our environment and who and what we are in contact with on a daily basis.
GBS in pregnancy usually carries over from your microbiome’s history.
By the time you became pregnant, if you already had some GBS as normal microbiome neighbors, then they just journeyed with you into pregnancy. Every mother's microbiome and overall health is unique at the time of pregnancy, and it does affect what can happen with GBS as pregnancy progresses.
If a mother has an overall healthy microbiome balance, then GBS may stay a normal neighbor in the intestines and not migrate and expand much past there. Or if it did migrate to the rectum as they catch a ride out of your body or even have a presence in your vagina, low colony levels are usually non-trouble makers in the body overall.
GBS can be a pretty harmless microbiome neighbor in our rectum and vaginas if its colony size stays low, and we maintain an overall healthy gut and vaginal microbiome balance. But when GBS does expand its colony size and its numbers grow, especially when there's also a microbiome imbalance, GBS can create challenges for mothers and for babies. That’s why it’s essential that you know about and can weigh both sides of those challenges to consider the full picture.
There are two primary outcomes for babies that you’ll want to assess for GBS in pregnancy.
How GBS can shift from harmless neighbor to harmful infection.
So even though Group B Streptococcus (GBS) is typically a harmless part of our microbiome, under certain conditions, it can become problematic for both mamas and babies. This shift often occurs when there's a microbiome imbalance or other factors emerge that allow GBS to overgrow.
When GBS becomes problematic, it can lead to various infections in pregnant women, including:
Urinary Tract Infections (UTIs)
Chorioamnionitis (infection of the amniotic fluid and membranes)
Uterine infections
For babies, a GBS infection can occur before, during, or after birth. Though it is not always clear how a baby becomes infected with GBS (which is different than just being colonized with GBS, which doesn’t cause illness), it is thought when GBS is able to migrate upwards from the vagina into the cervical area and closer to the uterus, it can cause infections once it gets past the amniotic membrane (either when waters are open or through another mechanism). A baby can then be exposed to GBS by swallowing amniotic fluid that has GBS in it, and this can sometimes lead to infection.
GBS infections in babies are categorized into two types:
Early-Onset GBS Disease and Late-Onset GBS Disease.
Babies with early-onset GBS disease often begin to show symptoms even before birth, with almost all early-onset infections being detected within 12 to 48 hours after birth. Symptoms can include fever, difficulty breathing or grunting, or very high or low heart rate. Late-onset GBS disease is often detected around one week to three months postpartum. So it is important for families to know how to observe and assess potential symptoms. The Association of Ontario Midwives’ website provides a beneficial overview of how to recognize any abnormal newborn behavior that might be related to GBS infection here: https://www.ontariomidwives.ca/gbs.
Babies with GBS disease usually need additional care in a hospital’s neonatal intensive care unit. For early-onset infections, 90 to 95% of babies fully recover when they receive early treatment for GBS-related sepsis or pneumonia. Some babies do experience long-term complications like hearing loss, developmental delays, or other neurological challenges.
For late-onset infections, the recovery rates can also be high if treated quickly, but GBS-related meningitis can increase the likelihood of longer-term neurological problems.
Overall, the infant mortality rate for babies with GBS infection is estimated to be between 2-3% for early-onset disease in babies at term and lower for late-onset disease, provided that babies receive care promptly as needed. However, rates of infant mortality do increase an estimated 10-fold (10x) for preterm infants, which makes preterm labor a special circumstance to consider.
Due to these potential risks and the challenges to newborns, mamas who test positive for GBS are commonly recommended to use antibiotics during birth. However, this preventive measure comes with its own set of considerations, particularly regarding the impact on the newborn's developing microbiome.
GBS antibiotic treatment has risks for babies, too.
While the use of antibiotics during labor for GBS-positive mothers has been a standard practice for years, recent research has shed light on the potential risks this approach poses to newborn health. It's crucial for expectant mothers to understand both sides of this important health decision.
In the last decade, there has been growing recognition of the risks that antibiotics used during labor can pose to babies. As of 2014, there was no research on the effects of antibiotics given during labor on babies' microbiomes. However, since then, at least nine observational studies have been conducted on fetal exposure to antibiotics during labor.
These studies have consistently shown that IV antibiotics during labor have at least a short-term negative effect on newborns' microbiomes. This includes:
Disrupting the initial colonization process of the infant's gut
Reducing beneficial bacteria
Increasing levels of non-beneficial bacteria
On the impact of disrupting a baby’s initial microbiome colonization, a 2016 Canadian study by Azad et al. found that microbiome richness was decreased in infants exposed to antibiotics, regardless of breastfeeding status. The effects were more pronounced in infants not exclusively breastfed.
Five of the nine studies examined the microbiome over time:
Two found that the infant's microbiome recovered or mostly recovered by 4-8 weeks of life
Three studies found important differences that persisted for 3 months up to 1 year of life
This suggests that for some babies, the impact of antibiotics used before birth on their microbiome can be long-lasting, potentially affecting their health and development well into infancy. Long-term impacts have included:
Altered immune system development, including potentially increased susceptibility to infections
Increased risk of allergies and asthma
Potential metabolic changes affecting weight gain and obesity risk due to a potential impact on nutrient absorption and metabolism
Possible influence on brain development and behavior
Because of this, it’s worth having a short-term and long-term view of the potential outcomes of routine antibiotic use for GBS-positive scenarios. For a summary of all 9 studies on the microbiome effects of antibiotics for GBS, visit the Evidence Based Birth® Signature Article on Group B Strep.
How do these two outcomes compare to one another?
It’s estimated that on average, 18% of women may have high colonization levels of GBS in pregnancy, with the range being anywhere from 8-35% of pregnant women being GBS positive.
Based on data analyzed in 2015, there were an estimated 205,000 cases of early-onset GBS disease globally, with about 78,500 related deaths out of 140,000,000 live births. Most of these cases and deaths occurred in low-resource countries where there was little to no access to healthcare facilities, or in countries where there is a mix of access to testing and care options for mothers with GBS.
For GBS-positive mothers who don't receive antibiotics, the infection rate in newborns is 1-2%. With universal screening and routine antibiotic treatment, which is the current practice in the United States, this rate drops to 0.2%.
So how can you compare the outcomes of the impact of GBS early-onset disease with the impact of routine antibiotics used in labor for GBS-positive mamas?
To put these risks in perspective:
Using these statistics, we can estimate that for every 1,000 births, on average about 180 women (18%) would be GBS positive
Without antibiotics, 2-4 babies (1-2% of 180) might develop early-onset GBS disease
With antibiotics, this would reduce to about 1 or no babies (0.2% of 180) developing early-onset GBS disease, though this doesn’t account for mamas who had a false negative GBS test result
However, all 180 GBS-positive women would likely receive antibiotics under the universal screening and routine antibiotics approach
Therefore, for every 1 to 4 babies that would avoid having early-onset GBS disease through the use of antibiotics, at least 180 babies (not including additional babies for mamas carrying multiples) would be exposed to potential short-term and long-term impacts of microbiome disruption
Given these estimates, it's clear that the decision to use antibiotics in labor for GBS prevention is more complex than often presented. While antibiotics do effectively reduce the risk of GBS disease, they also carry potential risks to the newborn's microbiome and long-term health.
As a mama making choices for you and your baby, it’s important that you’re empowered to weigh these risks and benefits, considering your individual needs, birth philosophy, values, and comfort level. This nuanced approach allows for more personalized and informed decision-making in prenatal care and can help you plan a more effective natural birth plan, which is what we discuss in the next sections.
Head over to part 2 of this GBS blog series to learn about your many options for care, testing, and your birth plan.
In part 2 of this blog series, we provide a full overview of your options for addressing GBS in pregnancy before birth and what to consider for your natural hospital birth plan. Head over to part 2 now to Know your Group Beta Strep (GBS) options for your natural hospital birth plan.
