Group B streptococcus is a type of bacterial infection. This bacterium naturally lives in the gastrointestinal tract. GBS is common and is in 10%-30% of pregnant women. Once you have this bacterium, it does not mean you will always have it, and it can come and go. Most women with group B strep do not experience any symptoms, and usually, this is not a big deal. However, it can create some complications for you when you are pregnant and cause some severe complications if you pass it to your baby. In the United States, it is standard practice to test all expecting mothers in week 36 or 37 for group B strep. This episode covers what is involved in the testing, how to treat group B strep, and how you can reduce the risks to your baby. This episode also explores the evidence on whether you can decrease your risk for group b strep during pregnancy.

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Group B Strep

Group B strep or GBS is short for group B streptococcus, a bacterial infection type. This bacterium naturally lives in the gastrointestinal tract and is present in the vagina or the rectum. According to the American College of Obstetricians and Gynecologists, the prevalence in pregnant women is between 10% and 30% and is reported to be higher in black women and may vary by geographic location. Once you have this bacteria, it does not mean you will always have it, and it can come and go. Most women with group B strep do not experience any symptoms, and usually, this is not a big deal. It can become an issue when you are pregnant and can cause bladder and uterine infections in rare cases. In severe cases, it can cause meningitis, sepsis, pneumonia, or stillbirth.

Group B Strep and Your Baby

Group B strep can be a severe complication for a newborn and is the leading cause of newborn infection. There are two types of infections that could affect your baby, early or late-onset group B strep.

Early-onset group B strep is the most common, and symptoms usually show up within a few hours after birth, up to seven days. The most common complications of early-onset GBS are sepsis, pneumonia, and meningitis. This bacteria can also cause breathing problems, heart and blood pressure instability, and gastrointestinal and kidney problems.

Late-onset usually shows up within a week up to three months after birth, and the most common symptom is meningitis. Late-onset could have resulted from the bacteria being passed from mom to baby at birth, or a baby could possibly contract it from coming into contact with someone who has GBS. This article focuses on early-onset and preventative treatment.

Testing for Group B Strep

According to the World Health Organization, At least 60 countries have a policy for antibiotic use in pregnancy to prevent newborn GBS disease. Of those, 35 have the policy to test all pregnant women to see if they carry GBS, and the remaining 25 countries identify women with clinical risk factors. In the United States, care providers routinely test pregnant women for GBS in week 36 or 37 of pregnancy. You need to wait until week 36 because your care provider wants to know if you are colonized during labor, which is when you could pass it to your baby. This is a non-invasive test, and your care provider will take a swab of your vagina and the rectum. Then the sample is sent to a lab, and results should be available within 24 to 48 hours.

If You Opt-Out of a GBS Test

Like any prenatal test, it is your choice whether to get tested for group B strep. If you decline a test, ACOG recommends antibiotics for mothers who have risk factors for GBS. This includes a GBS colonization in a previous pregnancy, preterm birth, preterm prelabor rupture of membranes, rupture of membranes for 18 or more hours at term, or who present with a fever of 100.4°F (38°C). If you plan for a home or birth center birth, decline a GBS test, and transfer to a hospital, the hospital may recommend antibiotics as a precautionary measure.

Testing Positive for Group B Strep

If you do have group B strep, that does not mean that your baby will have it also. Group B strep can be passed from mom to baby during birth, but you can do some things to prevent your baby from being colonized. In the United States, on average, each year, about 1,980 babies are affected by group B strep. According to the American College of Obstetricians and Gynecologists of mothers who carry group B strep, approximately 50% will transmit the bacteria to their newborns. Transmission to a newborn does not mean the newborn will develop an infection. You will be at higher risk of passing it to your baby if you go into labor or your water breaks before week 37, if your water breaks more than 18 hours before your baby is born, if you have a fever during labor, if you have a urinary tract infection as a result of group B strep, or if you had a previous baby with group B strep.

Group B Strep and Labor Induction

If you test positive for group B strep, it may limit other available interventions. Some methods to induce labor, including membrane sweeping and mechanical cervical ripening, may not be recommended by your doctor or midwife because of the potential risk of infecting your baby with GBS. If you are positive and plan to utilize any labor induction methods, please discuss it with your doctor or midwife.

Treating Group B Strep

There is currently no vaccine available for GBS, although researchers are working on this for the future. In the U.S., it is common practice to treat you with antibiotics if you are colonized with group B strep, even if you are considered low-risk. According to the CDC, if you have GBS without antibiotics, there is a 1 in 200 chance your baby will develop GBS disease. With antibiotics, your baby’s risk decreases to a 1 in 4,000 chance.

Antibiotic Administration

Antibiotics are given to you at the beginning of your labor through an IV, then every four hours during active labor until your baby is born. The reason you don’t get antibiotics before you are in labor is that group B strep lives in your gastrointestinal tract, and it could potentially come back after antibiotics but before you give birth. The antibiotic most commonly used is penicillin. If you have a penicillin allergy, there are a few other antibiotics your doctor or midwife can use.

Getting antibiotics does not necessarily mean that you will be continuously hooked up to an IV. Once your labor starts, you will have an IV put in, and it takes about 15-30 minutes. The antibiotics are only given every 4 hours until birth. In between getting intravenous antibiotics, you can have a help-lock in, which means the needle stays in your hand, but it is capped off. This allows you to move around without being hooked up to tubes and an IV pole. You could be hooked up to an IV for fluids, which is not related to group B strep. For more evidence on IV fluids, see this episode. Even if you are hooked up to an IV continuously for fluids or medications, you may be able to move around; you will just have to be connected by a tube to an IV pole on wheels.

Cesarean Birth

Group B strep is not generally passed to your baby if you have a cesarean birth and is only passed during vaginal birth. If your water breaks, the chances of infection are higher, and antibiotics may be recommended, even if you plan a cesarean section. Even with a positive GBS test, antibiotics are not typically given for a cesarean when your membranes are intact.

Although you may not receive antibiotics for GBS, antibiotics are routinely given in cesarean birth to prevent infection after the operation. A review of 95 studies involving over 15,000 women found that routine use of antibiotics at cesarean section reduced the risk of infections in mothers and the risk of severe complications of infections by 60% to 70%. 

How Antibiotics Affect Your Baby

You can probably guess that if you take antibiotics during your pregnancy, they are also reaching your baby. A review that looked at the comparison of the drug concentration in maternal and fetal plasma indicates the baby’s exposure to antibiotics taken by a mother. While the comparisons in concentrations differed, all antibiotics looked at in this review did cross the placenta. Just because these drugs cross the placenta doesn’t necessarily mean they are harmful to your baby. As with any medication, deciding to take it involves weighing the risks and benefits. In the case of GBS, you also need to consider the chances of your baby becoming infected.

At birth, your baby’s gastrointestinal tract is sterile, and it is rapidly colonized by bacteria originating from both you and their environment. If you have any concerns about how antibiotics could affect your baby’s gut microbiome, there is a lot you can do to help make sure they do have a healthy gut. One of the best things you can do for this is to breastfeed. If you have concerns, definitely discuss them with your care provider. Suppose you and your care provider decide the best course of action is to have antibiotics to protect your baby from a serious infection. In that case, that will likely outweigh concerns of the effects on your baby’s gut bacteria. For more in-depth information on taking antibiotics during pregnancy, see this episode.

Preventing Group B Strep

We know that 10% to 30% of pregnant women are colonized with group b streptococcus. This is just one of many different bacteria living in our bodies. There is some interesting research on taking a probiotic to decrease your risk for group b strep. Ideally, we can prevent the possibility of ever becoming colonized with group B strep in the first place.

A study found that high numbers of lactobacilli in women may contribute to a low vaginal pH and negatively influence Group B streptococci. This particular study used panty liners to introduce lactobacilli to the participants.

The Evidence on Preventing Group B Strep

The thought of using a panty liner colonized with bacteria might gross you out. There is a much easier and less gross way to introduce lactobacilli to your body. What if you could just take a daily prebiotic in the form of a pill? A small study found that a prenatal probiotic has the potential to reduce group B strep colonization. This study was significant because it justified a full controlled clinical trial.

The clinical trial that followed included 251 participants that were randomized to take a probiotic or a placebo. On average, they took this for 12 weeks leading up to birth. They found no significant difference in GBS colonization between 35-37 weeks between the two groups. 18.5% of the group that took the probiotic still tested positive for GBS, compared to 19.7% of the placebo group. The researchers note that larger studies are needed to further investigate the potential impact of probiotics on GBS.

Should You Take a Probiotic?

There is not overwhelming evidence to show taking a probiotic will prevent group B strep. There is evidence that there are other benefits to taking a probiotic. You are already taking a daily prenatal vitamin, and it wouldn’t be a significant inconvenience to add a probiotic.

There is evidence that probiotics can positively impact bowel movements for people experiencing constipation. The main probiotic in this study was bifidobacterium lactis. 

There is also some evidence that taking a probiotic when you are pregnant may decrease your risk for preeclampsia. One study looked at the association between the consumption of milk-based probiotic products in pregnancy and the development of preeclampsia. This was part of the Norweigan Mother and Child Cohort Study, which included over 33K participants. They found that milk-based probiotic foods containing lactobacilli decreased the risk for preeclampsia. 

Some common side effects of probiotics are digestive issues, like gas, bloating, or constipation. These symptoms tend to go away in a few weeks. One way to limit the side effects is to start with a lower dose of probiotics and gradually increase to the suggested daily amount. Many supplements will include instructions to do this on the label. Everyone’s gut microbiome is different. If you take a probiotic that has side effects, you can always stop taking it. For more in-depth information on probiotics, see this episode.

Click here for my favorite probiotic. I chose this one based on many factors, including the strains of probiotics included in it, the brand, the price, the ranking on Labdoor.com, an independent third party that ranks supplements based on quality.  This probiotic includes all of the strains of bacteria that are evidence-based to help things like constipation and possibly lower the risk for group B strep. Garden of Life also has a probiotic marketed specifically for pregnancy, and you can check it out here.

If you have any questions about taking a probiotic during pregnancy, please talk to your doctor or midwife.

Including Preferences for Group B Strep in Your Birth Plan

If you are group B strep positive, you may want to note this in your birth plan so you can make sure your care providers and nurses are aware of it as soon as you arrive at the hospital or birth center. If you are ready to write your birth plan and want to see a sample, I would be happy to send you a copy of my birth plan. Your preferences may be different, but at least you could see how one could be structured and worded. Click here if you would like to get a free copy of my birth plan.

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