Congratulations, those two matching pink lines on the pee stick show that you’re pregnant! Naturally, you’re excited and want to have the healthiest baby possible. You know that prenatal care is important, so you plan to be conscientious about your prenatal visits with a midwife or an obstetrician.

One of the tests your provider will likely recommend, about four weeks before your baby is due, is a swab for Group B strep (GBS). This Group B strep test determines whether an expectant mother has a very common form of streptococcus bacteria.

What is GBS?

GBS is normally harmless to adults. In fact, it is so common that approximately one quarter of all pregnant women may be “colonized” with GBS at any given moment. However, if you test positive for GBS during pregnancy, it can be problematic.

GBS is found in the intestines and the lower reproductive tracts of both men and women. It can be passed between sexual partners during lovemaking. However, GBS is not considered a sexually transmitted disease. That’s because it is also found in people with no prior sexual experience.

GBS strep colonization is not a steady state. The bacteria naturally comes and goes. Therefore, for GBS screening during pregnancy to provide reliable results, it must be done close to birth.

In a 2011 study of 559 women, GBS cultures done at 35–37 weeks were compared with cultures done during labor. Only 109 women tested positive on the first culture, while 133 tested positive while in labor. In addition, 17 of the original 109 women were negative by the time they gave birth an average of three and a half weeks later. So, the prenatal culture only correctly detected 92 (69 percent) of 133 women who were colonized with GBS while in labor, while it falsely identified 17 others.

Is GBS during pregnancy a problem?

Why is a pregnant woman’s GBS status so important? When GBS was first written about in the medical literature in 1973, it was found to be the leading cause of neonatal sepsis and meningitis in newborns and was reportedly fatal about half the time. GBS can make babies sick before birth and up to six months after birth.

GBS infection is categorized based on when it begins:

  • Prenatal onset: before birth
  • Early onset: one to six days after birth
  • Late onset: one week to six months after birth

In the 1990s, before universal GBS screening in the US, approximately 1 in 600 babies developed early-onset GBS infections, and some of those babies died.

So, in an effort to prevent these infections, in 1996 the CDC recommended universal screening and treatment with antibiotics during labor, usually penicillin or ampicillin.

As a result of this widespread testing and treatment protocol, the rate of early-onset GBS infection has declined by about 85 percent since the 1990s. But even treating more than a fourth of all laboring women with antibiotics does not prevent every case.

Indeed, according to the CDC, approximately 1 in 2,000 American babies still develop GBS infections. While the fatality rate has improved dramatically since the 1970s, approximately 5 percent of these babies, or 100 newborns, still die each year.

Antibiotics may not be the Best Choice

While it’s important to prevent lethal GBS infections in newborns, conventional medicine’s main prevention strategy, aggressive treatment with antibiotics, is problematic at best.

The overuse of antibiotics has been a hot topic in medical literature for at least a decade. Many medical experts have warned that the more antibiotics are prescribed, the less effective they are.

And public health officials have predicted the end of the “antibiotic era” due to the evolution of antibiotic-resistant bacteria.

In fact, a 2019 CDC report about antibiotic resistant bacteria, insists: “Stop referring to a coming post-antibiotic era — it’s already here.”

The Microbiome Matters

At the same time, a growing body of medical research highlights both the importance of the microbiome to good health and the long-term disruptions that antibiotics cause to the microbiome. Recent research published in the journal iScience has specifically found that antibiotic use near birth caused significant disruption to the guts of mouse pups. These gut changes led to changes in gene expression in the brain in several important pathways for neurodevelopment, suggesting that the overuse of antibiotics may be implicated in the steep rise in autism we have seen since the mid 1980s.

Given how few children are actually at risk of GBS infection, treating up to a third of all mothers with antibiotics which can potentially alter their babies’ gut health and brain development is like bringing a machine gun to a knife fight. It may do the trick, but at what cost? The collateral damage can be devastating.

Proactive Ways to Prevent GBS During Pregnancy

The best way to prevent GBS infection during pregnancy is to prevent GBS colonization in the first place. And, despite our culture’s emphasis on killing the enemy, the best way to prevent colonization is to promote diversity in your microbiome.

Hosting a wide variety of beneficial bacteria prevents overgrowth of any single strain of bacteria. The bonus is that by achieving diversity, you will also be improving your own health as well as that of your baby. Why? Because diversity of your “gut bugs” (or “microbial hitchhikers”) is highly associated with good general health.

Eating traditional fermented foods, like homemade sauerkraut and kimchi, are a key way to promote gut health and microbial diversity. Unsweetened yogurt, kefir, and other cultured products can also help. Try to eat some fermented foods with every meal.

In addition, there are some so-called “living” probiotic products that work like fermented foods. These include fermented barley water, which you can also make yourself or find in the refrigerated aisle of your local health food store, and the liquid Flourish. These living probiotics can be pricey, but since they help promote your unborn baby’s best health, they are worth it.

Improving the integrity of your gut’s lining can also improve the diversity of your microbiome. Intelligence of Nature’s (ION) Gut Support works to close up the tight junctions which may have been loosened by an overgrowth of one or more types of bacteria.

In addition, products that include glutamine, marshmallow (the plant), licorice, aloe, and slippery elm can help heal the gut’s lining.

Skip the Sugar, Eat a Variety of Real Foods Instead

To foster a wide variety of beneficial microbes in your body, you will want to eat a wide variety of healthy foods. Sometimes that’s hard during pregnancy, especially if you’re experiencing morning sickness. But you will be doing your baby and yourself (as well as all the good microbes in your gut) a favor if you feed them well. That means eating a wide variety of colorful vegetables and fruits. It also means cutting all refined sugar and simple carbohydrates out of your diet. Sugar, especially, promotes the overgrowth of unhealthy microbes that can lead to poor health, including an increased risk for gestational diabetes and GBS.

Garlic is a natural and powerful antibiotic which can keep GBS in check during pregnancy. Eating garlic feeds your beneficial bacteria. So also be sure to add lots of garlic to your diet. You can eat it raw in salad dressings, sauté it with other healthy vegetables, and add it to homemade soups and teas.

If you don’t love the taste of garlic, try roasting it. Roasted garlic has a buttery consistency and a sweet flavor that even the pickiest eaters find irresistible. (To roast garlic, cook a whole head wrapped lightly in aluminum foil in the oven or toaster oven at 400 degrees F for about 40 minutes.)

Natural Alternatives to Antibiotics

Okay, so what can you do if you test positive for GBS toward the end of your pregnancy even if you’ve been avoiding sugar and eating mindfully? Do you have to have a dose of IV penicillin every four hours in labor?

Perhaps not. Many women who test positive are no longer colonized by the time they give birth. There’s a good chance that you would be in this category without any further action.

There are several alternatives that can increase your odds of testing negative when you are closer to giving birth. The main idea is to kill enough of the GBS so that there will be no active colonization by the time you give birth.

  • Garlic: The very simplest treatment is to insert a clove of garlic in your vagina every day for 7 to 10 days. It may surprise you to know that Group B strep can be killed by something as simple and harmless as garlic, but it’s true. Follow this natural treatment protocol developed by Ronnie Falcao, a midwife based in Mountain View, California, and insist that your doctor or midwife tests you again after a couple weeks.
  • Tea tree oil: If you or your sexual partner hates the smell of garlic, tea tree oil suppositories could work just as well. Unfortunately, both garlic and tea tree oil can be irritating to sensitive vaginal tissue and neither will be appropriate for everyone.
  • ION*Biome Spray and Ozonated Suppositories: Use ozone spray before and after sexual activity (including oral sex) and urination to help ensure your culture does not come back negative. In conjunction, ozonated coconut oil suppositories may also help balance blood and urine cultures.
  • An over-the-counter antimicrobial: If all else fails, or you want to bring out the big guns, Hibiclens is an over-the-counter antimicrobial that can be used in the vagina. It’s important to note, however, that Hibiclens is similar to some products used for antiseptic douching. Douching is absolutely out in pregnancy. Instead of douching, you will gently squirt diluted Hibiclens using a peri-bottle at the bottom of the vagina.

If You Really Need Antibiotics Because You Have GBS During Pregnancy, Then What?

If you’re still carrying GBS when you give birth and your doctor or midwife thinks it’s necessary to give you antibiotics, don’t despair. There are things you can do to mitigate the disruption to your own and your infant’s microbiome.

Breast milk, nature’s perfect food: First and foremost, breastfeed often and exclusively, especially in the early days. Formula feeding is associated with decreased diversity in gut microbes that may be permanent. Breast milk is full of complex sugars called oligosaccharides that are important for promoting beneficial bacteria in the infant gut.

Supplement with B. infantis: Author Kristin Lawless has been writing about the scientific research on a type of bacteria that is disappearing in industrialized countries. Only about 1 in 10 American children currently carry this important strain. This is likely due to antibiotic overuse, the increase in Caesareans (which prevent proper “seeding” of the infant gut at birth), and the ubiquity of formula feeding. This bacterium is called B. infantis and it is crucial for establishing a healthy microbiome in newborn infants.

Rapid growth of B. infantis in the early days crowds out most of the potential “bad actors” of the microbiome world, including GBS. Perhaps it is the loss of B. infantis that makes modern babies susceptible to such a common, mostly innocuous bacterium in the first place.

A team of scientists at the University of California at Davis who discovered the importance of B. infantis have made it available in a powdered supplement. Giving your child Evivo, made by Evolve BioSystems, may be the single most important thing you can do to safeguard your baby’s health, whether you have been prescribed antibiotics or not.

Have a homebirth: Consider having a home birth or laboring at a birth center with an experienced midwife rather than with an obstetrician. In many states, midwives are qualified to administer IV antibiotics if they are necessary. But homebirth midwives tend to be more flexible with regard to GBS testing and protocols. They are more likely to regard the expectant mother as an individual rather than as a potential malpractice lawsuit. And if you are positive for GBS during pregnancy or labor, a homebirth midwife will work with you to devise the best treatment plan.

Jennifer Margulis, Ph.D., is an investigative health journalist and science writer based in Oregon. She is the author of Your Baby, Your Way: Taking Charge of Your Pregnancy, Childbirth, and Parenting Decisions for a Happier, Healthier Family (Scribner, 2015). She’s also a guest on THE FULLEST Podcast and regular contributor to THE FULLEST. Learn more and sign up for her free newsletter at

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