What is Group B Strep, and How Can It Affect Your Birth Plan?

Testing positive for group B strep (GBS) during pregnancy can be scary, but there's a simple treatment that can keep your baby safe. Check out our need-to-know guide.

When Allison Walters* of New York City found out she had tested positive for group B streptococcus (GBS)—a common bacteria that can be transmitted to a baby during delivery and can result in serious health issues for the newborn—during her second pregnancy, she started crying in her OB-GYN's office.

"As my doctor explained to me how incredibly important it was that I get treated with antibiotics before the baby was born, I knew this would be an added element of stress and worry," she recalls. "Knowing how dangerous it could be for the baby really scared me, and it also meant that I'd have to head to the hospital much earlier than I would have liked. I wanted to labor at home for as long as possible and have a 'natural' birth, just like I did with my first child."

Hearing you have GBS during pregnancy can certainly be frightening. But knowing precisely what it is—and how it might affect you and your baby —can help keep both of you safe.

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What is Group B Strep?

Group B streptococcus is a naturally occurring, common type of bacteria often found in healthy people's lower intestinal tract, rectum, or vagina. Around 25% of people carry these bacteria, which are usually not harmful, though they might cause a urinary tract infection and, rarely, more serious infections.

The real risk is that a pregnant parent can transmit GBS to their baby during labor and delivery, which can cause serious complications for the newborn, including pneumonia, meningitis, systemic infection, and sepsis (an infection in the blood). Simply put, it can be fatal in infants. That's why the Centers for Disease Control and Prevention (CDC) recommends that all pregnant people get screened for GBS.

How Do You Get Group B Strep?

Experts aren't sure why some people carry GBS while others don't. "Some individuals are more likely to become colonized with GBS than others when their gastrointestinal tract is randomly exposed to the organism," says Lynn Simpson, M.D., chief of the division of maternal-fetal medicine at Columbia University Medical Center. "Colonization can be transient, intermittent, or persistent."

Dana Stone, M.D., an OB-GYN in Oklahoma City and a spokesperson for the American Congress of Obstetricians and Gynecologists, adds, "We carry many bacteria in our bodies, and GBS seems to be one of them for many people. Women can carry it during one pregnancy and not in another, so we check for it in each pregnancy."

GBS Symptoms

The majority of pregnant people with GBS have no symptoms. Still, those with heavy colonization of the bacteria may have symptoms similar to a bladder infection, including fever, chills, and pelvic pain.

GBS can also lead to blood infection, urinary tract infection, pneumonia, skin infection, swelling, and bone and joint infections, so it is essential to be diagnosed and treated as soon as possible.

Group B Strep Test in Pregnancy

The Group B strep test is usually given during weeks 36 to 38 of pregnancy. In this quick and painless test, your practitioner takes a swab of your vagina and rectum. The sample is sent to a lab for a culture to test for the presence of Group B strep.

"Since GBS can be a normal gut flora and colonization can be intermittent or recurrent, it's optimal to screen late in pregnancy, when the culture results are likely to reflect the status at the time of delivery," says Dr. Simpson "Treating earlier has not been shown to be effective at decreasing early-onset GBS disease in infants and may result in the development of antibiotic resistance over time. Therefore, early treatment is not recommended." In other words, since GBS can grow back very quickly, antibiotics can help only when given during labor.

What Happens If You're GBS Positive?

If you test positive, ask your doctor what to expect. "All women who test positive for GBS during pregnancy (as well as those who have had a baby with a GBS infection in the past or those who had a GBS urinary tract infection during the pregnancy) should receive antibiotics—typically penicillin—during labor to prevent transmitting GBS to the baby," says Dr. Stone. "Women who have preterm labor and don't know their GBS status are also treated in case they carry GBS."

Stephanie Schrag, D. Phil., an epidemiologist at the CDC, agrees: "The best steps a mother can take to help protect her baby is to go to the hospital and get antibiotics for at least four hours before delivering, tell the labor and delivery staff at the hospital that she's a GBS carrier, and speak up if she's allergic to penicillin so another antibiotic can be given. Getting antibiotics intravenously throughout labor is the only proven strategy to protect a baby from getting GBS disease in the first week of life." If your water breaks, get to the hospital immediately so your doctor can start the antibiotic treatment.

Will GBS Affect Your Birth Plan?

"Being a GBS carrier does not always mean a woman needs to change her birth plan," says Dr. Schrag. "Regular checkups should continue, and she should talk with her doctor or midwife about a plan for labor so antibiotics can be given before delivering the baby."

If you're GBS-positive and scheduled for a C-section, specific GBS antibiotics aren't necessary, says Dr. Simpson. Instead, she says, you'll be given a broad-spectrum antibiotic before the skin incision to prevent maternal infections related to the surgery. But if your water breaks or labor starts before a cesarean delivery, you'll need treatment for GBS, just as those undergoing labor and a vaginal birth do.

Will GBS Transmit to Your Baby?

According to the CDC, if a person who tests positive for GBS gets antibiotics during labor, their baby has only a 1 in 4,000 chance of getting GBS (compared to a 1 in 200 chance if they don't get those antibiotics.) In other words, antibiotics during labor will prevent the vast majority of GBS.

Your pediatrician will evaluate your baby. If the baby shows any signs of infection, such as respiratory distress, apnea, difficulty feeding, or symptoms of sepsis, such as fever and an abnormally rapid heart rate. In that case, they will receive antibiotics and supportive therapy to treat it.

The Bottom Line

"I know it can be scary to find out you have these bacteria and that your baby has a chance of getting sick," says Dr. Schrag. "But pregnant women should take comfort in knowing that GBS prevention guidelines have been in place for two decades in the United States and have proven effective in protecting babies."

As for Walters, when her water broke a week shy of her due date, she headed straight to the hospital and got the antibiotics her baby needed. Yes, her birth plan changed slightly, but she says, "My son was born healthy—and ultimately, that's all that mattered."

*Name has been changed

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