Testing Positive for Group B Strep (GBS) in Pregnancy

Pregnant woman holding stomach in doctor's office
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While you’re pregnant, you will have a lot of different prenatal tests such as physical exams, blood work, and ultrasounds. One of the tests that you'll have toward the end of pregnancy is to screen for something called group B strep (GBS).

Here’s what you need to know about this test, what it means if you test positive for GBS during pregnancy, the next steps to take, and how to treat this common pregnancy concern.

What Is Group B Strep?

Group B streptococcus (GBS, group B strep, beta strep), is a type of bacteria that is normally found in the body of both men and women. In women, GBS can be in the urinary tract, the genital area, and the intestines.

According to the CDC, approximately 25%, or 1 in 4 pregnant women, carry group B strep in their bodies. GBS is usually not harmful to healthy adults and pregnant women, but it can be dangerous for newborns.


Since GBS is the most common cause of infections in newborns, the American College of Obstetricians and Gynecologists (ACOG) recommends a screening test for all pregnant women during the third trimester between 35 and 37 weeks.

During your prenatal examination, the doctor will take a swab of the vagina and rectum, then send it to the laboratory for testing. The swab test for GBS is quick, easy, and it doesn't hurt.

You will NOT need a swab screening test at 35 to 37 weeks if:

  • You had a urine test showing GBS in your urine during this pregnancy
  • You have experienced an infection or complication of GBS during this pregnancy
  • You've had a baby who developed a GBS infection before this pregnancy

Testing Positive 

It can be scary to find out that your screening test for group B strep came back positive. But, in most cases, having GBS in your body will not cause you any harm. Most women who are GBS positive don’t even know they have it. They are just carriers of the bacteria, and they do not have an infection or any symptoms. Here are a few facts about GBS:

  • The bacteria are not always present and detectable in the body. They may come and go. You may test positive in one pregnancy and negative in another.
  • You shouldn’t feel guilty about a positive test. You did not get it from anything you did. It is not a sexually transmitted disease, you did not get it from not washing well, and you didn’t catch it from something you touched or something you ate.
  • You cannot give GBS to your partner or your other children.
  • It is not the same as Streptococcus A, the bacteria that causes strep throat.

Next Steps

Now that you know your test was positive, what next? Here’s how to get through the last few weeks of your pregnancy after a positive GBS test:

  1. Try not to worry.
  2. Write down all of your questions and talk to your doctor. Understanding GBS and having the opportunity to get your questions answered can relieve some of the anxiety that you may be feeling.
  3. Talk to your doctor or midwife about your birth plan. If you are planning on a hospital birth, you won’t have to change your plans that much. But, the need for IV antibiotics during labor may make it more difficult to have a home birth.
  4. Since you will receive IV antibiotics when you go to the hospital in labor, tell the doctor if you have any drug allergies especially if you are allergic to penicillin or other antibiotics.
  5. Let your doctor know if you develop the symptoms of a urinary tract infection.
  6. Go about your everyday life preparing for your new little one. You don’t have to do anything special while you wait for labor to begin.
  7. When your water breaks or you begin to feel regular contractions, call your doctor’s office and go to the hospital. Well-meaning friends and family may tell you to wait and labor at home for a while before going to the hospital, but you want to try to get your antibiotics started at least four hours before your child is born. Some babies arrive more quickly than others, so don’t wait to head to the hospital.
  8. Let the hospital staff know that you tested positive for GBS. They may already have your chart and information but tell them anyway just in case. If you’re allergic to any antibiotics, tell them that, too.
  9. Once the hospital staff determines that you’re in labor, they will start an IV and give you your first dose of penicillin or an alternative antibiotic. You will get another dose every four hours until your baby is born.


If you have a positive GBS test and you do not have any symptoms or complications, the treatment is intravenous (IV) antibiotics at the beginning of labor or the rupture of membranes (when your water breaks).

Antibiotics are a type of medication that kills bacteria. Penicillin or ampicillin are the IV medications that doctors typically use to treat group B streptococcus during labor and delivery.

If you are allergic to penicillin, your doctor will give you a different antibiotic instead. And, you don't have to worry, the medications that you receive during labor will not harm your child.

When GBS Status Is Unknown

Your doctor screens for GBS between 35 and 37 weeks. So, if you go into labor early, you may not have had your screening yet. Women who miss their prenatal appointments or do not go for prenatal care, may also not know whether or not they are positive for group B strep. If your GBS status is unknown, you will receive antibiotics when you get to the hospital in labor.

You will receive IV antibiotics if:

  • You go into labor before 37 weeks.
  • You are in labor, and it has been more than 18 hours since your water broke.
  • You have a fever (a temperature higher than 38 C or 100.4 F).

Oral Antibiotics

Some women wonder why they don’t get a prescription for oral antibiotics when the test first comes back positive. The problem is that while taking antibiotics by mouth can reduce the bacteria, group B strep can multiply quickly and come back before labor begins, putting your baby at risk.

Currently, the most successful way to suppress the bacteria and prevent it from making its way to the baby is to get IV antibiotics as soon as labor starts and at least four hours before the delivery, if possible.

However, you will get oral antibiotics if GBS causes a urinary tract infection (UTI) during your pregnancy. You will still get IV antibiotics during labor and delivery, too.

Implications for C-Sections

A positive GBS screening test does not mean you need to have a C-section. If there are no other issues or complications in your pregnancy, you should be able to deliver your child vaginally.

If you are having a planned, scheduled C-section, the results of your GBS screening are still important. You may not need treatment if your water doesn’t break and you do not go into labor before your scheduled c-section. But, if your water does break and you do go into labor early, you will receive antibiotic treatment in your IV to prevent passing the infection to your baby.


Since most women who test positive for group B strep are carriers, they do not have an infection or any symptoms. For healthy women, the chances of developing an infection from the naturally occurring bacteria are low. However, even though complications due to GBS are extremely uncommon, when untreated GBS does overgrow, it can cause issues during pregnancy and after delivery such as:

  • A urinary tract infection
  • Changes in vaginal discharge
  • An infection in the amniotic fluid (the bag of water surrounding the baby)
  • Infection of the uterus
  • Bacteria in the blood
  • An infection in the surgery site after a c-section
  • In severe cases, GBS infection can lead to preterm birth and stillbirth

GBS Infection

A group B strep infection can pass from a mother to a child during childbirth. But, while many women test positive for GBS, the chances of the baby becoming very sick from a GBS infection are low.

Because of the current guidelines for screening and treatment, only 1-2 percent of newborns become infected:

  • Without treatment, the chances of a baby getting a GBS infection are 1 in 200.
  • With treatment, the chances are 1 in 4000.

Most full-term infants whose mothers had at least four hours of antibiotic therapy during labor are healthy at birth. Premature babies, low birth weight babies, and those who have a compromised immune system are more at risk of developing an infection.

Premature infants or newborns who show signs of illness will stay in the hospital for monitoring and treatment. They will have blood work and begin antibiotics, if necessary.

Even though most babies will be healthy and serious GBS infection is not common, it can be dangerous when it does happen. Premature babies and newborns with severe GBS infections can develop medical issues such as respiratory distress, pneumonia, sepsis, and meningitis. It can lead to long-term neurological problems and even death.

A Word From Verywell

It can be scary to hear that you tested positive for group B strep, or any other issue, especially when you’re pregnant. It’s even scarier when you look it up and start to read the complications it can cause. But, remember, GBS is fairly common and found in up to 40% of pregnant women.

Your doctor and the hospital staff see it regularly, and they know what to do. Your healthcare team is your best source of information, so be sure to ask questions and follow their advice.

With treatment, the complications of GBS are low. Most newborns born to moms who test positive for GBS are healthy and go home with their mother on the scheduled day of discharge.

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Article Sources
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  1. American College of Obstetrics and Gynecology. Group B Strep and Pregnancy. Updated July 2019.

  2. Prevention of Group B Streptococcal Early-Onset Disease in Newborns. Pediatrics. 2019;144(2):e20191882. doi:10.1542/peds.2019-1882

  3. Prevention of Group B Streptococcal Early-Onset Disease in Newborns: ACOG Committee Opinion, Number 782. Obstet Gynecol. 2019;134(1):e19-e40. doi:10.1097/AOG.0000000000003334

  4. Centers for Disease Control and Prevention. Group B Strep (GBS). Updated June 25, 2019.

  5. Centers for Disease Control and Prevention. Group B Strep (GBS) Clinical Overview. Updated June 25, 2019.

  6. Melville JM, Moss TJ. The immune consequences of preterm birthFront Neurosci. 2013;7:79. doi:10.3389/fnins.2013.00079

  7. Simonsen KA, Anderson-Berry AL, Delair SF, Davies HD. Early-onset neonatal sepsisClin Microbiol Rev. 2014;27(1):21–47. doi:10.1128/CMR.00031-13

  8. Centers for Disease Control and Prevention. Group B Strep (GBS) Fast Facts. Updated June 25, 2019.

Additional Reading
  • Bienstock JL, Fox HE, Wallach EE, Johnson CT, Hallock JL. Johns Hopkins Manual of Gynecology and Obstetrics. Lippincott Williams & Wilkins; 2015 Mar 23.