Group B Strep in Pregnancy

Pregnant woman holding stomach in doctor's office

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During pregnancy, you will have many prenatal tests, such as physical exams, blood work, and ultrasounds. One of these routine tests, which you'll have toward the end of pregnancy, is to screen for group B strep (GBS). Technically called group B Streptococcus, it may also be called beta strep. It may sound scary, but GBS is very common. While the bacteria can be harmful if passed on to your newborn, proper medical care can prevent transmission during childbirth.

Learn more about this test, what it means if you test positive for GBS during pregnancy, and how this common pregnancy concern is treated.

What Is Group B Strep?

Group B streptococcus, is a type of bacteria that is normally found in the body of both men and women. In women, GBS is often found in the urinary tract, the genital area, and the intestines. In adults, this infection is typically benign and rarely causes symptoms.

According to the CDC, approximately 25% of pregnant women carry group B strep in their bodies. As noted above, GBS is usually not harmful to healthy adults and pregnant women, but it can be dangerous for newborns. Babies are at the highest risk of infection during delivery.

Complications for Adults

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

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

Complications for Newborns

Group B strep infection can pass from a mother to a child during childbirth, which is called early GBS infection. Babies can also develop the disease a week or more after birth, which is called late GBS infection. Late GBS infections tend to be the less serious of the two types of GBS in newborns.

Because of the current guidelines for screening and treatment, it's rare for newborns born to carriers of GBS to become infected, particularly when proper care is received:

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

Most full-term infants whose mothers had at least four hours of antibiotic therapy during labor do not get sick from GBS. Premature babies, low birth weight babies, and those who have a compromised immune system are at higher 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.

Signs and symptoms of possible GBS infection include the following:

  • Blotches of red skin on the body
  • Cyanosis (blue tint to the skin)
  • Changes in blood pressure
  • Difficulty breathing, fast breathing, or periods of not breathing
  • Difficulty waking up from sleep
  • Fever
  • Fussiness or irritability
  • Lethargy or "limpness"
  • Moving one or more limbs less often than others
  • Poor feeding
  • Seizures or convulsions

Most babies who develop GBS recover without complications, but severe cases do occur. These babies are at risk of meningitis and inflammation of the lungs, spinal cord, or brain. Severe cases of GBS can also cause hearing or vision loss and the infection is also associated with cerebral palsy. Additionally, if there are complications from the infection, such as respiratory distress, sepsis, or pneumonia, group B strep can lead to long-term neurological problems and even death.

Misconceptions about Group B Strep

There are numerous misunderstandings about this infection. Below, we set the record straight:

  • Don't feel guilty about a positive test. You did not get it from anything you did.
  • GBS is found in the human body, most commonly the intestinal and genital tracts. In healthy individuals, it typically does not cause illness.
  • GBS is not a sexually transmitted infection, is not transmitted through sharing food or drinks, and you don't get it through surface transmission.
  • GBS is not passed through breastfeeding, so carriers can safely breastfeed their babies.
  • GBS is a different bacteria than the one that causes strep throat (group A strep).
  • In adults with advanced age and/or chronic medical conditions such as diabetes, cancer, and heart disease, GBS can infect other parts of the body (such as the lungs, brain, or blood) and make a person very sick. This is called GBS disease.
  • It is unknown (aside from during childbirth) how GBS spreads from person to person.
  • The bacteria is not always present and detectable in the body and may come and go. You may test positive in one pregnancy and negative in another.
  • You cannot give GBS to your partner or your other children.

GBS Testing

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

In the above cases, you will automatically be treated with antibiotics during labor to prevent transmission.


When someone tests positive for GBS, they will receive antibiotics in labor or after the rupture of membranes (when your water breaks).to stop the bacteria from passing to the baby during birth. Other reasons for IV antibiotics during labor include pre-term labor, your water breaking 18 hours or more before delivery, if your GBS status is unknown, or you currently have an infection (indicated by fever higher than 38 C or 100.4 F). 

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. The medications that you receive to treat GBS 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. Additionally, if you missed this prenatal appointment or do not have prenatal care, may not know your group B strep status. If your GBS status is unknown, you will receive antibiotics when you get to the hospital in labor.

Oral Antibiotics

If you are GBS positive and get an infection like a UTI during your pregnancy, you will get oral antibiotics to treat it. However, you will still need to get IV antibiotics during labor and delivery, too, as oral antibiotics don’t work to prevent transmission of the bacteria to the newborn.

Additionally, some women wonder why they don’t get a prescription for oral antibiotics when the test first comes back positive to knock out the bacteria. 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.

C-Section Not Required

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 go into labor early, you will receive antibiotic treatment in your IV to prevent passing the infection to your baby.

Coping If You Are GBS Positive

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

  • 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.
  • Let your doctor know if you develop any symptoms of a urinary tract infection.
  • 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.
  • Try not to worry—most likely, your GBS status will not impact your baby.
  • When your water breaks or you begin to feel regular contractions, call your doctor’s office and go to the hospital right away. Let the hospital staff know you tested positive for GBS as they'll ideally want to get your antibiotics started at least four hours before your child is born.

A Word From Verywell

It can be scary to hear that you tested positive for group B strep. But, remember, GBS is very common and complications for newborns are very rare. Your doctor and the hospital staff know what to do to protect your baby. Your healthcare team is your best source of information, so be sure to ask questions and follow their advice. With treatment, the vast majority of newborns born to moms who test positive for GBS are healthy and go home with their mother on the scheduled day of discharge.

9 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American College of Obstetrics and Gynecology. Group B Strep and Pregnancy.

  2. Centers for Disease Control and Prevention. Group B Strep (GBS) Clinical Overview.

  3. Centers for Disease Control and Prevention. Group B Strep (GBS) Fast Facts.

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

  5. World Health Organization (WHO). Group B Streptococcus infection causes an estimated 150,000 preventable stillbirths and infant deaths every year.

  6. 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

  7. Centers for Disease Control and Prevention. GBS: how it spreads.

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

  9. 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

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

By Donna Murray, RN, BSN
Donna Murray, RN, BSN has a Bachelor of Science in Nursing from Rutgers University and is a current member of Sigma Theta Tau, the Honor Society of Nursing.