Group B Streptococcus 



Morcos Hanna; Asif Noor. 

G Group B streptococcus (GBS) is a bacterium commonly present in the lower gastrointestinal and genital tracts of up to 35% of healthy women. Although most women colonized with GBS are healthy and have no symptoms, few develop GBS disease when the bacterium invades the body. In pregnant women, this can be critical and life-threatening to both the infant and/or mother. In expecting mothers, GBS disease may cause urinary tract infections, infection of the amniotic fluid surrounding the baby, or infection of the uterus after delivery. GBS infections may even lead to preterm labor or stillbirth. 

Pregnant women who carry GBS can also pass on the bacteria to their newborns, and some of those babies may then develop early-onset disease. Although most infants infected with GBS typically present with symptoms immediately after birth, some will develop an infection, months following birth. Symptoms include but are not limited to difficulty breathing, grunting sounds, fussiness, sleepiness, poor feeding, low blood pressure, low or high temperatures, or even seizures. 

To prevent transmission of GBS from mother to infant, all pregnant women should be screened for GBS as part of their routine prenatal care late in their third trimester (usually between 35 and 37 weeks of gestation). Those who test positive for GBS will receive IV antibiotics during labor to lower the risk of transmission to the baby. Penicillin is the most common and most effective antibiotic given for GBS. However, if a patient is allergic to penicillin, other antibiotics are also available and effective. If the GBS status is unknown at delivery, certain risk factors will determine whether to use antibiotic prophylaxis. Keep in mind; some babies will still get GBS disease even with testing and prophylactic treatment. 


What is Group B Streptococcus? 

Group B streptococcus (Group B Strep or GBS) is one of many bacteria that normally live in our bodies. GBS is commonly found in the intestines, rectum, urethra, or vagina. Many people have it, and it usually causes no health concerns or symptoms. This bacterium is transient, meaning that it comes and goes from your body. It is important to note that GBS is not sexually transmitted, nor is it a sign of poor hygiene. 

Being a carrier of GBS in pregnancy is not usually harmful to you and the infection risk for women who carry GBS is low, you have a 7 per cent chance of developing an infection of the amniotic fluid, sac, and placenta during or following labour, called Chorioamnionitis. Chorioamnionitis is treated the same way as GBS, with antibiotics.  

Many babies come into contact with GBS during labour or around the time of birth. Most of these babies won’t become unwell. However, if you carry GBS, there is a small chance (about 1 in 1000) that your baby will develop GBS infection in the first week after birth.  

How is GBS detected? 

Many Australian maternity hospitals do not recommend routine testing for GBS. In some states it has been agreed that the best way to prevent the transfer of GBS form mothers to babies is to give antibiotics in labour to women with risk factors. 

If your doctor does routinely screen for GBS, or you would prefer to be screened, then this should be performed between 35 and 37 weeks gestation. The swab should be taken from the lower vagina and rectal area. 

If you receive a positive result for GBS, this result is only reliable for the next five weeks due. Screening is not perfect and may not detect GBS in approximately five per cent of women who carry GBS. 

How Does Group B Strep Affect Babies? 

When women with GBS are treated with antibiotics during labor, most of their babies do not have any problems. But some babies can become very sick from GBS.  

Babies are more likely to become infected with GBS if: 

  • they are born prematurely 
  • your waters break before 37 weeks of pregnancy 
  • you give birth more than 18 hours after your waters break 
  • you have a fever (over 38°C) while in labour 
  • you've had a previous child with severe GBS infection 
  • a urine test during pregnancy detected GBS 
  • a swab taken no more than 5 weeks earlier detected GBS

There are two types of GBS disease in babies: 

  • Early-onset disease (EOGBS) which happens during the first week of life. Babies often have symptoms within 24 hours of birth. 
  • Late-onset disease (LOGBS) which develops weeks to months after birth. This type of GBS disease is not well understood.  

What Are the Signs & Symptoms of GBS Disease? 

Newborns and infants with GBS disease might show these signs: 

  • a fever 
  • irritability or fussiness 
  • abnormal breathing sounds, such as ‘grunting’ with each breath out 
  • difficulty breathing or breathing too fast or slow 
  • sleepiness and not interested in feeding
  • vomiting 
  • having trouble keeping their temperature at the right level (being too hot or too cold) 
  • looking pale or blotchy 
  • floppy arms and legs

If you notice any of these signs in hospital or at home, it is important that you contact your healthcare provider straight away. 

Babies with GBS disease can develop serious problems, such as: 

  • Pneumonia 
  • Sepsis 
  • Meningitis (infection of the fluid and lining around the brain). Meningitis is more common with late-onset GBS disease and, in some cases, can lead to hearing loss, vision loss, learning disabilities, seizures, and even death.

How is GBS treated? 

If your GBS test is positive, or if you have risk factors as listed above, your doctor or midwife will recommend that you have intravenous antibiotics when your water breaks or when labour starts. If your waters break before your labour starts your healthcare team may recommend inducing labour. 

The antibiotic given is usually penicillin, but other options are available if you are allergic to penicillin. The antibiotics pass through the placenta and into your baby’s blood. This reduces your baby's chances of GBS.

What happens after the birth? 

All babies are monitored for the first couple of days for signs of infection. Your baby’s health team will monitor their heart rate, breathing and temperature to check they are well. The chance of your baby being infected with GBS is extremely low. 


All women ‘should’ be screened during late pregnancy but not all Australia hospitals will routinely test for GBS between 35-37 weeks unless there are elevated risk factors or a previous birth with a GBS infection. 

There remains some controversy about whether to swab and test all women for the presence of GBS in the vagina and then subsequently treating all those women during their labour. 

1 in 5 (20%) of women will test positive – this means that she has the bacteria in her body – not that she or her baby will become sick from it. If you are GBS-positive and begin to go into labor, go to the hospital rather than labouring at home. By getting IV antibiotics for at least 4 hours before delivery, you can help protect your baby against early-onset GBS disease. 

1 in 200 babies will have a severe infection. However, severe GBS infection is a very serious infection when it occurs. It is an important topic to discuss with doctor or midwife. 

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Disclaimer: This publication by Miracle Babies Foundation is intended solely for general education and assistance and it is it is not medical advice or a healthcare recommendation. It should not be used for the purpose of medical diagnosis or treatment for any individual condition. This publication has been developed by our Parent Advisory Team (all who are parents of premature and sick babies) and has been reviewed and approved by a Clinical Advisory Team. This publication is not a substitute for professional medical advice. Miracle Babies Foundation recommends that professional medical advice and services be sought out from a qualified healthcare provider familiar with your personal circumstances. To the extent permitted by law, Miracle Babies Foundation excludes and disclaims any liability of any kind (directly or indirectly arising) to any reader of this publication who acts or does not act in reliance wholly or partly on the content of this general publication. If you would like to provide any feedback on the information please email [email protected].