Group B Streptococcus Prevention

Preventing Group B Streptococcus (GBS) Infection in Newborn Babies


Group B streptococcus (GBS) is one of many common bacteria (not virus) that normally lives in our bodies, including in the vagina and rectum, and usually causes no harm. GBS can be passed on from a mother to her baby. If this happens, it can occasionally cause severe illness in newborn babies. This is known as early onset neonatal GBS infection.

GBS carriage is routinely screened for between 34 – 36 weeks of pregnancy at Primavera Medical Centre. The most sensitive method of detection requires swabs from the vagina and rectum that are cultured in the laboratory in a special solution. It is important to be aware that a negative swab test does not guarantee that you are not a carrier of GBS. If there is a concern that a baby has GBS infection after birth, you will be offered treatment for your baby and testing to confirm if  GBS is the cause of the infection. 

Information for you

The risk of GBS being passed from a mother to a baby is highest during labour or at the time of the birth. If GBS is found in your vagina when you are pregnant, or if you have had a baby with neonatal GBS, you will be offered antibiotics during your labour. Your baby will also be screening for GBS after birth. If your baby develops early onset neonatal GBS, he or she should be treated with antibiotics. It is recommended that you breastfeed your new baby in the usual way. Breastfeeding has not been demonstrated to increase the risk of GBS and will protect your baby against other infections.

What could it mean for my baby?

About a quarter of pregnant women in the UK carry GBS in their vagina. Many babies therefore come into contact with GBS during labour or during birth, and GBS will colonise some of them. The vast majority of babies are not harmed by contact with GBS at birth. A small number of babies, however, develop GBS infection and may become seriously ill. Most babies who are infected show symptoms within 12 hours of birth. They may be floppy and unresponsive and may not feed well. Other symptoms may include grunting, high or low temperature, fast or slow heart rates, fast or slow breathing rates, irritability, low blood pressure and low blood sugar. Around one baby dies out of every ten who are diagnosed. Although it is rare, GBS is the most common cause of life-threatening infection in babies during the first week after birth.

For a few babies who become ill but who have already had antibiotics, the doctors may suspect the illness is due to GBS infection although it is not possible to confirm this diagnosis as the antibiotics will have already killed the bacteria. If there seems to be a higher risk of your baby being infected with GBS or if you have had a previous baby with GBS infection, you should be offered antibiotics during labour to reduce the chances of your baby developing the infection. Babies who show signs of GBS infection need to be treated with antibiotics to get well.

What can help reduce the risk of GBS?

In some circumstances antibiotics can help to reduce the risk of a baby developing GBS and so you may be offered antibiotics during labour if:

● GBS has been found in your urine in your current pregnancy

● GBS has been found on swabs from your vagina and/or rectum

● you have previously had a baby with GBS infection

● you are at higher risk of passing on GBS to your baby. This may be because:

  • you have a high temperature during labour
  • you go into labour prematurely (prior to 37 completed weeks of pregnancy)
  • you give birth more than 18 hours after your waters have broken.


Your doctor will discuss the option of antibiotic treatment during labour. Penicillin is normally given; if you are allergic to penicillin, you will be offered an appropriate alternative. If your doctor thinks you may have an infection but is not sure of the cause, you should be offered antibiotics that will treat a wide range of infections including GBS.

Usually antibiotics are not necessary if:

● GBS was detected in your vagina in a previous pregnancy and the baby was not affected and you are GBS negative now.

● during pregnancy, unless you have a symptomatic infection (for example, a urine infection which needs immediate treatment) though you may require antibiotics in labour.

● if you have a planned caesarean section before you go into labour and before your waters break.

The reason why antibiotics are not usually needed in these situations is that the risk of your baby becoming infected with GBS is so low and because antibiotics do not reduce your chances of carrying GBS at the time of the birth.


 What will my treatment involve?

If you need antibiotics during your labour, it is best if you can start them as soon as possible after your labour starts. This will be given through a vein (intravenously). You should be offered further doses as necessary until the birth. If you need antibiotics during labour there may be concern about the risk of infection for your baby if for some reason you were not able to receive them, or if you delivered very soon after receiving them. The best approach in these circumstances is not clear. The options of monitoring the health of your baby, or of treating him or her with penicillin, should be discussed between you and the medical staff taking account of the potential risks and benefits of each approach.

 What treatment is available for my baby?

Babies with any signs of GBS infection, for example, if the newborn baby is floppy and unresponsive and does not feed well, should be treated with antibiotics as soon as possible. If you have had a previous baby with GBS, your healthcare team should either monitor the health of your newborn baby closely for at least 12 hours after birth, or treat him or her with penicillin until blood tests confirm whether or not GBS is present.  Babies who show no signs of GBS and who are well do not routinely receive antibiotics or tests for GBS. More research is needed before we can be sure about the best way to identify and treat babies who were at ‘higher risk’ of GBS during labour and who appear healthy after birth. Your doctor will keep you informed about the need to test and treat your baby for GBS after birth.


 Are there any risks with antibiotics?

Some women have a specific allergy to antibiotics. Some women may experience temporary side effects such as diarrhea or nausea. However, for most women antibiotics are safe. Your doctor should discuss the benefits and risks of taking antibiotics during labour for you as an individual. It is thought that babies exposed to antibiotics very early in their lives may have a higher than normal risk of asthma and/or other allergies later in life.

What might happen without treatment?

If your doctor recommends that you take antibiotics because of risk factors such as a high temperature in labour, and you choose not to, your baby may be at higher risk of GBS infection. If your baby has GBS infection and is not treated with antibiotics, he or she is likely to become seriously ill and may die.

Is there anything else I should know?

● No screening test is entirely accurate. A screening test for GBS carriage could give a falsely negative result. In other words, a woman would be given a negative result when in fact she carried GBS in her vagina.

● No treatment can be guaranteed to work all the time for everyone. Even with antibiotic treatment in labour, some babies still develop GBS infection.

● You have the right to be fully informed about your health care and to make decisions about it. Your healthcare team should respect these decisions.