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What are the risks of group B streptococcus (GBS) infection during pregnancy?

Most pregnant women who carry group B streptococcus (GBS) bacteria have healthy babies.

But there's a small risk that GBS can pass to the baby during childbirth.

Sometimes GBS infection in newborn babies can cause serious complications that can be life threatening, but this is not common.

Extremely rarely, GBS infection during pregnancy can also cause miscarriage, early (premature) labour or stillbirth.

What is GBS?

GBS is one of many bacteria that can be present in our bodies. It does not usually cause any harm.

When this happens, it's called carrying GBS, or being colonised with GBS.

It's estimated about 1 pregnant woman in 5 in the UK carries GBS in their digestive system or vagina.

Around the time of labour and birth, many babies come into contact with GBS and are colonised by the bacteria.

Most are unaffected, but a small number can become infected.

Early-onset GBS infection

If a baby develops GBS infection less than 7 days after birth, it's known as early-onset GBS infection.

Most babies who become infected develop symptoms within 12 hours of birth.

Symptoms include:

  • being floppy and unresponsive
  • not feeding well
  • grunting
  • a high or low temperature
  • fast or slow heart rates
  • fast or slow breathing rates
  • irritability

What complications can GBS infection cause?

Most babies who become infected can be treated successfully and will make a full recovery.

But even with the best medical care, the infection can sometimes cause life-threatening complications and, in some cases, death.

Rarely, GBS can cause infection in the mother – for example, in the womb or urinary tract or, more seriously, an infection that spreads through the blood, causing symptoms to develop throughout the whole body (sepsis).

Preventing early-onset GBS infection

The Royal College of Obstetricians and Gynaecologists (RCOG) has published guidance for healthcare professionals on preventing early-onset GBS infection.

For more information, see Is my baby at risk of early-onset GBS infection?

If you have previously had a baby with GBS, your maternity team will either monitor the health of your newborn baby closely for at least 12 hours after birth, or treat them with antibiotics until blood tests confirm whether or not GBS is present.

Late-onset GBS infection

Late-onset GBS infection develops 7 or more days after a baby is born. This is not usually associated with pregnancy.

The baby probably became infected after the birth. For example, they may have caught the infection from someone else.

GBS infections after 3 months of age are extremely rare.

Breastfeeding does not increase the risk of GBS infection and will protect your baby against other infections.

Read the answers to more questions about pregnancy

Further information

Page last reviewed: 19 September 2018
Next review due: 19 September 2021