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 between 2 and 4 women in every 10 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. Most are unaffected, but a small number can become infected and very unwell.
Early-onset GBS infection
If a baby develops GBS infection in the first week after birth, it's known as early-onset GBS infection.
- being floppy and unresponsive
- grunting when breathing, or working hard to breathe when you look at their chest or tummy
- a high or low temperature
- very fast or slow heart rate
- very fast or slow breathing
- changes in their skin colour, including blotchy skin
- not feeding well or vomiting milk
- crying and unable to settle
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, such as sepsis or meningitis.
Rarely, GBS can cause infection in the mother. For example, in the womb or urinary tract or, more seriously, sepsis.
Preventing early-onset GBS infection
If you have GBS, or you've had a baby who's been affected by it before, you should be offered antibiotics during labour to reduce the risk of your baby getting ill.
If there's a chance your new baby could have GBS, you might be advised to stay in hospital for at least 12 hours after the birth so they can be checked regularly for signs of infection.
For more information, see Is my baby at risk of early-onset GBS infection?
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.
The symptoms of late-onset GBS are the same as early-onset GBS. Call 999 or take your baby to A&E if they have symptoms of GBS.
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.