Group B Streptococcus in Pregnancy. (GBS)

Group B streptococcus (GBS), also known as group B strep, is one of many different bacteria which live inside your body.

About a third of us has GBS in our gut without even knowing it. About a quarter of women also have GBS in their vagina. If you do, you won't know it's there, as GBS doesn't have any obvious symptoms. GBS bacteria can be passed from you to your baby during labour. But this doesn't usually cause problems, and most women who carry GBS bacteria have healthy babies. It is thankfully only in rare cases that GBS can cause serious illness and, even more rarely, the loss of a newborn baby. Though it's unusual, GBS is the most common cause of severe infection in newborns, particularly in the first week after birth (early onset infection).

In the UK, about 340 babies develop a GBS infection every year.




Most babies exposed to GBS before or during birth are healthy and suffer no ill-effects. However, about one in 2,000 babies in the UK develops a GBS infection shortly after being born. Sadly, about one in 10 of these babies dies. It's a very rare event when a baby does not survive a GBS infection. It isn't clear why some babies develop an infection, while others don't. What is clear is that most GBS infections in newborn babies can be prevented. If you are in a high-risk group, you can have antibiotics via a drip that a doctor or nurse will put in a vein in your arm.

This will be either from the start of your labour or from when your waters break, whichever comes first, and until your baby is born. Caesareans are not recommended as a method of preventing GBS infection in babies. That's because having a caesarean doesn't eliminate the risk of GBS being passed on to your baby. GBS may also cause you to have a uterus infection or urinary tract infection (UTI).

What are the signs of a GBS infection in my baby?

GBS infections in babies usually happen within seven days of birth (early onset), with 90 per cent occurring within 24 hours of birth. Symptoms of a GBS infection will be recognised when your baby is born, or soon after this. Typical signs of early-onset GBS infection in babies include:

  • grunting
  • poor feeding
  • lethargy
  • irritability
  • low blood pressure
  • abnormally high or low temperature
  • abnormally high or low heart rate or breathing rate

GBS infections can also develop when a baby is seven or more days old (late-onset), though it's not common. GBS bacteria may cause bacterial meningitis, though late-onset infections tend to be less severe than early-onset infections. Most babies respond well to treatment, though meningitis can leave some babies with long-term problems. GBS infections in babies are rare after they're one month old and are virtually unheard-of once they're over three months old.