Group B strep: in pregnancy, symptoms, testing and treatment

Group B streptococcus, usually shortened to GBS, group B strep or strep B, is a type of bacteria. According to the NHS it is very common in both men and women, normally lives in the bottom (rectum) or vagina, and is usually harmless. Most people do not realise they have it.

Group B Strep Support, the UK charity for this condition, explains that doctors call this "carrying" or being "colonised". Being a carrier is not an illness, there are no known harmful effects of carrying it, and it is not a sign of ill health or poor hygiene.

The NHS says GBS is usually only a problem in three situations: if you are pregnant, because it could spread to your baby; in young babies, because it can make them very ill; and in people who are older or already very ill, in whom it can cause repeated or serious infections.

Carriage can also come and go. Group B Strep Support points out that carriage status can change over longer periods of time, which is one reason a result from early in pregnancy may not describe what is present at birth.

Many babies come into contact with GBS during labour or around birth, and the great majority do not become ill. The NHS says that if you have group B strep while pregnant, your baby will usually be healthy, and that there is a small risk it could spread to the baby during labour and make them ill, which happens in about 1 in 1,750 pregnancies.

RCOG gives the same figure for early-onset GBS infection, meaning infection in the first week of life, and explains that the infections it most commonly causes in newborns are sepsis (infection of the blood), pneumonia (a lung infection) and meningitis (infection of the fluid and lining around the brain). With prompt treatment most babies recover fully, but RCOG says that of babies who develop early-onset infection, 1 in 19 (5.2%) will die and, of the survivors, 1 in 14 (7.4%) will have a long-term disability.

The NHS also notes an extremely small risk of miscarriage or losing the baby. RCOG adds that, very rarely, GBS can cause infection during pregnancy and before labour, and Group B Strep Support says carrying it can sometimes lead to serious infections in pregnant women themselves, though this is also rare.

In adults who carry GBS there are usually no symptoms at all. Group B Strep Support says it knows of no convincing evidence that carrying GBS causes vaginal symptoms, and that a positive vaginal swab only means the bacteria were present when the swab was taken, not that they are the cause of any symptoms being investigated.

GBS can cause infection, though. Group B Strep Support notes that it can cause urinary tract infections, which often do have symptoms. RCOG says that if GBS is found in a urine sample you will need antibiotics straight away to treat the infection.

In babies the picture is different, and the signs matter. Group B Strep Support says most early-onset infections show symptoms within the first 12 hours after birth, so are often picked up in the maternity unit. The NHS says symptoms can sometimes appear later, up to 3 months after birth.

• being floppy or not responding normally, or being very sleepy

• grunting when breathing, or working hard to breathe when you look at the chest or tummy

• very fast or very slow breathing

• an unusually high or low temperature, or feeling hot or cold to the touch

• changes in skin colour, or blotchy skin

• not feeding well, or vomiting milk

• an unusually fast or slow heart rate

• inconsolable crying

Carrying GBS does not need treatment outside pregnancy. Group B Strep Support says that if you are not pregnant and GBS carriage is found, you do not need to do anything.

In pregnancy the aim is to protect the baby. RCOG says that if GBS is found in a vaginal or rectal swab, treating you with antibiotics before labour does not reduce the chance of the baby developing infection, so you do not need antibiotic treatment until labour starts. Then you are offered antibiotics through a drip, started as soon as possible once labour begins or your waters break, and repeated at regular intervals (usually every 4 hours) until the baby is born.

RCOG says these antibiotics reduce the risk of a baby developing GBS infection in the first week of life from around 1 in 400 to 1 in 4,000. The antibiotic is usually penicillin, and an alternative is used if you are allergic. You should still be able to move around freely and have a water birth. Side effects such as feeling sick or diarrhoea can occur, and a serious allergic reaction is rare.

The NHS says that if GBS is found, or you have had a baby affected by it before, you may be advised to talk to your midwife about your birth plan (they may recommend giving birth in hospital), to contact your midwife as soon as you go into labour or your waters break, and to stay in hospital for at least 12 hours after the birth so the baby can be monitored, though this is not always necessary.

A baby who develops symptoms is given antibiotics into a vein in hospital. The NHS says most babies with a group B strep infection make a full recovery if treated, though some develop serious problems such as sepsis or meningitis, which can cause lasting problems like hearing loss or loss of vision.

The NHS says routine testing is not currently recommended and tests are rarely done on the NHS, because GBS is very common and testing cannot predict whether a baby will get an infection. Group B Strep Support adds that the UK National Screening Committee does not recommend screening all pregnant women, partly because no test is entirely accurate and because many severely affected babies are born preterm, before the suggested testing time.

GBS is often found by chance on a swab or urine test done for another reason. If you want a test, the NHS suggests speaking to your midwife or GP about the risks and whether testing is advisable, and says you can pay for a test privately.

Which test is used matters. Group B Strep Support says many maternity units still use a standard high vaginal swab, which only finds GBS about half of the times it is present, so a negative result from that test is not reliable. A test designed to find GBS, the enriched culture medium (ECM) test, is more dependable. When done within 5 weeks of birth, a negative ECM result was 96% predictive that the woman would not be carrying GBS at birth, and a positive result of any kind is highly reliable.

RCOG says an ECM swab at 35 to 37 weeks can help you decide about antibiotics in labour: if you are still carrying GBS the risk to your baby is around 1 in 400, and if you are not it is much lower (around 1 in 5,000). If GBS was found in an earlier pregnancy and your baby was unaffected, RCOG says there is a 1 in 2 chance you will be carrying it again.

Group B Strep Support says GBS is not a sexually transmitted disease, but like many bacteria it can be passed from one person to another through direct contact such as holding hands, kissing or close physical contact. Because it is often found in the vagina and rectum, it can also be passed on during sex.

It is so widespread that carriage is considered normal. There is nothing you did to "cause" it, and it is not a sign of ill health or poor hygiene. Because skin-to-skin contact can pass it on, the charity advises that everyone, whether or not they know they carry GBS, should wash and dry their hands properly before handling a newborn baby.

A baby usually meets GBS around birth when the mother, often without knowing, is carrying the bacteria. Group B Strep Support notes that babies can also be exposed after birth from the mother or from other people, which is relevant to later-onset infection.

Doctors divide GBS infection in babies into two groups. Early-onset infection is in babies up to 7 days old and happens in around 1 in 1,750 babies in the UK and Ireland, according to Group B Strep Support. It usually appears as sepsis with pneumonia.

Late-onset infection develops in babies older than 7 days and occurs in around 1 in 2,700 babies. The charity says it is usually meningitis with sepsis, is uncommon after a baby reaches one month, and is very rare after three months. Signs are similar to early-onset infection and may include an irritable, high-pitched or whimpering cry, a blank or staring expression, a tense or bulging soft spot (fontanelle), turning away from bright light, stiff or jerking movements, and pale, blotchy skin.

Antibiotics in labour prevent most early-onset infection but have not been shown to reduce late-onset infection, so the charity stresses speedy recognition of the signs. A vaccine is in development, but Group B Strep Support says it will take many years before it is available.

The NHS says to call 999 or go to A&E if your baby has symptoms of a group B strep infection, because they may need treatment with antibiotics in hospital immediately. It advises not to drive yourself: ask someone to drive you or call 999 for an ambulance.

Group B Strep Support says to urgently contact a healthcare professional, and mention GBS, if you notice any of the signs listed above or are worried about your baby, because delay can be very serious.

During pregnancy, contact your midwife as soon as labour starts or your waters break if you know you carry GBS or have had an affected baby, so antibiotics can be started promptly.

On the NHS, GBS care is usually organised by your midwife and maternity unit. Testing is not routinely offered, but a result found for another reason is acted on: your notes are marked, and you are offered antibiotics in labour. Discuss your planned place of birth with your midwife, because RCOG notes that a drip may not always be possible at home or in some midwifery-led units.

You can pay for an ECM test privately if you would like to know your status. Group B Strep Support recommends telling your midwife or doctor the result, whether positive or negative, and explains that most women who test privately aim for 35 to 37 weeks.

Group B Strep Support, a UK charity, runs a helpline and publishes information for families, and both the NHS and RCOG point readers to its website.

The sources we read describe no home remedy for group B strep, and none is needed for carriage. The prevention RCOG describes is antibiotics through a drip in labour.

What you can do is share information: tell your midwife if you have had a positive test or a previously affected baby, make a plan for when labour starts, and know the signs of infection in a newborn.