Group B strep

Also called GBS, Streptococcus agalactiae

A common, harmless bacterium in adults that occasionally causes serious infection in newborns. Antibiotics in labour prevent most of it.

What it is

A bacterium carried harmlessly in the gut or vagina by around one in four pregnant women. It causes no symptoms and is not a sexually transmitted infection.

The issue is transmission to a baby around birth. Group B strep is the commonest cause of severe infection in newborns in the UK, causing sepsis, pneumonia and meningitis. It is uncommon, affecting roughly one baby in 1,750, but it is serious: some babies die and some are left with lasting disability.

Most of it is preventable. Antibiotics given intravenously during labour, to women with recognised risk factors, substantially reduce the risk.

The UK does not routinely screen all pregnant women, unlike several other countries, and instead uses a risk-factor approach. That is contested, and a large trial has been examining it. In the meantime, carriage found incidentally, on a urine or vaginal sample taken for another reason, does count and should trigger antibiotics in labour. Women are not always told this, and it is worth checking that it is on the notes.

Testing privately is possible, using the enriched culture medium test, and is not available on the NHS in most areas.

Late-onset infection, after the first week, also occurs and is not prevented by antibiotics in labour, which is why knowing the newborn warning signs matters.

Signs you might notice

In the mother: nothing. Carriage causes no symptoms.

Risk factors meaning antibiotics in labour: group B strep found in this pregnancy; a previous baby with group B strep infection; labour before 37 weeks; waters broken more than 18 hours; or a fever in labour.

In a newborn, needing immediate assessment: grunting or noisy breathing, working hard to breathe, or breathing very fast or slow; being floppy or unresponsive; not feeding; a temperature that is high or low; being unusually irritable or unusually still; pale, blotchy or blue skin.

999 or straight to hospital for any of these in a baby, at any point in the first three months. Say group B strep if it is known about.

Trust instinct. A baby who is not right is a reason to be seen, and clinicians would far rather see a well baby.

How it can affect day-to-day life

Being told you carry it in pregnancy is frightening, and the reassurance is genuine: with antibiotics in labour, the risk to the baby is very low.

The practical failure points are administrative: the result not reaching the labour ward, antibiotics not being started early enough in labour, or a rapid labour leaving no time. Carrying a copy of the result and stating it on arrival helps.

Antibiotics need to be given at least four hours before birth for full effect, which is an argument for going in promptly once labour starts or waters break.

Carriage comes and goes, so a positive result in one pregnancy does not necessarily mean carriage in the next, but a previous infected baby does change the plan for every subsequent pregnancy.

Bereaved parents and those whose babies were harmed frequently describe not having been told group B strep existed, and that lack of information is what the charity in this field campaigns on.

Supporting someone well

Ask whether group B strep has been found at any point in the pregnancy, including on urine samples, and make sure it is written in the notes and on the front of the record.

Go into hospital promptly when labour starts or waters break, if antibiotics are planned; timing matters.

Ask for the antibiotics to be started as soon as labour is established.

Learn the newborn warning signs and act on them at any hour, in the first three months.

Say group B strep at the door if the baby becomes unwell.

Consider a private test late in pregnancy, between 35 and 37 weeks, if that is something you want; understand it is not NHS-funded in most areas.

For a previous baby affected, make sure this is flagged at booking.

Where to get help

The midwife or maternity unit during pregnancy and labour.

999 or straight to A and E for any unwell newborn.

Group B Strep Support are the specialist charity, with clear information and support for affected families.

Sands on 0808 164 3332 for bereavement support.