Group B Streptococcus (GBS) is a leading cause of sepsis in newborn babies in developed countries.
The bacteria are commonly found in the gastrointestinal tract, and colonise the vagina in 10-30% of women.
Depending on where you live, routine screening for GBS during pregnancy might or might not be recommended by maternity care providers.
Group B strep test
Recommendations for routine GBS screening are currently a matter for debate among global health experts.
This is due to differences of opinion, and evidence determining how best to identify women who need antibiotic treatment, as well as the potential negative side effects of antibiotics during pregnancy.
Leading health experts in the US and Australia recommend pregnant women between 35 and 37 weeks be routinely screened for GBS.
In Europe, some countries recommend routine screening; others take a risk-based management view. There are also countries that don’t have national guidelines.
In the UK, routine screening for GBS is not recommended.
What Is GBS?
GBS is a bacterial group commonly found in the intestinal, vaginal, and rectal areas. In healthy adults, GBS poses few problems.
However, GBS can cause a serious illness known as Group B Strep disease, which is potentially life threatening.
You can read more about this in Group B Strep During Pregnancy – What You Need To Know.
Between 10% and 30% of pregnant women will be colonised by GBS. If you are colonised by GBS, it doesn’t necessarily mean you will pass the bacteria on to your baby, but it does increase the risk.
There are two main types of GBS disease in babies:
- Early-onset GBS disease: symptoms begin within a week of birth, but almost all babies will have symptoms within 24-48 hours.
- Late-onset GBS disease: occurs within a week to a few months after birth, usually in the first month.
Most GBS infections in newborns are early onset. Research shows most babies who develop early GBS infection will be diagnosed within an hour of birth. This suggests it’s likely GBS infection begins before birth.
Infection by GBS is caused by direct transfer of the bacteria from mother to baby.
Why Doesn’t The UK Screen for GBS?
Leading health authorities in the UK, including those at the National Institute of Health and Social Care Excellence (NICE) and the National Screening Committee, do not recommend routine GBS screening for pregnant women.
These health experts have reviewed the available research and have determined there’s not enough clear evidence to demonstrate routine screening would be beneficial.
NICE is also concerned about the cost effectiveness of routine screening.
The key reasons for not offering routine GBS testing are:
- Most babies born to mothers who are GBS positive don’t become infected
- It’s unclear whether screening during pregnancy does more harm than good, as treating many women and babies would potentially prevent only a very small number of infections
- Research has shown treatment with antibiotics during labour doesn’t have any effect on neonatal deaths from infection.
- There are serious concerns about using antibiotics on this scale. Ongoing research has shown the negative effects of antibiotics on healthy bacteria in mothers and babies.
- There is an increased risk of interventions during labour, resulting in poor outcomes for mothers and babies.
- Routine screening programmes are carried out at 35-37 weeks gestation; this means mothers of preterm babies haven’t been screened.
Women who wish to be screened, or who have risk factors for GBS, are able to discuss it with their care providers, and find out how to obtain a test.
UK mothers who have fever, or prolonged rupture of membranes (longer than 18 hours), have tested positive to GBS during pregnancy, have previously had a baby with GBS, or are in preterm labour, will be treated with antibiotics specifically for GBS infection.