Group B Strep
What is GBS?
Group B streptococcus (GBS) is a common bacterium. Up to a third of men and women "carry" GBS in their intestines and a quarter of women carry it in their vagina. Most of us are unaware it's there, as GBS carriage causes no symptoms and can be difficult to detect. GBS is one of a number of different bacteria that normally live in our bodies and carrying it is perfectly normal. Once GBS has colonized the intestines, no antibiotics tested so far can reliably eradicate it.
What do I need to know about GBS?
Although GBS is the UK's most common cause of bacterial infection in newborn babies, this happens relatively rarely - without preventative medicine, it is estimated that roughly one in every 1,000 babies in the UK develops GBS infection: about 700 babies a year (however, recent UK research shows this figure may be a significant underestimate). Babies who develop GBS infection are usually exposed to GBS in the womb, although this can also happen during labour or passage through the birth canal, or after birth. Yet many thousands of babies are exposed to GBS with no ill effects - just why some babies are susceptible to the bacteria and develop infection while others don't is not clear. Most GBS infection in newborn babies can be prevented by giving women in known, higher-risk situations antibiotics intravenously (through a vein) from the start of labour or waters breaking until the baby is born.
Giving oral antibiotics for GBS carriage have not been shown to be effective at preventing GBS infection in babies, although if GBS is found in the urine during pregnancy this should be treated with oral antibiotics at the time of diagnosis.
Caesareans are not recommended to prevent GBS infection in babies since there are risks associated with Caesarean sections. Caesareans don't eliminate GBS infection in babies and the recommended intravenous antibiotics in labour are highly effective. Very occasionally, GBS causes infection of the waters around the baby, womb or urinary tract in pregnant women and those who have recently given birth.
Who is most at risk of GBS infection?
There are six situations where a baby is more likely to be exposed to GBS and, if susceptible, to develop GBS infection:
Risk factors for GBS infection in newborn babies
Clinical risk factors: each increases the risk at least 3 times:
1. Where labour or membrane rupture is preterm (before 37 completed weeks of pregnancy);
2. Where there is prolonged rupture of membranes (more than 18 to 24 hours before delivery);
3. Where the pregnant woman has a raised temperature during labour (37.8°C or higher).
Mothers who carry GBS during the present pregnancy:
multiplies the risk at least 4 times:
4. Where the pregnant woman has been found to carry GBS during
the present pregnancy;
5. Where the pregnant woman has GBS bacteria in her urine at any
time during the present pregnancy (this should be treated at the
time of diagnosis).
Mothers who have previously had a baby infected with GBS multiplies the risk about 10 times.
6. Where the pregnant woman has had a baby who developed a
How can most GBS infection in babies be prevented?
Giving pregnant women in the above situations intravenous antibiotics at regular intervals from the start of labour or waters breaking until delivery has been shown to be effective in stopping most GBS infection in newborn babies.
The recommended antibiotics are highly effective - if a mother known to carry GBS at delivery receives them as recommended, the risk of her baby developing GBS infection falls from around 1 in 300 to less than 1 in 6,000.
What else need I know?
GBS bacteria may be passed from the hands so everyone (including the parents), whether they carry GBS or not, should wash their hands properly and dry them carefully before handling a baby for its first 3 months.
What if it is discovered that I am carrying GBS?
You should discuss GBS with your midwife and obstetrician and agree a pregnancy and birth plan which includes strategies against GBS infection in your baby. Most GBS infection in newborn babies can be prevented: pregnancy can normally be managed so babies born to women who carry GBS are protected against GBS infection.
A woman who has had any positive test result during the current pregnancy should be offered intravenous antibiotics from the onset of labour through until delivery.
A woman who receives a negative result to the more sensitive test at 35-37 weeks of pregnancy does NOT need to be offered intravenous antibiotics in labour against GBS infection in her baby (though antibiotics may be indicated for other reasons).
A woman who has not had a result from the more sensitive test OR who has had a negative result from the less reliable HVS test during the pregnancy should be offered intravenous antibiotics from the onset of labour if one or more other risk factors is present.
This information was provided by Group B Strep Support; a national charity providing accurate and up to date information on GBS for families and health professionals. For further information visit GBSS website: www.gbss.org.uk