Group B Strep – All You Need to Know

Group B streptococcus is the most common cause of early onset infection in babies (within the first 7 days). In this country, the incidence is one in 2000 births.

1 in 4 pregnant women may have group B strep in their vagina.  This carries no health risks for the woman and has no symptoms.  Bacteria appears to come and go in a random way.  In this country pregnant women are not routinely screened for this infection during pregnancy.   This was last reviewed by a national screening committee some 4 yrs ago and it was decided that there were more disadvantages than advantages presented by routine screening.

Why don’t We have a Routine Screening Test For Group B Strep?

There is a routine screening test for pregnant women in the USA, Canada and some European Countries.  Many women in this country therefore sometimes wonder why there is no similar programme here in the UK. The problem with the screening is that in the UK the test available at most NHS hospitals only correctly identifies about 50% of women carrying GBS at the time the test is taken.  However, there is now a new PCR test available (privately) which is very accurate (90%) and can be done quickly at the onset of labour in the labour ward.  It takes 30-40 minutes to get a result.  The ECM test when done at 35-37 weeks is very good at predicting GBS carriage status for 5 weeks from doing the test.  This means that, by the time the woman goes into labour, she will know her GBS status and therefore decisions can be made about her care in labour.  This also means that women’s labours can be managed using the information from the swab – and given how hard-pressed labour wards are, those found negative can pretty confidently be encouraged to labour at home longer without the need for antibiotics than those found to carry GBS.

Although these are currently the most accurate way of identifying which babies might be at risk, neither of these tests is currently available in most obstetric units.  It is however likely that the screening policy will be reviewed in the light of these new tests and universal screening may yet be adopted.

What is clear is that certain babies are at extra risk of group B strep infection around the time of a vaginal birth.  Carrying the bacteria seems to have no particular risk for the baby if he or she is born by planned Caesarean Section.  This is not however a reason to have a planned Caesarean Section as preventative measures are highly effective.  Those babies at particular risk are those who are born to mothers who have previous babies affected by the group B strep infection.  Mothers who are currently carrying the infection in their vagina or urine will also be more at risk of passing it to their babies.  Also at risk are those delivering before 37 weeks or where the waters have been broken for more than 24 hours.  An additional risk factor is the presence of a fever of over 38 degrees during labour.

What Happens If I have Strep B?

If you are identified as being at extra risk of passing on a group B strep infection to your baby you will be advised about particular precautions that will be taken once you are in labour or once your waters have broken.  Treatment usually involves 4 hourly doses of intravenous penicillin or similar antibiotics.  Serious reactions from these drugs are extremely rare and there have been no serious reactions reported recently from this treatment.

If your labour is very rapid and there is no time to receive antibiotics then your baby will probably receive intravenous antibiotics for the first 48 hours and will be watched very carefully for any signs of infection.  Sometimes this may require you to stay in hospital a little longer than you expected, but this will be worth it.

If you have any concerns that you might be carrying group B strep you should talk to your midwife or doctor.

The Group B Strep Support Website  also has information for those affected by Group Strep B

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