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Group B Strep (GBS) and Homebirth

Group B Strep (GBS)

25% of women are thought to carry GBS.

The incidence of early onset GBS (less than 7 days old) is 0.5/1000 births (1:2000)

Advice is often to offer all women known to carry GBS prophylactic antibiotics in labour.

Use of the acronym B.R.A.I.N can help with decision making on many issues affecting your pregnancy:=20

B     Benefits

R     Risks

A     Alternatives

I       Intuition

N     Nothing

Benefits

• The use of antibiotics directly into a vein during labour is thought to reduce the incidence of the baby having a GBS infection by 65-80%. GBS infection in newborn babies has a mortality rate of 5.7% in babies born after 37 weeks of pregnancy.[1]
• For every 1000 women treated with antibiotics, 1.4 cases of GBS infection is prevented. [1]

Risks

• Hospital birth increases the risk of your baby contracting an infection (thought to be approx double).
• Hospital birth increases the risks of procedures which are thought to increase the risk of transmission of GBS to your baby such as artificial rupture of the baby's waters and more frequent vaginal examinations.
• The risk of a woman having an anaphylactic shock after antibiotics is 1:10,000 with a 1:10 mortality rate  [1]
• Sntibiotics need to be given at least four hours prior to birth to have a good impact on reducing the transmission rate to the baby. Women are therefore admitted into hospital as soon as possible in their labour (particularly if this is your second or subsequent baby). Admission to hospital at an early stage of labour has been shown to increase the risk of interventions2, increase difficult births2, increase the risk of caesarean2, and increase the chances of dissatisfaction with your birth experience.

Alternatives

Some women with GBS infection choose to only have antibiotics if they also have one of the clinical factors noted below. This results in 15% of women who know they carry the GBS bacteria having antibiotics and reduces the incidence of GBS by 51%. 1

The risk of passing GBS infection to your baby is increased if you have any of the following clinical factors. Having more than one clinical risk factor is thought to increase the risk of transmission. The need to treat (NTT) with antibiotics rate to prevent one case of GBS infection in one baby is given in brackets, where available.

1.   Previous baby infected with GBS

2.   GBS found in your urine as this increases the chance of your baby becoming infected to around 8%. If you have not had your urine tested please ask your midwife to do so.

3.   Premature labour less than 35 week (NTT 357 women to prevent one baby having GBS infection1)

4.   premature labour, between 35-37 weeks (NTT 500 women to prevent one baby having GBS infection1)

5.   baby's waters have gone for more than 18 hours before the birth (NTT 595 women to prevent one baby having GBS infection1)

6.   raised temperature in labour (NTT 208 women in labour to prevent one baby having GBS infection1)

Having your baby at home means you cannot have antibiotics in labour but in low risk women has the following advantages2:

1.   reduced incidence of medical interventions

2.   reduced incidence of low apgar scores

3.   reduced newborn breathing problems

4.   reduced birth trauma for babies

Intuition

What is your gut feeling? What do you think is best for you and your baby? Where do you think is the best place for you to labour? Only the pregnant mum can answer these questions.

Nothing

There may not be a period of four hours recommended from some risk factors appearing (eg a temperature in labour), administering antibiotics and the birth of your baby. For a pregnancy with no additional risk factors for GBS you could have your baby at home or in hospital with no antibiotics in labour accepting that it is thought you need to give antibiotics to at least 70001 GBS carrying women to prevent one baby from dying from GBS.

References obtained from:

1. Royal College of Obstetricians and Gynaecologist (2003) 'Prevention of Early onset Neonatal Group B Streptococcal Disease' Guideline number 36.

2. Enkin et al (2000) 'A guide to effective care in pregnancy and childbirth' Oxford University Press