Group B Strep (GBS) in Pregnancy


What is GBS?


Group B Streptococcus (GBS) is a type of bacteria that live in our bodies. It is commonly found in the intestines, rectum or vagina.

If you happen to carry GBS while you’re healthy, it is not a disease and does not require treatment. About 20% of women have GBS in their vagina around the time of giving birth.

It is important to know that GBS is not a sexually transmitted disease or caused by poor hygiene.



Why does it matter to your baby?


If GBS is present during labour, there is a chance it could be passed to your baby. Most babies will remain well, but some babies do get very sick. Potential infections include pneumonia, blood poisoning or meningitis (inflammation in the brain and spinal cord). They will need nursery admission and intravenous antibiotics in the first few days of life.

GBS infections can affect up to 0.4- 4 in 1,000 babies and antibiotics given in labour can reduce this risk by 80-90%.



Which babies are at higher risk?


Risk of GBS infections may be higher for the following group of babies:

· Premature labour before 37 weeks

· Fever above 38oC in labour

· You have an infection of the placental tissues and amniotic fluid

· If your waters have been broken for more than 18 hours

· If GBS is detected in your urine during pregnancy

· A previous baby with severe GBS infection

· GBS detected on a vaginal swab performed within the last 5 weeks



What tests are available?


GBS tests are performed as part of a pregnant women’s routine antenatal tests. Dr Adeline Chan will perform a vaginal + anorectal swab when you are between 35 – 37 weeks. Studies have showed that a vaginal swab earlier in pregnancy can be inaccurate, as GBS may not be present then.

Alternatively, antibiotics may be given to women with risk factors mentioned above.



If I am GBS positive, what will that mean?


If you have tested positive for GBS or if you have the risk factors mentioned above, we will recommend you have intravenous antibiotics when your waters break or labour starts to reduce your baby’s chances of getting infected.

If you have tested positive for GBS and have a urinary tract infection during your pregnancy, it should be treated with a course of oral antibiotics.

The antibiotics given is usually penicillin. Please discuss with your obstetrician if you’re allergic to penicillin and alternatives can be provided i.e. cefazolin or clindamycin.



What if I was GBS positive in a previous pregnancy?


You may or may not have GBS again but you will be tested for GBS again as part of your routine antenatal tests. If your results are positive, you will receive antibiotics.

If you do not have GBS, treatment will not be required. However, if your previous baby has been affected by GBS infection, then GBS treatment is recommended during the delivery of your current pregnancy.

GBS tests are performed as part of a pregnant women’s routine antenatal tests. Dr Adeline Chan will perform a vaginal and anal swab when you are between 35 – 37 weeks. Studies have showed that a vaginal swab earlier in pregnancy can be inaccurate, as GBS may not be present then.


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