Group B Streptococcus (GBS) is one of the many bacteria that normally live in our bodies, including in the vagina, and the rectum, and usually causes no harm. If GBS is passed on from mother to baby at birth then this can occasionally cause serious illness in the newborn baby, such as a pneumonia or meningitis.
15 – 20% of pregnant women are colonised with GBS. To detect GBS a simple vaginal +/- rectal swab is done between 35-37 weeks of pregnancy. If the swab is positive for GBS, the recommendation is for the mother to be given antibiotics once labour is established or the membranes have ruptured. Penicillin is the antibiotic of choice and it is given every 4 hours intravenously using a small cannula. An alternative antibiotic is used for those allergic to penicillin. There are no benefits of taking antibiotics before labour begins.
Women found to be GBS positive at earlier gestations are treated in the same way. There is no benefit in repeating the swab later in the pregnancy.
Babies of GBS positive mothers will require observations ie. temperature, heart rate and respiratory rate before each feed for the first 24 hours. No antibiotics are usually prescribed for babies unless they are unwell.