GBS is a bacteria found in the vagina or urinary tract. At 35 to 36 weeks of pregnancy you will be tested to see if the bacteria is present. If so IV antibiotics are administered during labor to reduce the risk of a GBS infection in the newborn. Sometimes your initial urine culture will indicate the GBS bacteria is present. In that case you will be treated with oral antibiotics at the time the urine results are noted and again during labor.