What Happens during Labor and Delivery?
Carriage of GBS becomes important during labor and delivery when a woman is administered a course of IV antibiotics such as penicillin or ampicillin (clindamycin or erythromycin are usually substituted for women allergic to penicillin) every four hours.
Pregnant women who have been diagnosed as GBS-positive carriers should not be given oral antibiotics before labor because any treatment at this time will not prevent their babies from possible exposure to this infection. According to the guidelines published in August 2003 by the CDC, the only exception to this rule is when GBS is, "identified in urine during pregnancy." Group B strep found in the urine of expectant mothers should be treated at the time of discovery.
What if You Labor before Being Tested?
There is an inherent risk involved in the testing time frame. It has been widely researched and reported that cultures collected before week 35 to week 37 don't accurately predict whether a woman will have GBS at the time of delivery.
What if a woman goes into labor before the 35th week of pregnancy and hasn't been tested for GBS? If this should happen, both the American College of Obstetricians and Gynecologists (ACOG) and the CDC recommend that the mom-to-be is administered IV antibiotics at the time of labor.
"Premature babies are at a higher risk, so preterm labor is usually treated with antibiotics," explains Dr. Tharakan. When the laboring woman's contractions are stopped and a premature delivery is avoided, the antibiotic treatment is halted.
One out of every 100 to 200 babies born to women who carry GBS develop signs and symptoms of the infection. Generally, babies are exposed to the GBS bacterium during labor and delivery; however, there are several other ways that they can come in contact with it—when the mother's water breaks, when the bacteria travel up from the mother's vagina into the uterus, or swallowing/inhaling the bacteria while passing through the birth canal.