Nobody likes to hear that they have some sort of obscure infection, but, as I found out from my cousin recently, this is especially true for pregnant women. We were sitting on my front porch discussing her impending due date when she blurted out she is GBS positive. I ran through my mental index of medical acronyms, but this is not one that popped up. What was GBS and why did my cousin have it? Did this warrant concern for her health or her baby? Did I need to be angry at her husband?

Group B streptococcal
bacterial colonization is relatively common among healthy women. Colonization of this bacteria occurs primarily in the intestines but can spread to the vagina, and though many carriers will test positively for the bacteria consistently, it causes no ill health effects in these carriers. A GBS positive result is not an indication of being sick, nor is it considered a sexually transmitted infection. In fact, though researchers estimate up to 50% of the population are carriers of the bacteria, yet the majority would never know if they were not tested during pregnancy. Pregnant women are routinely tested for colonization of this bacteria via swabbing of the vaginal and rectal openings. Some practitioners test during both the second and third trimesters so they will know if a woman is a carrier in the event of a premature delivery. Swabbing is performed in the course of a normal prenatal visit and the results are processed quite quickly.

GBS results are important for pregnant women because babies who are exposed to this bacteria during birth while passing through the vagina can develop a serious infection of the lungs. Women who test positive for the bacteria will need to receive intravenous antibiotics throughout the labor and delivery process to ensure the baby is protected. Generally two doses are given, separated by two to three hours. If a woman’s labor progresses very quickly and she is unable to receive both doses of the antibiotics before the baby is born, the hospital may want mother and baby to remain in the hospital for an extra day for observation as the GBS infection will be evident within the first 48 hours after birth if it is contracted.

In the event a woman goes into labor without having been tested or has had multiple inconsistent results, her practitioner may recommend she automatically receive intravenous or oral antibiotics during labor and delivery, or that she have a planned C-section. An emergency C-section may be recommended for mothers who have tested positive and are progressing through labor at a very fast rate, or have stalled in labor with ruptured membranes for more than 18 hours.

Source: Colbourn T, et al. Prenatal screening and treatment strategies to prevent group B streptococcal and other bacterial infections in early infancy, Health Technology Assessment 2007; Volume 11, Issue 29.