Third Trimester: Group B Streptococcus
Group B streptococcus (GBS) is a bacterium that is present as part of the normal flora in the vagina and gastrointestinal areas of about 25% of women. It is usually not a problem, except when it is present in the vagina during delivery. In this case, it can spread to infect the uterus, amniotic fluid, urinary tract, and any incision made during a cesarean section. At delivery, when the baby passes through the birth canal, the bacteria can be inhaled or ingested.
Infected infants may display symptoms within 6 hours of birth or as late as 2 months of age. If untreated, the baby may become septic, develop pneumonia, suffer hearing or vision loss, or develop varying degrees of physical and learning disabilities.
To best assess the risk of a pregnant woman infecting her baby at delivery, the U.S. Centers for Disease Control and Prevention recommend that all pregnant women be screened for Group B strep between 35 and 37 weeks of gestation. Specimens from the mother's vaginal and rectal areas are collected, and within 24 to 48 hours the laboratory can determine if Group B strep bacteria are present. If the bacteria are present, or if the woman goes into labor before testing can be completed, it is recommended that she receive antibiotics intravenously during labor. Treatment with oral antibiotics taken before labor has not proven to be effective in preventing Group B strep infections in the newborn.
This is different bacteria than the more commonly known Group A streptococcus that causes strep throat.