Final answer:
If a pregnant woman tests positive for group B strep, it is standard to provide intravenous antibiotics during labor, often after 36 weeks of pregnancy, to prevent transmission of GBS to the infant and reduce the risk of early-onset neonatal meningitis.
Step-by-step explanation:
During pregnancy, a positive culture for group B strep is typically treated at 36 weeks, more precisely, it is treated with intravenous antibiotics during labor to prevent the transmission of the bacteria to the infant during childbirth and reduce the incidence of early onset neonatal meningitis. Group B streptococcus (GBS) can be transmitted from the mother's vagina to the infant during delivery, leading to serious infections such as meningitis, pneumonia, or sepsis. Antibiotic treatment is not initiated immediately upon detection during pregnancy because the bacteria could recolonize before delivery. However, prophylactic antibiotics are given during labor, usually after 36 weeks of pregnancy, which is critical in preventing the vertical transmission of GBS from mother to newborn, thus reducing the risk of early-onset disease in newborns.