North American Registry of Midwives (NARM) Practice Exam

When is it standard to culture a client for GBS?

1. 28-30 weeks

2. 30-32 weeks

3. 35-37 weeks

4. 38-40 weeks

The correct answer is: 35-37 weeks

Culturing a client for Group B Streptococcus (GBS) is standardized between 35 and 37 weeks of gestation. This timing is crucial because it allows for the identification of carriers of GBS close to the time of delivery, which is important for deciding whether to implement prophylactic antibiotic treatment during labor. The reason for culturing during this window is that it reflects the GBS status at the time of labor, considering that a woman may test negative earlier in pregnancy but may later become a carrier as she approaches her due date. Testing before 35 weeks can yield results that may not accurately represent a woman's GBS status at the time of delivery, while testing after 37 weeks may pose risks if the baby is born earlier than anticipated. Thus, culturing between 35 and 37 weeks aligns with best practices for maternal-fetal care and aims to reduce the risk of early-onset GBS infections in newborns.