When is it recommended to screen pregnant women for Group B Streptococcus (GBS)?

• A. During labor only if risk factors are present
• B. At 36-37 weeks gestation
• C. At 12 weeks gestation
• D. At delivery

Answer: (B)

Screening for Group B Streptococcus is done late in pregnancy to accurately identify who will be at risk at the time of delivery, so that appropriate preventive treatment can be given during labor. Performing the test around 36–37 weeks gestation hits a balance: it’s close enough to delivery that the colonization status is still relevant, but far enough in advance to arrange intrapartum antibiotics if the result is positive. If a mother tests positive, she can receive prophylactic antibiotics during labor to significantly reduce the chance of transmitting GBS to the newborn. If tested earlier, the colonization status might change before birth, making the result less reliable; testing at delivery offers no time to administer prophylaxis. While a risk-based approach during labor (only if risk factors are present) can miss some cases, universal screening at 36–37 weeks provides the most effective prevention strategy.