When is a GBS screening typically performed in pregnant women?

Group B Streptococcus (GBS) screening is typically performed between 35 and 37 weeks of gestation. This timing is crucial because it allows for the identification of women who are carriers of the bacteria before they go into labor. If a woman tests positive for GBS, appropriate prophylactic antibiotics can be administered during labor to reduce the risk of transmitting the infection to the newborn, which can lead to serious complications such as sepsis or meningitis.

Screening at this stage of pregnancy balances the need for timely identification of GBS with the gestational age of the fetus, ensuring that the results are valid for the immediate perinatal period. Other times, such as earlier in the pregnancy, may not provide reliable results, as the GBS status can change later in pregnancy. Additionally, screening too late could result in missed opportunities to provide prophylactic treatment during labor, which is why the 35-37 weeks window is the standard recommendation.