When should universal Group B Streptococcus (GBS) screening occur?

The recommended timing for universal Group B Streptococcus (GBS) screening is between 35 to 37 weeks of gestation. This timing is critical because it allows for accurate identification of GBS carriers shortly before labor begins, which is essential for implementing appropriate prophylactic measures to prevent neonatal GBS disease. Screening too early, such as in the second trimester, could lead to false negatives as GBS colonization can change over time. Screening after delivery does not serve the purpose of preventing GBS transmission during labor and delivery. Therefore, the 35 to 37 weeks window is optimal for ensuring both the health of the newborn and effective management of potential GBS infection.