What is the ideal timing for GBS screening during pregnancy?

The ideal timing for Group B Streptococcus (GBS) screening during pregnancy is between 35-37 weeks of gestation. This timeframe is crucial because it allows for optimal identification of GBS colonization in expectant mothers, which is typically transient and can change throughout pregnancy. Screening too early, such as before 35 weeks, may yield inaccurate results as the mothers' microflora can shift closer to the time of delivery. This screening is vital because GBS can be passed from mother to newborn during labor and delivery, potentially leading to serious infections in the newborn.

Conducting the screening within the window of 35-37 weeks ensures that clinicians have the most relevant and effective information to decide on potential intrapartum antibiotic prophylaxis, should the mother test positive for GBS. By administering antibiotics during labor, the risks of early-onset GBS disease in the infant can be significantly reduced. Therefore, screening at this specific time frame aligns with established guidelines aimed at improving maternal and neonatal outcomes.