What is the goal minimum duration of antibiotic administration before delivery for GBS prophylaxis?

• A. At least 2 hours
• B. At least 6 hours
• C. At least 8 hours
• D. At least 4 hours

Answer: (D)

The aim is to lower the newborn’s risk of GBS infection by ensuring the antibiotic has time to reach protective levels in the mother's bloodstream and cross to the fetus before delivery. Four hours is the minimum window needed to achieve meaningful intrapartum prophylaxis, allowing the drug to suppress maternal carriage and reduce the chance of transmission during birth. In practice, a penicillin G loading dose is given and continued every four hours until delivery. If labor ends sooner than four hours after starting antibiotics, some protection may still be present but it’s not as robust. If the mother has a penicillin allergy, an alternative is used, but the principle of allowing enough lead time before delivery remains the same.