Note: This is a reply to a letter by Dr Siegel that was published in the January 1999 issue of Pediatrics on pages 197-198. We regret that this reply was not published in that issue.

It was never our intent when charged with providing revised guidelines for the prevention of early-onset group B streptococcal (GBS) disease^1,2 to disregard or minimize the importance of observations by Dr Siegel and her associates.^3-5 She points out correctly that intramuscular ampicillin or penicillin administered to newborns after intrapartum chemoprophylaxis in their mothers may have contributed to their protection against early-onset GBS disease. Nevertheless, maternal intrapartum antibiotic prophylaxis alone also prevents early-onset GBS disease.^6-8 The consensus guidelines were design to intervene in the hours before delivery before fetal GBS . . . [Full Text of this Article]