Does antibiotic treatment during labor prevent all forms of GBS disease of newborns and infants?

Unfortunately not. In some cases, the GBS bacteria has move up the birth canal and invade the amniotic fluid before labor begins. The unborn fetus may become infected and already be severely ill when born. In addition, the antibiotic treatment during labor is effective only against the early-onset form of GBS disease, that is, the illnesses that develop within 1 week of birth. Infants who exposed to and become infected with GBS after being born will not be protected by the antibiotics given during labor.