On the flip side, I was positive for GBS with my last pregnancy. My labour was only 3 hours long, so even if I had had the antibiotics, there wouldn't have been been enough time for it to have any affect on the baby. She is perfectly healthy.
It's just another thing creating hysteria, like listeria. Should all pregnant women be enclosed in a completely sterile room only feeding them some formula that's been developed to prevent any slight risk? That's ridiculous.
The risk is so very minimal, and monitoring a baby is far more effective than relying on antibiotics. In my opinion antibiotics poses more of a risk to my baby. It's thrown around so much and now we are getting super bugs and becoming resistant to antibiotics.
A lot of hospitals in Australia are starting to wipe the routine testing for strep b because it is just so unreliable because one week you can be positive, the next negative. It also would be ridiculous to administer antibiotics routinely to cover every woman in case she is positive at the time of birth. The risk just isn't worth it.